[ltt-dev] Liblttd patch

Mathieu Desnoyers compudj at krystal.dyndns.org
Fri Mar 26 16:00:50 EDT 2010


* Mathieu Desnoyers (compudj at krystal.dyndns.org) wrote:
> * Mathieu Desnoyers (compudj at krystal.dyndns.org) wrote:
> > * Michael Sills Lavoie (michael.sills-lavoie at polymtl.ca) wrote:
> > > Hey,
> > > 
> > > Here is the completed version of the new lttd and liblttd. We splitted the
> > > work in 3 parts.
> > > 
> > > 1) Move the code from lttd to liblttd and adapt everything so it works
> > > 2) Adds the multiple instances feature
> > > 3) Create utility methods in the library to support local write to disk
> > > 
> > > We have done the last patch to make it possible for other programs to write
> > > traces to disk without creating a new process (lttd). This way, we can share
> > > the callbacks to write to the disk with other programs.
> > > 
> > > What do you think about it?
> > 
> > I am merging these patches, thanks ! (will also merge the following fix
> > you sent).
> > 
> > I will rename the "utility" library in a subsequent patch though, as
> > "local" does not seem to be appropriate here. I propose to call that
> > "vfswrite".
> 
> finally I'll just use the "vfs" suffix.
> 
> I will also change the liblttd* license to LGPLv2.1 (unless you have any
> objection).

It's now available in ltt-control 0.81. Please see commit

8ba26eaefd4104c2951d4a29bec7ddd2059bbeff

for the cleanups and error handling fixes I added.

Thanks,

Mathieu

> 
> Thanks,
> 
> Mathieu
> 
> > 
> > Thanks,
> > 
> > Mathieu
> > 
> > > 
> > > Thanks
> > > 
> > > Michael and Oumarou
> > > 
> > > 2010/2/16 Mathieu Desnoyers <compudj at krystal.dyndns.org>
> > > 
> > > > * Michael Sills Lavoie (michael.sills-lavoie at polymtl.ca) wrote:
> > > > > Hey,
> > > > >
> > > > > This is a working implementation of the new liblttd and lttd. This is
> > > > only a
> > > > > work in progress because we don't have the possibility to create multiple
> > > > > instances of the "daemon" yet.
> > > > >
> > > > > You can apply the patch with : git apply liblttd.patch in the ltt-control
> > > > > root directory.
> > > > >
> > > > > What do you think about it ?
> > > >
> > > >
> > > > A few things: please take the habit of writing your comments in english
> > > > so everyone on the mailing list can parse them ;)
> > > >
> > > > You should probably review the kernel doc coding styles for the function
> > > > comments.
> > > >
> > > > Besides that, things seems to be generally on the right track.
> > > >
> > > > You should probably submit these changes in two patches:
> > > >
> > > > - first, just move the code from lttd to liblttd and adapt everything so
> > > >  it works (more or less this patch).
> > > > - second, a patch that adds the multiple instances feature.
> > > >
> > > > Thanks,
> > > >
> > > > Mathieu
> > > >
> > > > >
> > > > > Michael
> > > >
> > > > > diff --git a/Makefile.am b/Makefile.am
> > > > > index 8f9974d..06500fd 100644
> > > > > --- a/Makefile.am
> > > > > +++ b/Makefile.am
> > > > > @@ -1,2 +1,2 @@
> > > > > -SUBDIRS = liblttctl lttctl lttd specs
> > > > > +SUBDIRS = liblttctl lttctl liblttd lttd specs
> > > > >
> > > > > diff --git a/configure.in b/configure.in
> > > > > index d67e7d4..a992cd8 100644
> > > > > --- a/configure.in
> > > > > +++ b/configure.in
> > > > > @@ -76,8 +76,10 @@ DEFAULT_INCLUDES="-I\$(top_srcdir) -I\$(top_builddir)"
> > > > >  #AC_SUBST(CPPFLAGS)
> > > > >
> > > > >  lttctlincludedir="${includedir}/liblttctl"
> > > > > +liblttdincludedir="${includedir}/liblttd"
> > > > >
> > > > >  AC_SUBST(lttctlincludedir)
> > > > > +AC_SUBST(liblttdincludedir)
> > > > >  AC_SUBST(UTIL_LIBS)
> > > > >  AC_SUBST(THREAD_LIBS)
> > > > >  AC_SUBST(DEFAULT_INCLUDES)
> > > > > @@ -85,6 +87,7 @@ AC_SUBST(DEFAULT_INCLUDES)
> > > > >  AC_CONFIG_FILES([Makefile
> > > > >       liblttctl/Makefile
> > > > >       lttctl/Makefile
> > > > > +     liblttd/Makefile
> > > > >       lttd/Makefile
> > > > >       specs/Makefile])
> > > > >  AC_OUTPUT
> > > > > diff --git a/liblttd/Makefile.am b/liblttd/Makefile.am
> > > > > new file mode 100644
> > > > > index 0000000..3c1eeda
> > > > > --- /dev/null
> > > > > +++ b/liblttd/Makefile.am
> > > > > @@ -0,0 +1,7 @@
> > > > > +
> > > > > +
> > > > > +lib_LTLIBRARIES = liblttd.la
> > > > > +liblttd_la_SOURCES = liblttd.c
> > > > > +
> > > > > +liblttdinclude_HEADERS = \
> > > > > +     liblttd.h
> > > > > diff --git a/liblttd/liblttd.c b/liblttd/liblttd.c
> > > > > new file mode 100644
> > > > > index 0000000..941ca87
> > > > > --- /dev/null
> > > > > +++ b/liblttd/liblttd.c
> > > > > @@ -0,0 +1,754 @@
> > > > > +/* lttd
> > > > > + *
> > > > > + * Linux Trace Toolkit Daemon
> > > > > + *
> > > > > + * This is a simple daemon that reads a few relay+debugfs channels and
> > > > save
> > > > > + * them in a trace.
> > > > > + *
> > > > > + * CPU hot-plugging is supported using inotify.
> > > > > + *
> > > > > + * Copyright 2005 -
> > > > > + *   Mathieu Desnoyers <mathieu.desnoyers at polymtl.ca>
> > > > > + */
> > > > > +
> > > > > +#ifdef HAVE_CONFIG_H
> > > > > +#include <config.h>
> > > > > +#endif
> > > > > +
> > > > > +#include "liblttd.h"
> > > > > +
> > > > > +#define _REENTRANT
> > > > > +#define _GNU_SOURCE
> > > > > +#include <features.h>
> > > > > +#include <stdio.h>
> > > > > +#include <unistd.h>
> > > > > +#include <errno.h>
> > > > > +#include <sys/types.h>
> > > > > +#include <stdlib.h>
> > > > > +#include <dirent.h>
> > > > > +#include <string.h>
> > > > > +#include <fcntl.h>
> > > > > +#include <sys/stat.h>
> > > > > +#include <sys/poll.h>
> > > > > +#include <sys/mman.h>
> > > > > +#include <sys/syscall.h>
> > > > > +#include <unistd.h>
> > > > > +#include <asm/ioctls.h>
> > > > > +
> > > > > +#include <linux/version.h>
> > > > > +
> > > > > +/* Relayfs IOCTL */
> > > > > +#include <asm/ioctl.h>
> > > > > +#include <asm/types.h>
> > > > > +
> > > > > +/* Get the next sub buffer that can be read. */
> > > > > +#define RELAY_GET_SB         _IOR(0xF5, 0x00,__u32)
> > > > > +/* Release the oldest reserved (by "get") sub buffer. */
> > > > > +#define RELAY_PUT_SB         _IOW(0xF5, 0x01,__u32)
> > > > > +/* returns the number of sub buffers in the per cpu channel. */
> > > > > +#define RELAY_GET_N_SB               _IOR(0xF5, 0x02,__u32)
> > > > > +/* returns the size of the current sub buffer. */
> > > > > +#define RELAY_GET_SB_SIZE    _IOR(0xF5, 0x03, __u32)
> > > > > +/* returns the size of data to consume in the current sub-buffer. */
> > > > > +#define RELAY_GET_MAX_SB_SIZE        _IOR(0xF5, 0x04, __u32)
> > > > > +
> > > > > +
> > > > > +#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,14)
> > > > > +#include <sys/inotify.h>
> > > > > +
> > > > > +#define HAS_INOTIFY
> > > > > +#else
> > > > > +static inline int inotify_init (void)
> > > > > +{
> > > > > +     return -1;
> > > > > +}
> > > > > +
> > > > > +static inline int inotify_add_watch (int fd, const char *name, __u32
> > > > mask)
> > > > > +{
> > > > > +     return 0;
> > > > > +}
> > > > > +
> > > > > +static inline int inotify_rm_watch (int fd, __u32 wd)
> > > > > +{
> > > > > +     return 0;
> > > > > +}
> > > > > +#undef HAS_INOTIFY
> > > > > +#endif
> > > > > +
> > > > > +/* !modif! Enlever, seulement utilisé pendant l'implémentation*/
> > > > > +struct liblttd_callbacks *callbacks;
> > > > > +
> > > > > +struct channel_trace_fd {
> > > > > +     struct fd_pair *pair;
> > > > > +     int num_pairs;
> > > > > +};
> > > > > +
> > > > > +/* !modif! Modifier pour pas utiliser le chemin de la trace*/
> > > > > +struct inotify_watch {
> > > > > +     int wd;
> > > > > +     char path_channel[PATH_MAX];
> > > > > +     char *base_path_channel;
> > > > > +};
> > > > > +
> > > > > +struct inotify_watch_array {
> > > > > +     struct inotify_watch *elem;
> > > > > +     int num;
> > > > > +};
> > > > > +
> > > > > +struct channel_trace_fd fd_pairs = { NULL, 0 };
> > > > > +int inotify_fd = -1;
> > > > > +struct inotify_watch_array inotify_watch_array = { NULL, 0 };
> > > > > +
> > > > > +/* protects fd_pairs and inotify_watch_array */
> > > > > +pthread_rwlock_t fd_pairs_lock = PTHREAD_RWLOCK_INITIALIZER;
> > > > > +
> > > > > +/* !modif! Mettre dans une structure s'il faut avoir plus d'une
> > > > instance*/
> > > > > +static char          *channel_name = NULL;
> > > > > +static unsigned long num_threads = 1;
> > > > > +volatile static int  quit_program = 0;       /* For signal handler */
> > > > > +static int           dump_flight_only = 0;
> > > > > +static int           dump_normal_only = 0;
> > > > > +static int           verbose_mode = 0;
> > > > > +
> > > > > +#define printf_verbose(fmt, args...) \
> > > > > +  do {                               \
> > > > > +    if (verbose_mode)                \
> > > > > +      printf(fmt, ##args);           \
> > > > > +  } while (0)
> > > > > +
> > > > > +
> > > > > +int open_buffer_file(char *filename, char *path_channel,
> > > > > +     char *base_path_channel, struct channel_trace_fd *fd_pairs)
> > > > > +{
> > > > > +     int open_ret = 0;
> > > > > +     int ret = 0;
> > > > > +
> > > > > +     if(strncmp(filename, "flight-", sizeof("flight-")-1) != 0) {
> > > > > +             if(dump_flight_only) {
> > > > > +                     printf_verbose("Skipping normal channel %s\n",
> > > > > +                             path_channel);
> > > > > +                     return 0;
> > > > > +             }
> > > > > +     } else {
> > > > > +             if(dump_normal_only) {
> > > > > +                     printf_verbose("Skipping flight channel %s\n",
> > > > > +                             path_channel);
> > > > > +                     return 0;
> > > > > +             }
> > > > > +     }
> > > > > +     printf_verbose("Opening file.\n");
> > > > > +
> > > > > +     fd_pairs->pair = realloc(fd_pairs->pair,
> > > > > +                     ++fd_pairs->num_pairs * sizeof(struct fd_pair));
> > > > > +
> > > > > +     /* Open the channel in read mode */
> > > > > +     fd_pairs->pair[fd_pairs->num_pairs-1].channel =
> > > > > +             open(path_channel, O_RDONLY | O_NONBLOCK);
> > > > > +     if(fd_pairs->pair[fd_pairs->num_pairs-1].channel == -1) {
> > > > > +             perror(path_channel);
> > > > > +             fd_pairs->num_pairs--;
> > > > > +             return 0;       /* continue */
> > > > > +     }
> > > > > +
> > > > > +     /*!callback! Ajouter un callback pour l'ouverture.*/
> > > > > +     if(callbacks->on_open_channel) ret = callbacks->on_open_channel(
> > > > > +                     callbacks, &fd_pairs->pair[fd_pairs->num_pairs-1],
> > > > > +                     base_path_channel);
> > > > > +
> > > > > +     if(ret != 0) {
> > > > > +             open_ret = -1;
> > > > > +             close(fd_pairs->pair[fd_pairs->num_pairs-1].channel);
> > > > > +             fd_pairs->num_pairs--;
> > > > > +             goto end;
> > > > > +     }
> > > > > +
> > > > > +end:
> > > > > +     return open_ret;
> > > > > +}
> > > > > +
> > > > > +int open_channel_trace_pairs(char *subchannel_name,
> > > > > +             char *base_subchannel_name,
> > > > > +             struct channel_trace_fd *fd_pairs, int *inotify_fd,
> > > > > +             struct inotify_watch_array *iwatch_array)
> > > > > +{
> > > > > +     DIR *channel_dir = opendir(subchannel_name);
> > > > > +     struct dirent *entry;
> > > > > +     struct stat stat_buf;
> > > > > +     int ret;
> > > > > +     char path_channel[PATH_MAX];
> > > > > +     int path_channel_len;
> > > > > +     char *path_channel_ptr;
> > > > > +     char *base_subchannel_ptr;
> > > > > +
> > > > > +     int open_ret = 0;
> > > > > +
> > > > > +     if(channel_dir == NULL) {
> > > > > +             perror(subchannel_name);
> > > > > +             open_ret = ENOENT;
> > > > > +             goto end;
> > > > > +     }
> > > > > +
> > > > > +     printf_verbose("Calling on new channels folder");
> > > > > +     if(callbacks->on_new_channels_folder) ret = callbacks->
> > > > > +                     on_new_channels_folder(callbacks,
> > > > > +                     base_subchannel_name);
> > > > > +     if(ret == -1) {
> > > > > +             open_ret = -1;
> > > > > +             goto end;
> > > > > +     }
> > > > > +
> > > > > +     strncpy(path_channel, subchannel_name, PATH_MAX-1);
> > > > > +     path_channel_len = strlen(path_channel);
> > > > > +     path_channel[path_channel_len] = '/';
> > > > > +     path_channel_len++;
> > > > > +     path_channel_ptr = path_channel + path_channel_len;
> > > > > +     base_subchannel_ptr = path_channel +
> > > > > +             (base_subchannel_name - subchannel_name);
> > > > > +
> > > > > +#ifdef HAS_INOTIFY
> > > > > +     iwatch_array->elem = realloc(iwatch_array->elem,
> > > > > +             ++iwatch_array->num * sizeof(struct inotify_watch));
> > > > > +
> > > > > +     printf_verbose("Adding inotify for channel %s\n", path_channel);
> > > > > +     iwatch_array->elem[iwatch_array->num-1].wd =
> > > > inotify_add_watch(*inotify_fd, path_channel, IN_CREATE);
> > > > > +     strcpy(iwatch_array->elem[iwatch_array->num-1].path_channel,
> > > > path_channel);
> > > > > +     iwatch_array->elem[iwatch_array->num-1].base_path_channel =
> > > > > +             iwatch_array->elem[iwatch_array->num-1].path_channel +
> > > > > +             (base_subchannel_name - subchannel_name);
> > > > > +     printf_verbose("Added inotify for channel %s, wd %u\n",
> > > > > +             iwatch_array->elem[iwatch_array->num-1].path_channel,
> > > > > +             iwatch_array->elem[iwatch_array->num-1].wd);
> > > > > +#endif
> > > > > +
> > > > > +     while((entry = readdir(channel_dir)) != NULL) {
> > > > > +
> > > > > +             if(entry->d_name[0] == '.') continue;
> > > > > +
> > > > > +             strncpy(path_channel_ptr, entry->d_name, PATH_MAX -
> > > > path_channel_len);
> > > > > +
> > > > > +             ret = stat(path_channel, &stat_buf);
> > > > > +             if(ret == -1) {
> > > > > +                     perror(path_channel);
> > > > > +                     continue;
> > > > > +             }
> > > > > +
> > > > > +             printf_verbose("Channel file : %s\n", path_channel);
> > > > > +
> > > > > +             if(S_ISDIR(stat_buf.st_mode)) {
> > > > > +
> > > > > +                     printf_verbose("Entering channel
> > > > subdirectory...\n");
> > > > > +                     ret = open_channel_trace_pairs(path_channel,
> > > > base_subchannel_ptr, fd_pairs,
> > > > > +                             inotify_fd, iwatch_array);
> > > > > +                     if(ret < 0) continue;
> > > > > +             } else if(S_ISREG(stat_buf.st_mode)) {
> > > > > +                     open_ret = open_buffer_file(entry->d_name,
> > > > path_channel, base_subchannel_ptr,
> > > > > +                             fd_pairs);
> > > > > +                     if(open_ret)
> > > > > +                             goto end;
> > > > > +             }
> > > > > +     }
> > > > > +
> > > > > +end:
> > > > > +     closedir(channel_dir);
> > > > > +
> > > > > +     return open_ret;
> > > > > +}
> > > > > +
> > > > > +
> > > > > +int read_subbuffer(struct fd_pair *pair)
> > > > > +{
> > > > > +     unsigned int consumed_old, len;
> > > > > +     int err;
> > > > > +     long ret;
> > > > > +     off_t offset;
> > > > > +
> > > > > +
> > > > > +     err = ioctl(pair->channel, RELAY_GET_SB, &consumed_old);
> > > > > +     printf_verbose("cookie : %u\n", consumed_old);
> > > > > +     if(err != 0) {
> > > > > +             ret = errno;
> > > > > +             perror("Reserving sub buffer failed (everything is normal,
> > > > it is due to concurrency)");
> > > > > +             goto get_error;
> > > > > +     }
> > > > > +
> > > > > +     err = ioctl(pair->channel, RELAY_GET_SB_SIZE, &len);
> > > > > +     if(err != 0) {
> > > > > +             ret = errno;
> > > > > +             perror("Getting sub-buffer len failed.");
> > > > > +             goto get_error;
> > > > > +     }
> > > > > +
> > > > > +     if(callbacks->on_read_subbuffer) ret =
> > > > callbacks->on_read_subbuffer(
> > > > > +             callbacks, pair, len);
> > > > > +
> > > > > +write_error:
> > > > > +     ret = 0;
> > > > > +     err = ioctl(pair->channel, RELAY_PUT_SB, &consumed_old);
> > > > > +     if(err != 0) {
> > > > > +             ret = errno;
> > > > > +             if(errno == EFAULT) {
> > > > > +                     perror("Error in unreserving sub buffer\n");
> > > > > +             } else if(errno == EIO) {
> > > > > +                     /* Should never happen with newer LTTng versions */
> > > > > +                     perror("Reader has been pushed by the writer, last
> > > > sub-buffer corrupted.");
> > > > > +             }
> > > > > +             goto get_error;
> > > > > +     }
> > > > > +
> > > > > +get_error:
> > > > > +     return ret;
> > > > > +}
> > > > > +
> > > > > +
> > > > > +int map_channels(struct channel_trace_fd *fd_pairs,
> > > > > +     int idx_begin, int idx_end)
> > > > > +{
> > > > > +     int i,j;
> > > > > +     int ret=0;
> > > > > +
> > > > > +     if(fd_pairs->num_pairs <= 0) {
> > > > > +             printf("No channel to read\n");
> > > > > +             goto end;
> > > > > +     }
> > > > > +
> > > > > +     /* Get the subbuf sizes and number */
> > > > > +
> > > > > +     for(i=idx_begin;i<idx_end;i++) {
> > > > > +             struct fd_pair *pair = &fd_pairs->pair[i];
> > > > > +
> > > > > +             ret = ioctl(pair->channel, RELAY_GET_N_SB, &pair->n_sb);
> > > > > +             if(ret != 0) {
> > > > > +                     perror("Error in getting the number of
> > > > sub-buffers");
> > > > > +                     goto end;
> > > > > +             }
> > > > > +             ret = ioctl(pair->channel, RELAY_GET_MAX_SB_SIZE,
> > > > > +                         &pair->max_sb_size);
> > > > > +             if(ret != 0) {
> > > > > +                     perror("Error in getting the max sub-buffer size");
> > > > > +                     goto end;
> > > > > +             }
> > > > > +             ret = pthread_mutex_init(&pair->mutex, NULL);   /* Fast
> > > > mutex */
> > > > > +             if(ret != 0) {
> > > > > +                     perror("Error in mutex init");
> > > > > +                     goto end;
> > > > > +             }
> > > > > +     }
> > > > > +
> > > > > +end:
> > > > > +     return ret;
> > > > > +}
> > > > > +
> > > > > +int unmap_channels(struct channel_trace_fd *fd_pairs)
> > > > > +{
> > > > > +     int j;
> > > > > +     int ret=0;
> > > > > +
> > > > > +     /* Munmap each FD */
> > > > > +     for(j=0;j<fd_pairs->num_pairs;j++) {
> > > > > +             struct fd_pair *pair = &fd_pairs->pair[j];
> > > > > +             int err_ret;
> > > > > +
> > > > > +             err_ret = pthread_mutex_destroy(&pair->mutex);
> > > > > +             if(err_ret != 0) {
> > > > > +                     perror("Error in mutex destroy");
> > > > > +             }
> > > > > +             ret |= err_ret;
> > > > > +     }
> > > > > +
> > > > > +     return ret;
> > > > > +}
> > > > > +
> > > > > +#ifdef HAS_INOTIFY
> > > > > +/* Inotify event arrived.
> > > > > + *
> > > > > + * Only support add file for now.
> > > > > + */
> > > > > +
> > > > > +int read_inotify(int inotify_fd,
> > > > > +     struct channel_trace_fd *fd_pairs,
> > > > > +     struct inotify_watch_array *iwatch_array)
> > > > > +{
> > > > > +     char buf[sizeof(struct inotify_event) + PATH_MAX];
> > > > > +     char path_channel[PATH_MAX];
> > > > > +     ssize_t len;
> > > > > +     struct inotify_event *ievent;
> > > > > +     size_t offset;
> > > > > +     unsigned int i;
> > > > > +     int ret;
> > > > > +     int old_num;
> > > > > +
> > > > > +     offset = 0;
> > > > > +     len = read(inotify_fd, buf, sizeof(struct inotify_event) +
> > > > PATH_MAX);
> > > > > +     if(len < 0) {
> > > > > +
> > > > > +             if(errno == EAGAIN)
> > > > > +                     return 0;  /* another thread got the data before us
> > > > */
> > > > > +
> > > > > +             printf("Error in read from inotify FD %s.\n",
> > > > strerror(len));
> > > > > +             return -1;
> > > > > +     }
> > > > > +     while(offset < len) {
> > > > > +             ievent = (struct inotify_event *)&(buf[offset]);
> > > > > +             for(i=0; i<iwatch_array->num; i++) {
> > > > > +                     if(iwatch_array->elem[i].wd == ievent->wd &&
> > > > > +                             ievent->mask == IN_CREATE) {
> > > > > +                             printf_verbose(
> > > > > +                                     "inotify wd %u event mask : %u for
> > > > %s%s\n",
> > > > > +                                     ievent->wd, ievent->mask,
> > > > > +                                     iwatch_array->elem[i].path_channel,
> > > > > +                                     ievent->name);
> > > > > +                             old_num = fd_pairs->num_pairs;
> > > > > +                             strcpy(path_channel,
> > > > iwatch_array->elem[i].path_channel);
> > > > > +                             strcat(path_channel, ievent->name);
> > > > > +                             if(ret = open_buffer_file(ievent->name,
> > > > path_channel,
> > > > > +                                     path_channel +
> > > > (iwatch_array->elem[i].base_path_channel -
> > > > > +
> > > > iwatch_array->elem[i].path_channel), fd_pairs)) {
> > > > > +                                     printf("Error opening buffer
> > > > file\n");
> > > > > +                                     return -1;
> > > > > +                             }
> > > > > +                             if(ret = map_channels(fd_pairs, old_num,
> > > > fd_pairs->num_pairs)) {
> > > > > +                                     printf("Error mapping channel\n");
> > > > > +                                     return -1;
> > > > > +                             }
> > > > > +
> > > > > +                     }
> > > > > +             }
> > > > > +             offset += sizeof(*ievent) + ievent->len;
> > > > > +     }
> > > > > +}
> > > > > +#endif //HAS_INOTIFY
> > > > > +
> > > > > +/* read_channels
> > > > > + *
> > > > > + * Thread worker.
> > > > > + *
> > > > > + * Read the debugfs channels and write them in the paired tracefiles.
> > > > > + *
> > > > > + * @fd_pairs : paired channels and trace files.
> > > > > + *
> > > > > + * returns 0 on success, -1 on error.
> > > > > + *
> > > > > + * Note that the high priority polled channels are consumed first. We
> > > > then poll
> > > > > + * again to see if these channels are still in priority. Only when no
> > > > > + * high priority channel is left, we start reading low priority
> > > > channels.
> > > > > + *
> > > > > + * Note that a channel is considered high priority when the buffer is
> > > > almost
> > > > > + * full.
> > > > > + */
> > > > > +
> > > > > +int read_channels(unsigned long thread_num, struct channel_trace_fd
> > > > *fd_pairs,
> > > > > +     int inotify_fd, struct inotify_watch_array *iwatch_array)
> > > > > +{
> > > > > +     struct pollfd *pollfd = NULL;
> > > > > +     int num_pollfd;
> > > > > +     int i,j;
> > > > > +     int num_rdy, num_hup;
> > > > > +     int high_prio;
> > > > > +     int ret = 0;
> > > > > +     int inotify_fds;
> > > > > +     unsigned int old_num;
> > > > > +
> > > > > +#ifdef HAS_INOTIFY
> > > > > +     inotify_fds = 1;
> > > > > +#else
> > > > > +     inotify_fds = 0;
> > > > > +#endif
> > > > > +
> > > > > +     pthread_rwlock_rdlock(&fd_pairs_lock);
> > > > > +
> > > > > +     /* Start polling the FD. Keep one fd for inotify */
> > > > > +     pollfd = malloc((inotify_fds + fd_pairs->num_pairs) * sizeof(struct
> > > > pollfd));
> > > > > +
> > > > > +#ifdef HAS_INOTIFY
> > > > > +     pollfd[0].fd = inotify_fd;
> > > > > +     pollfd[0].events = POLLIN|POLLPRI;
> > > > > +#endif
> > > > > +
> > > > > +     for(i=0;i<fd_pairs->num_pairs;i++) {
> > > > > +             pollfd[inotify_fds+i].fd = fd_pairs->pair[i].channel;
> > > > > +             pollfd[inotify_fds+i].events = POLLIN|POLLPRI;
> > > > > +     }
> > > > > +     num_pollfd = inotify_fds + fd_pairs->num_pairs;
> > > > > +
> > > > > +
> > > > > +     pthread_rwlock_unlock(&fd_pairs_lock);
> > > > > +
> > > > > +     while(1) {
> > > > > +             high_prio = 0;
> > > > > +             num_hup = 0;
> > > > > +#ifdef DEBUG
> > > > > +             printf("Press a key for next poll...\n");
> > > > > +             char buf[1];
> > > > > +             read(STDIN_FILENO, &buf, 1);
> > > > > +             printf("Next poll (polling %d fd) :\n", num_pollfd);
> > > > > +#endif //DEBUG
> > > > > +
> > > > > +             /* Have we received a signal ? */
> > > > > +             if(quit_program) break;
> > > > > +
> > > > > +             num_rdy = poll(pollfd, num_pollfd, -1);
> > > > > +
> > > > > +             if(num_rdy == -1) {
> > > > > +                     perror("Poll error");
> > > > > +                     goto free_fd;
> > > > > +             }
> > > > > +
> > > > > +             printf_verbose("Data received\n");
> > > > > +#ifdef HAS_INOTIFY
> > > > > +             switch(pollfd[0].revents) {
> > > > > +                     case POLLERR:
> > > > > +                             printf_verbose(
> > > > > +                                     "Error returned in polling inotify
> > > > fd %d.\n",
> > > > > +                                     pollfd[0].fd);
> > > > > +                             break;
> > > > > +                     case POLLHUP:
> > > > > +                             printf_verbose(
> > > > > +                                     "Polling inotify fd %d tells it has
> > > > hung up.\n",
> > > > > +                                     pollfd[0].fd);
> > > > > +                             break;
> > > > > +                     case POLLNVAL:
> > > > > +                             printf_verbose(
> > > > > +                                     "Polling inotify fd %d tells fd is
> > > > not open.\n",
> > > > > +                                     pollfd[0].fd);
> > > > > +                             break;
> > > > > +                     case POLLPRI:
> > > > > +                     case POLLIN:
> > > > > +                             printf_verbose(
> > > > > +                                     "Polling inotify fd %d : data
> > > > ready.\n",
> > > > > +                                     pollfd[0].fd);
> > > > > +
> > > > > +                             pthread_rwlock_wrlock(&fd_pairs_lock);
> > > > > +                             read_inotify(inotify_fd, fd_pairs,
> > > > iwatch_array);
> > > > > +                             pthread_rwlock_unlock(&fd_pairs_lock);
> > > > > +
> > > > > +                     break;
> > > > > +             }
> > > > > +#endif
> > > > > +
> > > > > +             for(i=inotify_fds;i<num_pollfd;i++) {
> > > > > +                     switch(pollfd[i].revents) {
> > > > > +                             case POLLERR:
> > > > > +                                     printf_verbose(
> > > > > +                                             "Error returned in polling
> > > > fd %d.\n",
> > > > > +                                             pollfd[i].fd);
> > > > > +                                     num_hup++;
> > > > > +                                     break;
> > > > > +                             case POLLHUP:
> > > > > +                                     printf_verbose(
> > > > > +                                             "Polling fd %d tells it has
> > > > hung up.\n",
> > > > > +                                             pollfd[i].fd);
> > > > > +                                     num_hup++;
> > > > > +                                     break;
> > > > > +                             case POLLNVAL:
> > > > > +                                     printf_verbose(
> > > > > +                                             "Polling fd %d tells fd is
> > > > not open.\n",
> > > > > +                                             pollfd[i].fd);
> > > > > +                                     num_hup++;
> > > > > +                                     break;
> > > > > +                             case POLLPRI:
> > > > > +
> > > > pthread_rwlock_rdlock(&fd_pairs_lock);
> > > > > +
> > > > if(pthread_mutex_trylock(&fd_pairs->pair[i-inotify_fds].mutex) == 0) {
> > > > > +                                             printf_verbose(
> > > > > +                                                     "Urgent read on fd
> > > > %d\n",
> > > > > +                                                     pollfd[i].fd);
> > > > > +                                             /* Take care of high
> > > > priority channels first. */
> > > > > +                                             high_prio = 1;
> > > > > +                                             /* it's ok to have an
> > > > unavailable sub-buffer */
> > > > > +                                             ret =
> > > > read_subbuffer(&fd_pairs->pair[i-inotify_fds]);
> > > > > +                                             if(ret == EAGAIN) ret = 0;
> > > > > +
> > > > > +                                             ret =
> > > > pthread_mutex_unlock(&fd_pairs->pair[i-inotify_fds].mutex);
> > > > > +                                             if(ret)
> > > > > +                                                     printf("Error in
> > > > mutex unlock : %s\n", strerror(ret));
> > > > > +                                     }
> > > > > +
> > > > pthread_rwlock_unlock(&fd_pairs_lock);
> > > > > +                                     break;
> > > > > +                     }
> > > > > +             }
> > > > > +             /* If every buffer FD has hung up, we end the read loop
> > > > here */
> > > > > +             if(num_hup == num_pollfd - inotify_fds) break;
> > > > > +
> > > > > +             if(!high_prio) {
> > > > > +                     for(i=inotify_fds;i<num_pollfd;i++) {
> > > > > +                             switch(pollfd[i].revents) {
> > > > > +                                     case POLLIN:
> > > > > +
> > > > pthread_rwlock_rdlock(&fd_pairs_lock);
> > > > > +
> > > > if(pthread_mutex_trylock(&fd_pairs->pair[i-inotify_fds].mutex) == 0) {
> > > > > +                                                     /* Take care of low
> > > > priority channels. */
> > > > > +                                                     printf_verbose(
> > > > > +                                                             "Normal
> > > > read on fd %d\n",
> > > > > +
> > > > pollfd[i].fd);
> > > > > +                                                     /* it's ok to have
> > > > an unavailable subbuffer */
> > > > > +                                                     ret =
> > > > read_subbuffer(&fd_pairs->pair[i-inotify_fds]);
> > > > > +                                                     if(ret == EAGAIN)
> > > > ret = 0;
> > > > > +
> > > > > +                                                     ret =
> > > > pthread_mutex_unlock(&fd_pairs->pair[i-inotify_fds].mutex);
> > > > > +                                                     if(ret)
> > > > > +
> > > > printf("Error in mutex unlock : %s\n", strerror(ret));
> > > > > +                                             }
> > > > > +
> > > > pthread_rwlock_unlock(&fd_pairs_lock);
> > > > > +                                             break;
> > > > > +                             }
> > > > > +                     }
> > > > > +             }
> > > > > +
> > > > > +             /* Update pollfd array if an entry was added to fd_pairs */
> > > > > +             pthread_rwlock_rdlock(&fd_pairs_lock);
> > > > > +             if((inotify_fds + fd_pairs->num_pairs) != num_pollfd) {
> > > > > +                     pollfd = realloc(pollfd,
> > > > > +                                     (inotify_fds + fd_pairs->num_pairs)
> > > > * sizeof(struct pollfd));
> > > > > +
> > > > for(i=num_pollfd-inotify_fds;i<fd_pairs->num_pairs;i++) {
> > > > > +                             pollfd[inotify_fds+i].fd =
> > > > fd_pairs->pair[i].channel;
> > > > > +                             pollfd[inotify_fds+i].events =
> > > > POLLIN|POLLPRI;
> > > > > +                     }
> > > > > +                     num_pollfd = fd_pairs->num_pairs + inotify_fds;
> > > > > +             }
> > > > > +             pthread_rwlock_unlock(&fd_pairs_lock);
> > > > > +
> > > > > +             /* NB: If the fd_pairs structure is updated by another
> > > > thread from this
> > > > > +              *     point forward, the current thread will wait in the
> > > > poll without
> > > > > +              *     monitoring the new channel. However, this thread
> > > > will add the
> > > > > +              *     new channel on next poll (and this should not take
> > > > too much time
> > > > > +              *     on a loaded system).
> > > > > +              *
> > > > > +              *     This event is quite unlikely and can only occur if a
> > > > CPU is
> > > > > +              *     hot-plugged while multple lttd threads are running.
> > > > > +              */
> > > > > +     }
> > > > > +
> > > > > +free_fd:
> > > > > +     free(pollfd);
> > > > > +
> > > > > +end:
> > > > > +     return ret;
> > > > > +}
> > > > > +
> > > > > +
> > > > > +void close_channel_trace_pairs(struct channel_trace_fd *fd_pairs, int
> > > > inotify_fd,
> > > > > +     struct inotify_watch_array *iwatch_array)
> > > > > +{
> > > > > +     int i;
> > > > > +     int ret;
> > > > > +
> > > > > +     for(i=0;i<fd_pairs->num_pairs;i++) {
> > > > > +             ret = close(fd_pairs->pair[i].channel);
> > > > > +             if(ret == -1) perror("Close error on channel");
> > > > > +             if(callbacks->on_close_channel) {
> > > > > +                     ret = callbacks->on_close_channel(
> > > > > +                             callbacks, &fd_pairs->pair[i]);
> > > > > +                     if(ret != 0) perror("Error on close channel
> > > > callback");
> > > > > +             }
> > > > > +     }
> > > > > +     free(fd_pairs->pair);
> > > > > +     free(iwatch_array->elem);
> > > > > +}
> > > > > +
> > > > > +/* Thread worker */
> > > > > +void * thread_main(void *arg)
> > > > > +{
> > > > > +     long ret = 0;
> > > > > +     unsigned long thread_num = (unsigned long)arg;
> > > > > +
> > > > > +     if(callbacks->on_new_thread)
> > > > > +             ret = callbacks->on_new_thread(callbacks, thread_num);
> > > > > +
> > > > > +     if (ret < 0) {
> > > > > +             return (void*)ret;
> > > > > +     }
> > > > > +     ret = read_channels(thread_num, &fd_pairs, inotify_fd,
> > > > &inotify_watch_array);
> > > > > +
> > > > > +     if(callbacks->on_close_thread)
> > > > > +             callbacks->on_close_thread(callbacks, thread_num);
> > > > > +
> > > > > +     return (void*)ret;
> > > > > +}
> > > > > +
> > > > > +/*on_close_thread has to be reentrant, it'll be called by many threads*/
> > > > > +int(*on_close_thread)(struct liblttd_callbacks *data, unsigned long
> > > > thread_num);
> > > > > +
> > > > > +int channels_init()
> > > > > +{
> > > > > +     int ret = 0;
> > > > > +
> > > > > +     inotify_fd = inotify_init();
> > > > > +     fcntl(inotify_fd, F_SETFL, O_NONBLOCK);
> > > > > +
> > > > > +     if(ret = open_channel_trace_pairs(channel_name,
> > > > > +                     channel_name + strlen(channel_name), &fd_pairs,
> > > > > +                     &inotify_fd, &inotify_watch_array))
> > > > > +             goto close_channel;
> > > > > +     if (fd_pairs.num_pairs == 0) {
> > > > > +             printf("No channel available for reading, exiting\n");
> > > > > +             ret = -ENOENT;
> > > > > +             goto close_channel;
> > > > > +     }
> > > > > +     if(ret = map_channels(&fd_pairs, 0, fd_pairs.num_pairs))
> > > > > +             goto close_channel;
> > > > > +     return 0;
> > > > > +
> > > > > +close_channel:
> > > > > +     close_channel_trace_pairs(&fd_pairs, inotify_fd,
> > > > &inotify_watch_array);
> > > > > +     if(inotify_fd >= 0)
> > > > > +             close(inotify_fd);
> > > > > +     return ret;
> > > > > +}
> > > > > +
> > > > > +int liblttd_start(char *channel_path, unsigned long n_threads,
> > > > > +             int flight_only, int normal_only, int verbose,
> > > > > +             struct liblttd_callbacks *user_data){
> > > > > +     int ret = 0;
> > > > > +     pthread_t *tids;
> > > > > +     unsigned long i;
> > > > > +     void *tret;
> > > > > +
> > > > > +     /*!modif! C'est seulement la pour tester, on devrait tester pour
> > > > voir si
> > > > > +     les arguments sont valide. On fera surement ca autrement avec
> > > > plusieurs
> > > > > +     instances*/
> > > > > +     channel_name = channel_path;
> > > > > +     num_threads = n_threads;
> > > > > +     dump_flight_only = flight_only;
> > > > > +     dump_normal_only = normal_only;
> > > > > +     verbose_mode = verbose;
> > > > > +     callbacks = user_data;
> > > > > +
> > > > > +     if(ret = channels_init())
> > > > > +             return ret;
> > > > > +
> > > > > +     tids = malloc(sizeof(pthread_t) * num_threads);
> > > > > +     for(i=0; i<num_threads; i++) {
> > > > > +
> > > > > +             ret = pthread_create(&tids[i], NULL, thread_main,
> > > > (void*)i);
> > > > > +             if(ret) {
> > > > > +                     perror("Error creating thread");
> > > > > +                     break;
> > > > > +             }
> > > > > +     }
> > > > > +
> > > > > +     for(i=0; i<num_threads; i++) {
> > > > > +             ret = pthread_join(tids[i], &tret);
> > > > > +             if(ret) {
> > > > > +                     perror("Error joining thread");
> > > > > +                     break;
> > > > > +             }
> > > > > +             if((long)tret != 0) {
> > > > > +                     printf("Error %s occured in thread %ld\n",
> > > > > +                             strerror((long)tret), i);
> > > > > +             }
> > > > > +     }
> > > > > +
> > > > > +     free(tids);
> > > > > +     ret = unmap_channels(&fd_pairs);
> > > > > +     close_channel_trace_pairs(&fd_pairs, inotify_fd,
> > > > &inotify_watch_array);
> > > > > +     if(inotify_fd >= 0)
> > > > > +             close(inotify_fd);
> > > > > +
> > > > > +     if(callbacks->on_trace_end) callbacks->on_trace_end(callbacks);
> > > > > +
> > > > > +     return ret;
> > > > > +}
> > > > > +
> > > > > +int liblttd_stop() {
> > > > > +     quit_program = 1;
> > > > > +     return 0;
> > > > > +}
> > > > > +
> > > > > diff --git a/liblttd/liblttd.h b/liblttd/liblttd.h
> > > > > new file mode 100644
> > > > > index 0000000..bd76eeb
> > > > > --- /dev/null
> > > > > +++ b/liblttd/liblttd.h
> > > > > @@ -0,0 +1,218 @@
> > > > > +/* liblttd header file
> > > > > + *
> > > > > + * Copyright 2010-
> > > > > + *            Oumarou Dicko <oumarou.dicko at polymtl.ca>
> > > > > + *            Michael Sills-Lavoie <michael.sills-lavoie at polymtl.ca>
> > > > > + *
> > > > > + *
> > > > > + * This program is free software; you can redistribute it and/or modify
> > > > > + * it under the terms of the GNU General Public License as published by
> > > > > + * the Free Software Foundation; either version 2 of the License, or
> > > > > + * (at your option) any later version.
> > > > > + *
> > > > > + * This program is distributed in the hope that it will be useful,
> > > > > + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> > > > > + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.      See the
> > > > > + * GNU General Public License for more details.
> > > > > + *
> > > > > + */
> > > > > +
> > > > > +#ifndef _LIBLTTD_H
> > > > > +#define _LIBLTTD_H
> > > > > +
> > > > > +#include <pthread.h>
> > > > > +
> > > > > +/**
> > > > > +* This structure contains the data associated with the channel file
> > > > descriptor.
> > > > > +* The lib user can use user_data to store the data associated to the
> > > > specified
> > > > > +* channel. The lib user can read but MUST NOT change the other
> > > > attributes.
> > > > > +*/
> > > > > +struct fd_pair {
> > > > > +     /**
> > > > > +     * This is the channel file descriptor.
> > > > > +     */
> > > > > +     int channel;
> > > > > +
> > > > > +     /**
> > > > > +     * This is the number of subbuffer for this channel.
> > > > > +     */
> > > > > +     unsigned int n_sb;
> > > > > +
> > > > > +     /**
> > > > > +     * This is the subbuffer size for this channel.
> > > > > +     */
> > > > > +     unsigned int max_sb_size;
> > > > > +
> > > > > +     /**
> > > > > +     * Not used anymore.
> > > > > +     */
> > > > > +     void *mmap;
> > > > > +
> > > > > +     /**
> > > > > +     * This is a mutex for internal library usage.
> > > > > +     */
> > > > > +     pthread_mutex_t mutex;
> > > > > +
> > > > > +     /**
> > > > > +     * Library user data.
> > > > > +     */
> > > > > +     void *user_data;
> > > > > +};
> > > > > +
> > > > > +/**
> > > > > +* This structure contains the necessary callbacks for a tracing session.
> > > > The
> > > > > +* user can set the unnecessary functions to NULL if he does not need
> > > > them.
> > > > > +*/
> > > > > +struct liblttd_callbacks {
> > > > > +     /**
> > > > > +     * This callback is called after a channel file is open.
> > > > > +     *
> > > > > +     * @args data This argument is a pointeur to the callbacks struct
> > > > that
> > > > > +     *            has been passed to the lib.
> > > > > +     * @args pair This structure contains the data associated with the
> > > > > +     *            channel file descriptor. The lib user can use
> > > > user_data to
> > > > > +     *            store the data associated to the specified channel.
> > > > > +     * @args relative_channel_path This argument represents a relative
> > > > path
> > > > > +     *            to the channel file. This path is relative to the root
> > > > > +     *            folder of the trace channels.
> > > > > +     *
> > > > > +     * @return Should return 0 if the callback succeeds else not 0.
> > > > > +     */
> > > > > +     int(*on_open_channel)(struct liblttd_callbacks *data,
> > > > > +             struct fd_pair *pair, char *relative_channel_path);
> > > > > +
> > > > > +     /**
> > > > > +     * This callback is called after a channel file is closed.
> > > > > +     *
> > > > > +     * @remarks After a channel file has been closed, it will never be
> > > > read
> > > > > +     *            again.
> > > > > +     *
> > > > > +     * @args data This argument is a pointeur to the callbacks struct
> > > > that
> > > > > +     *            has been passed to the lib.
> > > > > +     * @args pair This structure contains the data associated with the
> > > > > +     *            channel file descriptor. The lib user should clean
> > > > > +     *            user_data at this time.
> > > > > +     *
> > > > > +     * @return Should return 0 if the callback succeeds else not 0.
> > > > > +     */
> > > > > +     int(*on_close_channel)(struct liblttd_callbacks *data,
> > > > > +             struct fd_pair *pair);
> > > > > +
> > > > > +
> > > > > +     /**
> > > > > +     * This callback is called when the library enter in a new subfolder
> > > > > +     * while it is scanning the trace channel tree. It can be used to
> > > > create
> > > > > +     * the output file structure of the trace.
> > > > > +     *
> > > > > +     * @args data This argument is a pointeur to the callbacks struct
> > > > that
> > > > > +     *            has been passed to the lib.
> > > > > +     * @args relative_folder_path This argument represents a relative
> > > > path
> > > > > +     *            to the channel folder. This path is relative to the
> > > > root
> > > > > +     *            folder of the trace channels.
> > > > > +     *
> > > > > +     * @return Should return 0 if the callback succeeds else not 0.
> > > > > +     */
> > > > > +     int(*on_new_channels_folder)(struct liblttd_callbacks *data,
> > > > > +             char *relative_folder_path);
> > > > > +
> > > > > +     /**
> > > > > +     * This callback is called after a subbuffer is a reserved.
> > > > > +     *
> > > > > +     * @attention It has to be thread safe, it'll be called by many
> > > > threads.
> > > > > +     *
> > > > > +     * @args data This argument is a pointeur to the callbacks struct
> > > > that
> > > > > +     *            has been passed to the lib.
> > > > > +     * @args pair This structure contains the data associated with the
> > > > > +     *            channel file descriptor. The lib user should clean
> > > > > +     *            user_data at this time.
> > > > > +     * @args len This argument represents the length the data that has
> > > > to be
> > > > > +     *            read.
> > > > > +     *
> > > > > +     * @return Should return 0 if the callback succeeds else not 0.
> > > > > +     */
> > > > > +     int(*on_read_subbuffer)(struct liblttd_callbacks *data,
> > > > > +             struct fd_pair *pair, unsigned int len);
> > > > > +
> > > > > +     /**
> > > > > +     * This callback is called at the very end of the tracing session.
> > > > At
> > > > > +     * this time, all the channels have been closed and the threads have
> > > > been
> > > > > +     * destroyed.
> > > > > +     *
> > > > > +     * @remarks After this callback is called, no other callback will be
> > > > > +     *            called again.
> > > > > +     *
> > > > > +     * @attention It has to be thread safe, it'll be called by many
> > > > threads.
> > > > > +     *
> > > > > +     * @args data This argument is a pointeur to the callbacks struct
> > > > that
> > > > > +     *            has been passed to the lib.
> > > > > +     *
> > > > > +     * @return Should return 0 if the callback succeeds else not 0.
> > > > > +     */
> > > > > +     int(*on_trace_end)(struct liblttd_callbacks *data);
> > > > > +
> > > > > +     /**
> > > > > +     * This callback is called after a new thread has been created.
> > > > > +     *
> > > > > +     * @attention It has to be thread safe, it'll be called by many
> > > > threads.
> > > > > +     *
> > > > > +     * @args data This argument is a pointeur to the callbacks struct
> > > > that
> > > > > +     *            has been passed to the lib.
> > > > > +     * @args thread_num This argument represents the id of the thread.
> > > > > +     *
> > > > > +     * @return Should return 0 if the callback succeeds else not 0.
> > > > > +     */
> > > > > +     int(*on_new_thread)(struct liblttd_callbacks *data,
> > > > > +             unsigned long thread_num);
> > > > > +
> > > > > +     /**
> > > > > +     * This callback is called just before a thread is destroyed.
> > > > > +     *
> > > > > +     * @attention It has to be thread safe, it'll be called by many
> > > > threads.
> > > > > +     *
> > > > > +     * @args data This argument is a pointeur to the callbacks struct
> > > > that
> > > > > +     *            has been passed to the lib.
> > > > > +     * @args thread_num This argument represents the number of the
> > > > thread.
> > > > > +     *
> > > > > +     * @return Should return 0 if the callback succeeds else not 0.
> > > > > +     */
> > > > > +     int(*on_close_thread)(struct liblttd_callbacks *data,
> > > > > +             unsigned long thread_num);
> > > > > +
> > > > > +     /**
> > > > > +     * This is where the user can put the library's data.
> > > > > +     */
> > > > > +     void *user_data;
> > > > > +};
> > > > > +
> > > > > +/**
> > > > > +* This function is called to start a new tracing session.
> > > > > +*
> > > > > +* @attention It has to be thread safe, it'll be called by many threads.
> > > > > +*
> > > > > +* @args channel_path This argument is a path to the root folder of the
> > > > trace's
> > > > > +*            channels.
> > > > > +* @args n_threads This argument represents the number of threads that
> > > > will be
> > > > > +*            used by the library.
> > > > > +* @args flight_only If this argument to set to 1, only the channel that
> > > > are in
> > > > > +*            flight recorder mode will be recorded.
> > > > > +* @args normal_only If this argument to set to 1, only the channel that
> > > > are in
> > > > > +*            normal mode will be recorded.
> > > > > +* @args verbose If this argument to set to 1, more informations will be
> > > > printed.
> > > > > +* @args user_data This argument is a pointeur to the callbacks struct
> > > > that
> > > > > +*            contains the user's functions.
> > > > > +*
> > > > > +* @return Return 0 if the function succeeds else not 0.
> > > > > +*/
> > > > > +int liblttd_start(char *channel_path, unsigned long n_threads,
> > > > > +     int flight_only, int normal_only, int verbose,
> > > > > +     struct liblttd_callbacks *user_data);
> > > > > +
> > > > > +/**
> > > > > +* This function is called to stop a tracing session.
> > > > > +*
> > > > > +* @return Return 0 if the function succeeds.
> > > > > +*/
> > > > > +int liblttd_stop();
> > > > > +
> > > > > +#endif /*_LIBLTTD_H */
> > > > > +
> > > > > diff --git a/lttd/Makefile.am b/lttd/Makefile.am
> > > > > index bb860bc..fc9b219 100644
> > > > > --- a/lttd/Makefile.am
> > > > > +++ b/lttd/Makefile.am
> > > > > @@ -6,3 +6,6 @@ bin_PROGRAMS = lttd
> > > > >
> > > > >  lttd_SOURCES = lttd.c
> > > > >
> > > > > +lttd_DEPENDENCIES = ../liblttd/liblttd.la
> > > > > +lttd_LDADD = $(lttd_DEPENDENCIES)
> > > > > +
> > > > > diff --git a/lttd/lttd.c b/lttd/lttd.c
> > > > > index 773cb23..9143ef7 100644
> > > > > --- a/lttd/lttd.c
> > > > > +++ b/lttd/lttd.c
> > > > > @@ -17,125 +17,36 @@
> > > > >
> > > > >  #define _REENTRANT
> > > > >  #define _GNU_SOURCE
> > > > > -#include <features.h>
> > > > > +
> > > > >  #include <stdio.h>
> > > > > -#include <unistd.h>
> > > > > -#include <errno.h>
> > > > > -#include <sys/types.h>
> > > > > -#include <sys/stat.h>
> > > > >  #include <stdlib.h>
> > > > > -#include <dirent.h>
> > > > >  #include <string.h>
> > > > > -#include <fcntl.h>
> > > > > -#include <sys/poll.h>
> > > > > -#include <sys/mman.h>
> > > > >  #include <signal.h>
> > > > > -#include <pthread.h>
> > > > > -#include <sys/syscall.h>
> > > > > -#include <unistd.h>
> > > > > -#include <asm/ioctls.h>
> > > > > -
> > > > > -#include <linux/version.h>
> > > > > -
> > > > > -/* Relayfs IOCTL */
> > > > > -#include <asm/ioctl.h>
> > > > > -#include <asm/types.h>
> > > > > -
> > > > > -/* Get the next sub buffer that can be read. */
> > > > > -#define RELAY_GET_SB         _IOR(0xF5, 0x00,__u32)
> > > > > -/* Release the oldest reserved (by "get") sub buffer. */
> > > > > -#define RELAY_PUT_SB         _IOW(0xF5, 0x01,__u32)
> > > > > -/* returns the number of sub buffers in the per cpu channel. */
> > > > > -#define RELAY_GET_N_SB               _IOR(0xF5, 0x02,__u32)
> > > > > -/* returns the size of the current sub buffer. */
> > > > > -#define RELAY_GET_SB_SIZE    _IOR(0xF5, 0x03, __u32)
> > > > > -/* returns the size of data to consume in the current sub-buffer. */
> > > > > -#define RELAY_GET_MAX_SB_SIZE        _IOR(0xF5, 0x04, __u32)
> > > > > -
> > > > > -
> > > > > -#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,14)
> > > > > -#include <sys/inotify.h>
> > > > > -#if 0        /* should now be provided by libc. */
> > > > > -/* From the inotify-tools 2.6 package */
> > > > > -static inline int inotify_init (void)
> > > > > -{
> > > > > -     return syscall (__NR_inotify_init);
> > > > > -}
> > > > > -
> > > > > -static inline int inotify_add_watch (int fd, const char *name, __u32
> > > > mask)
> > > > > -{
> > > > > -     return syscall (__NR_inotify_add_watch, fd, name, mask);
> > > > > -}
> > > > > -
> > > > > -static inline int inotify_rm_watch (int fd, __u32 wd)
> > > > > -{
> > > > > -     return syscall (__NR_inotify_rm_watch, fd, wd);
> > > > > -}
> > > > > -#endif //0
> > > > > -#define HAS_INOTIFY
> > > > > -#else
> > > > > -static inline int inotify_init (void)
> > > > > -{
> > > > > -     return -1;
> > > > > -}
> > > > > +#include <errno.h>
> > > > > +#include <fcntl.h>
> > > > > +#include <dirent.h>
> > > > > +#include <sys/stat.h>
> > > > >
> > > > > -static inline int inotify_add_watch (int fd, const char *name, __u32
> > > > mask)
> > > > > -{
> > > > > -     return 0;
> > > > > -}
> > > > > +#include <liblttd/liblttd.h>
> > > > >
> > > > > -static inline int inotify_rm_watch (int fd, __u32 wd)
> > > > > -{
> > > > > -     return 0;
> > > > > -}
> > > > > -#undef HAS_INOTIFY
> > > > > -#endif
> > > > > -
> > > > > -struct fd_pair {
> > > > > -     int channel;
> > > > > +struct lttd_channel_data {
> > > > >       int trace;
> > > > > -     unsigned int n_sb;
> > > > > -     unsigned int max_sb_size;
> > > > > -     void *mmap;
> > > > > -     pthread_mutex_t mutex;
> > > > > -};
> > > > > -
> > > > > -struct channel_trace_fd {
> > > > > -     struct fd_pair *pair;
> > > > > -     int num_pairs;
> > > > > -};
> > > > > -
> > > > > -struct inotify_watch {
> > > > > -     int wd;
> > > > > -     char path_channel[PATH_MAX];
> > > > > -     char path_trace[PATH_MAX];
> > > > > -};
> > > > > -
> > > > > -struct inotify_watch_array {
> > > > > -     struct inotify_watch *elem;
> > > > > -     int num;
> > > > >  };
> > > > >
> > > > > -static __thread int thread_pipe[2];
> > > > > -
> > > > > -struct channel_trace_fd fd_pairs = { NULL, 0 };
> > > > > -int inotify_fd = -1;
> > > > > -struct inotify_watch_array inotify_watch_array = { NULL, 0 };
> > > > > -
> > > > > -/* protects fd_pairs and inotify_watch_array */
> > > > > -pthread_rwlock_t fd_pairs_lock = PTHREAD_RWLOCK_INITIALIZER;
> > > > > -
> > > > > -
> > > > > +static char          path_trace[PATH_MAX];
> > > > > +static char          *end_path_trace;
> > > > > +static int           path_trace_len = 0;
> > > > >  static char          *trace_name = NULL;
> > > > >  static char          *channel_name = NULL;
> > > > >  static int           daemon_mode = 0;
> > > > >  static int           append_mode = 0;
> > > > >  static unsigned long num_threads = 1;
> > > > > -volatile static int  quit_program = 0;       /* For signal handler */
> > > > >  static int           dump_flight_only = 0;
> > > > >  static int           dump_normal_only = 0;
> > > > >  static int           verbose_mode = 0;
> > > > >
> > > > > +static __thread int thread_pipe[2];
> > > > > +
> > > > >  #define printf_verbose(fmt, args...) \
> > > > >    do {                               \
> > > > >      if (verbose_mode)                \
> > > > > @@ -178,7 +89,7 @@ int parse_arguments(int argc, char **argv)
> > > > >  {
> > > > >       int ret = 0;
> > > > >       int argn = 1;
> > > > > -
> > > > > +
> > > > >       if(argc == 2) {
> > > > >               if(strcmp(argv[1], "-h") == 0) {
> > > > >                       return 1;
> > > > > @@ -236,19 +147,19 @@ int parse_arguments(int argc, char **argv)
> > > > >               }
> > > > >               argn++;
> > > > >       }
> > > > > -
> > > > > +
> > > > >       if(trace_name == NULL) {
> > > > >               printf("Please specify a trace name.\n");
> > > > >               printf("\n");
> > > > >               ret = -1;
> > > > >       }
> > > > > -
> > > > > +
> > > > >       if(channel_name == NULL) {
> > > > >               printf("Please specify a channel name.\n");
> > > > >               printf("\n");
> > > > >               ret = -1;
> > > > >       }
> > > > > -
> > > > > +
> > > > >       return ret;
> > > > >  }
> > > > >
> > > > > @@ -267,223 +178,96 @@ void show_info(void)
> > > > >  static void handler(int signo)
> > > > >  {
> > > > >       printf("Signal %d received : exiting cleanly\n", signo);
> > > > > -     quit_program = 1;
> > > > > +     liblttd_stop();
> > > > >  }
> > > > >
> > > > > -
> > > > > -int open_buffer_file(char *filename, char *path_channel, char
> > > > *path_trace,
> > > > > -     struct channel_trace_fd *fd_pairs)
> > > > > +int lttd_on_open_channel(struct liblttd_callbacks *data, struct fd_pair
> > > > *pair, char *relative_channel_path)
> > > > >  {
> > > > >       int open_ret = 0;
> > > > > -     int ret = 0;
> > > > > +     int ret;
> > > > >       struct stat stat_buf;
> > > > > +     struct lttd_channel_data *channel_data;
> > > > >
> > > > > -     if(strncmp(filename, "flight-", sizeof("flight-")-1) != 0) {
> > > > > -             if(dump_flight_only) {
> > > > > -                     printf_verbose("Skipping normal channel %s\n",
> > > > > -                             path_channel);
> > > > > -                     return 0;
> > > > > -             }
> > > > > -     } else {
> > > > > -             if(dump_normal_only) {
> > > > > -                     printf_verbose("Skipping flight channel %s\n",
> > > > > -                             path_channel);
> > > > > -                     return 0;
> > > > > -             }
> > > > > -     }
> > > > > -     printf_verbose("Opening file.\n");
> > > > > -
> > > > > -     fd_pairs->pair = realloc(fd_pairs->pair,
> > > > > -                     ++fd_pairs->num_pairs * sizeof(struct fd_pair));
> > > > > +     pair->user_data = malloc(sizeof(struct lttd_channel_data));
> > > > > +     channel_data = pair->user_data;
> > > > > +
> > > > > +     strncpy(end_path_trace, relative_channel_path, PATH_MAX -
> > > > path_trace_len);
> > > > > +     printf_verbose("Creating trace file %s\n", path_trace);
> > > > >
> > > > > -     /* Open the channel in read mode */
> > > > > -     fd_pairs->pair[fd_pairs->num_pairs-1].channel =
> > > > > -             open(path_channel, O_RDONLY | O_NONBLOCK);
> > > > > -     if(fd_pairs->pair[fd_pairs->num_pairs-1].channel == -1) {
> > > > > -             perror(path_channel);
> > > > > -             fd_pairs->num_pairs--;
> > > > > -             return 0;       /* continue */
> > > > > -     }
> > > > > -     /* Open the trace in write mode, only append if append_mode */
> > > > >       ret = stat(path_trace, &stat_buf);
> > > > >       if(ret == 0) {
> > > > >               if(append_mode) {
> > > > >                       printf_verbose("Appending to file %s as
> > > > requested\n",
> > > > >                               path_trace);
> > > > >
> > > > > -                     fd_pairs->pair[fd_pairs->num_pairs-1].trace =
> > > > > -                             open(path_trace, O_WRONLY,
> > > > > -                                             S_IRWXU|S_IRWXG|S_IRWXO);
> > > > > -                     if(fd_pairs->pair[fd_pairs->num_pairs-1].trace ==
> > > > -1) {
> > > > > +                     channel_data->trace = open(path_trace, O_WRONLY,
> > > > S_IRWXU|S_IRWXG|S_IRWXO);
> > > > > +                     if(channel_data->trace == -1) {
> > > > >                               perror(path_trace);
> > > > >                               open_ret = -1;
> > > > > -
> > > > close(fd_pairs->pair[fd_pairs->num_pairs-1].channel);
> > > > > -                             fd_pairs->num_pairs--;
> > > > >                               goto end;
> > > > >                       }
> > > > > -                     ret =
> > > > lseek(fd_pairs->pair[fd_pairs->num_pairs-1].trace,
> > > > > -                                 0, SEEK_END);
> > > > > +                     ret = lseek(channel_data->trace, 0, SEEK_END);
> > > > >                       if (ret < 0) {
> > > > >                               perror(path_trace);
> > > > >                               open_ret = -1;
> > > > > -
> > > > close(fd_pairs->pair[fd_pairs->num_pairs-1].channel);
> > > > > -
> > > > close(fd_pairs->pair[fd_pairs->num_pairs-1].trace);
> > > > > -                             fd_pairs->num_pairs--;
> > > > > +                             close(channel_data->trace);
> > > > >                               goto end;
> > > > >                       }
> > > > >               } else {
> > > > >                       printf("File %s exists, cannot open. Try append
> > > > mode.\n", path_trace);
> > > > >                       open_ret = -1;
> > > > > -
> > > > close(fd_pairs->pair[fd_pairs->num_pairs-1].channel);
> > > > > -                     fd_pairs->num_pairs--;
> > > > >                       goto end;
> > > > >               }
> > > > >       } else {
> > > > >               if(errno == ENOENT) {
> > > > > -                     fd_pairs->pair[fd_pairs->num_pairs-1].trace =
> > > > > -                             open(path_trace, O_WRONLY|O_CREAT|O_EXCL,
> > > > > -                                             S_IRWXU|S_IRWXG|S_IRWXO);
> > > > > -                     if(fd_pairs->pair[fd_pairs->num_pairs-1].trace ==
> > > > -1) {
> > > > > +                     channel_data->trace = open(path_trace,
> > > > O_WRONLY|O_CREAT|O_EXCL, S_IRWXU|S_IRWXG|S_IRWXO);
> > > > > +                     if(channel_data->trace == -1) {
> > > > >                               perror(path_trace);
> > > > >                               open_ret = -1;
> > > > > -
> > > > close(fd_pairs->pair[fd_pairs->num_pairs-1].channel);
> > > > > -                             fd_pairs->num_pairs--;
> > > > >                               goto end;
> > > > >                       }
> > > > >               }
> > > > >       }
> > > > > +
> > > > >  end:
> > > > >       return open_ret;
> > > > > +
> > > > >  }
> > > > >
> > > > > -int open_channel_trace_pairs(char *subchannel_name, char *subtrace_name,
> > > > > -             struct channel_trace_fd *fd_pairs, int *inotify_fd,
> > > > > -             struct inotify_watch_array *iwatch_array)
> > > > > +int lttd_on_close_channel(struct liblttd_callbacks *data, struct fd_pair
> > > > *pair)
> > > > > +{
> > > > > +     int ret;
> > > > > +     ret = close(((struct lttd_channel_data
> > > > *)(pair->user_data))->trace);
> > > > > +     free(pair->user_data);
> > > > > +     return ret;
> > > > > +}
> > > > > +
> > > > > +int lttd_on_new_channels_folder(struct liblttd_callbacks *data, char
> > > > *relative_folder_path)
> > > > >  {
> > > > > -     DIR *channel_dir = opendir(subchannel_name);
> > > > > -     struct dirent *entry;
> > > > > -     struct stat stat_buf;
> > > > >       int ret;
> > > > > -     char path_channel[PATH_MAX];
> > > > > -     int path_channel_len;
> > > > > -     char *path_channel_ptr;
> > > > > -     char path_trace[PATH_MAX];
> > > > > -     int path_trace_len;
> > > > > -     char *path_trace_ptr;
> > > > >       int open_ret = 0;
> > > > >
> > > > > -     if(channel_dir == NULL) {
> > > > > -             perror(subchannel_name);
> > > > > -             open_ret = ENOENT;
> > > > > -             goto end;
> > > > > -     }
> > > > > +     strncpy(end_path_trace, relative_folder_path, PATH_MAX -
> > > > path_trace_len);
> > > > > +     printf_verbose("Creating trace subdirectory %s\n", path_trace);
> > > > >
> > > > > -     printf_verbose("Creating trace subdirectory %s\n", subtrace_name);
> > > > > -     ret = mkdir(subtrace_name, S_IRWXU|S_IRWXG|S_IRWXO);
> > > > > +     ret = mkdir(path_trace, S_IRWXU|S_IRWXG|S_IRWXO);
> > > > >       if(ret == -1) {
> > > > >               if(errno != EEXIST) {
> > > > > -                     perror(subtrace_name);
> > > > > +                     perror(path_trace);
> > > > >                       open_ret = -1;
> > > > >                       goto end;
> > > > >               }
> > > > >       }
> > > > >
> > > > > -     strncpy(path_channel, subchannel_name, PATH_MAX-1);
> > > > > -     path_channel_len = strlen(path_channel);
> > > > > -     path_channel[path_channel_len] = '/';
> > > > > -     path_channel_len++;
> > > > > -     path_channel_ptr = path_channel + path_channel_len;
> > > > > -
> > > > > -     strncpy(path_trace, subtrace_name, PATH_MAX-1);
> > > > > -     path_trace_len = strlen(path_trace);
> > > > > -     path_trace[path_trace_len] = '/';
> > > > > -     path_trace_len++;
> > > > > -     path_trace_ptr = path_trace + path_trace_len;
> > > > > -
> > > > > -#ifdef HAS_INOTIFY
> > > > > -     iwatch_array->elem = realloc(iwatch_array->elem,
> > > > > -             ++iwatch_array->num * sizeof(struct inotify_watch));
> > > > > -
> > > > > -     printf_verbose("Adding inotify for channel %s\n", path_channel);
> > > > > -     iwatch_array->elem[iwatch_array->num-1].wd =
> > > > inotify_add_watch(*inotify_fd, path_channel, IN_CREATE);
> > > > > -     strcpy(iwatch_array->elem[iwatch_array->num-1].path_channel,
> > > > path_channel);
> > > > > -     strcpy(iwatch_array->elem[iwatch_array->num-1].path_trace,
> > > > path_trace);
> > > > > -     printf_verbose("Added inotify for channel %s, wd %u\n",
> > > > > -             iwatch_array->elem[iwatch_array->num-1].path_channel,
> > > > > -             iwatch_array->elem[iwatch_array->num-1].wd);
> > > > > -#endif
> > > > > -
> > > > > -     while((entry = readdir(channel_dir)) != NULL) {
> > > > > -
> > > > > -             if(entry->d_name[0] == '.') continue;
> > > > > -
> > > > > -             strncpy(path_channel_ptr, entry->d_name, PATH_MAX -
> > > > path_channel_len);
> > > > > -             strncpy(path_trace_ptr, entry->d_name, PATH_MAX -
> > > > path_trace_len);
> > > > > -
> > > > > -             ret = stat(path_channel, &stat_buf);
> > > > > -             if(ret == -1) {
> > > > > -                     perror(path_channel);
> > > > > -                     continue;
> > > > > -             }
> > > > > -
> > > > > -             printf_verbose("Channel file : %s\n", path_channel);
> > > > > -
> > > > > -             if(S_ISDIR(stat_buf.st_mode)) {
> > > > > -
> > > > > -                     printf_verbose("Entering channel
> > > > subdirectory...\n");
> > > > > -                     ret = open_channel_trace_pairs(path_channel,
> > > > path_trace, fd_pairs,
> > > > > -                             inotify_fd, iwatch_array);
> > > > > -                     if(ret < 0) continue;
> > > > > -             } else if(S_ISREG(stat_buf.st_mode)) {
> > > > > -                     open_ret = open_buffer_file(entry->d_name,
> > > > path_channel, path_trace,
> > > > > -                             fd_pairs);
> > > > > -                     if(open_ret)
> > > > > -                             goto end;
> > > > > -             }
> > > > > -     }
> > > > > -
> > > > >  end:
> > > > > -     closedir(channel_dir);
> > > > > -
> > > > >       return open_ret;
> > > > >  }
> > > > >
> > > > > -
> > > > > -int read_subbuffer(struct fd_pair *pair)
> > > > > +int lttd_on_read_subbuffer(struct liblttd_callbacks *data, struct
> > > > fd_pair *pair, unsigned int len)
> > > > >  {
> > > > > -     unsigned int consumed_old, len;
> > > > > -     int err;
> > > > >       long ret;
> > > > > -     off_t offset;
> > > > > -
> > > > > +     off_t offset = 0;
> > > > >
> > > > > -     err = ioctl(pair->channel, RELAY_GET_SB, &consumed_old);
> > > > > -     printf_verbose("cookie : %u\n", consumed_old);
> > > > > -     if(err != 0) {
> > > > > -             ret = errno;
> > > > > -             perror("Reserving sub buffer failed (everything is normal,
> > > > it is due to concurrency)");
> > > > > -             goto get_error;
> > > > > -     }
> > > > > -#if 0
> > > > > -     err = TEMP_FAILURE_RETRY(write(pair->trace,
> > > > > -                             pair->mmap
> > > > > -                                     + (consumed_old & ((pair->n_subbufs
> > > > * pair->subbuf_size)-1)),
> > > > > -                             pair->subbuf_size));
> > > > > -
> > > > > -     if(err < 0) {
> > > > > -             ret = errno;
> > > > > -             perror("Error in writing to file");
> > > > > -             goto write_error;
> > > > > -     }
> > > > > -#endif //0
> > > > > -     err = ioctl(pair->channel, RELAY_GET_SB_SIZE, &len);
> > > > > -     if(err != 0) {
> > > > > -             ret = errno;
> > > > > -             perror("Getting sub-buffer len failed.");
> > > > > -             goto get_error;
> > > > > -     }
> > > > > -
> > > > > -     offset = 0;
> > > > >       while (len > 0) {
> > > > >               printf_verbose("splice chan to pipe offset %lu\n",
> > > > >                       (unsigned long)offset);
> > > > > @@ -494,8 +278,9 @@ int read_subbuffer(struct fd_pair *pair)
> > > > >                       perror("Error in relay splice");
> > > > >                       goto write_error;
> > > > >               }
> > > > > -             ret = splice(thread_pipe[0], NULL, pair->trace, NULL,
> > > > > -                     ret, SPLICE_F_MOVE | SPLICE_F_MORE);
> > > > > +             ret = splice(thread_pipe[0], NULL,
> > > > > +                     ((struct lttd_channel_data
> > > > *)(pair->user_data))->trace,
> > > > > +                     NULL, ret, SPLICE_F_MOVE | SPLICE_F_MORE);
> > > > >               printf_verbose("splice pipe to file %ld\n", ret);
> > > > >               if (ret < 0) {
> > > > >                       perror("Error in file splice");
> > > > > @@ -504,466 +289,42 @@ int read_subbuffer(struct fd_pair *pair)
> > > > >               len -= ret;
> > > > >       }
> > > > >
> > > > > -#if 0
> > > > > -     err = fsync(pair->trace);
> > > > > -     if(err < 0) {
> > > > > -             ret = errno;
> > > > > -             perror("Error in writing to file");
> > > > > -             goto write_error;
> > > > > -     }
> > > > > -#endif //0
> > > > >  write_error:
> > > > > -     ret = 0;
> > > > > -     err = ioctl(pair->channel, RELAY_PUT_SB, &consumed_old);
> > > > > -     if(err != 0) {
> > > > > -             ret = errno;
> > > > > -             if(errno == EFAULT) {
> > > > > -                     perror("Error in unreserving sub buffer\n");
> > > > > -             } else if(errno == EIO) {
> > > > > -                     /* Should never happen with newer LTTng versions */
> > > > > -                     perror("Reader has been pushed by the writer, last
> > > > sub-buffer corrupted.");
> > > > > -             }
> > > > > -             goto get_error;
> > > > > -     }
> > > > > -
> > > > > -get_error:
> > > > > -     return ret;
> > > > > -}
> > > > > -
> > > > > -
> > > > > -int map_channels(struct channel_trace_fd *fd_pairs,
> > > > > -     int idx_begin, int idx_end)
> > > > > -{
> > > > > -     int i,j;
> > > > > -     int ret=0;
> > > > > -
> > > > > -     if(fd_pairs->num_pairs <= 0) {
> > > > > -             printf("No channel to read\n");
> > > > > -             goto end;
> > > > > -     }
> > > > > -
> > > > > -     /* Get the subbuf sizes and number */
> > > > > -
> > > > > -     for(i=idx_begin;i<idx_end;i++) {
> > > > > -             struct fd_pair *pair = &fd_pairs->pair[i];
> > > > > -
> > > > > -             ret = ioctl(pair->channel, RELAY_GET_N_SB, &pair->n_sb);
> > > > > -             if(ret != 0) {
> > > > > -                     perror("Error in getting the number of
> > > > sub-buffers");
> > > > > -                     goto end;
> > > > > -             }
> > > > > -             ret = ioctl(pair->channel, RELAY_GET_MAX_SB_SIZE,
> > > > > -                         &pair->max_sb_size);
> > > > > -             if(ret != 0) {
> > > > > -                     perror("Error in getting the max sub-buffer size");
> > > > > -                     goto end;
> > > > > -             }
> > > > > -             ret = pthread_mutex_init(&pair->mutex, NULL);   /* Fast
> > > > mutex */
> > > > > -             if(ret != 0) {
> > > > > -                     perror("Error in mutex init");
> > > > > -                     goto end;
> > > > > -             }
> > > > > -     }
> > > > > -
> > > > > -#if 0
> > > > > -     /* Mmap each FD */
> > > > > -     for(i=idx_begin;i<idx_end;i++) {
> > > > > -             struct fd_pair *pair = &fd_pairs->pair[i];
> > > > > -
> > > > > -             pair->mmap = mmap(0, pair->subbuf_size * pair->n_subbufs,
> > > > PROT_READ,
> > > > > -                             MAP_SHARED, pair->channel, 0);
> > > > > -             if(pair->mmap == MAP_FAILED) {
> > > > > -                     perror("Mmap error");
> > > > > -                     goto munmap;
> > > > > -             }
> > > > > -     }
> > > > > -
> > > > > -     goto end; /* success */
> > > > > -
> > > > > -     /* Error handling */
> > > > > -     /* munmap only the successfully mmapped indexes */
> > > > > -munmap:
> > > > > -             /* Munmap each FD */
> > > > > -     for(j=idx_begin;j<i;j++) {
> > > > > -             struct fd_pair *pair = &fd_pairs->pair[j];
> > > > > -             int err_ret;
> > > > > -
> > > > > -             err_ret = munmap(pair->mmap, pair->subbuf_size *
> > > > pair->n_subbufs);
> > > > > -             if(err_ret != 0) {
> > > > > -                     perror("Error in munmap");
> > > > > -             }
> > > > > -             ret |= err_ret;
> > > > > -     }
> > > > > -
> > > > > -#endif //0
> > > > > -end:
> > > > >       return ret;
> > > > >  }
> > > > >
> > > > > -int unmap_channels(struct channel_trace_fd *fd_pairs)
> > > > > -{
> > > > > -     int j;
> > > > > -     int ret=0;
> > > > > -
> > > > > -     /* Munmap each FD */
> > > > > -     for(j=0;j<fd_pairs->num_pairs;j++) {
> > > > > -             struct fd_pair *pair = &fd_pairs->pair[j];
> > > > > -             int err_ret;
> > > > > -
> > > > > -#if 0
> > > > > -             err_ret = munmap(pair->mmap, pair->subbuf_size *
> > > > pair->n_subbufs);
> > > > > -             if(err_ret != 0) {
> > > > > -                     perror("Error in munmap");
> > > > > -             }
> > > > > -             ret |= err_ret;
> > > > > -#endif //0
> > > > > -             err_ret = pthread_mutex_destroy(&pair->mutex);
> > > > > -             if(err_ret != 0) {
> > > > > -                     perror("Error in mutex destroy");
> > > > > -             }
> > > > > -             ret |= err_ret;
> > > > > -     }
> > > > > -
> > > > > -     return ret;
> > > > > -}
> > > > > -
> > > > > -#ifdef HAS_INOTIFY
> > > > > -/* Inotify event arrived.
> > > > > - *
> > > > > - * Only support add file for now.
> > > > > - */
> > > > > -
> > > > > -int read_inotify(int inotify_fd,
> > > > > -     struct channel_trace_fd *fd_pairs,
> > > > > -     struct inotify_watch_array *iwatch_array)
> > > > > -{
> > > > > -     char buf[sizeof(struct inotify_event) + PATH_MAX];
> > > > > -     char path_channel[PATH_MAX];
> > > > > -     char path_trace[PATH_MAX];
> > > > > -     ssize_t len;
> > > > > -     struct inotify_event *ievent;
> > > > > -     size_t offset;
> > > > > -     unsigned int i;
> > > > > -     int ret;
> > > > > -     int old_num;
> > > > > -
> > > > > -     offset = 0;
> > > > > -     len = read(inotify_fd, buf, sizeof(struct inotify_event) +
> > > > PATH_MAX);
> > > > > -     if(len < 0) {
> > > > > -
> > > > > -             if(errno == EAGAIN)
> > > > > -                     return 0;  /* another thread got the data before us
> > > > */
> > > > > -
> > > > > -             printf("Error in read from inotify FD %s.\n",
> > > > strerror(len));
> > > > > -             return -1;
> > > > > -     }
> > > > > -     while(offset < len) {
> > > > > -             ievent = (struct inotify_event *)&(buf[offset]);
> > > > > -             for(i=0; i<iwatch_array->num; i++) {
> > > > > -                     if(iwatch_array->elem[i].wd == ievent->wd &&
> > > > > -                             ievent->mask == IN_CREATE) {
> > > > > -                             printf_verbose(
> > > > > -                                     "inotify wd %u event mask : %u for
> > > > %s%s\n",
> > > > > -                                     ievent->wd, ievent->mask,
> > > > > -                                     iwatch_array->elem[i].path_channel,
> > > > > -                                     ievent->name);
> > > > > -                             old_num = fd_pairs->num_pairs;
> > > > > -                             strcpy(path_channel,
> > > > iwatch_array->elem[i].path_channel);
> > > > > -                             strcat(path_channel, ievent->name);
> > > > > -                             strcpy(path_trace,
> > > > iwatch_array->elem[i].path_trace);
> > > > > -                             strcat(path_trace, ievent->name);
> > > > > -                             if(ret = open_buffer_file(ievent->name,
> > > > path_channel,
> > > > > -                                     path_trace, fd_pairs)) {
> > > > > -                                     printf("Error opening buffer
> > > > file\n");
> > > > > -                                     return -1;
> > > > > -                             }
> > > > > -                             if(ret = map_channels(fd_pairs, old_num,
> > > > fd_pairs->num_pairs)) {
> > > > > -                                     printf("Error mapping channel\n");
> > > > > -                                     return -1;
> > > > > -                             }
> > > > > -
> > > > > -                     }
> > > > > -             }
> > > > > -             offset += sizeof(*ievent) + ievent->len;
> > > > > -     }
> > > > > -}
> > > > > -#endif //HAS_INOTIFY
> > > > > -
> > > > > -/* read_channels
> > > > > - *
> > > > > - * Thread worker.
> > > > > - *
> > > > > - * Read the debugfs channels and write them in the paired tracefiles.
> > > > > - *
> > > > > - * @fd_pairs : paired channels and trace files.
> > > > > - *
> > > > > - * returns 0 on success, -1 on error.
> > > > > - *
> > > > > - * Note that the high priority polled channels are consumed first. We
> > > > then poll
> > > > > - * again to see if these channels are still in priority. Only when no
> > > > > - * high priority channel is left, we start reading low priority
> > > > channels.
> > > > > - *
> > > > > - * Note that a channel is considered high priority when the buffer is
> > > > almost
> > > > > - * full.
> > > > > - */
> > > > > -
> > > > > -int read_channels(unsigned long thread_num, struct channel_trace_fd
> > > > *fd_pairs,
> > > > > -     int inotify_fd, struct inotify_watch_array *iwatch_array)
> > > > > -{
> > > > > -     struct pollfd *pollfd = NULL;
> > > > > -     int num_pollfd;
> > > > > -     int i,j;
> > > > > -     int num_rdy, num_hup;
> > > > > -     int high_prio;
> > > > > -     int ret = 0;
> > > > > -     int inotify_fds;
> > > > > -     unsigned int old_num;
> > > > > -
> > > > > -#ifdef HAS_INOTIFY
> > > > > -     inotify_fds = 1;
> > > > > -#else
> > > > > -     inotify_fds = 0;
> > > > > -#endif
> > > > > -
> > > > > -     pthread_rwlock_rdlock(&fd_pairs_lock);
> > > > > -
> > > > > -     /* Start polling the FD. Keep one fd for inotify */
> > > > > -     pollfd = malloc((inotify_fds + fd_pairs->num_pairs) * sizeof(struct
> > > > pollfd));
> > > > > -
> > > > > -#ifdef HAS_INOTIFY
> > > > > -     pollfd[0].fd = inotify_fd;
> > > > > -     pollfd[0].events = POLLIN|POLLPRI;
> > > > > -#endif
> > > > > -
> > > > > -     for(i=0;i<fd_pairs->num_pairs;i++) {
> > > > > -             pollfd[inotify_fds+i].fd = fd_pairs->pair[i].channel;
> > > > > -             pollfd[inotify_fds+i].events = POLLIN|POLLPRI;
> > > > > -     }
> > > > > -     num_pollfd = inotify_fds + fd_pairs->num_pairs;
> > > > > -
> > > > > -
> > > > > -     pthread_rwlock_unlock(&fd_pairs_lock);
> > > > > -
> > > > > -     while(1) {
> > > > > -             high_prio = 0;
> > > > > -             num_hup = 0;
> > > > > -#ifdef DEBUG
> > > > > -             printf("Press a key for next poll...\n");
> > > > > -             char buf[1];
> > > > > -             read(STDIN_FILENO, &buf, 1);
> > > > > -             printf("Next poll (polling %d fd) :\n", num_pollfd);
> > > > > -#endif //DEBUG
> > > > > -
> > > > > -             /* Have we received a signal ? */
> > > > > -             if(quit_program) break;
> > > > > -
> > > > > -             num_rdy = poll(pollfd, num_pollfd, -1);
> > > > > -
> > > > > -             if(num_rdy == -1) {
> > > > > -                     perror("Poll error");
> > > > > -                     goto free_fd;
> > > > > -             }
> > > > > -
> > > > > -             printf_verbose("Data received\n");
> > > > > -#ifdef HAS_INOTIFY
> > > > > -             switch(pollfd[0].revents) {
> > > > > -                     case POLLERR:
> > > > > -                             printf_verbose(
> > > > > -                                     "Error returned in polling inotify
> > > > fd %d.\n",
> > > > > -                                     pollfd[0].fd);
> > > > > -                             break;
> > > > > -                     case POLLHUP:
> > > > > -                             printf_verbose(
> > > > > -                                     "Polling inotify fd %d tells it has
> > > > hung up.\n",
> > > > > -                                     pollfd[0].fd);
> > > > > -                             break;
> > > > > -                     case POLLNVAL:
> > > > > -                             printf_verbose(
> > > > > -                                     "Polling inotify fd %d tells fd is
> > > > not open.\n",
> > > > > -                                     pollfd[0].fd);
> > > > > -                             break;
> > > > > -                     case POLLPRI:
> > > > > -                     case POLLIN:
> > > > > -                             printf_verbose(
> > > > > -                                     "Polling inotify fd %d : data
> > > > ready.\n",
> > > > > -                                     pollfd[0].fd);
> > > > > -
> > > > > -                             pthread_rwlock_wrlock(&fd_pairs_lock);
> > > > > -                             read_inotify(inotify_fd, fd_pairs,
> > > > iwatch_array);
> > > > > -                             pthread_rwlock_unlock(&fd_pairs_lock);
> > > > > -
> > > > > -                     break;
> > > > > -             }
> > > > > -#endif
> > > > > -
> > > > > -             for(i=inotify_fds;i<num_pollfd;i++) {
> > > > > -                     switch(pollfd[i].revents) {
> > > > > -                             case POLLERR:
> > > > > -                                     printf_verbose(
> > > > > -                                             "Error returned in polling
> > > > fd %d.\n",
> > > > > -                                             pollfd[i].fd);
> > > > > -                                     num_hup++;
> > > > > -                                     break;
> > > > > -                             case POLLHUP:
> > > > > -                                     printf_verbose(
> > > > > -                                             "Polling fd %d tells it has
> > > > hung up.\n",
> > > > > -                                             pollfd[i].fd);
> > > > > -                                     num_hup++;
> > > > > -                                     break;
> > > > > -                             case POLLNVAL:
> > > > > -                                     printf_verbose(
> > > > > -                                             "Polling fd %d tells fd is
> > > > not open.\n",
> > > > > -                                             pollfd[i].fd);
> > > > > -                                     num_hup++;
> > > > > -                                     break;
> > > > > -                             case POLLPRI:
> > > > > -
> > > > pthread_rwlock_rdlock(&fd_pairs_lock);
> > > > > -
> > > > if(pthread_mutex_trylock(&fd_pairs->pair[i-inotify_fds].mutex) == 0) {
> > > > > -                                             printf_verbose(
> > > > > -                                                     "Urgent read on fd
> > > > %d\n",
> > > > > -                                                     pollfd[i].fd);
> > > > > -                                             /* Take care of high
> > > > priority channels first. */
> > > > > -                                             high_prio = 1;
> > > > > -                                             /* it's ok to have an
> > > > unavailable sub-buffer */
> > > > > -                                             ret =
> > > > read_subbuffer(&fd_pairs->pair[i-inotify_fds]);
> > > > > -                                             if(ret == EAGAIN) ret = 0;
> > > > > -
> > > > > -                                             ret =
> > > > pthread_mutex_unlock(&fd_pairs->pair[i-inotify_fds].mutex);
> > > > > -                                             if(ret)
> > > > > -                                                     printf("Error in
> > > > mutex unlock : %s\n", strerror(ret));
> > > > > -                                     }
> > > > > -
> > > > pthread_rwlock_unlock(&fd_pairs_lock);
> > > > > -                                     break;
> > > > > -                     }
> > > > > -             }
> > > > > -             /* If every buffer FD has hung up, we end the read loop
> > > > here */
> > > > > -             if(num_hup == num_pollfd - inotify_fds) break;
> > > > > -
> > > > > -             if(!high_prio) {
> > > > > -                     for(i=inotify_fds;i<num_pollfd;i++) {
> > > > > -                             switch(pollfd[i].revents) {
> > > > > -                                     case POLLIN:
> > > > > -
> > > > pthread_rwlock_rdlock(&fd_pairs_lock);
> > > > > -
> > > > if(pthread_mutex_trylock(&fd_pairs->pair[i-inotify_fds].mutex) == 0) {
> > > > > -                                                     /* Take care of low
> > > > priority channels. */
> > > > > -                                                     printf_verbose(
> > > > > -                                                             "Normal
> > > > read on fd %d\n",
> > > > > -
> > > > pollfd[i].fd);
> > > > > -                                                     /* it's ok to have
> > > > an unavailable subbuffer */
> > > > > -                                                     ret =
> > > > read_subbuffer(&fd_pairs->pair[i-inotify_fds]);
> > > > > -                                                     if(ret == EAGAIN)
> > > > ret = 0;
> > > > > -
> > > > > -                                                     ret =
> > > > pthread_mutex_unlock(&fd_pairs->pair[i-inotify_fds].mutex);
> > > > > -                                                     if(ret)
> > > > > -
> > > > printf("Error in mutex unlock : %s\n", strerror(ret));
> > > > > -                                             }
> > > > > -
> > > > pthread_rwlock_unlock(&fd_pairs_lock);
> > > > > -                                             break;
> > > > > -                             }
> > > > > -                     }
> > > > > -             }
> > > > > -
> > > > > -             /* Update pollfd array if an entry was added to fd_pairs */
> > > > > -             pthread_rwlock_rdlock(&fd_pairs_lock);
> > > > > -             if((inotify_fds + fd_pairs->num_pairs) != num_pollfd) {
> > > > > -                     pollfd = realloc(pollfd,
> > > > > -                                     (inotify_fds + fd_pairs->num_pairs)
> > > > * sizeof(struct pollfd));
> > > > > -
> > > > for(i=num_pollfd-inotify_fds;i<fd_pairs->num_pairs;i++) {
> > > > > -                             pollfd[inotify_fds+i].fd =
> > > > fd_pairs->pair[i].channel;
> > > > > -                             pollfd[inotify_fds+i].events =
> > > > POLLIN|POLLPRI;
> > > > > -                     }
> > > > > -                     num_pollfd = fd_pairs->num_pairs + inotify_fds;
> > > > > -             }
> > > > > -             pthread_rwlock_unlock(&fd_pairs_lock);
> > > > > -
> > > > > -             /* NB: If the fd_pairs structure is updated by another
> > > > thread from this
> > > > > -              *     point forward, the current thread will wait in the
> > > > poll without
> > > > > -              *     monitoring the new channel. However, this thread
> > > > will add the
> > > > > -              *     new channel on next poll (and this should not take
> > > > too much time
> > > > > -              *     on a loaded system).
> > > > > -              *
> > > > > -              *     This event is quite unlikely and can only occur if a
> > > > CPU is
> > > > > -              *     hot-plugged while multple lttd threads are running.
> > > > > -              */
> > > > > -     }
> > > > > -
> > > > > -free_fd:
> > > > > -     free(pollfd);
> > > > > -
> > > > > -end:
> > > > > -     return ret;
> > > > > -}
> > > > > -
> > > > > -
> > > > > -void close_channel_trace_pairs(struct channel_trace_fd *fd_pairs, int
> > > > inotify_fd,
> > > > > -     struct inotify_watch_array *iwatch_array)
> > > > > -{
> > > > > -     int i;
> > > > > +int on_new_thread(struct liblttd_callbacks *data, unsigned long
> > > > thread_num) {
> > > > >       int ret;
> > > > > -
> > > > > -     for(i=0;i<fd_pairs->num_pairs;i++) {
> > > > > -             ret = close(fd_pairs->pair[i].channel);
> > > > > -             if(ret == -1) perror("Close error on channel");
> > > > > -             ret = close(fd_pairs->pair[i].trace);
> > > > > -             if(ret == -1) perror("Close error on trace");
> > > > > -     }
> > > > > -     free(fd_pairs->pair);
> > > > > -     free(iwatch_array->elem);
> > > > > -}
> > > > > -
> > > > > -/* Thread worker */
> > > > > -void * thread_main(void *arg)
> > > > > -{
> > > > > -     long ret;
> > > > > -     unsigned long thread_num = (unsigned long)arg;
> > > > > -
> > > > >       ret = pipe(thread_pipe);
> > > > >       if (ret < 0) {
> > > > >               perror("Error creating pipe");
> > > > > -             return (void*)ret;
> > > > > +             return ret;
> > > > >       }
> > > > > -     ret = read_channels(thread_num, &fd_pairs, inotify_fd,
> > > > &inotify_watch_array);
> > > > > -     close(thread_pipe[0]);  /* close read end */
> > > > > -     close(thread_pipe[1]);  /* close write end */
> > > > > -     return (void*)ret;
> > > > > +     return 0;
> > > > >  }
> > > > >
> > > > > -
> > > > > -int channels_init()
> > > > > -{
> > > > > -     int ret = 0;
> > > > > -
> > > > > -     inotify_fd = inotify_init();
> > > > > -     fcntl(inotify_fd, F_SETFL, O_NONBLOCK);
> > > > > -
> > > > > -     if(ret = open_channel_trace_pairs(channel_name, trace_name,
> > > > &fd_pairs,
> > > > > -                     &inotify_fd, &inotify_watch_array))
> > > > > -             goto close_channel;
> > > > > -     if (fd_pairs.num_pairs == 0) {
> > > > > -             printf("No channel available for reading, exiting\n");
> > > > > -             ret = -ENOENT;
> > > > > -             goto close_channel;
> > > > > -     }
> > > > > -     if(ret = map_channels(&fd_pairs, 0, fd_pairs.num_pairs))
> > > > > -             goto close_channel;
> > > > > +int on_close_thread(struct liblttd_callbacks *data, unsigned long
> > > > thread_num) {
> > > > > +     close(thread_pipe[0]);  /* close read end */
> > > > > +     close(thread_pipe[1]);  /* close write end */
> > > > >       return 0;
> > > > > -
> > > > > -close_channel:
> > > > > -     close_channel_trace_pairs(&fd_pairs, inotify_fd,
> > > > &inotify_watch_array);
> > > > > -     if(inotify_fd >= 0)
> > > > > -             close(inotify_fd);
> > > > > -     return ret;
> > > > >  }
> > > > >
> > > > > -
> > > > >  int main(int argc, char ** argv)
> > > > >  {
> > > > >       int ret = 0;
> > > > >       struct sigaction act;
> > > > > -     pthread_t *tids;
> > > > > -     unsigned long i;
> > > > > -     void *tret;
> > > > > -
> > > > > +
> > > > > +     struct liblttd_callbacks callbacks = {
> > > > > +             lttd_on_open_channel,
> > > > > +             lttd_on_close_channel,
> > > > > +             lttd_on_new_channels_folder,
> > > > > +             lttd_on_read_subbuffer,
> > > > > +             NULL,
> > > > > +             on_new_thread,
> > > > > +             on_close_thread,
> > > > > +             NULL
> > > > > +     };
> > > > > +
> > > > >       ret = parse_arguments(argc, argv);
> > > > >
> > > > >       if(ret != 0) show_arguments();
> > > > > @@ -983,9 +344,6 @@ int main(int argc, char ** argv)
> > > > >       sigaction(SIGQUIT, &act, NULL);
> > > > >       sigaction(SIGINT, &act, NULL);
> > > > >
> > > > > -     if(ret = channels_init())
> > > > > -             return ret;
> > > > > -
> > > > >       if(daemon_mode) {
> > > > >               ret = daemon(0, 0);
> > > > >
> > > > > @@ -995,33 +353,13 @@ int main(int argc, char ** argv)
> > > > >               }
> > > > >       }
> > > > >
> > > > > -     tids = malloc(sizeof(pthread_t) * num_threads);
> > > > > -     for(i=0; i<num_threads; i++) {
> > > > > -
> > > > > -             ret = pthread_create(&tids[i], NULL, thread_main,
> > > > (void*)i);
> > > > > -             if(ret) {
> > > > > -                     perror("Error creating thread");
> > > > > -                     break;
> > > > > -             }
> > > > > -     }
> > > > > +     strncpy(path_trace, trace_name, PATH_MAX-1);
> > > > > +     path_trace_len = strlen(path_trace);
> > > > > +     end_path_trace = path_trace + path_trace_len;
> > > > >
> > > > > -     for(i=0; i<num_threads; i++) {
> > > > > -             ret = pthread_join(tids[i], &tret);
> > > > > -             if(ret) {
> > > > > -                     perror("Error joining thread");
> > > > > -                     break;
> > > > > -             }
> > > > > -             if((long)tret != 0) {
> > > > > -                     printf("Error %s occured in thread %u\n",
> > > > > -                             strerror((long)tret), i);
> > > > > -             }
> > > > > -     }
> > > > > +     liblttd_start(channel_name, num_threads, dump_flight_only,
> > > > dump_normal_only,
> > > > > +             verbose_mode, &callbacks);
> > > > >
> > > > > -     free(tids);
> > > > > -     ret = unmap_channels(&fd_pairs);
> > > > > -     close_channel_trace_pairs(&fd_pairs, inotify_fd,
> > > > &inotify_watch_array);
> > > > > -     if(inotify_fd >= 0)
> > > > > -             close(inotify_fd);
> > > > > -
> > > > >       return ret;
> > > > >  }
> > > > > +
> > > >
> > > >
> > > > --
> > > > Mathieu Desnoyers
> > > > OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F  BA06 3F25 A8FE 3BAE 9A68
> > > >
> > 
> > > diff --git a/Makefile.am b/Makefile.am
> > > index 8f9974d..06500fd 100644
> > > --- a/Makefile.am
> > > +++ b/Makefile.am
> > > @@ -1,2 +1,2 @@
> > > -SUBDIRS = liblttctl lttctl lttd specs
> > > +SUBDIRS = liblttctl lttctl liblttd lttd specs
> > >  
> > > diff --git a/configure.in b/configure.in
> > > index d67e7d4..a992cd8 100644
> > > --- a/configure.in
> > > +++ b/configure.in
> > > @@ -76,8 +76,10 @@ DEFAULT_INCLUDES="-I\$(top_srcdir) -I\$(top_builddir)"
> > >  #AC_SUBST(CPPFLAGS)
> > >  
> > >  lttctlincludedir="${includedir}/liblttctl"
> > > +liblttdincludedir="${includedir}/liblttd"
> > >  
> > >  AC_SUBST(lttctlincludedir)
> > > +AC_SUBST(liblttdincludedir)
> > >  AC_SUBST(UTIL_LIBS)
> > >  AC_SUBST(THREAD_LIBS)
> > >  AC_SUBST(DEFAULT_INCLUDES)
> > > @@ -85,6 +87,7 @@ AC_SUBST(DEFAULT_INCLUDES)
> > >  AC_CONFIG_FILES([Makefile
> > >       liblttctl/Makefile
> > >       lttctl/Makefile
> > > +     liblttd/Makefile
> > >       lttd/Makefile
> > >       specs/Makefile])
> > >  AC_OUTPUT
> > > diff --git a/liblttd/Makefile.am b/liblttd/Makefile.am
> > > new file mode 100644
> > > index 0000000..3c1eeda
> > > --- /dev/null
> > > +++ b/liblttd/Makefile.am
> > > @@ -0,0 +1,7 @@
> > > +
> > > +
> > > +lib_LTLIBRARIES = liblttd.la
> > > +liblttd_la_SOURCES = liblttd.c
> > > +
> > > +liblttdinclude_HEADERS = \
> > > +	liblttd.h
> > > diff --git a/liblttd/liblttd.c b/liblttd/liblttd.c
> > > new file mode 100644
> > > index 0000000..0f0e5b5
> > > --- /dev/null
> > > +++ b/liblttd/liblttd.c
> > > @@ -0,0 +1,747 @@
> > > +/* lttd
> > > + *
> > > + * Linux Trace Toolkit Daemon
> > > + *
> > > + * This is a simple daemon that reads a few relay+debugfs channels and save
> > > + * them in a trace.
> > > + *
> > > + * CPU hot-plugging is supported using inotify.
> > > + *
> > > + * Copyright 2005 -
> > > + * 	Mathieu Desnoyers <mathieu.desnoyers at polymtl.ca>
> > > + */
> > > +
> > > +#ifdef HAVE_CONFIG_H
> > > +#include <config.h>
> > > +#endif
> > > +
> > > +#include "liblttd.h"
> > > +
> > > +#define _REENTRANT
> > > +#define _GNU_SOURCE
> > > +#include <features.h>
> > > +#include <stdio.h>
> > > +#include <unistd.h>
> > > +#include <errno.h>
> > > +#include <sys/types.h>
> > > +#include <stdlib.h>
> > > +#include <dirent.h>
> > > +#include <string.h>
> > > +#include <fcntl.h>
> > > +#include <sys/stat.h>
> > > +#include <sys/poll.h>
> > > +#include <sys/mman.h>
> > > +#include <sys/syscall.h>
> > > +#include <unistd.h>
> > > +#include <asm/ioctls.h>
> > > +
> > > +#include <linux/version.h>
> > > +
> > > +/* Relayfs IOCTL */
> > > +#include <asm/ioctl.h>
> > > +#include <asm/types.h>
> > > +
> > > +/* Get the next sub buffer that can be read. */
> > > +#define RELAY_GET_SB		_IOR(0xF5, 0x00,__u32)
> > > +/* Release the oldest reserved (by "get") sub buffer. */
> > > +#define RELAY_PUT_SB		_IOW(0xF5, 0x01,__u32)
> > > +/* returns the number of sub buffers in the per cpu channel. */
> > > +#define RELAY_GET_N_SB		_IOR(0xF5, 0x02,__u32)
> > > +/* returns the size of the current sub buffer. */
> > > +#define RELAY_GET_SB_SIZE	_IOR(0xF5, 0x03, __u32)
> > > +/* returns the size of data to consume in the current sub-buffer. */
> > > +#define RELAY_GET_MAX_SB_SIZE	_IOR(0xF5, 0x04, __u32)
> > > +
> > > +
> > > +#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,14)
> > > +#include <sys/inotify.h>
> > > +
> > > +#define HAS_INOTIFY
> > > +#else
> > > +static inline int inotify_init (void)
> > > +{
> > > +	return -1;
> > > +}
> > > +
> > > +static inline int inotify_add_watch (int fd, const char *name, __u32 mask)
> > > +{
> > > +	return 0;
> > > +}
> > > +
> > > +static inline int inotify_rm_watch (int fd, __u32 wd)
> > > +{
> > > +	return 0;
> > > +}
> > > +#undef HAS_INOTIFY
> > > +#endif
> > > +
> > > +struct liblttd_callbacks *callbacks;
> > > +
> > > +struct channel_trace_fd {
> > > +	struct fd_pair *pair;
> > > +	int num_pairs;
> > > +};
> > > +
> > > +struct inotify_watch {
> > > +	int wd;
> > > +	char path_channel[PATH_MAX];
> > > +	char *base_path_channel;
> > > +};
> > > +
> > > +struct inotify_watch_array {
> > > +	struct inotify_watch *elem;
> > > +	int num;
> > > +};
> > > +
> > > +struct channel_trace_fd fd_pairs = { NULL, 0 };
> > > +int inotify_fd = -1;
> > > +struct inotify_watch_array inotify_watch_array = { NULL, 0 };
> > > +
> > > +/* protects fd_pairs and inotify_watch_array */
> > > +pthread_rwlock_t fd_pairs_lock = PTHREAD_RWLOCK_INITIALIZER;
> > > +
> > > +static char		*channel_name = NULL;
> > > +static unsigned long	num_threads = 1;
> > > +volatile static int	quit_program = 0;	/* For signal handler */
> > > +static int		dump_flight_only = 0;
> > > +static int		dump_normal_only = 0;
> > > +static int		verbose_mode = 0;
> > > +
> > > +#define printf_verbose(fmt, args...) \
> > > +  do {                               \
> > > +    if (verbose_mode)                \
> > > +      printf(fmt, ##args);           \
> > > +  } while (0)
> > > +
> > > +
> > > +int open_buffer_file(char *filename, char *path_channel,
> > > +	char *base_path_channel, struct channel_trace_fd *fd_pairs)
> > > +{
> > > +	int open_ret = 0;
> > > +	int ret = 0;
> > > +
> > > +	if(strncmp(filename, "flight-", sizeof("flight-")-1) != 0) {
> > > +		if(dump_flight_only) {
> > > +			printf_verbose("Skipping normal channel %s\n",
> > > +				path_channel);
> > > +			return 0;
> > > +		}
> > > +	} else {
> > > +		if(dump_normal_only) {
> > > +			printf_verbose("Skipping flight channel %s\n",
> > > +				path_channel);
> > > +			return 0;
> > > +		}
> > > +	}
> > > +	printf_verbose("Opening file.\n");
> > > +
> > > +	fd_pairs->pair = realloc(fd_pairs->pair,
> > > +			++fd_pairs->num_pairs * sizeof(struct fd_pair));
> > > +
> > > +	/* Open the channel in read mode */
> > > +	fd_pairs->pair[fd_pairs->num_pairs-1].channel =
> > > +		open(path_channel, O_RDONLY | O_NONBLOCK);
> > > +	if(fd_pairs->pair[fd_pairs->num_pairs-1].channel == -1) {
> > > +		perror(path_channel);
> > > +		fd_pairs->num_pairs--;
> > > +		return 0;	/* continue */
> > > +	}
> > > +
> > > +	if(callbacks->on_open_channel) ret = callbacks->on_open_channel(
> > > +			callbacks, &fd_pairs->pair[fd_pairs->num_pairs-1],
> > > +			base_path_channel);
> > > +
> > > +	if(ret != 0) {
> > > +		open_ret = -1;
> > > +		close(fd_pairs->pair[fd_pairs->num_pairs-1].channel);
> > > +		fd_pairs->num_pairs--;
> > > +		goto end;
> > > +	}
> > > +
> > > +end:
> > > +	return open_ret;
> > > +}
> > > +
> > > +int open_channel_trace_pairs(char *subchannel_name,
> > > +		char *base_subchannel_name,
> > > +		struct channel_trace_fd *fd_pairs, int *inotify_fd,
> > > +		struct inotify_watch_array *iwatch_array)
> > > +{
> > > +	DIR *channel_dir = opendir(subchannel_name);
> > > +	struct dirent *entry;
> > > +	struct stat stat_buf;
> > > +	int ret;
> > > +	char path_channel[PATH_MAX];
> > > +	int path_channel_len;
> > > +	char *path_channel_ptr;
> > > +	char *base_subchannel_ptr;
> > > +
> > > +	int open_ret = 0;
> > > +
> > > +	if(channel_dir == NULL) {
> > > +		perror(subchannel_name);
> > > +		open_ret = ENOENT;
> > > +		goto end;
> > > +	}
> > > +
> > > +	printf_verbose("Calling on new channels folder");
> > > +	if(callbacks->on_new_channels_folder) ret = callbacks->
> > > +			on_new_channels_folder(callbacks,
> > > +			base_subchannel_name);
> > > +	if(ret == -1) {
> > > +		open_ret = -1;
> > > +		goto end;
> > > +	}
> > > +
> > > +	strncpy(path_channel, subchannel_name, PATH_MAX-1);
> > > +	path_channel_len = strlen(path_channel);
> > > +	path_channel[path_channel_len] = '/';
> > > +	path_channel_len++;
> > > +	path_channel_ptr = path_channel + path_channel_len;
> > > +	base_subchannel_ptr = path_channel +
> > > +		(base_subchannel_name - subchannel_name);
> > > +
> > > +#ifdef HAS_INOTIFY
> > > +	iwatch_array->elem = realloc(iwatch_array->elem,
> > > +		++iwatch_array->num * sizeof(struct inotify_watch));
> > > +
> > > +	printf_verbose("Adding inotify for channel %s\n", path_channel);
> > > +	iwatch_array->elem[iwatch_array->num-1].wd = inotify_add_watch(*inotify_fd, path_channel, IN_CREATE);
> > > +	strcpy(iwatch_array->elem[iwatch_array->num-1].path_channel, path_channel);
> > > +	iwatch_array->elem[iwatch_array->num-1].base_path_channel =
> > > +		iwatch_array->elem[iwatch_array->num-1].path_channel +
> > > +		(base_subchannel_name - subchannel_name);
> > > +	printf_verbose("Added inotify for channel %s, wd %u\n",
> > > +		iwatch_array->elem[iwatch_array->num-1].path_channel,
> > > +		iwatch_array->elem[iwatch_array->num-1].wd);
> > > +#endif
> > > +
> > > +	while((entry = readdir(channel_dir)) != NULL) {
> > > +
> > > +		if(entry->d_name[0] == '.') continue;
> > > +
> > > +		strncpy(path_channel_ptr, entry->d_name, PATH_MAX - path_channel_len);
> > > +
> > > +		ret = stat(path_channel, &stat_buf);
> > > +		if(ret == -1) {
> > > +			perror(path_channel);
> > > +			continue;
> > > +		}
> > > +
> > > +		printf_verbose("Channel file : %s\n", path_channel);
> > > +
> > > +		if(S_ISDIR(stat_buf.st_mode)) {
> > > +
> > > +			printf_verbose("Entering channel subdirectory...\n");
> > > +			ret = open_channel_trace_pairs(path_channel, base_subchannel_ptr, fd_pairs,
> > > +				inotify_fd, iwatch_array);
> > > +			if(ret < 0) continue;
> > > +		} else if(S_ISREG(stat_buf.st_mode)) {
> > > +			open_ret = open_buffer_file(entry->d_name, path_channel, base_subchannel_ptr,
> > > +				fd_pairs);
> > > +			if(open_ret)
> > > +				goto end;
> > > +		}
> > > +	}
> > > +
> > > +end:
> > > +	closedir(channel_dir);
> > > +
> > > +	return open_ret;
> > > +}
> > > +
> > > +
> > > +int read_subbuffer(struct fd_pair *pair)
> > > +{
> > > +	unsigned int consumed_old, len;
> > > +	int err;
> > > +	long ret;
> > > +	off_t offset;
> > > +
> > > +
> > > +	err = ioctl(pair->channel, RELAY_GET_SB, &consumed_old);
> > > +	printf_verbose("cookie : %u\n", consumed_old);
> > > +	if(err != 0) {
> > > +		ret = errno;
> > > +		perror("Reserving sub buffer failed (everything is normal, it is due to concurrency)");
> > > +		goto get_error;
> > > +	}
> > > +
> > > +	err = ioctl(pair->channel, RELAY_GET_SB_SIZE, &len);
> > > +	if(err != 0) {
> > > +		ret = errno;
> > > +		perror("Getting sub-buffer len failed.");
> > > +		goto get_error;
> > > +	}
> > > +
> > > +	if(callbacks->on_read_subbuffer) ret = callbacks->on_read_subbuffer(
> > > +		callbacks, pair, len);
> > > +
> > > +write_error:
> > > +	ret = 0;
> > > +	err = ioctl(pair->channel, RELAY_PUT_SB, &consumed_old);
> > > +	if(err != 0) {
> > > +		ret = errno;
> > > +		if(errno == EFAULT) {
> > > +			perror("Error in unreserving sub buffer\n");
> > > +		} else if(errno == EIO) {
> > > +			/* Should never happen with newer LTTng versions */
> > > +			perror("Reader has been pushed by the writer, last sub-buffer corrupted.");
> > > +		}
> > > +		goto get_error;
> > > +	}
> > > +
> > > +get_error:
> > > +	return ret;
> > > +}
> > > +
> > > +
> > > +int map_channels(struct channel_trace_fd *fd_pairs,
> > > +	int idx_begin, int idx_end)
> > > +{
> > > +	int i,j;
> > > +	int ret=0;
> > > +
> > > +	if(fd_pairs->num_pairs <= 0) {
> > > +		printf("No channel to read\n");
> > > +		goto end;
> > > +	}
> > > +
> > > +	/* Get the subbuf sizes and number */
> > > +
> > > +	for(i=idx_begin;i<idx_end;i++) {
> > > +		struct fd_pair *pair = &fd_pairs->pair[i];
> > > +
> > > +		ret = ioctl(pair->channel, RELAY_GET_N_SB, &pair->n_sb);
> > > +		if(ret != 0) {
> > > +			perror("Error in getting the number of sub-buffers");
> > > +			goto end;
> > > +		}
> > > +		ret = ioctl(pair->channel, RELAY_GET_MAX_SB_SIZE,
> > > +			    &pair->max_sb_size);
> > > +		if(ret != 0) {
> > > +			perror("Error in getting the max sub-buffer size");
> > > +			goto end;
> > > +		}
> > > +		ret = pthread_mutex_init(&pair->mutex, NULL);	/* Fast mutex */
> > > +		if(ret != 0) {
> > > +			perror("Error in mutex init");
> > > +			goto end;
> > > +		}
> > > +	}
> > > +
> > > +end:
> > > +	return ret;
> > > +}
> > > +
> > > +int unmap_channels(struct channel_trace_fd *fd_pairs)
> > > +{
> > > +	int j;
> > > +	int ret=0;
> > > +
> > > +	/* Munmap each FD */
> > > +	for(j=0;j<fd_pairs->num_pairs;j++) {
> > > +		struct fd_pair *pair = &fd_pairs->pair[j];
> > > +		int err_ret;
> > > +
> > > +		err_ret = pthread_mutex_destroy(&pair->mutex);
> > > +		if(err_ret != 0) {
> > > +			perror("Error in mutex destroy");
> > > +		}
> > > +		ret |= err_ret;
> > > +	}
> > > +
> > > +	return ret;
> > > +}
> > > +
> > > +#ifdef HAS_INOTIFY
> > > +/* Inotify event arrived.
> > > + *
> > > + * Only support add file for now.
> > > + */
> > > +
> > > +int read_inotify(int inotify_fd,
> > > +	struct channel_trace_fd *fd_pairs,
> > > +	struct inotify_watch_array *iwatch_array)
> > > +{
> > > +	char buf[sizeof(struct inotify_event) + PATH_MAX];
> > > +	char path_channel[PATH_MAX];
> > > +	ssize_t len;
> > > +	struct inotify_event *ievent;
> > > +	size_t offset;
> > > +	unsigned int i;
> > > +	int ret;
> > > +	int old_num;
> > > +
> > > +	offset = 0;
> > > +	len = read(inotify_fd, buf, sizeof(struct inotify_event) + PATH_MAX);
> > > +	if(len < 0) {
> > > +
> > > +		if(errno == EAGAIN)
> > > +			return 0;  /* another thread got the data before us */
> > > +
> > > +		printf("Error in read from inotify FD %s.\n", strerror(len));
> > > +		return -1;
> > > +	}
> > > +	while(offset < len) {
> > > +		ievent = (struct inotify_event *)&(buf[offset]);
> > > +		for(i=0; i<iwatch_array->num; i++) {
> > > +			if(iwatch_array->elem[i].wd == ievent->wd &&
> > > +				ievent->mask == IN_CREATE) {
> > > +				printf_verbose(
> > > +					"inotify wd %u event mask : %u for %s%s\n",
> > > +					ievent->wd, ievent->mask,
> > > +					iwatch_array->elem[i].path_channel,
> > > +					ievent->name);
> > > +				old_num = fd_pairs->num_pairs;
> > > +				strcpy(path_channel, iwatch_array->elem[i].path_channel);
> > > +				strcat(path_channel, ievent->name);
> > > +				if(ret = open_buffer_file(ievent->name, path_channel,
> > > +					path_channel + (iwatch_array->elem[i].base_path_channel -
> > > +					iwatch_array->elem[i].path_channel), fd_pairs)) {
> > > +					printf("Error opening buffer file\n");
> > > +					return -1;
> > > +				}
> > > +				if(ret = map_channels(fd_pairs, old_num, fd_pairs->num_pairs)) {
> > > +					printf("Error mapping channel\n");
> > > +					return -1;
> > > +				}
> > > +
> > > +			}
> > > +		}
> > > +		offset += sizeof(*ievent) + ievent->len;
> > > +	}
> > > +}
> > > +#endif //HAS_INOTIFY
> > > +
> > > +/* read_channels
> > > + *
> > > + * Thread worker.
> > > + *
> > > + * Read the debugfs channels and write them in the paired tracefiles.
> > > + *
> > > + * @fd_pairs : paired channels and trace files.
> > > + *
> > > + * returns 0 on success, -1 on error.
> > > + *
> > > + * Note that the high priority polled channels are consumed first. We then poll
> > > + * again to see if these channels are still in priority. Only when no
> > > + * high priority channel is left, we start reading low priority channels.
> > > + *
> > > + * Note that a channel is considered high priority when the buffer is almost
> > > + * full.
> > > + */
> > > +
> > > +int read_channels(unsigned long thread_num, struct channel_trace_fd *fd_pairs,
> > > +	int inotify_fd, struct inotify_watch_array *iwatch_array)
> > > +{
> > > +	struct pollfd *pollfd = NULL;
> > > +	int num_pollfd;
> > > +	int i,j;
> > > +	int num_rdy, num_hup;
> > > +	int high_prio;
> > > +	int ret = 0;
> > > +	int inotify_fds;
> > > +	unsigned int old_num;
> > > +
> > > +#ifdef HAS_INOTIFY
> > > +	inotify_fds = 1;
> > > +#else
> > > +	inotify_fds = 0;
> > > +#endif
> > > +
> > > +	pthread_rwlock_rdlock(&fd_pairs_lock);
> > > +
> > > +	/* Start polling the FD. Keep one fd for inotify */
> > > +	pollfd = malloc((inotify_fds + fd_pairs->num_pairs) * sizeof(struct pollfd));
> > > +
> > > +#ifdef HAS_INOTIFY
> > > +	pollfd[0].fd = inotify_fd;
> > > +	pollfd[0].events = POLLIN|POLLPRI;
> > > +#endif
> > > +
> > > +	for(i=0;i<fd_pairs->num_pairs;i++) {
> > > +		pollfd[inotify_fds+i].fd = fd_pairs->pair[i].channel;
> > > +		pollfd[inotify_fds+i].events = POLLIN|POLLPRI;
> > > +	}
> > > +	num_pollfd = inotify_fds + fd_pairs->num_pairs;
> > > +
> > > +
> > > +	pthread_rwlock_unlock(&fd_pairs_lock);
> > > +
> > > +	while(1) {
> > > +		high_prio = 0;
> > > +		num_hup = 0;
> > > +#ifdef DEBUG
> > > +		printf("Press a key for next poll...\n");
> > > +		char buf[1];
> > > +		read(STDIN_FILENO, &buf, 1);
> > > +		printf("Next poll (polling %d fd) :\n", num_pollfd);
> > > +#endif //DEBUG
> > > +
> > > +		/* Have we received a signal ? */
> > > +		if(quit_program) break;
> > > +
> > > +		num_rdy = poll(pollfd, num_pollfd, -1);
> > > +
> > > +		if(num_rdy == -1) {
> > > +			perror("Poll error");
> > > +			goto free_fd;
> > > +		}
> > > +
> > > +		printf_verbose("Data received\n");
> > > +#ifdef HAS_INOTIFY
> > > +		switch(pollfd[0].revents) {
> > > +			case POLLERR:
> > > +				printf_verbose(
> > > +					"Error returned in polling inotify fd %d.\n",
> > > +					pollfd[0].fd);
> > > +				break;
> > > +			case POLLHUP:
> > > +				printf_verbose(
> > > +					"Polling inotify fd %d tells it has hung up.\n",
> > > +					pollfd[0].fd);
> > > +				break;
> > > +			case POLLNVAL:
> > > +				printf_verbose(
> > > +					"Polling inotify fd %d tells fd is not open.\n",
> > > +					pollfd[0].fd);
> > > +				break;
> > > +			case POLLPRI:
> > > +			case POLLIN:
> > > +				printf_verbose(
> > > +					"Polling inotify fd %d : data ready.\n",
> > > +					pollfd[0].fd);
> > > +
> > > +				pthread_rwlock_wrlock(&fd_pairs_lock);
> > > +				read_inotify(inotify_fd, fd_pairs, iwatch_array);
> > > +				pthread_rwlock_unlock(&fd_pairs_lock);
> > > +
> > > +			break;
> > > +		}
> > > +#endif
> > > +
> > > +		for(i=inotify_fds;i<num_pollfd;i++) {
> > > +			switch(pollfd[i].revents) {
> > > +				case POLLERR:
> > > +					printf_verbose(
> > > +						"Error returned in polling fd %d.\n",
> > > +						pollfd[i].fd);
> > > +					num_hup++;
> > > +					break;
> > > +				case POLLHUP:
> > > +					printf_verbose(
> > > +						"Polling fd %d tells it has hung up.\n",
> > > +						pollfd[i].fd);
> > > +					num_hup++;
> > > +					break;
> > > +				case POLLNVAL:
> > > +					printf_verbose(
> > > +						"Polling fd %d tells fd is not open.\n",
> > > +						pollfd[i].fd);
> > > +					num_hup++;
> > > +					break;
> > > +				case POLLPRI:
> > > +					pthread_rwlock_rdlock(&fd_pairs_lock);
> > > +					if(pthread_mutex_trylock(&fd_pairs->pair[i-inotify_fds].mutex) == 0) {
> > > +						printf_verbose(
> > > +							"Urgent read on fd %d\n",
> > > +							pollfd[i].fd);
> > > +						/* Take care of high priority channels first. */
> > > +						high_prio = 1;
> > > +						/* it's ok to have an unavailable sub-buffer */
> > > +						ret = read_subbuffer(&fd_pairs->pair[i-inotify_fds]);
> > > +						if(ret == EAGAIN) ret = 0;
> > > +
> > > +						ret = pthread_mutex_unlock(&fd_pairs->pair[i-inotify_fds].mutex);
> > > +						if(ret)
> > > +							printf("Error in mutex unlock : %s\n", strerror(ret));
> > > +					}
> > > +					pthread_rwlock_unlock(&fd_pairs_lock);
> > > +					break;
> > > +			}
> > > +		}
> > > +		/* If every buffer FD has hung up, we end the read loop here */
> > > +		if(num_hup == num_pollfd - inotify_fds) break;
> > > +
> > > +		if(!high_prio) {
> > > +			for(i=inotify_fds;i<num_pollfd;i++) {
> > > +				switch(pollfd[i].revents) {
> > > +					case POLLIN:
> > > +						pthread_rwlock_rdlock(&fd_pairs_lock);
> > > +						if(pthread_mutex_trylock(&fd_pairs->pair[i-inotify_fds].mutex) == 0) {
> > > +							/* Take care of low priority channels. */
> > > +							printf_verbose(
> > > +								"Normal read on fd %d\n",
> > > +								pollfd[i].fd);
> > > +							/* it's ok to have an unavailable subbuffer */
> > > +							ret = read_subbuffer(&fd_pairs->pair[i-inotify_fds]);
> > > +							if(ret == EAGAIN) ret = 0;
> > > +
> > > +							ret = pthread_mutex_unlock(&fd_pairs->pair[i-inotify_fds].mutex);
> > > +							if(ret)
> > > +								printf("Error in mutex unlock : %s\n", strerror(ret));
> > > +						}
> > > +						pthread_rwlock_unlock(&fd_pairs_lock);
> > > +						break;
> > > +				}
> > > +			}
> > > +		}
> > > +
> > > +		/* Update pollfd array if an entry was added to fd_pairs */
> > > +		pthread_rwlock_rdlock(&fd_pairs_lock);
> > > +		if((inotify_fds + fd_pairs->num_pairs) != num_pollfd) {
> > > +			pollfd = realloc(pollfd,
> > > +					(inotify_fds + fd_pairs->num_pairs) * sizeof(struct pollfd));
> > > +			for(i=num_pollfd-inotify_fds;i<fd_pairs->num_pairs;i++) {
> > > +				pollfd[inotify_fds+i].fd = fd_pairs->pair[i].channel;
> > > +				pollfd[inotify_fds+i].events = POLLIN|POLLPRI;
> > > +			}
> > > +			num_pollfd = fd_pairs->num_pairs + inotify_fds;
> > > +		}
> > > +		pthread_rwlock_unlock(&fd_pairs_lock);
> > > +
> > > +		/* NB: If the fd_pairs structure is updated by another thread from this
> > > +		 *     point forward, the current thread will wait in the poll without
> > > +		 *     monitoring the new channel. However, this thread will add the
> > > +		 *     new channel on next poll (and this should not take too much time
> > > +		 *     on a loaded system).
> > > +		 *
> > > +		 *     This event is quite unlikely and can only occur if a CPU is
> > > +		 *     hot-plugged while multple lttd threads are running.
> > > +		 */
> > > +	}
> > > +
> > > +free_fd:
> > > +	free(pollfd);
> > > +
> > > +end:
> > > +	return ret;
> > > +}
> > > +
> > > +
> > > +void close_channel_trace_pairs(struct channel_trace_fd *fd_pairs, int inotify_fd,
> > > +	struct inotify_watch_array *iwatch_array)
> > > +{
> > > +	int i;
> > > +	int ret;
> > > +
> > > +	for(i=0;i<fd_pairs->num_pairs;i++) {
> > > +		ret = close(fd_pairs->pair[i].channel);
> > > +		if(ret == -1) perror("Close error on channel");
> > > +		if(callbacks->on_close_channel) {
> > > +			ret = callbacks->on_close_channel(
> > > +				callbacks, &fd_pairs->pair[i]);
> > > +			if(ret != 0) perror("Error on close channel callback");
> > > +		}
> > > +	}
> > > +	free(fd_pairs->pair);
> > > +	free(iwatch_array->elem);
> > > +}
> > > +
> > > +/* Thread worker */
> > > +void * thread_main(void *arg)
> > > +{
> > > +	long ret = 0;
> > > +	unsigned long thread_num = (unsigned long)arg;
> > > +
> > > +	if(callbacks->on_new_thread)
> > > +		ret = callbacks->on_new_thread(callbacks, thread_num);
> > > +
> > > +	if (ret < 0) {
> > > +		return (void*)ret;
> > > +	}
> > > +	ret = read_channels(thread_num, &fd_pairs, inotify_fd, &inotify_watch_array);
> > > +
> > > +	if(callbacks->on_close_thread)
> > > +		callbacks->on_close_thread(callbacks, thread_num);
> > > +
> > > +	return (void*)ret;
> > > +}
> > > +
> > > +/*on_close_thread has to be reentrant, it'll be called by many threads*/
> > > +int(*on_close_thread)(struct liblttd_callbacks *data, unsigned long thread_num);
> > > +
> > > +int channels_init()
> > > +{
> > > +	int ret = 0;
> > > +
> > > +	inotify_fd = inotify_init();
> > > +	fcntl(inotify_fd, F_SETFL, O_NONBLOCK);
> > > +
> > > +	if(ret = open_channel_trace_pairs(channel_name,
> > > +			channel_name + strlen(channel_name), &fd_pairs,
> > > +			&inotify_fd, &inotify_watch_array))
> > > +		goto close_channel;
> > > +	if (fd_pairs.num_pairs == 0) {
> > > +		printf("No channel available for reading, exiting\n");
> > > +		ret = -ENOENT;
> > > +		goto close_channel;
> > > +	}
> > > +	if(ret = map_channels(&fd_pairs, 0, fd_pairs.num_pairs))
> > > +		goto close_channel;
> > > +	return 0;
> > > +
> > > +close_channel:
> > > +	close_channel_trace_pairs(&fd_pairs, inotify_fd, &inotify_watch_array);
> > > +	if(inotify_fd >= 0)
> > > +		close(inotify_fd);
> > > +	return ret;
> > > +}
> > > +
> > > +int liblttd_start(char *channel_path, unsigned long n_threads,
> > > +		int flight_only, int normal_only, int verbose,
> > > +		struct liblttd_callbacks *user_data){
> > > +	int ret = 0;
> > > +	pthread_t *tids;
> > > +	unsigned long i;
> > > +	void *tret;
> > > +
> > > +	channel_name = channel_path;
> > > +	num_threads = n_threads;
> > > +	dump_flight_only = flight_only;
> > > +	dump_normal_only = normal_only;
> > > +	verbose_mode = verbose;
> > > +	callbacks = user_data;
> > > +
> > > +	if(ret = channels_init())
> > > +		return ret;
> > > +
> > > +	tids = malloc(sizeof(pthread_t) * num_threads);
> > > +	for(i=0; i<num_threads; i++) {
> > > +
> > > +		ret = pthread_create(&tids[i], NULL, thread_main, (void*)i);
> > > +		if(ret) {
> > > +			perror("Error creating thread");
> > > +			break;
> > > +		}
> > > +	}
> > > +
> > > +	for(i=0; i<num_threads; i++) {
> > > +		ret = pthread_join(tids[i], &tret);
> > > +		if(ret) {
> > > +			perror("Error joining thread");
> > > +			break;
> > > +		}
> > > +		if((long)tret != 0) {
> > > +			printf("Error %s occured in thread %ld\n",
> > > +				strerror((long)tret), i);
> > > +		}
> > > +	}
> > > +
> > > +	free(tids);
> > > +	ret = unmap_channels(&fd_pairs);
> > > +	close_channel_trace_pairs(&fd_pairs, inotify_fd, &inotify_watch_array);
> > > +	if(inotify_fd >= 0)
> > > +		close(inotify_fd);
> > > +
> > > +	if(callbacks->on_trace_end) callbacks->on_trace_end(callbacks);
> > > +
> > > +	return ret;
> > > +}
> > > +
> > > +int liblttd_stop() {
> > > +	quit_program = 1;
> > > +	return 0;
> > > +}
> > > +
> > > diff --git a/liblttd/liblttd.h b/liblttd/liblttd.h
> > > new file mode 100644
> > > index 0000000..bd76eeb
> > > --- /dev/null
> > > +++ b/liblttd/liblttd.h
> > > @@ -0,0 +1,218 @@
> > > +/* liblttd header file
> > > + *
> > > + * Copyright 2010-
> > > + *		 Oumarou Dicko <oumarou.dicko at polymtl.ca>
> > > + *		 Michael Sills-Lavoie <michael.sills-lavoie at polymtl.ca>
> > > + *
> > > + *
> > > + * This program is free software; you can redistribute it and/or modify
> > > + * it under the terms of the GNU General Public License as published by
> > > + * the Free Software Foundation; either version 2 of the License, or
> > > + * (at your option) any later version.
> > > + *
> > > + * This program is distributed in the hope that it will be useful,
> > > + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> > > + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	See the
> > > + * GNU General Public License for more details.
> > > + *
> > > + */
> > > +
> > > +#ifndef _LIBLTTD_H
> > > +#define _LIBLTTD_H
> > > +
> > > +#include <pthread.h>
> > > +
> > > +/**
> > > +* This structure contains the data associated with the channel file descriptor.
> > > +* The lib user can use user_data to store the data associated to the specified
> > > +* channel. The lib user can read but MUST NOT change the other attributes.
> > > +*/
> > > +struct fd_pair {
> > > +	/**
> > > +	* This is the channel file descriptor.
> > > +	*/
> > > +	int channel;
> > > +
> > > +	/**
> > > +	* This is the number of subbuffer for this channel.
> > > +	*/
> > > +	unsigned int n_sb;
> > > +
> > > +	/**
> > > +	* This is the subbuffer size for this channel.
> > > +	*/
> > > +	unsigned int max_sb_size;
> > > +
> > > +	/**
> > > +	* Not used anymore.
> > > +	*/
> > > +	void *mmap;
> > > +
> > > +	/**
> > > +	* This is a mutex for internal library usage.
> > > +	*/
> > > +	pthread_mutex_t	mutex;
> > > +
> > > +	/**
> > > +	* Library user data.
> > > +	*/
> > > +	void *user_data;
> > > +};
> > > +
> > > +/**
> > > +* This structure contains the necessary callbacks for a tracing session. The
> > > +* user can set the unnecessary functions to NULL if he does not need them.
> > > +*/
> > > +struct liblttd_callbacks {
> > > +	/**
> > > +	* This callback is called after a channel file is open.
> > > +	*
> > > +	* @args data This argument is a pointeur to the callbacks struct that
> > > +	*            has been passed to the lib.
> > > +	* @args pair This structure contains the data associated with the
> > > +	*            channel file descriptor. The lib user can use user_data to
> > > +	*            store the data associated to the specified channel.
> > > +	* @args relative_channel_path This argument represents a relative path
> > > +	*            to the channel file. This path is relative to the root
> > > +	*            folder of the trace channels.
> > > +	*
> > > +	* @return Should return 0 if the callback succeeds else not 0.
> > > +	*/
> > > +	int(*on_open_channel)(struct liblttd_callbacks *data,
> > > +		struct fd_pair *pair, char *relative_channel_path);
> > > +
> > > +	/**
> > > +	* This callback is called after a channel file is closed.
> > > +	*
> > > +	* @remarks After a channel file has been closed, it will never be read
> > > +	*            again.
> > > +	*
> > > +	* @args data This argument is a pointeur to the callbacks struct that
> > > +	*            has been passed to the lib.
> > > +	* @args pair This structure contains the data associated with the
> > > +	*            channel file descriptor. The lib user should clean
> > > +	*            user_data at this time.
> > > +	*
> > > +	* @return Should return 0 if the callback succeeds else not 0.
> > > +	*/
> > > +	int(*on_close_channel)(struct liblttd_callbacks *data,
> > > +		struct fd_pair *pair);
> > > +
> > > +
> > > +	/**
> > > +	* This callback is called when the library enter in a new subfolder
> > > +	* while it is scanning the trace channel tree. It can be used to create
> > > +	* the output file structure of the trace.
> > > +	*
> > > +	* @args data This argument is a pointeur to the callbacks struct that
> > > +	*            has been passed to the lib.
> > > +	* @args relative_folder_path This argument represents a relative path
> > > +	*            to the channel folder. This path is relative to the root
> > > +	*            folder of the trace channels.
> > > +	*
> > > +	* @return Should return 0 if the callback succeeds else not 0.
> > > +	*/
> > > +	int(*on_new_channels_folder)(struct liblttd_callbacks *data,
> > > +		char *relative_folder_path);
> > > +
> > > +	/**
> > > +	* This callback is called after a subbuffer is a reserved.
> > > +	*
> > > +	* @attention It has to be thread safe, it'll be called by many threads.
> > > +	*
> > > +	* @args data This argument is a pointeur to the callbacks struct that
> > > +	*            has been passed to the lib.
> > > +	* @args pair This structure contains the data associated with the
> > > +	*            channel file descriptor. The lib user should clean
> > > +	*            user_data at this time.
> > > +	* @args len This argument represents the length the data that has to be
> > > +	*            read.
> > > +	*
> > > +	* @return Should return 0 if the callback succeeds else not 0.
> > > +	*/
> > > +	int(*on_read_subbuffer)(struct liblttd_callbacks *data,
> > > +		struct fd_pair *pair, unsigned int len);
> > > +
> > > +	/**
> > > +	* This callback is called at the very end of the tracing session. At
> > > +	* this time, all the channels have been closed and the threads have been
> > > +	* destroyed.
> > > +	*
> > > +	* @remarks After this callback is called, no other callback will be
> > > +	*            called again.
> > > +	*
> > > +	* @attention It has to be thread safe, it'll be called by many threads.
> > > +	*
> > > +	* @args data This argument is a pointeur to the callbacks struct that
> > > +	*            has been passed to the lib.
> > > +	*
> > > +	* @return Should return 0 if the callback succeeds else not 0.
> > > +	*/
> > > +	int(*on_trace_end)(struct liblttd_callbacks *data);
> > > +
> > > +	/**
> > > +	* This callback is called after a new thread has been created.
> > > +	*
> > > +	* @attention It has to be thread safe, it'll be called by many threads.
> > > +	*
> > > +	* @args data This argument is a pointeur to the callbacks struct that
> > > +	*            has been passed to the lib.
> > > +	* @args thread_num This argument represents the id of the thread.
> > > +	*
> > > +	* @return Should return 0 if the callback succeeds else not 0.
> > > +	*/
> > > +	int(*on_new_thread)(struct liblttd_callbacks *data,
> > > +		unsigned long thread_num);
> > > +
> > > +	/**
> > > +	* This callback is called just before a thread is destroyed.
> > > +	*
> > > +	* @attention It has to be thread safe, it'll be called by many threads.
> > > +	*
> > > +	* @args data This argument is a pointeur to the callbacks struct that
> > > +	*            has been passed to the lib.
> > > +	* @args thread_num This argument represents the number of the thread.
> > > +	*
> > > +	* @return Should return 0 if the callback succeeds else not 0.
> > > +	*/
> > > +	int(*on_close_thread)(struct liblttd_callbacks *data,
> > > +		unsigned long thread_num);
> > > +
> > > +	/**
> > > +	* This is where the user can put the library's data.
> > > +	*/
> > > +	void *user_data;
> > > +};
> > > +
> > > +/**
> > > +* This function is called to start a new tracing session.
> > > +*
> > > +* @attention It has to be thread safe, it'll be called by many threads.
> > > +*
> > > +* @args channel_path This argument is a path to the root folder of the trace's
> > > +*            channels.
> > > +* @args n_threads This argument represents the number of threads that will be
> > > +*            used by the library.
> > > +* @args flight_only If this argument to set to 1, only the channel that are in
> > > +*            flight recorder mode will be recorded.
> > > +* @args normal_only If this argument to set to 1, only the channel that are in
> > > +*            normal mode will be recorded.
> > > +* @args verbose If this argument to set to 1, more informations will be printed.
> > > +* @args user_data This argument is a pointeur to the callbacks struct that
> > > +*            contains the user's functions.
> > > +*
> > > +* @return Return 0 if the function succeeds else not 0.
> > > +*/
> > > +int liblttd_start(char *channel_path, unsigned long n_threads,
> > > +	int flight_only, int normal_only, int verbose,
> > > +	struct liblttd_callbacks *user_data);
> > > +
> > > +/**
> > > +* This function is called to stop a tracing session.
> > > +*
> > > +* @return Return 0 if the function succeeds.
> > > +*/
> > > +int liblttd_stop();
> > > +
> > > +#endif /*_LIBLTTD_H */
> > > +
> > > diff --git a/lttd/Makefile.am b/lttd/Makefile.am
> > > index bb860bc..fc9b219 100644
> > > --- a/lttd/Makefile.am
> > > +++ b/lttd/Makefile.am
> > > @@ -6,3 +6,6 @@ bin_PROGRAMS = lttd
> > >  
> > >  lttd_SOURCES = lttd.c
> > >  
> > > +lttd_DEPENDENCIES = ../liblttd/liblttd.la
> > > +lttd_LDADD = $(lttd_DEPENDENCIES)
> > > +
> > > diff --git a/lttd/lttd.c b/lttd/lttd.c
> > > index 78c2c80..ec757ae 100644
> > > --- a/lttd/lttd.c
> > > +++ b/lttd/lttd.c
> > > @@ -30,125 +30,36 @@
> > >  
> > >  #define _REENTRANT
> > >  #define _GNU_SOURCE
> > > -#include <features.h>
> > > +
> > >  #include <stdio.h>
> > > -#include <unistd.h>
> > > -#include <errno.h>
> > > -#include <sys/types.h>
> > > -#include <sys/stat.h>
> > >  #include <stdlib.h>
> > > -#include <dirent.h>
> > >  #include <string.h>
> > > -#include <fcntl.h>
> > > -#include <sys/poll.h>
> > > -#include <sys/mman.h>
> > >  #include <signal.h>
> > > -#include <pthread.h>
> > > -#include <sys/syscall.h>
> > > -#include <unistd.h>
> > > -#include <asm/ioctls.h>
> > > -
> > > -#include <linux/version.h>
> > > -
> > > -/* Relayfs IOCTL */
> > > -#include <asm/ioctl.h>
> > > -#include <asm/types.h>
> > > -
> > > -/* Get the next sub buffer that can be read. */
> > > -#define RELAY_GET_SB		_IOR(0xF5, 0x00,__u32)
> > > -/* Release the oldest reserved (by "get") sub buffer. */
> > > -#define RELAY_PUT_SB		_IOW(0xF5, 0x01,__u32)
> > > -/* returns the number of sub buffers in the per cpu channel. */
> > > -#define RELAY_GET_N_SB		_IOR(0xF5, 0x02,__u32)
> > > -/* returns the size of the current sub buffer. */
> > > -#define RELAY_GET_SB_SIZE	_IOR(0xF5, 0x03, __u32)
> > > -/* returns the size of data to consume in the current sub-buffer. */
> > > -#define RELAY_GET_MAX_SB_SIZE	_IOR(0xF5, 0x04, __u32)
> > > -
> > > -
> > > -#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,14)
> > > -#include <sys/inotify.h>
> > > -#if 0	/* should now be provided by libc. */
> > > -/* From the inotify-tools 2.6 package */
> > > -static inline int inotify_init (void)
> > > -{
> > > -	return syscall (__NR_inotify_init);
> > > -}
> > > -
> > > -static inline int inotify_add_watch (int fd, const char *name, __u32 mask)
> > > -{
> > > -	return syscall (__NR_inotify_add_watch, fd, name, mask);
> > > -}
> > > -
> > > -static inline int inotify_rm_watch (int fd, __u32 wd)
> > > -{
> > > -	return syscall (__NR_inotify_rm_watch, fd, wd);
> > > -}
> > > -#endif //0
> > > -#define HAS_INOTIFY
> > > -#else
> > > -static inline int inotify_init (void)
> > > -{
> > > -	return -1;
> > > -}
> > > +#include <errno.h>
> > > +#include <fcntl.h>
> > > +#include <dirent.h>
> > > +#include <sys/stat.h>
> > >  
> > > -static inline int inotify_add_watch (int fd, const char *name, __u32 mask)
> > > -{
> > > -	return 0;
> > > -}
> > > +#include <liblttd/liblttd.h>
> > >  
> > > -static inline int inotify_rm_watch (int fd, __u32 wd)
> > > -{
> > > -	return 0;
> > > -}
> > > -#undef HAS_INOTIFY
> > > -#endif
> > > -
> > > -struct fd_pair {
> > > -	int channel;
> > > +struct lttd_channel_data {
> > >  	int trace;
> > > -	unsigned int n_sb;
> > > -	unsigned int max_sb_size;
> > > -	void *mmap;
> > > -	pthread_mutex_t	mutex;
> > > -};
> > > -
> > > -struct channel_trace_fd {
> > > -	struct fd_pair *pair;
> > > -	int num_pairs;
> > > -};
> > > -
> > > -struct inotify_watch {
> > > -	int wd;
> > > -	char path_channel[PATH_MAX];
> > > -	char path_trace[PATH_MAX];
> > > -};
> > > -
> > > -struct inotify_watch_array {
> > > -	struct inotify_watch *elem;
> > > -	int num;
> > >  };
> > >  
> > > -static __thread int thread_pipe[2];
> > > -
> > > -struct channel_trace_fd fd_pairs = { NULL, 0 };
> > > -int inotify_fd = -1;
> > > -struct inotify_watch_array inotify_watch_array = { NULL, 0 };
> > > -
> > > -/* protects fd_pairs and inotify_watch_array */
> > > -pthread_rwlock_t fd_pairs_lock = PTHREAD_RWLOCK_INITIALIZER;
> > > -
> > > -
> > > +static char		path_trace[PATH_MAX];
> > > +static char		*end_path_trace;
> > > +static int		path_trace_len = 0;
> > >  static char		*trace_name = NULL;
> > >  static char		*channel_name = NULL;
> > >  static int		daemon_mode = 0;
> > >  static int		append_mode = 0;
> > >  static unsigned long	num_threads = 1;
> > > -volatile static int	quit_program = 0;	/* For signal handler */
> > >  static int		dump_flight_only = 0;
> > >  static int		dump_normal_only = 0;
> > >  static int		verbose_mode = 0;
> > >  
> > > +static __thread int thread_pipe[2];
> > > +
> > >  #define printf_verbose(fmt, args...) \
> > >    do {                               \
> > >      if (verbose_mode)                \
> > > @@ -191,7 +102,7 @@ int parse_arguments(int argc, char **argv)
> > >  {
> > >  	int ret = 0;
> > >  	int argn = 1;
> > > -	
> > > +
> > >  	if(argc == 2) {
> > >  		if(strcmp(argv[1], "-h") == 0) {
> > >  			return 1;
> > > @@ -249,19 +160,19 @@ int parse_arguments(int argc, char **argv)
> > >  		}
> > >  		argn++;
> > >  	}
> > > -	
> > > +
> > >  	if(trace_name == NULL) {
> > >  		printf("Please specify a trace name.\n");
> > >  		printf("\n");
> > >  		ret = -1;
> > >  	}
> > > -	
> > > +
> > >  	if(channel_name == NULL) {
> > >  		printf("Please specify a channel name.\n");
> > >  		printf("\n");
> > >  		ret = -1;
> > >  	}
> > > -	
> > > +
> > >  	return ret;
> > >  }
> > >  
> > > @@ -280,223 +191,96 @@ void show_info(void)
> > >  static void handler(int signo)
> > >  {
> > >  	printf("Signal %d received : exiting cleanly\n", signo);
> > > -	quit_program = 1;
> > > +	liblttd_stop();
> > >  }
> > >  
> > > -
> > > -int open_buffer_file(char *filename, char *path_channel, char *path_trace,
> > > -	struct channel_trace_fd *fd_pairs)
> > > +int lttd_on_open_channel(struct liblttd_callbacks *data, struct fd_pair *pair, char *relative_channel_path)
> > >  {
> > >  	int open_ret = 0;
> > > -	int ret = 0;
> > > +	int ret;
> > >  	struct stat stat_buf;
> > > +	struct lttd_channel_data *channel_data;
> > >  
> > > -	if(strncmp(filename, "flight-", sizeof("flight-")-1) != 0) {
> > > -		if(dump_flight_only) {
> > > -			printf_verbose("Skipping normal channel %s\n",
> > > -				path_channel);
> > > -			return 0;
> > > -		}
> > > -	} else {
> > > -		if(dump_normal_only) {
> > > -			printf_verbose("Skipping flight channel %s\n",
> > > -				path_channel);
> > > -			return 0;
> > > -		}
> > > -	}
> > > -	printf_verbose("Opening file.\n");
> > > -	
> > > -	fd_pairs->pair = realloc(fd_pairs->pair,
> > > -			++fd_pairs->num_pairs * sizeof(struct fd_pair));
> > > +	pair->user_data = malloc(sizeof(struct lttd_channel_data));
> > > +	channel_data = pair->user_data;
> > > +
> > > +	strncpy(end_path_trace, relative_channel_path, PATH_MAX - path_trace_len);
> > > +	printf_verbose("Creating trace file %s\n", path_trace);
> > >  
> > > -	/* Open the channel in read mode */
> > > -	fd_pairs->pair[fd_pairs->num_pairs-1].channel = 
> > > -		open(path_channel, O_RDONLY | O_NONBLOCK);
> > > -	if(fd_pairs->pair[fd_pairs->num_pairs-1].channel == -1) {
> > > -		perror(path_channel);
> > > -		fd_pairs->num_pairs--;
> > > -		return 0;	/* continue */
> > > -	}
> > > -	/* Open the trace in write mode, only append if append_mode */
> > >  	ret = stat(path_trace, &stat_buf);
> > >  	if(ret == 0) {
> > >  		if(append_mode) {
> > >  			printf_verbose("Appending to file %s as requested\n",
> > >  				path_trace);
> > >  
> > > -			fd_pairs->pair[fd_pairs->num_pairs-1].trace = 
> > > -				open(path_trace, O_WRONLY,
> > > -						S_IRWXU|S_IRWXG|S_IRWXO);
> > > -			if(fd_pairs->pair[fd_pairs->num_pairs-1].trace == -1) {
> > > +			channel_data->trace = open(path_trace, O_WRONLY, S_IRWXU|S_IRWXG|S_IRWXO);
> > > +			if(channel_data->trace == -1) {
> > >  				perror(path_trace);
> > >  				open_ret = -1;
> > > -				close(fd_pairs->pair[fd_pairs->num_pairs-1].channel);
> > > -				fd_pairs->num_pairs--;
> > >  				goto end;
> > >  			}
> > > -			ret = lseek(fd_pairs->pair[fd_pairs->num_pairs-1].trace,
> > > -				    0, SEEK_END);
> > > +			ret = lseek(channel_data->trace, 0, SEEK_END);
> > >  			if (ret < 0) {
> > >  				perror(path_trace);
> > >  				open_ret = -1;
> > > -				close(fd_pairs->pair[fd_pairs->num_pairs-1].channel);
> > > -				close(fd_pairs->pair[fd_pairs->num_pairs-1].trace);
> > > -				fd_pairs->num_pairs--;
> > > +				close(channel_data->trace);
> > >  				goto end;
> > >  			}
> > >  		} else {
> > >  			printf("File %s exists, cannot open. Try append mode.\n", path_trace);
> > >  			open_ret = -1;
> > > -			close(fd_pairs->pair[fd_pairs->num_pairs-1].channel);
> > > -			fd_pairs->num_pairs--;
> > >  			goto end;
> > >  		}
> > >  	} else {
> > >  		if(errno == ENOENT) {
> > > -			fd_pairs->pair[fd_pairs->num_pairs-1].trace = 
> > > -				open(path_trace, O_WRONLY|O_CREAT|O_EXCL,
> > > -						S_IRWXU|S_IRWXG|S_IRWXO);
> > > -			if(fd_pairs->pair[fd_pairs->num_pairs-1].trace == -1) {
> > > +			channel_data->trace = open(path_trace, O_WRONLY|O_CREAT|O_EXCL, S_IRWXU|S_IRWXG|S_IRWXO);
> > > +			if(channel_data->trace == -1) {
> > >  				perror(path_trace);
> > >  				open_ret = -1;
> > > -				close(fd_pairs->pair[fd_pairs->num_pairs-1].channel);
> > > -				fd_pairs->num_pairs--;
> > >  				goto end;
> > >  			}
> > >  		}
> > >  	}
> > > +
> > >  end:
> > >  	return open_ret;
> > > +
> > >  }
> > >  
> > > -int open_channel_trace_pairs(char *subchannel_name, char *subtrace_name,
> > > -		struct channel_trace_fd *fd_pairs, int *inotify_fd,
> > > -		struct inotify_watch_array *iwatch_array)
> > > +int lttd_on_close_channel(struct liblttd_callbacks *data, struct fd_pair *pair)
> > > +{
> > > +	int ret;
> > > +	ret = close(((struct lttd_channel_data *)(pair->user_data))->trace);
> > > +	free(pair->user_data);
> > > +	return ret;
> > > +}
> > > +
> > > +int lttd_on_new_channels_folder(struct liblttd_callbacks *data, char *relative_folder_path)
> > >  {
> > > -	DIR *channel_dir = opendir(subchannel_name);
> > > -	struct dirent *entry;
> > > -	struct stat stat_buf;
> > >  	int ret;
> > > -	char path_channel[PATH_MAX];
> > > -	int path_channel_len;
> > > -	char *path_channel_ptr;
> > > -	char path_trace[PATH_MAX];
> > > -	int path_trace_len;
> > > -	char *path_trace_ptr;
> > >  	int open_ret = 0;
> > >  
> > > -	if(channel_dir == NULL) {
> > > -		perror(subchannel_name);
> > > -		open_ret = ENOENT;
> > > -		goto end;
> > > -	}
> > > +	strncpy(end_path_trace, relative_folder_path, PATH_MAX - path_trace_len);
> > > +	printf_verbose("Creating trace subdirectory %s\n", path_trace);
> > >  
> > > -	printf_verbose("Creating trace subdirectory %s\n", subtrace_name);
> > > -	ret = mkdir(subtrace_name, S_IRWXU|S_IRWXG|S_IRWXO);
> > > +	ret = mkdir(path_trace, S_IRWXU|S_IRWXG|S_IRWXO);
> > >  	if(ret == -1) {
> > >  		if(errno != EEXIST) {
> > > -			perror(subtrace_name);
> > > +			perror(path_trace);
> > >  			open_ret = -1;
> > >  			goto end;
> > >  		}
> > >  	}
> > >  
> > > -	strncpy(path_channel, subchannel_name, PATH_MAX-1);
> > > -	path_channel_len = strlen(path_channel);
> > > -	path_channel[path_channel_len] = '/';
> > > -	path_channel_len++;
> > > -	path_channel_ptr = path_channel + path_channel_len;
> > > -
> > > -	strncpy(path_trace, subtrace_name, PATH_MAX-1);
> > > -	path_trace_len = strlen(path_trace);
> > > -	path_trace[path_trace_len] = '/';
> > > -	path_trace_len++;
> > > -	path_trace_ptr = path_trace + path_trace_len;
> > > -	
> > > -#ifdef HAS_INOTIFY
> > > -	iwatch_array->elem = realloc(iwatch_array->elem,
> > > -		++iwatch_array->num * sizeof(struct inotify_watch));
> > > -	
> > > -	printf_verbose("Adding inotify for channel %s\n", path_channel);
> > > -	iwatch_array->elem[iwatch_array->num-1].wd = inotify_add_watch(*inotify_fd, path_channel, IN_CREATE);
> > > -	strcpy(iwatch_array->elem[iwatch_array->num-1].path_channel, path_channel);
> > > -	strcpy(iwatch_array->elem[iwatch_array->num-1].path_trace, path_trace);
> > > -	printf_verbose("Added inotify for channel %s, wd %u\n",
> > > -		iwatch_array->elem[iwatch_array->num-1].path_channel,
> > > -		iwatch_array->elem[iwatch_array->num-1].wd);
> > > -#endif
> > > -
> > > -	while((entry = readdir(channel_dir)) != NULL) {
> > > -
> > > -		if(entry->d_name[0] == '.') continue;
> > > -		
> > > -		strncpy(path_channel_ptr, entry->d_name, PATH_MAX - path_channel_len);
> > > -		strncpy(path_trace_ptr, entry->d_name, PATH_MAX - path_trace_len);
> > > -		
> > > -		ret = stat(path_channel, &stat_buf);
> > > -		if(ret == -1) {
> > > -			perror(path_channel);
> > > -			continue;
> > > -		}
> > > -		
> > > -		printf_verbose("Channel file : %s\n", path_channel);
> > > -		
> > > -		if(S_ISDIR(stat_buf.st_mode)) {
> > > -
> > > -			printf_verbose("Entering channel subdirectory...\n");
> > > -			ret = open_channel_trace_pairs(path_channel, path_trace, fd_pairs,
> > > -				inotify_fd, iwatch_array);
> > > -			if(ret < 0) continue;
> > > -		} else if(S_ISREG(stat_buf.st_mode)) {
> > > -			open_ret = open_buffer_file(entry->d_name, path_channel, path_trace,
> > > -				fd_pairs);
> > > -			if(open_ret)
> > > -				goto end;
> > > -		}
> > > -	}
> > > -	
> > >  end:
> > > -	closedir(channel_dir);
> > > -
> > >  	return open_ret;
> > >  }
> > >  
> > > -
> > > -int read_subbuffer(struct fd_pair *pair)
> > > +int lttd_on_read_subbuffer(struct liblttd_callbacks *data, struct fd_pair *pair, unsigned int len)
> > >  {
> > > -	unsigned int consumed_old, len;
> > > -	int err;
> > >  	long ret;
> > > -	off_t offset;
> > > -
> > > +	off_t offset = 0;
> > >  
> > > -	err = ioctl(pair->channel, RELAY_GET_SB, &consumed_old);
> > > -	printf_verbose("cookie : %u\n", consumed_old);
> > > -	if(err != 0) {
> > > -		ret = errno;
> > > -		perror("Reserving sub buffer failed (everything is normal, it is due to concurrency)");
> > > -		goto get_error;
> > > -	}
> > > -#if 0
> > > -	err = TEMP_FAILURE_RETRY(write(pair->trace,
> > > -				pair->mmap 
> > > -					+ (consumed_old & ((pair->n_subbufs * pair->subbuf_size)-1)),
> > > -				pair->subbuf_size));
> > > -
> > > -	if(err < 0) {
> > > -		ret = errno;
> > > -		perror("Error in writing to file");
> > > -		goto write_error;
> > > -	}
> > > -#endif //0
> > > -	err = ioctl(pair->channel, RELAY_GET_SB_SIZE, &len);
> > > -	if(err != 0) {
> > > -		ret = errno;
> > > -		perror("Getting sub-buffer len failed.");
> > > -		goto get_error;
> > > -	}
> > > -
> > > -	offset = 0;
> > >  	while (len > 0) {
> > >  		printf_verbose("splice chan to pipe offset %lu\n",
> > >  			(unsigned long)offset);
> > > @@ -507,8 +291,9 @@ int read_subbuffer(struct fd_pair *pair)
> > >  			perror("Error in relay splice");
> > >  			goto write_error;
> > >  		}
> > > -		ret = splice(thread_pipe[0], NULL, pair->trace, NULL,
> > > -			ret, SPLICE_F_MOVE | SPLICE_F_MORE);
> > > +		ret = splice(thread_pipe[0], NULL,
> > > +			((struct lttd_channel_data *)(pair->user_data))->trace,
> > > +			NULL, ret, SPLICE_F_MOVE | SPLICE_F_MORE);
> > >  		printf_verbose("splice pipe to file %ld\n", ret);
> > >  		if (ret < 0) {
> > >  			perror("Error in file splice");
> > > @@ -517,466 +302,42 @@ int read_subbuffer(struct fd_pair *pair)
> > >  		len -= ret;
> > >  	}
> > >  
> > > -#if 0
> > > -	err = fsync(pair->trace);
> > > -	if(err < 0) {
> > > -		ret = errno;
> > > -		perror("Error in writing to file");
> > > -		goto write_error;
> > > -	}
> > > -#endif //0
> > >  write_error:
> > > -	ret = 0;
> > > -	err = ioctl(pair->channel, RELAY_PUT_SB, &consumed_old);
> > > -	if(err != 0) {
> > > -		ret = errno;
> > > -		if(errno == EFAULT) {
> > > -			perror("Error in unreserving sub buffer\n");
> > > -		} else if(errno == EIO) {
> > > -			/* Should never happen with newer LTTng versions */
> > > -			perror("Reader has been pushed by the writer, last sub-buffer corrupted.");
> > > -		}
> > > -		goto get_error;
> > > -	}
> > > -
> > > -get_error:
> > > -	return ret;
> > > -}
> > > -
> > > -
> > > -int map_channels(struct channel_trace_fd *fd_pairs,
> > > -	int idx_begin, int idx_end)
> > > -{
> > > -	int i,j;
> > > -	int ret=0;
> > > -
> > > -	if(fd_pairs->num_pairs <= 0) {
> > > -		printf("No channel to read\n");
> > > -		goto end;
> > > -	}
> > > -	
> > > -	/* Get the subbuf sizes and number */
> > > -
> > > -	for(i=idx_begin;i<idx_end;i++) {
> > > -		struct fd_pair *pair = &fd_pairs->pair[i];
> > > -
> > > -		ret = ioctl(pair->channel, RELAY_GET_N_SB, &pair->n_sb);
> > > -		if(ret != 0) {
> > > -			perror("Error in getting the number of sub-buffers");
> > > -			goto end;
> > > -		}
> > > -		ret = ioctl(pair->channel, RELAY_GET_MAX_SB_SIZE, 
> > > -			    &pair->max_sb_size);
> > > -		if(ret != 0) {
> > > -			perror("Error in getting the max sub-buffer size");
> > > -			goto end;
> > > -		}
> > > -		ret = pthread_mutex_init(&pair->mutex, NULL);	/* Fast mutex */
> > > -		if(ret != 0) {
> > > -			perror("Error in mutex init");
> > > -			goto end;
> > > -		}
> > > -	}
> > > -
> > > -#if 0
> > > -	/* Mmap each FD */
> > > -	for(i=idx_begin;i<idx_end;i++) {
> > > -		struct fd_pair *pair = &fd_pairs->pair[i];
> > > -
> > > -		pair->mmap = mmap(0, pair->subbuf_size * pair->n_subbufs, PROT_READ,
> > > -				MAP_SHARED, pair->channel, 0);
> > > -		if(pair->mmap == MAP_FAILED) {
> > > -			perror("Mmap error");
> > > -			goto munmap;
> > > -		}
> > > -	}
> > > -
> > > -	goto end; /* success */
> > > -
> > > -	/* Error handling */
> > > -	/* munmap only the successfully mmapped indexes */
> > > -munmap:
> > > -		/* Munmap each FD */
> > > -	for(j=idx_begin;j<i;j++) {
> > > -		struct fd_pair *pair = &fd_pairs->pair[j];
> > > -		int err_ret;
> > > -
> > > -		err_ret = munmap(pair->mmap, pair->subbuf_size * pair->n_subbufs);
> > > -		if(err_ret != 0) {
> > > -			perror("Error in munmap");
> > > -		}
> > > -		ret |= err_ret;
> > > -	}
> > > -
> > > -#endif //0
> > > -end:
> > >  	return ret;
> > >  }
> > >  
> > > -int unmap_channels(struct channel_trace_fd *fd_pairs)
> > > -{
> > > -	int j;
> > > -	int ret=0;
> > > -
> > > -	/* Munmap each FD */
> > > -	for(j=0;j<fd_pairs->num_pairs;j++) {
> > > -		struct fd_pair *pair = &fd_pairs->pair[j];
> > > -		int err_ret;
> > > -
> > > -#if 0
> > > -		err_ret = munmap(pair->mmap, pair->subbuf_size * pair->n_subbufs);
> > > -		if(err_ret != 0) {
> > > -			perror("Error in munmap");
> > > -		}
> > > -		ret |= err_ret;
> > > -#endif //0
> > > -		err_ret = pthread_mutex_destroy(&pair->mutex);
> > > -		if(err_ret != 0) {
> > > -			perror("Error in mutex destroy");
> > > -		}
> > > -		ret |= err_ret;
> > > -	}
> > > -
> > > -	return ret;
> > > -}
> > > -
> > > -#ifdef HAS_INOTIFY
> > > -/* Inotify event arrived.
> > > - *
> > > - * Only support add file for now.
> > > - */
> > > -
> > > -int read_inotify(int inotify_fd,
> > > -	struct channel_trace_fd *fd_pairs,
> > > -	struct inotify_watch_array *iwatch_array)
> > > -{
> > > -	char buf[sizeof(struct inotify_event) + PATH_MAX];
> > > -	char path_channel[PATH_MAX];
> > > -	char path_trace[PATH_MAX];
> > > -	ssize_t len;
> > > -	struct inotify_event *ievent;
> > > -	size_t offset;
> > > -	unsigned int i;
> > > -	int ret;
> > > -	int old_num;
> > > -	
> > > -	offset = 0;
> > > -	len = read(inotify_fd, buf, sizeof(struct inotify_event) + PATH_MAX);
> > > -	if(len < 0) {
> > > -
> > > -		if(errno == EAGAIN)
> > > -			return 0;  /* another thread got the data before us */
> > > -
> > > -		printf("Error in read from inotify FD %s.\n", strerror(len));
> > > -		return -1;
> > > -	}
> > > -	while(offset < len) {
> > > -		ievent = (struct inotify_event *)&(buf[offset]);
> > > -		for(i=0; i<iwatch_array->num; i++) {
> > > -			if(iwatch_array->elem[i].wd == ievent->wd &&
> > > -				ievent->mask == IN_CREATE) {
> > > -				printf_verbose(
> > > -					"inotify wd %u event mask : %u for %s%s\n",
> > > -					ievent->wd, ievent->mask,
> > > -					iwatch_array->elem[i].path_channel,
> > > -					ievent->name);
> > > -				old_num = fd_pairs->num_pairs;
> > > -				strcpy(path_channel, iwatch_array->elem[i].path_channel);
> > > -				strcat(path_channel, ievent->name);
> > > -				strcpy(path_trace, iwatch_array->elem[i].path_trace);
> > > -				strcat(path_trace, ievent->name);
> > > -				if(ret = open_buffer_file(ievent->name, path_channel,
> > > -					path_trace, fd_pairs)) {
> > > -					printf("Error opening buffer file\n");
> > > -					return -1;
> > > -				}
> > > -				if(ret = map_channels(fd_pairs, old_num, fd_pairs->num_pairs)) {
> > > -					printf("Error mapping channel\n");
> > > -					return -1;
> > > -				}
> > > -
> > > -			}
> > > -		}
> > > -		offset += sizeof(*ievent) + ievent->len;
> > > -	}
> > > -}
> > > -#endif //HAS_INOTIFY
> > > -
> > > -/* read_channels
> > > - *
> > > - * Thread worker.
> > > - *
> > > - * Read the debugfs channels and write them in the paired tracefiles.
> > > - *
> > > - * @fd_pairs : paired channels and trace files.
> > > - *
> > > - * returns 0 on success, -1 on error.
> > > - *
> > > - * Note that the high priority polled channels are consumed first. We then poll
> > > - * again to see if these channels are still in priority. Only when no
> > > - * high priority channel is left, we start reading low priority channels.
> > > - *
> > > - * Note that a channel is considered high priority when the buffer is almost
> > > - * full.
> > > - */
> > > -
> > > -int read_channels(unsigned long thread_num, struct channel_trace_fd *fd_pairs,
> > > -	int inotify_fd, struct inotify_watch_array *iwatch_array)
> > > -{
> > > -	struct pollfd *pollfd = NULL;
> > > -	int num_pollfd;
> > > -	int i,j;
> > > -	int num_rdy, num_hup;
> > > -	int high_prio;
> > > -	int ret = 0;
> > > -	int inotify_fds;
> > > -	unsigned int old_num;
> > > -
> > > -#ifdef HAS_INOTIFY
> > > -	inotify_fds = 1;
> > > -#else
> > > -	inotify_fds = 0;
> > > -#endif
> > > -
> > > -	pthread_rwlock_rdlock(&fd_pairs_lock);
> > > -
> > > -	/* Start polling the FD. Keep one fd for inotify */
> > > -	pollfd = malloc((inotify_fds + fd_pairs->num_pairs) * sizeof(struct pollfd));
> > > -
> > > -#ifdef HAS_INOTIFY
> > > -	pollfd[0].fd = inotify_fd;
> > > -	pollfd[0].events = POLLIN|POLLPRI;
> > > -#endif
> > > -
> > > -	for(i=0;i<fd_pairs->num_pairs;i++) {
> > > -		pollfd[inotify_fds+i].fd = fd_pairs->pair[i].channel;
> > > -		pollfd[inotify_fds+i].events = POLLIN|POLLPRI;
> > > -	}
> > > -	num_pollfd = inotify_fds + fd_pairs->num_pairs;
> > > -
> > > -
> > > -	pthread_rwlock_unlock(&fd_pairs_lock);
> > > -
> > > -	while(1) {
> > > -		high_prio = 0;
> > > -		num_hup = 0; 
> > > -#ifdef DEBUG
> > > -		printf("Press a key for next poll...\n");
> > > -		char buf[1];
> > > -		read(STDIN_FILENO, &buf, 1);
> > > -		printf("Next poll (polling %d fd) :\n", num_pollfd);
> > > -#endif //DEBUG
> > > -
> > > -		/* Have we received a signal ? */
> > > -		if(quit_program) break;
> > > -		
> > > -		num_rdy = poll(pollfd, num_pollfd, -1);
> > > -
> > > -		if(num_rdy == -1) {
> > > -			perror("Poll error");
> > > -			goto free_fd;
> > > -		}
> > > -
> > > -		printf_verbose("Data received\n");
> > > -#ifdef HAS_INOTIFY
> > > -		switch(pollfd[0].revents) {
> > > -			case POLLERR:
> > > -				printf_verbose(
> > > -					"Error returned in polling inotify fd %d.\n",
> > > -					pollfd[0].fd);
> > > -				break;
> > > -			case POLLHUP:
> > > -				printf_verbose(
> > > -					"Polling inotify fd %d tells it has hung up.\n",
> > > -					pollfd[0].fd);
> > > -				break;
> > > -			case POLLNVAL:
> > > -				printf_verbose(
> > > -					"Polling inotify fd %d tells fd is not open.\n",
> > > -					pollfd[0].fd);
> > > -				break;
> > > -			case POLLPRI:
> > > -			case POLLIN:
> > > -				printf_verbose(
> > > -					"Polling inotify fd %d : data ready.\n",
> > > -					pollfd[0].fd);
> > > -
> > > -				pthread_rwlock_wrlock(&fd_pairs_lock);
> > > -				read_inotify(inotify_fd, fd_pairs, iwatch_array);
> > > -				pthread_rwlock_unlock(&fd_pairs_lock);
> > > -
> > > -			break;
> > > -		}
> > > -#endif
> > > -
> > > -		for(i=inotify_fds;i<num_pollfd;i++) {
> > > -			switch(pollfd[i].revents) {
> > > -				case POLLERR:
> > > -					printf_verbose(
> > > -						"Error returned in polling fd %d.\n",
> > > -						pollfd[i].fd);
> > > -					num_hup++;
> > > -					break;
> > > -				case POLLHUP:
> > > -					printf_verbose(
> > > -						"Polling fd %d tells it has hung up.\n",
> > > -						pollfd[i].fd);
> > > -					num_hup++;
> > > -					break;
> > > -				case POLLNVAL:
> > > -					printf_verbose(
> > > -						"Polling fd %d tells fd is not open.\n",
> > > -						pollfd[i].fd);
> > > -					num_hup++;
> > > -					break;
> > > -				case POLLPRI:
> > > -					pthread_rwlock_rdlock(&fd_pairs_lock);
> > > -					if(pthread_mutex_trylock(&fd_pairs->pair[i-inotify_fds].mutex) == 0) {
> > > -						printf_verbose(
> > > -							"Urgent read on fd %d\n",
> > > -							pollfd[i].fd);
> > > -						/* Take care of high priority channels first. */
> > > -						high_prio = 1;
> > > -						/* it's ok to have an unavailable sub-buffer */
> > > -						ret = read_subbuffer(&fd_pairs->pair[i-inotify_fds]);
> > > -						if(ret == EAGAIN) ret = 0;
> > > -
> > > -						ret = pthread_mutex_unlock(&fd_pairs->pair[i-inotify_fds].mutex);
> > > -						if(ret)
> > > -							printf("Error in mutex unlock : %s\n", strerror(ret));
> > > -					}
> > > -					pthread_rwlock_unlock(&fd_pairs_lock);
> > > -					break;
> > > -			}
> > > -		}
> > > -		/* If every buffer FD has hung up, we end the read loop here */
> > > -		if(num_hup == num_pollfd - inotify_fds) break;
> > > -
> > > -		if(!high_prio) {
> > > -			for(i=inotify_fds;i<num_pollfd;i++) {
> > > -				switch(pollfd[i].revents) {
> > > -					case POLLIN:
> > > -						pthread_rwlock_rdlock(&fd_pairs_lock);
> > > -						if(pthread_mutex_trylock(&fd_pairs->pair[i-inotify_fds].mutex) == 0) {
> > > -							/* Take care of low priority channels. */
> > > -							printf_verbose(
> > > -								"Normal read on fd %d\n",
> > > -								pollfd[i].fd);
> > > -							/* it's ok to have an unavailable subbuffer */
> > > -							ret = read_subbuffer(&fd_pairs->pair[i-inotify_fds]);
> > > -							if(ret == EAGAIN) ret = 0;
> > > -
> > > -							ret = pthread_mutex_unlock(&fd_pairs->pair[i-inotify_fds].mutex);
> > > -							if(ret)
> > > -								printf("Error in mutex unlock : %s\n", strerror(ret));
> > > -						}
> > > -						pthread_rwlock_unlock(&fd_pairs_lock);
> > > -						break;
> > > -				}
> > > -			}
> > > -		}
> > > -
> > > -		/* Update pollfd array if an entry was added to fd_pairs */
> > > -		pthread_rwlock_rdlock(&fd_pairs_lock);
> > > -		if((inotify_fds + fd_pairs->num_pairs) != num_pollfd) {
> > > -			pollfd = realloc(pollfd,
> > > -					(inotify_fds + fd_pairs->num_pairs) * sizeof(struct pollfd));
> > > -			for(i=num_pollfd-inotify_fds;i<fd_pairs->num_pairs;i++) {
> > > -				pollfd[inotify_fds+i].fd = fd_pairs->pair[i].channel;
> > > -				pollfd[inotify_fds+i].events = POLLIN|POLLPRI;
> > > -			}
> > > -			num_pollfd = fd_pairs->num_pairs + inotify_fds;
> > > -		}
> > > -		pthread_rwlock_unlock(&fd_pairs_lock);
> > > -
> > > -		/* NB: If the fd_pairs structure is updated by another thread from this
> > > -		 *     point forward, the current thread will wait in the poll without
> > > -		 *     monitoring the new channel. However, this thread will add the
> > > -		 *     new channel on next poll (and this should not take too much time
> > > -		 *     on a loaded system).
> > > -		 *
> > > -		 *     This event is quite unlikely and can only occur if a CPU is
> > > -		 *     hot-plugged while multple lttd threads are running.
> > > -		 */
> > > -	}
> > > -
> > > -free_fd:
> > > -	free(pollfd);
> > > -
> > > -end:
> > > -	return ret;
> > > -}
> > > -
> > > -
> > > -void close_channel_trace_pairs(struct channel_trace_fd *fd_pairs, int inotify_fd,
> > > -	struct inotify_watch_array *iwatch_array)
> > > -{
> > > -	int i;
> > > +int on_new_thread(struct liblttd_callbacks *data, unsigned long thread_num) {
> > >  	int ret;
> > > -
> > > -	for(i=0;i<fd_pairs->num_pairs;i++) {
> > > -		ret = close(fd_pairs->pair[i].channel);
> > > -		if(ret == -1) perror("Close error on channel");
> > > -		ret = close(fd_pairs->pair[i].trace);
> > > -		if(ret == -1) perror("Close error on trace");
> > > -	}
> > > -	free(fd_pairs->pair);
> > > -	free(iwatch_array->elem);
> > > -}
> > > -
> > > -/* Thread worker */
> > > -void * thread_main(void *arg)
> > > -{
> > > -	long ret;
> > > -	unsigned long thread_num = (unsigned long)arg;
> > > -
> > >  	ret = pipe(thread_pipe);
> > >  	if (ret < 0) {
> > >  		perror("Error creating pipe");
> > > -		return (void*)ret;
> > > +		return ret;
> > >  	}
> > > -	ret = read_channels(thread_num, &fd_pairs, inotify_fd, &inotify_watch_array);
> > > -	close(thread_pipe[0]);	/* close read end */
> > > -	close(thread_pipe[1]);	/* close write end */
> > > -	return (void*)ret;
> > > +	return 0;
> > >  }
> > >  
> > > -
> > > -int channels_init()
> > > -{
> > > -	int ret = 0;
> > > -
> > > -	inotify_fd = inotify_init();
> > > -	fcntl(inotify_fd, F_SETFL, O_NONBLOCK);
> > > -
> > > -	if(ret = open_channel_trace_pairs(channel_name, trace_name, &fd_pairs,
> > > -			&inotify_fd, &inotify_watch_array))
> > > -		goto close_channel;
> > > -	if (fd_pairs.num_pairs == 0) {
> > > -		printf("No channel available for reading, exiting\n");
> > > -		ret = -ENOENT;
> > > -		goto close_channel;
> > > -	}
> > > -	if(ret = map_channels(&fd_pairs, 0, fd_pairs.num_pairs))
> > > -		goto close_channel;
> > > +int on_close_thread(struct liblttd_callbacks *data, unsigned long thread_num) {
> > > +	close(thread_pipe[0]);	/* close read end */
> > > +	close(thread_pipe[1]);	/* close write end */
> > >  	return 0;
> > > -
> > > -close_channel:
> > > -	close_channel_trace_pairs(&fd_pairs, inotify_fd, &inotify_watch_array);
> > > -	if(inotify_fd >= 0)
> > > -		close(inotify_fd);
> > > -	return ret;
> > >  }
> > >  
> > > -
> > >  int main(int argc, char ** argv)
> > >  {
> > >  	int ret = 0;
> > >  	struct sigaction act;
> > > -	pthread_t *tids;
> > > -	unsigned long i;
> > > -	void *tret;
> > > -	
> > > +
> > > +	struct liblttd_callbacks callbacks = {
> > > +		lttd_on_open_channel,
> > > +		lttd_on_close_channel,
> > > +		lttd_on_new_channels_folder,
> > > +		lttd_on_read_subbuffer,
> > > +		NULL,
> > > +		on_new_thread,
> > > +		on_close_thread,
> > > +		NULL
> > > +	};
> > > +
> > >  	ret = parse_arguments(argc, argv);
> > >  
> > >  	if(ret != 0) show_arguments();
> > > @@ -996,9 +357,6 @@ int main(int argc, char ** argv)
> > >  	sigaction(SIGQUIT, &act, NULL);
> > >  	sigaction(SIGINT, &act, NULL);
> > >  
> > > -	if(ret = channels_init())
> > > -		return ret;
> > > -
> > >  	if(daemon_mode) {
> > >  		ret = daemon(0, 0);
> > >  
> > > @@ -1008,33 +366,13 @@ int main(int argc, char ** argv)
> > >  		}
> > >  	}
> > >  
> > > -	tids = malloc(sizeof(pthread_t) * num_threads);
> > > -	for(i=0; i<num_threads; i++) {
> > > -
> > > -		ret = pthread_create(&tids[i], NULL, thread_main, (void*)i);
> > > -		if(ret) {
> > > -			perror("Error creating thread");
> > > -			break;
> > > -		}
> > > -	}
> > > +	strncpy(path_trace, trace_name, PATH_MAX-1);
> > > +	path_trace_len = strlen(path_trace);
> > > +	end_path_trace = path_trace + path_trace_len;
> > >  
> > > -	for(i=0; i<num_threads; i++) {
> > > -		ret = pthread_join(tids[i], &tret);
> > > -		if(ret) {
> > > -			perror("Error joining thread");
> > > -			break;
> > > -		}
> > > -		if((long)tret != 0) {
> > > -			printf("Error %s occured in thread %u\n",
> > > -				strerror((long)tret), i);
> > > -		}
> > > -	}
> > > +	liblttd_start(channel_name, num_threads, dump_flight_only, dump_normal_only,
> > > +		verbose_mode, &callbacks);
> > >  
> > > -	free(tids);
> > > -	ret = unmap_channels(&fd_pairs);
> > > -	close_channel_trace_pairs(&fd_pairs, inotify_fd, &inotify_watch_array);
> > > -	if(inotify_fd >= 0)
> > > -		close(inotify_fd);
> > > -			
> > >  	return ret;
> > >  }
> > > +
> > 
> > > diff --git a/liblttd/liblttd.c b/liblttd/liblttd.c
> > > index 0f0e5b5..0f703f5 100644
> > > --- a/liblttd/liblttd.c
> > > +++ b/liblttd/liblttd.c
> > > @@ -75,8 +75,6 @@ static inline int inotify_rm_watch (int fd, __u32 wd)
> > >  #undef HAS_INOTIFY
> > >  #endif
> > >  
> > > -struct liblttd_callbacks *callbacks;
> > > -
> > >  struct channel_trace_fd {
> > >  	struct fd_pair *pair;
> > >  	int num_pairs;
> > > @@ -93,41 +91,50 @@ struct inotify_watch_array {
> > >  	int num;
> > >  };
> > >  
> > > -struct channel_trace_fd fd_pairs = { NULL, 0 };
> > > -int inotify_fd = -1;
> > > -struct inotify_watch_array inotify_watch_array = { NULL, 0 };
> > > +struct liblttd_instance {
> > > +	struct liblttd_callbacks *callbacks;
> > > +
> > > +	int inotify_fd;
> > > +	struct channel_trace_fd fd_pairs;
> > > +	struct inotify_watch_array inotify_watch_array;
> > >  
> > > -/* protects fd_pairs and inotify_watch_array */
> > > -pthread_rwlock_t fd_pairs_lock = PTHREAD_RWLOCK_INITIALIZER;
> > > +	/* protects fd_pairs and inotify_watch_array */
> > > +	pthread_rwlock_t fd_pairs_lock;
> > >  
> > > -static char		*channel_name = NULL;
> > > -static unsigned long	num_threads = 1;
> > > -volatile static int	quit_program = 0;	/* For signal handler */
> > > -static int		dump_flight_only = 0;
> > > -static int		dump_normal_only = 0;
> > > -static int		verbose_mode = 0;
> > > +	char		channel_name[PATH_MAX];
> > > +	unsigned long	num_threads;
> > > +	int		quit_program;	/* For signal handler */
> > > +	int		dump_flight_only;
> > > +	int		dump_normal_only;
> > > +	int		verbose_mode;
> > > +};
> > > +
> > > +struct liblttd_thread_data {
> > > +	int thread_num;
> > > +	struct liblttd_instance *instance;
> > > +};
> > >  
> > >  #define printf_verbose(fmt, args...) \
> > >    do {                               \
> > > -    if (verbose_mode)                \
> > > +    if (instance->verbose_mode)      \
> > >        printf(fmt, ##args);           \
> > >    } while (0)
> > >  
> > >  
> > > -int open_buffer_file(char *filename, char *path_channel,
> > > -	char *base_path_channel, struct channel_trace_fd *fd_pairs)
> > > +int open_buffer_file(struct liblttd_instance *instance, char *filename,
> > > +	char *path_channel, char *base_path_channel)
> > >  {
> > >  	int open_ret = 0;
> > >  	int ret = 0;
> > >  
> > >  	if(strncmp(filename, "flight-", sizeof("flight-")-1) != 0) {
> > > -		if(dump_flight_only) {
> > > +		if(instance->dump_flight_only) {
> > >  			printf_verbose("Skipping normal channel %s\n",
> > >  				path_channel);
> > >  			return 0;
> > >  		}
> > >  	} else {
> > > -		if(dump_normal_only) {
> > > +		if(instance->dump_normal_only) {
> > >  			printf_verbose("Skipping flight channel %s\n",
> > >  				path_channel);
> > >  			return 0;
> > > @@ -135,26 +142,26 @@ int open_buffer_file(char *filename, char *path_channel,
> > >  	}
> > >  	printf_verbose("Opening file.\n");
> > >  
> > > -	fd_pairs->pair = realloc(fd_pairs->pair,
> > > -			++fd_pairs->num_pairs * sizeof(struct fd_pair));
> > > +	instance->fd_pairs.pair = realloc(instance->fd_pairs.pair,
> > > +			++instance->fd_pairs.num_pairs * sizeof(struct fd_pair));
> > >  
> > >  	/* Open the channel in read mode */
> > > -	fd_pairs->pair[fd_pairs->num_pairs-1].channel =
> > > +	instance->fd_pairs.pair[instance->fd_pairs.num_pairs-1].channel =
> > >  		open(path_channel, O_RDONLY | O_NONBLOCK);
> > > -	if(fd_pairs->pair[fd_pairs->num_pairs-1].channel == -1) {
> > > +	if(instance->fd_pairs.pair[instance->fd_pairs.num_pairs-1].channel == -1) {
> > >  		perror(path_channel);
> > > -		fd_pairs->num_pairs--;
> > > +		instance->fd_pairs.num_pairs--;
> > >  		return 0;	/* continue */
> > >  	}
> > >  
> > > -	if(callbacks->on_open_channel) ret = callbacks->on_open_channel(
> > > -			callbacks, &fd_pairs->pair[fd_pairs->num_pairs-1],
> > > +	if(instance->callbacks->on_open_channel) ret = instance->callbacks->on_open_channel(
> > > +			instance->callbacks, &instance->fd_pairs.pair[instance->fd_pairs.num_pairs-1],
> > >  			base_path_channel);
> > >  
> > >  	if(ret != 0) {
> > >  		open_ret = -1;
> > > -		close(fd_pairs->pair[fd_pairs->num_pairs-1].channel);
> > > -		fd_pairs->num_pairs--;
> > > +		close(instance->fd_pairs.pair[instance->fd_pairs.num_pairs-1].channel);
> > > +		instance->fd_pairs.num_pairs--;
> > >  		goto end;
> > >  	}
> > >  
> > > @@ -162,10 +169,8 @@ end:
> > >  	return open_ret;
> > >  }
> > >  
> > > -int open_channel_trace_pairs(char *subchannel_name,
> > > -		char *base_subchannel_name,
> > > -		struct channel_trace_fd *fd_pairs, int *inotify_fd,
> > > -		struct inotify_watch_array *iwatch_array)
> > > +int open_channel_trace_pairs(struct liblttd_instance *instance,
> > > +	char *subchannel_name, char *base_subchannel_name)
> > >  {
> > >  	DIR *channel_dir = opendir(subchannel_name);
> > >  	struct dirent *entry;
> > > @@ -184,9 +189,9 @@ int open_channel_trace_pairs(char *subchannel_name,
> > >  		goto end;
> > >  	}
> > >  
> > > -	printf_verbose("Calling on new channels folder");
> > > -	if(callbacks->on_new_channels_folder) ret = callbacks->
> > > -			on_new_channels_folder(callbacks,
> > > +	printf_verbose("Calling on new channels folder\n");
> > > +	if(instance->callbacks->on_new_channels_folder) ret = instance->callbacks->
> > > +			on_new_channels_folder(instance->callbacks,
> > >  			base_subchannel_name);
> > >  	if(ret == -1) {
> > >  		open_ret = -1;
> > > @@ -202,18 +207,18 @@ int open_channel_trace_pairs(char *subchannel_name,
> > >  		(base_subchannel_name - subchannel_name);
> > >  
> > >  #ifdef HAS_INOTIFY
> > > -	iwatch_array->elem = realloc(iwatch_array->elem,
> > > -		++iwatch_array->num * sizeof(struct inotify_watch));
> > > +	instance->inotify_watch_array.elem = realloc(instance->inotify_watch_array.elem,
> > > +		++instance->inotify_watch_array.num * sizeof(struct inotify_watch));
> > >  
> > >  	printf_verbose("Adding inotify for channel %s\n", path_channel);
> > > -	iwatch_array->elem[iwatch_array->num-1].wd = inotify_add_watch(*inotify_fd, path_channel, IN_CREATE);
> > > -	strcpy(iwatch_array->elem[iwatch_array->num-1].path_channel, path_channel);
> > > -	iwatch_array->elem[iwatch_array->num-1].base_path_channel =
> > > -		iwatch_array->elem[iwatch_array->num-1].path_channel +
> > > +	instance->inotify_watch_array.elem[instance->inotify_watch_array.num-1].wd = inotify_add_watch(instance->inotify_fd, path_channel, IN_CREATE);
> > > +	strcpy(instance->inotify_watch_array.elem[instance->inotify_watch_array.num-1].path_channel, path_channel);
> > > +	instance->inotify_watch_array.elem[instance->inotify_watch_array.num-1].base_path_channel =
> > > +		instance->inotify_watch_array.elem[instance->inotify_watch_array.num-1].path_channel +
> > >  		(base_subchannel_name - subchannel_name);
> > >  	printf_verbose("Added inotify for channel %s, wd %u\n",
> > > -		iwatch_array->elem[iwatch_array->num-1].path_channel,
> > > -		iwatch_array->elem[iwatch_array->num-1].wd);
> > > +		instance->inotify_watch_array.elem[instance->inotify_watch_array.num-1].path_channel,
> > > +		instance->inotify_watch_array.elem[instance->inotify_watch_array.num-1].wd);
> > >  #endif
> > >  
> > >  	while((entry = readdir(channel_dir)) != NULL) {
> > > @@ -233,12 +238,11 @@ int open_channel_trace_pairs(char *subchannel_name,
> > >  		if(S_ISDIR(stat_buf.st_mode)) {
> > >  
> > >  			printf_verbose("Entering channel subdirectory...\n");
> > > -			ret = open_channel_trace_pairs(path_channel, base_subchannel_ptr, fd_pairs,
> > > -				inotify_fd, iwatch_array);
> > > +			ret = open_channel_trace_pairs(instance, path_channel, base_subchannel_ptr);
> > >  			if(ret < 0) continue;
> > >  		} else if(S_ISREG(stat_buf.st_mode)) {
> > > -			open_ret = open_buffer_file(entry->d_name, path_channel, base_subchannel_ptr,
> > > -				fd_pairs);
> > > +			open_ret = open_buffer_file(instance, entry->d_name,
> > > +				path_channel, base_subchannel_ptr);
> > >  			if(open_ret)
> > >  				goto end;
> > >  		}
> > > @@ -251,7 +255,7 @@ end:
> > >  }
> > >  
> > >  
> > > -int read_subbuffer(struct fd_pair *pair)
> > > +int read_subbuffer(struct liblttd_instance *instance, struct fd_pair *pair)
> > >  {
> > >  	unsigned int consumed_old, len;
> > >  	int err;
> > > @@ -274,8 +278,8 @@ int read_subbuffer(struct fd_pair *pair)
> > >  		goto get_error;
> > >  	}
> > >  
> > > -	if(callbacks->on_read_subbuffer) ret = callbacks->on_read_subbuffer(
> > > -		callbacks, pair, len);
> > > +	if(instance->callbacks->on_read_subbuffer) ret = instance->callbacks->on_read_subbuffer(
> > > +		instance->callbacks, pair, len);
> > >  
> > >  write_error:
> > >  	ret = 0;
> > > @@ -296,13 +300,12 @@ get_error:
> > >  }
> > >  
> > >  
> > > -int map_channels(struct channel_trace_fd *fd_pairs,
> > > -	int idx_begin, int idx_end)
> > > +int map_channels(struct liblttd_instance *instance, int idx_begin, int idx_end)
> > >  {
> > >  	int i,j;
> > >  	int ret=0;
> > >  
> > > -	if(fd_pairs->num_pairs <= 0) {
> > > +	if(instance->fd_pairs.num_pairs <= 0) {
> > >  		printf("No channel to read\n");
> > >  		goto end;
> > >  	}
> > > @@ -310,7 +313,7 @@ int map_channels(struct channel_trace_fd *fd_pairs,
> > >  	/* Get the subbuf sizes and number */
> > >  
> > >  	for(i=idx_begin;i<idx_end;i++) {
> > > -		struct fd_pair *pair = &fd_pairs->pair[i];
> > > +		struct fd_pair *pair = &instance->fd_pairs.pair[i];
> > >  
> > >  		ret = ioctl(pair->channel, RELAY_GET_N_SB, &pair->n_sb);
> > >  		if(ret != 0) {
> > > @@ -334,14 +337,14 @@ end:
> > >  	return ret;
> > >  }
> > >  
> > > -int unmap_channels(struct channel_trace_fd *fd_pairs)
> > > +int unmap_channels(struct liblttd_instance *instance)
> > >  {
> > >  	int j;
> > >  	int ret=0;
> > >  
> > >  	/* Munmap each FD */
> > > -	for(j=0;j<fd_pairs->num_pairs;j++) {
> > > -		struct fd_pair *pair = &fd_pairs->pair[j];
> > > +	for(j=0;j<instance->fd_pairs.num_pairs;j++) {
> > > +		struct fd_pair *pair = &instance->fd_pairs.pair[j];
> > >  		int err_ret;
> > >  
> > >  		err_ret = pthread_mutex_destroy(&pair->mutex);
> > > @@ -359,10 +362,7 @@ int unmap_channels(struct channel_trace_fd *fd_pairs)
> > >   *
> > >   * Only support add file for now.
> > >   */
> > > -
> > > -int read_inotify(int inotify_fd,
> > > -	struct channel_trace_fd *fd_pairs,
> > > -	struct inotify_watch_array *iwatch_array)
> > > +int read_inotify(struct liblttd_instance *instance)
> > >  {
> > >  	char buf[sizeof(struct inotify_event) + PATH_MAX];
> > >  	char path_channel[PATH_MAX];
> > > @@ -374,7 +374,7 @@ int read_inotify(int inotify_fd,
> > >  	int old_num;
> > >  
> > >  	offset = 0;
> > > -	len = read(inotify_fd, buf, sizeof(struct inotify_event) + PATH_MAX);
> > > +	len = read(instance->inotify_fd, buf, sizeof(struct inotify_event) + PATH_MAX);
> > >  	if(len < 0) {
> > >  
> > >  		if(errno == EAGAIN)
> > > @@ -385,24 +385,24 @@ int read_inotify(int inotify_fd,
> > >  	}
> > >  	while(offset < len) {
> > >  		ievent = (struct inotify_event *)&(buf[offset]);
> > > -		for(i=0; i<iwatch_array->num; i++) {
> > > -			if(iwatch_array->elem[i].wd == ievent->wd &&
> > > +		for(i=0; i<instance->inotify_watch_array.num; i++) {
> > > +			if(instance->inotify_watch_array.elem[i].wd == ievent->wd &&
> > >  				ievent->mask == IN_CREATE) {
> > >  				printf_verbose(
> > >  					"inotify wd %u event mask : %u for %s%s\n",
> > >  					ievent->wd, ievent->mask,
> > > -					iwatch_array->elem[i].path_channel,
> > > +					instance->inotify_watch_array.elem[i].path_channel,
> > >  					ievent->name);
> > > -				old_num = fd_pairs->num_pairs;
> > > -				strcpy(path_channel, iwatch_array->elem[i].path_channel);
> > > +				old_num = instance->fd_pairs.num_pairs;
> > > +				strcpy(path_channel, instance->inotify_watch_array.elem[i].path_channel);
> > >  				strcat(path_channel, ievent->name);
> > > -				if(ret = open_buffer_file(ievent->name, path_channel,
> > > -					path_channel + (iwatch_array->elem[i].base_path_channel -
> > > -					iwatch_array->elem[i].path_channel), fd_pairs)) {
> > > +				if(ret = open_buffer_file(instance, ievent->name, path_channel,
> > > +					path_channel + (instance->inotify_watch_array.elem[i].base_path_channel -
> > > +					instance->inotify_watch_array.elem[i].path_channel))) {
> > >  					printf("Error opening buffer file\n");
> > >  					return -1;
> > >  				}
> > > -				if(ret = map_channels(fd_pairs, old_num, fd_pairs->num_pairs)) {
> > > +				if(ret = map_channels(instance, old_num, instance->fd_pairs.num_pairs)) {
> > >  					printf("Error mapping channel\n");
> > >  					return -1;
> > >  				}
> > > @@ -432,8 +432,7 @@ int read_inotify(int inotify_fd,
> > >   * full.
> > >   */
> > >  
> > > -int read_channels(unsigned long thread_num, struct channel_trace_fd *fd_pairs,
> > > -	int inotify_fd, struct inotify_watch_array *iwatch_array)
> > > +int read_channels(struct liblttd_instance *instance, unsigned long thread_num)
> > >  {
> > >  	struct pollfd *pollfd = NULL;
> > >  	int num_pollfd;
> > > @@ -450,24 +449,24 @@ int read_channels(unsigned long thread_num, struct channel_trace_fd *fd_pairs,
> > >  	inotify_fds = 0;
> > >  #endif
> > >  
> > > -	pthread_rwlock_rdlock(&fd_pairs_lock);
> > > +	pthread_rwlock_rdlock(&instance->fd_pairs_lock);
> > >  
> > >  	/* Start polling the FD. Keep one fd for inotify */
> > > -	pollfd = malloc((inotify_fds + fd_pairs->num_pairs) * sizeof(struct pollfd));
> > > +	pollfd = malloc((inotify_fds + instance->fd_pairs.num_pairs) * sizeof(struct pollfd));
> > >  
> > >  #ifdef HAS_INOTIFY
> > > -	pollfd[0].fd = inotify_fd;
> > > +	pollfd[0].fd = instance->inotify_fd;
> > >  	pollfd[0].events = POLLIN|POLLPRI;
> > >  #endif
> > >  
> > > -	for(i=0;i<fd_pairs->num_pairs;i++) {
> > > -		pollfd[inotify_fds+i].fd = fd_pairs->pair[i].channel;
> > > +	for(i=0;i<instance->fd_pairs.num_pairs;i++) {
> > > +		pollfd[inotify_fds+i].fd = instance->fd_pairs.pair[i].channel;
> > >  		pollfd[inotify_fds+i].events = POLLIN|POLLPRI;
> > >  	}
> > > -	num_pollfd = inotify_fds + fd_pairs->num_pairs;
> > > +	num_pollfd = inotify_fds + instance->fd_pairs.num_pairs;
> > >  
> > >  
> > > -	pthread_rwlock_unlock(&fd_pairs_lock);
> > > +	pthread_rwlock_unlock(&instance->fd_pairs_lock);
> > >  
> > >  	while(1) {
> > >  		high_prio = 0;
> > > @@ -480,7 +479,7 @@ int read_channels(unsigned long thread_num, struct channel_trace_fd *fd_pairs,
> > >  #endif //DEBUG
> > >  
> > >  		/* Have we received a signal ? */
> > > -		if(quit_program) break;
> > > +		if(instance->quit_program) break;
> > >  
> > >  		num_rdy = poll(pollfd, num_pollfd, -1);
> > >  
> > > @@ -513,9 +512,9 @@ int read_channels(unsigned long thread_num, struct channel_trace_fd *fd_pairs,
> > >  					"Polling inotify fd %d : data ready.\n",
> > >  					pollfd[0].fd);
> > >  
> > > -				pthread_rwlock_wrlock(&fd_pairs_lock);
> > > -				read_inotify(inotify_fd, fd_pairs, iwatch_array);
> > > -				pthread_rwlock_unlock(&fd_pairs_lock);
> > > +				pthread_rwlock_wrlock(&instance->fd_pairs_lock);
> > > +				read_inotify(instance);
> > > +				pthread_rwlock_unlock(&instance->fd_pairs_lock);
> > >  
> > >  			break;
> > >  		}
> > > @@ -542,22 +541,22 @@ int read_channels(unsigned long thread_num, struct channel_trace_fd *fd_pairs,
> > >  					num_hup++;
> > >  					break;
> > >  				case POLLPRI:
> > > -					pthread_rwlock_rdlock(&fd_pairs_lock);
> > > -					if(pthread_mutex_trylock(&fd_pairs->pair[i-inotify_fds].mutex) == 0) {
> > > +					pthread_rwlock_rdlock(&instance->fd_pairs_lock);
> > > +					if(pthread_mutex_trylock(&instance->fd_pairs.pair[i-inotify_fds].mutex) == 0) {
> > >  						printf_verbose(
> > >  							"Urgent read on fd %d\n",
> > >  							pollfd[i].fd);
> > >  						/* Take care of high priority channels first. */
> > >  						high_prio = 1;
> > >  						/* it's ok to have an unavailable sub-buffer */
> > > -						ret = read_subbuffer(&fd_pairs->pair[i-inotify_fds]);
> > > +						ret = read_subbuffer(instance, &instance->fd_pairs.pair[i-inotify_fds]);
> > >  						if(ret == EAGAIN) ret = 0;
> > >  
> > > -						ret = pthread_mutex_unlock(&fd_pairs->pair[i-inotify_fds].mutex);
> > > +						ret = pthread_mutex_unlock(&instance->fd_pairs.pair[i-inotify_fds].mutex);
> > >  						if(ret)
> > >  							printf("Error in mutex unlock : %s\n", strerror(ret));
> > >  					}
> > > -					pthread_rwlock_unlock(&fd_pairs_lock);
> > > +					pthread_rwlock_unlock(&instance->fd_pairs_lock);
> > >  					break;
> > >  			}
> > >  		}
> > > @@ -568,38 +567,38 @@ int read_channels(unsigned long thread_num, struct channel_trace_fd *fd_pairs,
> > >  			for(i=inotify_fds;i<num_pollfd;i++) {
> > >  				switch(pollfd[i].revents) {
> > >  					case POLLIN:
> > > -						pthread_rwlock_rdlock(&fd_pairs_lock);
> > > -						if(pthread_mutex_trylock(&fd_pairs->pair[i-inotify_fds].mutex) == 0) {
> > > +						pthread_rwlock_rdlock(&instance->fd_pairs_lock);
> > > +						if(pthread_mutex_trylock(&instance->fd_pairs.pair[i-inotify_fds].mutex) == 0) {
> > >  							/* Take care of low priority channels. */
> > >  							printf_verbose(
> > >  								"Normal read on fd %d\n",
> > >  								pollfd[i].fd);
> > >  							/* it's ok to have an unavailable subbuffer */
> > > -							ret = read_subbuffer(&fd_pairs->pair[i-inotify_fds]);
> > > +							ret = read_subbuffer(instance, &instance->fd_pairs.pair[i-inotify_fds]);
> > >  							if(ret == EAGAIN) ret = 0;
> > >  
> > > -							ret = pthread_mutex_unlock(&fd_pairs->pair[i-inotify_fds].mutex);
> > > +							ret = pthread_mutex_unlock(&instance->fd_pairs.pair[i-inotify_fds].mutex);
> > >  							if(ret)
> > >  								printf("Error in mutex unlock : %s\n", strerror(ret));
> > >  						}
> > > -						pthread_rwlock_unlock(&fd_pairs_lock);
> > > +						pthread_rwlock_unlock(&instance->fd_pairs_lock);
> > >  						break;
> > >  				}
> > >  			}
> > >  		}
> > >  
> > >  		/* Update pollfd array if an entry was added to fd_pairs */
> > > -		pthread_rwlock_rdlock(&fd_pairs_lock);
> > > -		if((inotify_fds + fd_pairs->num_pairs) != num_pollfd) {
> > > +		pthread_rwlock_rdlock(&instance->fd_pairs_lock);
> > > +		if((inotify_fds + instance->fd_pairs.num_pairs) != num_pollfd) {
> > >  			pollfd = realloc(pollfd,
> > > -					(inotify_fds + fd_pairs->num_pairs) * sizeof(struct pollfd));
> > > -			for(i=num_pollfd-inotify_fds;i<fd_pairs->num_pairs;i++) {
> > > -				pollfd[inotify_fds+i].fd = fd_pairs->pair[i].channel;
> > > +					(inotify_fds + instance->fd_pairs.num_pairs) * sizeof(struct pollfd));
> > > +			for(i=num_pollfd-inotify_fds;i<instance->fd_pairs.num_pairs;i++) {
> > > +				pollfd[inotify_fds+i].fd = instance->fd_pairs.pair[i].channel;
> > >  				pollfd[inotify_fds+i].events = POLLIN|POLLPRI;
> > >  			}
> > > -			num_pollfd = fd_pairs->num_pairs + inotify_fds;
> > > +			num_pollfd = instance->fd_pairs.num_pairs + inotify_fds;
> > >  		}
> > > -		pthread_rwlock_unlock(&fd_pairs_lock);
> > > +		pthread_rwlock_unlock(&instance->fd_pairs_lock);
> > >  
> > >  		/* NB: If the fd_pairs structure is updated by another thread from this
> > >  		 *     point forward, the current thread will wait in the poll without
> > > @@ -620,104 +619,111 @@ end:
> > >  }
> > >  
> > >  
> > > -void close_channel_trace_pairs(struct channel_trace_fd *fd_pairs, int inotify_fd,
> > > -	struct inotify_watch_array *iwatch_array)
> > > +void close_channel_trace_pairs(struct liblttd_instance *instance)
> > >  {
> > >  	int i;
> > >  	int ret;
> > >  
> > > -	for(i=0;i<fd_pairs->num_pairs;i++) {
> > > -		ret = close(fd_pairs->pair[i].channel);
> > > +	for(i=0;i<instance->fd_pairs.num_pairs;i++) {
> > > +		ret = close(instance->fd_pairs.pair[i].channel);
> > >  		if(ret == -1) perror("Close error on channel");
> > > -		if(callbacks->on_close_channel) {
> > > -			ret = callbacks->on_close_channel(
> > > -				callbacks, &fd_pairs->pair[i]);
> > > +		if(instance->callbacks->on_close_channel) {
> > > +			ret = instance->callbacks->on_close_channel(
> > > +				instance->callbacks, &instance->fd_pairs.pair[i]);
> > >  			if(ret != 0) perror("Error on close channel callback");
> > >  		}
> > >  	}
> > > -	free(fd_pairs->pair);
> > > -	free(iwatch_array->elem);
> > > +	free(instance->fd_pairs.pair);
> > > +	free(instance->inotify_watch_array.elem);
> > >  }
> > >  
> > >  /* Thread worker */
> > >  void * thread_main(void *arg)
> > >  {
> > >  	long ret = 0;
> > > -	unsigned long thread_num = (unsigned long)arg;
> > > +	struct liblttd_thread_data *thread_data = (struct liblttd_thread_data*) arg;
> > >  
> > > -	if(callbacks->on_new_thread)
> > > -		ret = callbacks->on_new_thread(callbacks, thread_num);
> > > +	if(thread_data->instance->callbacks->on_new_thread)
> > > +		ret = thread_data->instance->callbacks->on_new_thread(
> > > +		thread_data->instance->callbacks, thread_data->thread_num);
> > >  
> > >  	if (ret < 0) {
> > >  		return (void*)ret;
> > >  	}
> > > -	ret = read_channels(thread_num, &fd_pairs, inotify_fd, &inotify_watch_array);
> > > +	ret = read_channels(thread_data->instance, thread_data->thread_num);
> > > +
> > > +	if(thread_data->instance->callbacks->on_close_thread)
> > > +		thread_data->instance->callbacks->on_close_thread(
> > > +		thread_data->instance->callbacks, thread_data->thread_num);
> > >  
> > > -	if(callbacks->on_close_thread)
> > > -		callbacks->on_close_thread(callbacks, thread_num);
> > > +	free(thread_data);
> > >  
> > >  	return (void*)ret;
> > >  }
> > >  
> > > -/*on_close_thread has to be reentrant, it'll be called by many threads*/
> > > -int(*on_close_thread)(struct liblttd_callbacks *data, unsigned long thread_num);
> > > -
> > > -int channels_init()
> > > +int channels_init(struct liblttd_instance *instance)
> > >  {
> > >  	int ret = 0;
> > >  
> > > -	inotify_fd = inotify_init();
> > > -	fcntl(inotify_fd, F_SETFL, O_NONBLOCK);
> > > +	instance->inotify_fd = inotify_init();
> > > +	fcntl(instance->inotify_fd, F_SETFL, O_NONBLOCK);
> > >  
> > > -	if(ret = open_channel_trace_pairs(channel_name,
> > > -			channel_name + strlen(channel_name), &fd_pairs,
> > > -			&inotify_fd, &inotify_watch_array))
> > > +	if(ret = open_channel_trace_pairs(instance, instance->channel_name,
> > > +			instance->channel_name +
> > > +			strlen(instance->channel_name)))
> > >  		goto close_channel;
> > > -	if (fd_pairs.num_pairs == 0) {
> > > +	if (instance->fd_pairs.num_pairs == 0) {
> > >  		printf("No channel available for reading, exiting\n");
> > >  		ret = -ENOENT;
> > >  		goto close_channel;
> > >  	}
> > > -	if(ret = map_channels(&fd_pairs, 0, fd_pairs.num_pairs))
> > > +
> > > +	if(ret = map_channels(instance, 0, instance->fd_pairs.num_pairs))
> > >  		goto close_channel;
> > >  	return 0;
> > >  
> > >  close_channel:
> > > -	close_channel_trace_pairs(&fd_pairs, inotify_fd, &inotify_watch_array);
> > > -	if(inotify_fd >= 0)
> > > -		close(inotify_fd);
> > > +	close_channel_trace_pairs(instance);
> > > +	if(instance->inotify_fd >= 0)
> > > +		close(instance->inotify_fd);
> > >  	return ret;
> > >  }
> > >  
> > > -int liblttd_start(char *channel_path, unsigned long n_threads,
> > > -		int flight_only, int normal_only, int verbose,
> > > -		struct liblttd_callbacks *user_data){
> > > +int delete_instance(struct liblttd_instance *instance)
> > > +{
> > > +	pthread_rwlock_destroy(&instance->fd_pairs_lock);
> > > +	free(instance);
> > > +	return 0;
> > > +}
> > > +
> > > +int liblttd_start_instance(struct liblttd_instance *instance)
> > > +{
> > >  	int ret = 0;
> > >  	pthread_t *tids;
> > >  	unsigned long i;
> > >  	void *tret;
> > >  
> > > -	channel_name = channel_path;
> > > -	num_threads = n_threads;
> > > -	dump_flight_only = flight_only;
> > > -	dump_normal_only = normal_only;
> > > -	verbose_mode = verbose;
> > > -	callbacks = user_data;
> > > +	if(!instance)
> > > +		return -EINVAL;
> > >  
> > > -	if(ret = channels_init())
> > > +	if(ret = channels_init(instance))
> > >  		return ret;
> > >  
> > > -	tids = malloc(sizeof(pthread_t) * num_threads);
> > > -	for(i=0; i<num_threads; i++) {
> > > +	tids = malloc(sizeof(pthread_t) * instance->num_threads);
> > > +	for(i=0; i<instance->num_threads; i++) {
> > > +		struct liblttd_thread_data *thread_data =
> > > +			malloc(sizeof(struct liblttd_thread_data));
> > > +		thread_data->thread_num = i;
> > > +		thread_data->instance = instance;
> > >  
> > > -		ret = pthread_create(&tids[i], NULL, thread_main, (void*)i);
> > > +		ret = pthread_create(&tids[i], NULL, thread_main, thread_data);
> > >  		if(ret) {
> > >  			perror("Error creating thread");
> > >  			break;
> > >  		}
> > >  	}
> > >  
> > > -	for(i=0; i<num_threads; i++) {
> > > +	for(i=0; i<instance->num_threads; i++) {
> > >  		ret = pthread_join(tids[i], &tret);
> > >  		if(ret) {
> > >  			perror("Error joining thread");
> > > @@ -730,18 +736,55 @@ int liblttd_start(char *channel_path, unsigned long n_threads,
> > >  	}
> > >  
> > >  	free(tids);
> > > -	ret = unmap_channels(&fd_pairs);
> > > -	close_channel_trace_pairs(&fd_pairs, inotify_fd, &inotify_watch_array);
> > > -	if(inotify_fd >= 0)
> > > -		close(inotify_fd);
> > > +	ret = unmap_channels(instance);
> > > +	close_channel_trace_pairs(instance);
> > > +	if(instance->inotify_fd >= 0)
> > > +		close(instance->inotify_fd);
> > >  
> > > -	if(callbacks->on_trace_end) callbacks->on_trace_end(callbacks);
> > > +	if(instance->callbacks->on_trace_end)
> > > +		instance->callbacks->on_trace_end(instance->callbacks);
> > > +
> > > +	delete_instance(instance);
> > >  
> > >  	return ret;
> > >  }
> > >  
> > > -int liblttd_stop() {
> > > -	quit_program = 1;
> > > +struct liblttd_instance * liblttd_new_instance(
> > > +	struct liblttd_callbacks *callbacks, char *channel_path,
> > > +	unsigned long n_threads, int flight_only, int normal_only, int verbose)
> > > +{
> > > +	struct liblttd_instance * instance;
> > > +	if(!channel_path || !callbacks) return NULL;
> > > +	if(n_threads == 0) n_threads = 1;
> > > +	if(flight_only && normal_only) return NULL;
> > > +
> > > +	instance = malloc(sizeof(struct liblttd_instance));
> > > +	if(!instance) return NULL;
> > > +
> > > +	instance->callbacks = callbacks;
> > > +
> > > +	instance->inotify_fd = -1;
> > > +
> > > +	instance->fd_pairs.pair = NULL;
> > > +	instance->fd_pairs.num_pairs = 0;
> > > +
> > > +	instance->inotify_watch_array.elem = NULL;
> > > +	instance->inotify_watch_array.num = 0;
> > > +
> > > +	pthread_rwlock_init(&instance->fd_pairs_lock, NULL);
> > > +
> > > +	strncpy(instance->channel_name, channel_path, PATH_MAX -1);
> > > +	instance->num_threads = n_threads;
> > > +	instance->dump_flight_only = flight_only;
> > > +	instance->dump_normal_only = normal_only;
> > > +	instance->verbose_mode = verbose;
> > > +
> > > +	return instance;
> > > +}
> > > +
> > > +int liblttd_stop_instance(struct liblttd_instance *instance)
> > > +{
> > > +	instance->quit_program = 1;
> > >  	return 0;
> > >  }
> > >  
> > > diff --git a/liblttd/liblttd.h b/liblttd/liblttd.h
> > > index bd76eeb..02e7e9c 100644
> > > --- a/liblttd/liblttd.h
> > > +++ b/liblttd/liblttd.h
> > > @@ -23,196 +23,192 @@
> > >  #include <pthread.h>
> > >  
> > >  /**
> > > -* This structure contains the data associated with the channel file descriptor.
> > > -* The lib user can use user_data to store the data associated to the specified
> > > -* channel. The lib user can read but MUST NOT change the other attributes.
> > > -*/
> > > + * struct fd_pair - Contains the data associated with the channel file
> > > + * descriptor. The lib user can use user_data to store the data associated to
> > > + * the specified channel. The lib user can read but MUST NOT change the other
> > > + * attributes.
> > > + * @channel: channel file descriptor
> > > + * @n_sb: the number of subbuffer for this channel
> > > + * @max_sb_size: the subbuffer size for this channel
> > > + * @mmap: Not used anymore.
> > > + * @mutex: a mutex for internal library usage
> > > + * @user_data: library user data
> > > + */
> > >  struct fd_pair {
> > > -	/**
> > > -	* This is the channel file descriptor.
> > > -	*/
> > >  	int channel;
> > > -
> > > -	/**
> > > -	* This is the number of subbuffer for this channel.
> > > -	*/
> > >  	unsigned int n_sb;
> > > -
> > > -	/**
> > > -	* This is the subbuffer size for this channel.
> > > -	*/
> > >  	unsigned int max_sb_size;
> > > -
> > > -	/**
> > > -	* Not used anymore.
> > > -	*/
> > >  	void *mmap;
> > > -
> > > -	/**
> > > -	* This is a mutex for internal library usage.
> > > -	*/
> > >  	pthread_mutex_t	mutex;
> > > -
> > > -	/**
> > > -	* Library user data.
> > > -	*/
> > >  	void *user_data;
> > >  };
> > >  
> > > +struct liblttd_instance;
> > > +
> > >  /**
> > > -* This structure contains the necessary callbacks for a tracing session. The
> > > -* user can set the unnecessary functions to NULL if he does not need them.
> > > +* struct liblttd_callbacks - Contains the necessary callbacks for a tracing
> > > +* session. The user can set the unnecessary functions to NULL if he does not
> > > +* need them.
> > >  */
> > >  struct liblttd_callbacks {
> > >  	/**
> > > -	* This callback is called after a channel file is open.
> > > -	*
> > > -	* @args data This argument is a pointeur to the callbacks struct that
> > > -	*            has been passed to the lib.
> > > -	* @args pair This structure contains the data associated with the
> > > -	*            channel file descriptor. The lib user can use user_data to
> > > -	*            store the data associated to the specified channel.
> > > -	* @args relative_channel_path This argument represents a relative path
> > > -	*            to the channel file. This path is relative to the root
> > > -	*            folder of the trace channels.
> > > -	*
> > > -	* @return Should return 0 if the callback succeeds else not 0.
> > > -	*/
> > > +	 * on_open_channel - Is called after a channel file is open.
> > > +	 * @data: pointeur to the callbacks struct that has been passed to the
> > > +	 * lib.
> > > +	 * @pair: structure that contains the data associated with the
> > > +	 * channel file descriptor. The lib user can use user_data to
> > > +	 * store the data associated to the specified channel.
> > > +	 * @relative_channel_path: represents a relative path to the channel
> > > +	 * file. This path is relative to the root folder of the trace channels.
> > > +	 *
> > > +	 * Returns 0 if the callback succeeds else not 0.
> > > +	 */
> > >  	int(*on_open_channel)(struct liblttd_callbacks *data,
> > >  		struct fd_pair *pair, char *relative_channel_path);
> > >  
> > >  	/**
> > > -	* This callback is called after a channel file is closed.
> > > -	*
> > > -	* @remarks After a channel file has been closed, it will never be read
> > > -	*            again.
> > > -	*
> > > -	* @args data This argument is a pointeur to the callbacks struct that
> > > -	*            has been passed to the lib.
> > > -	* @args pair This structure contains the data associated with the
> > > -	*            channel file descriptor. The lib user should clean
> > > -	*            user_data at this time.
> > > -	*
> > > -	* @return Should return 0 if the callback succeeds else not 0.
> > > -	*/
> > > +	 * on_close_channel - Is called after a channel file is closed.
> > > +	 * @data: pointeur to the callbacks struct that has been passed to the
> > > +	 * lib.
> > > +	 * @pair: structure that contains the data associated with the channel
> > > +         * file descriptor. The lib user should clean user_data at this time.
> > > +	 *
> > > +	 * Returns 0 if the callback succeeds else not 0.
> > > +	 *
> > > +	 * After a channel file has been closed, it will never be read again.
> > > +	 */
> > >  	int(*on_close_channel)(struct liblttd_callbacks *data,
> > >  		struct fd_pair *pair);
> > >  
> > > -
> > >  	/**
> > > -	* This callback is called when the library enter in a new subfolder
> > > -	* while it is scanning the trace channel tree. It can be used to create
> > > -	* the output file structure of the trace.
> > > -	*
> > > -	* @args data This argument is a pointeur to the callbacks struct that
> > > -	*            has been passed to the lib.
> > > -	* @args relative_folder_path This argument represents a relative path
> > > -	*            to the channel folder. This path is relative to the root
> > > -	*            folder of the trace channels.
> > > -	*
> > > -	* @return Should return 0 if the callback succeeds else not 0.
> > > -	*/
> > > +	 * on_new_channels_folder - Is called when the library enter in a new
> > > +         * subfolder while it is scanning the trace channel tree. It can be used
> > > +         * to create the output file structure of the trace.
> > > +	 * @data: pointeur to the callbacks struct that has been passed to the
> > > +	 * lib.
> > > +	 * @relative_folder_path: represents a relative path
> > > +	 * to the channel folder. This path is relative to the root
> > > +	 * folder of the trace channels.
> > > +	 *
> > > +	 * Returns 0 if the callback succeeds else not 0.
> > > +	 */
> > >  	int(*on_new_channels_folder)(struct liblttd_callbacks *data,
> > >  		char *relative_folder_path);
> > >  
> > >  	/**
> > > -	* This callback is called after a subbuffer is a reserved.
> > > -	*
> > > -	* @attention It has to be thread safe, it'll be called by many threads.
> > > -	*
> > > -	* @args data This argument is a pointeur to the callbacks struct that
> > > -	*            has been passed to the lib.
> > > -	* @args pair This structure contains the data associated with the
> > > -	*            channel file descriptor. The lib user should clean
> > > -	*            user_data at this time.
> > > -	* @args len This argument represents the length the data that has to be
> > > -	*            read.
> > > -	*
> > > -	* @return Should return 0 if the callback succeeds else not 0.
> > > -	*/
> > > +	 * on_read_subbuffer - Is called after a subbuffer is a reserved.
> > > +	 *
> > > +	 * @data: pointeur to the callbacks struct that has been passed to the
> > > +	 * lib.
> > > +	 * @pair: structure that contains the data associated with the
> > > +	 * channel file descriptor.
> > > +	 * @len: represents the length the data that has to be read.
> > > +	 *
> > > +	 * Returns 0 if the callback succeeds else not 0.
> > > +	 *
> > > +	 * It has to be thread safe, it'll be called by many threads.
> > > +	 */
> > >  	int(*on_read_subbuffer)(struct liblttd_callbacks *data,
> > >  		struct fd_pair *pair, unsigned int len);
> > >  
> > >  	/**
> > > -	* This callback is called at the very end of the tracing session. At
> > > -	* this time, all the channels have been closed and the threads have been
> > > -	* destroyed.
> > > -	*
> > > -	* @remarks After this callback is called, no other callback will be
> > > -	*            called again.
> > > -	*
> > > -	* @attention It has to be thread safe, it'll be called by many threads.
> > > -	*
> > > -	* @args data This argument is a pointeur to the callbacks struct that
> > > -	*            has been passed to the lib.
> > > -	*
> > > -	* @return Should return 0 if the callback succeeds else not 0.
> > > -	*/
> > > +	 * on_trace_en - Is called at the very end of the tracing session. At
> > > +	 * this time, all the channels have been closed and the threads have
> > > +	 * been destroyed.
> > > +	 *
> > > +	 * @data: pointeur to the callbacks struct that has been passed to the
> > > +	 * lib.
> > > +	 *
> > > +	 * Returns 0 if the callback succeeds else not 0.
> > > +	 *
> > > +	 * It has to be thread safe, it'll be called by many threads.
> > > +	 * After this callback is called, no other callback will be called
> > > +	 * again and the tracing instance will be deleted automatically by
> > > +	 * liblttd. After this call, the user must not use the liblttd instance.
> > > +	 */
> > >  	int(*on_trace_end)(struct liblttd_callbacks *data);
> > >  
> > >  	/**
> > > -	* This callback is called after a new thread has been created.
> > > -	*
> > > -	* @attention It has to be thread safe, it'll be called by many threads.
> > > -	*
> > > -	* @args data This argument is a pointeur to the callbacks struct that
> > > -	*            has been passed to the lib.
> > > -	* @args thread_num This argument represents the id of the thread.
> > > -	*
> > > -	* @return Should return 0 if the callback succeeds else not 0.
> > > -	*/
> > > +	 * on_new_thread - Is called after a new thread has been created.
> > > +	 *
> > > +	 * @data: pointeur to the callbacks struct that has been passed to the
> > > +	 * lib.
> > > +	 * @thread_num: represents the id of the thread.
> > > +	 *
> > > +	 * Returns 0 if the callback succeeds else not 0.
> > > +	 *
> > > +	 * It has to be thread safe, it'll be called by many threads.
> > > +	 */
> > >  	int(*on_new_thread)(struct liblttd_callbacks *data,
> > >  		unsigned long thread_num);
> > >  
> > >  	/**
> > > -	* This callback is called just before a thread is destroyed.
> > > -	*
> > > -	* @attention It has to be thread safe, it'll be called by many threads.
> > > -	*
> > > -	* @args data This argument is a pointeur to the callbacks struct that
> > > -	*            has been passed to the lib.
> > > -	* @args thread_num This argument represents the number of the thread.
> > > -	*
> > > -	* @return Should return 0 if the callback succeeds else not 0.
> > > -	*/
> > > +	 * on_close_thread - Is Called just before a thread is destroyed.
> > > +	 *
> > > +	 * @data: pointeur to the callbacks struct that has been passed to the
> > > +	 * lib.
> > > +	 * @thread_num: represents the number of the thread.
> > > +	 *
> > > +	 * Returns 0 if the callback succeeds else not 0.
> > > +	 *
> > > +	 * It has to be thread safe, it'll be called by many threads.
> > > +	 */
> > >  	int(*on_close_thread)(struct liblttd_callbacks *data,
> > >  		unsigned long thread_num);
> > >  
> > >  	/**
> > > -	* This is where the user can put the library's data.
> > > -	*/
> > > +	 * The library's data.
> > > +	 */
> > >  	void *user_data;
> > >  };
> > >  
> > >  /**
> > > -* This function is called to start a new tracing session.
> > > -*
> > > -* @attention It has to be thread safe, it'll be called by many threads.
> > > -*
> > > -* @args channel_path This argument is a path to the root folder of the trace's
> > > -*            channels.
> > > -* @args n_threads This argument represents the number of threads that will be
> > > -*            used by the library.
> > > -* @args flight_only If this argument to set to 1, only the channel that are in
> > > -*            flight recorder mode will be recorded.
> > > -* @args normal_only If this argument to set to 1, only the channel that are in
> > > -*            normal mode will be recorded.
> > > -* @args verbose If this argument to set to 1, more informations will be printed.
> > > -* @args user_data This argument is a pointeur to the callbacks struct that
> > > -*            contains the user's functions.
> > > -*
> > > -* @return Return 0 if the function succeeds else not 0.
> > > -*/
> > > -int liblttd_start(char *channel_path, unsigned long n_threads,
> > > -	int flight_only, int normal_only, int verbose,
> > > -	struct liblttd_callbacks *user_data);
> > > + * liblttd_new_instance - Is called to create a new tracing session.
> > > + *
> > > + * @callbacks: Pointer to a callbacks struct that contain the user callbacks and
> > > + * data.
> > > + * @channel_path: This argument is a path to the root folder of the trace's
> > > + * channels.
> > > + * @n_threads: This argument represents the number of threads that will be
> > > + * used by the library.
> > > + * @flight_only: If this argument to set to 1, only the channel that are in
> > > + * flight recorder mode will be recorded.
> > > + * @normal_only: If this argument to set to 1, only the channel that are in
> > > + * normal mode will be recorded.
> > > + * @verbose: If this argument to set to 1, more informations will be printed.
> > > + *
> > > + * Returns the instance if the function succeeds else NULL.
> > > + */
> > > +struct liblttd_instance * liblttd_new_instance(
> > > +	struct liblttd_callbacks *callbacks, char *channel_path,
> > > +	unsigned long n_threads, int flight_only, int normal_only, int verbose);
> > >  
> > >  /**
> > > -* This function is called to stop a tracing session.
> > > -*
> > > -* @return Return 0 if the function succeeds.
> > > -*/
> > > -int liblttd_stop();
> > > + * liblttd_start - Is called to start a new tracing session.
> > > + *
> > > + * @instance: The tracing session instance that needs to be starded.
> > > + *
> > > + * Returns 0 if the function succeeds.
> > > + *
> > > + * This is a blocking function. The caller will be bloked on it until the
> > > + * tracing session is stoped by the user usign liblttd_stop_instance or until
> > > + * the trace is stoped by LTTng directly.
> > > + */
> > > +int liblttd_start_instance(struct liblttd_instance *instance);
> > > +
> > > +/**
> > > + * liblttd_stop - Is called to stop a tracing session.
> > > + *
> > > + * @instance: The tracing session instance that needs to be stoped.
> > > + *
> > > + * Returns 0 if the function succeeds.
> > > + *
> > > + * This function return immediately, it only tells liblttd to stop the instance.
> > > + * The on_trace_end callback will be called when the tracing session will really
> > > + * be stoped (after every thread will be done). The instance is deleted
> > > + * automatically by liblttd after on_trace_end is called.
> > > + */
> > > +int liblttd_stop_instance(struct liblttd_instance *instance);
> > >  
> > >  #endif /*_LIBLTTD_H */
> > >  
> > > diff --git a/lttd/lttd.c b/lttd/lttd.c
> > > index ec757ae..d3c12d5 100644
> > > --- a/lttd/lttd.c
> > > +++ b/lttd/lttd.c
> > > @@ -46,6 +46,7 @@ struct lttd_channel_data {
> > >  	int trace;
> > >  };
> > >  
> > > +struct liblttd_instance *instance;
> > >  static char		path_trace[PATH_MAX];
> > >  static char		*end_path_trace;
> > >  static int		path_trace_len = 0;
> > > @@ -191,7 +192,7 @@ void show_info(void)
> > >  static void handler(int signo)
> > >  {
> > >  	printf("Signal %d received : exiting cleanly\n", signo);
> > > -	liblttd_stop();
> > > +	liblttd_stop_instance(instance);
> > >  }
> > >  
> > >  int lttd_on_open_channel(struct liblttd_callbacks *data, struct fd_pair *pair, char *relative_channel_path)
> > > @@ -306,7 +307,8 @@ write_error:
> > >  	return ret;
> > >  }
> > >  
> > > -int on_new_thread(struct liblttd_callbacks *data, unsigned long thread_num) {
> > > +int lttd_on_new_thread(struct liblttd_callbacks *data, unsigned long thread_num)
> > > +{
> > >  	int ret;
> > >  	ret = pipe(thread_pipe);
> > >  	if (ret < 0) {
> > > @@ -316,7 +318,8 @@ int on_new_thread(struct liblttd_callbacks *data, unsigned long thread_num) {
> > >  	return 0;
> > >  }
> > >  
> > > -int on_close_thread(struct liblttd_callbacks *data, unsigned long thread_num) {
> > > +int lttd_on_close_thread(struct liblttd_callbacks *data, unsigned long thread_num)
> > > +{
> > >  	close(thread_pipe[0]);	/* close read end */
> > >  	close(thread_pipe[1]);	/* close write end */
> > >  	return 0;
> > > @@ -333,8 +336,8 @@ int main(int argc, char ** argv)
> > >  		lttd_on_new_channels_folder,
> > >  		lttd_on_read_subbuffer,
> > >  		NULL,
> > > -		on_new_thread,
> > > -		on_close_thread,
> > > +		lttd_on_new_thread,
> > > +		lttd_on_close_thread,
> > >  		NULL
> > >  	};
> > >  
> > > @@ -365,13 +368,18 @@ int main(int argc, char ** argv)
> > >  			exit(-1);
> > >  		}
> > >  	}
> > > -
> > >  	strncpy(path_trace, trace_name, PATH_MAX-1);
> > >  	path_trace_len = strlen(path_trace);
> > >  	end_path_trace = path_trace + path_trace_len;
> > >  
> > > -	liblttd_start(channel_name, num_threads, dump_flight_only, dump_normal_only,
> > > -		verbose_mode, &callbacks);
> > > +	instance = liblttd_new_instance(&callbacks, channel_name, num_threads,
> > > +		dump_flight_only, dump_normal_only, verbose_mode);
> > > +	if(!instance) {
> > > +		perror("An error occured while creating the liblttd instance");
> > > +		return ret;
> > > +	}
> > > +
> > > +	liblttd_start_instance(instance);
> > >  
> > >  	return ret;
> > >  }
> > 
> > > diff --git a/liblttd/Makefile.am b/liblttd/Makefile.am
> > > index 3c1eeda..43859be 100644
> > > --- a/liblttd/Makefile.am
> > > +++ b/liblttd/Makefile.am
> > > @@ -1,7 +1,7 @@
> > >  
> > >  
> > >  lib_LTLIBRARIES = liblttd.la
> > > -liblttd_la_SOURCES = liblttd.c
> > > +liblttd_la_SOURCES = liblttd.c liblttdutils.c
> > >  
> > >  liblttdinclude_HEADERS = \
> > > -	liblttd.h
> > > +	liblttd.h liblttdutils.h
> > > diff --git a/liblttd/liblttd.c b/liblttd/liblttd.c
> > > index 0f703f5..7ae01f8 100644
> > > --- a/liblttd/liblttd.c
> > > +++ b/liblttd/liblttd.c
> > > @@ -1,4 +1,4 @@
> > > -/* lttd
> > > +/* libttd
> > >   *
> > >   * Linux Trace Toolkit Daemon
> > >   *
> > > @@ -9,6 +9,9 @@
> > >   *
> > >   * Copyright 2005 -
> > >   * 	Mathieu Desnoyers <mathieu.desnoyers at polymtl.ca>
> > > + * Copyright 2010 -
> > > + *	Michael Sills-Lavoie <michael.sills-lavoie at polymtl.ca>
> > > + *	Oumarou Dicko <oumarou.dicko at polymtl.ca>
> > >   */
> > >  
> > >  #ifdef HAVE_CONFIG_H
> > > @@ -75,40 +78,6 @@ static inline int inotify_rm_watch (int fd, __u32 wd)
> > >  #undef HAS_INOTIFY
> > >  #endif
> > >  
> > > -struct channel_trace_fd {
> > > -	struct fd_pair *pair;
> > > -	int num_pairs;
> > > -};
> > > -
> > > -struct inotify_watch {
> > > -	int wd;
> > > -	char path_channel[PATH_MAX];
> > > -	char *base_path_channel;
> > > -};
> > > -
> > > -struct inotify_watch_array {
> > > -	struct inotify_watch *elem;
> > > -	int num;
> > > -};
> > > -
> > > -struct liblttd_instance {
> > > -	struct liblttd_callbacks *callbacks;
> > > -
> > > -	int inotify_fd;
> > > -	struct channel_trace_fd fd_pairs;
> > > -	struct inotify_watch_array inotify_watch_array;
> > > -
> > > -	/* protects fd_pairs and inotify_watch_array */
> > > -	pthread_rwlock_t fd_pairs_lock;
> > > -
> > > -	char		channel_name[PATH_MAX];
> > > -	unsigned long	num_threads;
> > > -	int		quit_program;	/* For signal handler */
> > > -	int		dump_flight_only;
> > > -	int		dump_normal_only;
> > > -	int		verbose_mode;
> > > -};
> > > -
> > >  struct liblttd_thread_data {
> > >  	int thread_num;
> > >  	struct liblttd_instance *instance;
> > > @@ -189,7 +158,7 @@ int open_channel_trace_pairs(struct liblttd_instance *instance,
> > >  		goto end;
> > >  	}
> > >  
> > > -	printf_verbose("Calling on new channels folder\n");
> > > +	printf_verbose("Calling : on new channels folder\n");
> > >  	if(instance->callbacks->on_new_channels_folder) ret = instance->callbacks->
> > >  			on_new_channels_folder(instance->callbacks,
> > >  			base_subchannel_name);
> > > @@ -742,7 +711,7 @@ int liblttd_start_instance(struct liblttd_instance *instance)
> > >  		close(instance->inotify_fd);
> > >  
> > >  	if(instance->callbacks->on_trace_end)
> > > -		instance->callbacks->on_trace_end(instance->callbacks);
> > > +		instance->callbacks->on_trace_end(instance);
> > >  
> > >  	delete_instance(instance);
> > >  
> > > diff --git a/liblttd/liblttd.h b/liblttd/liblttd.h
> > > index 02e7e9c..d871dd7 100644
> > > --- a/liblttd/liblttd.h
> > > +++ b/liblttd/liblttd.h
> > > @@ -1,10 +1,11 @@
> > >  /* liblttd header file
> > >   *
> > > + * Copyright 2005 -
> > > + * 		 Mathieu Desnoyers <mathieu.desnoyers at polymtl.ca>
> > >   * Copyright 2010-
> > >   *		 Oumarou Dicko <oumarou.dicko at polymtl.ca>
> > >   *		 Michael Sills-Lavoie <michael.sills-lavoie at polymtl.ca>
> > >   *
> > > - *
> > >   * This program is free software; you can redistribute it and/or modify
> > >   * it under the terms of the GNU General Public License as published by
> > >   * the Free Software Foundation; either version 2 of the License, or
> > > @@ -21,6 +22,7 @@
> > >  #define _LIBLTTD_H
> > >  
> > >  #include <pthread.h>
> > > +#include <dirent.h>
> > >  
> > >  /**
> > >   * struct fd_pair - Contains the data associated with the channel file
> > > @@ -43,7 +45,46 @@ struct fd_pair {
> > >  	void *user_data;
> > >  };
> > >  
> > > -struct liblttd_instance;
> > > +struct channel_trace_fd {
> > > +	struct fd_pair *pair;
> > > +	int num_pairs;
> > > +};
> > > +
> > > +struct inotify_watch {
> > > +	int wd;
> > > +	char path_channel[PATH_MAX];
> > > +	char *base_path_channel;
> > > +};
> > > +
> > > +struct inotify_watch_array {
> > > +	struct inotify_watch *elem;
> > > +	int num;
> > > +};
> > > +
> > > +struct liblttd_callbacks;
> > > +
> > > +/**
> > > + * struct liblttd_instance - Contains the data associated with a trace instance.
> > > + * The lib user can read but MUST NOT change any attributes but callbacks.
> > > + * @callbacks: Contains the necessary callbacks for a tracing session.
> > > + */
> > > +struct liblttd_instance {
> > > +	struct liblttd_callbacks *callbacks;
> > > +
> > > +	int inotify_fd;
> > > +	struct channel_trace_fd fd_pairs;
> > > +	struct inotify_watch_array inotify_watch_array;
> > > +
> > > +	/* protects fd_pairs and inotify_watch_array */
> > > +	pthread_rwlock_t fd_pairs_lock;
> > > +
> > > +	char channel_name[PATH_MAX];
> > > +	unsigned long num_threads;
> > > +	int quit_program;
> > > +	int dump_flight_only;
> > > +	int dump_normal_only;
> > > +	int verbose_mode;
> > > +};
> > >  
> > >  /**
> > >  * struct liblttd_callbacks - Contains the necessary callbacks for a tracing
> > > @@ -116,17 +157,16 @@ struct liblttd_callbacks {
> > >  	 * this time, all the channels have been closed and the threads have
> > >  	 * been destroyed.
> > >  	 *
> > > -	 * @data: pointeur to the callbacks struct that has been passed to the
> > > -	 * lib.
> > > +	 * @instance: pointeur to the instance struct that has been passed to
> > > +	 * the lib.
> > >  	 *
> > >  	 * Returns 0 if the callback succeeds else not 0.
> > >  	 *
> > > -	 * It has to be thread safe, it'll be called by many threads.
> > >  	 * After this callback is called, no other callback will be called
> > >  	 * again and the tracing instance will be deleted automatically by
> > >  	 * liblttd. After this call, the user must not use the liblttd instance.
> > >  	 */
> > > -	int(*on_trace_end)(struct liblttd_callbacks *data);
> > > +	int(*on_trace_end)(struct liblttd_instance *instance);
> > >  
> > >  	/**
> > >  	 * on_new_thread - Is called after a new thread has been created.
> > > diff --git a/liblttd/liblttdutils.c b/liblttd/liblttdutils.c
> > > new file mode 100644
> > > index 0000000..3368aba
> > > --- /dev/null
> > > +++ b/liblttd/liblttdutils.c
> > > @@ -0,0 +1,229 @@
> > > +/* liblttdutils
> > > + *
> > > + * Linux Trace Toolkit utility library
> > > + *
> > > + * This is a simple daemon implementation that reads a few relay+debugfs
> > > + * channels and save them in a trace.
> > > + *
> > > + * CPU hot-plugging is supported using inotify.
> > > + *
> > > + * Copyright 2005 -
> > > + * 	Mathieu Desnoyers <mathieu.desnoyers at polymtl.ca>
> > > + * Copyright 2010 -
> > > + *	Michael Sills-Lavoie <michael.sills-lavoie at polymtl.ca>
> > > + *	Oumarou Dicko <oumarou.dicko at polymtl.ca>
> > > + */
> > > +
> > > +#ifdef HAVE_CONFIG_H
> > > +#include <config.h>
> > > +#endif
> > > +
> > > +#define _REENTRANT
> > > +#define _GNU_SOURCE
> > > +
> > > +#include <stdio.h>
> > > +#include <stdlib.h>
> > > +#include <string.h>
> > > +#include <errno.h>
> > > +#include <fcntl.h>
> > > +#include <dirent.h>
> > > +#include <pthread.h>
> > > +#include <sys/stat.h>
> > > +
> > > +#include "liblttdutils.h"
> > > +
> > > +struct liblttdutils_channel_data {
> > > +	int trace;
> > > +};
> > > +
> > > +struct liblttdutils_data {
> > > +	char path_trace[PATH_MAX];
> > > +	char *end_path_trace;
> > > +	int path_trace_len;
> > > +	int append_mode;
> > > +	int verbose_mode;
> > > +};
> > > +
> > > +static __thread int thread_pipe[2];
> > > +
> > > +#define printf_verbose(fmt, args...) \
> > > +  do {                               \
> > > +    if (callbacks_data->verbose_mode)                \
> > > +      printf(fmt, ##args);           \
> > > +  } while (0)
> > > +
> > > +int liblttdutils_local_on_open_channel(struct liblttd_callbacks *data, struct fd_pair *pair, char *relative_channel_path)
> > > +{
> > > +	int open_ret = 0;
> > > +	int ret;
> > > +	struct stat stat_buf;
> > > +	struct liblttdutils_channel_data *channel_data;
> > > +
> > > +	pair->user_data = malloc(sizeof(struct liblttdutils_channel_data));
> > > +	channel_data = pair->user_data;
> > > +
> > > +	struct liblttdutils_data* callbacks_data = data->user_data;
> > > +
> > > +	strncpy(callbacks_data->end_path_trace, relative_channel_path, PATH_MAX - callbacks_data->path_trace_len);
> > > +	printf_verbose("Creating trace file %s\n", callbacks_data->path_trace);
> > > +
> > > +	ret = stat(callbacks_data->path_trace, &stat_buf);
> > > +	if(ret == 0) {
> > > +		if(callbacks_data->append_mode) {
> > > +			printf_verbose("Appending to file %s as requested\n",
> > > +				callbacks_data->path_trace);
> > > +
> > > +			channel_data->trace = open(callbacks_data->path_trace, O_WRONLY, S_IRWXU|S_IRWXG|S_IRWXO);
> > > +			if(channel_data->trace == -1) {
> > > +				perror(callbacks_data->path_trace);
> > > +				open_ret = -1;
> > > +				goto end;
> > > +			}
> > > +			ret = lseek(channel_data->trace, 0, SEEK_END);
> > > +			if (ret < 0) {
> > > +				perror(callbacks_data->path_trace);
> > > +				open_ret = -1;
> > > +				close(channel_data->trace);
> > > +				goto end;
> > > +			}
> > > +		} else {
> > > +			printf("File %s exists, cannot open. Try append mode.\n", callbacks_data->path_trace);
> > > +			open_ret = -1;
> > > +			goto end;
> > > +		}
> > > +	} else {
> > > +		if(errno == ENOENT) {
> > > +			channel_data->trace =
> > > +				open(callbacks_data->path_trace, O_WRONLY|O_CREAT|O_EXCL, S_IRWXU|S_IRWXG|S_IRWXO);
> > > +			if(channel_data->trace == -1) {
> > > +				perror(callbacks_data->path_trace);
> > > +				open_ret = -1;
> > > +				goto end;
> > > +			}
> > > +		}
> > > +	}
> > > +
> > > +end:
> > > +	return open_ret;
> > > +
> > > +}
> > > +
> > > +int liblttdutils_local_on_close_channel(struct liblttd_callbacks *data, struct fd_pair *pair)
> > > +{
> > > +	int ret;
> > > +	ret = close(((struct liblttdutils_channel_data *)(pair->user_data))->trace);
> > > +	free(pair->user_data);
> > > +	return ret;
> > > +}
> > > +
> > > +int liblttdutils_local_on_new_channels_folder(struct liblttd_callbacks *data, char *relative_folder_path)
> > > +{
> > > +	int ret;
> > > +	int open_ret = 0;
> > > +	struct liblttdutils_data* callbacks_data = data->user_data;
> > > +
> > > +	strncpy(callbacks_data->end_path_trace, relative_folder_path, PATH_MAX - callbacks_data->path_trace_len);
> > > +	printf_verbose("Creating trace subdirectory %s\n", callbacks_data->path_trace);
> > > +
> > > +	ret = mkdir(callbacks_data->path_trace, S_IRWXU|S_IRWXG|S_IRWXO);
> > > +	if(ret == -1) {
> > > +		if(errno != EEXIST) {
> > > +			perror(callbacks_data->path_trace);
> > > +			open_ret = -1;
> > > +			goto end;
> > > +		}
> > > +	}
> > > +
> > > +end:
> > > +	return open_ret;
> > > +}
> > > +
> > > +int liblttdutils_local_on_read_subbuffer(struct liblttd_callbacks *data, struct fd_pair *pair, unsigned int len)
> > > +{
> > > +	long ret;
> > > +	off_t offset = 0;
> > > +
> > > +	struct liblttdutils_data* callbacks_data = data->user_data;
> > > +
> > > +	while (len > 0) {
> > > +		printf_verbose("splice chan to pipe offset %lu\n",
> > > +			(unsigned long)offset);
> > > +		ret = splice(pair->channel, &offset, thread_pipe[1], NULL,
> > > +			len, SPLICE_F_MOVE | SPLICE_F_MORE);
> > > +		printf_verbose("splice chan to pipe ret %ld\n", ret);
> > > +		if (ret < 0) {
> > > +			perror("Error in relay splice");
> > > +			goto write_error;
> > > +		}
> > > +		ret = splice(thread_pipe[0], NULL,
> > > +			((struct liblttdutils_channel_data *)(pair->user_data))->trace,
> > > +			NULL, ret, SPLICE_F_MOVE | SPLICE_F_MORE);
> > > +		printf_verbose("splice pipe to file %ld\n", ret);
> > > +		if (ret < 0) {
> > > +			perror("Error in file splice");
> > > +			goto write_error;
> > > +		}
> > > +		len -= ret;
> > > +	}
> > > +
> > > +write_error:
> > > +	return ret;
> > > +}
> > > +
> > > +int liblttdutils_local_on_new_thread(struct liblttd_callbacks *data, unsigned long thread_num)
> > > +{
> > > +	int ret;
> > > +	ret = pipe(thread_pipe);
> > > +	if (ret < 0) {
> > > +		perror("Error creating pipe");
> > > +		return ret;
> > > +	}
> > > +	return 0;
> > > +}
> > > +
> > > +int liblttdutils_local_on_close_thread(struct liblttd_callbacks *data, unsigned long thread_num)
> > > +{
> > > +	close(thread_pipe[0]);	/* close read end */
> > > +	close(thread_pipe[1]);	/* close write end */
> > > +	return 0;
> > > +}
> > > +
> > > +int liblttdutils_local_on_trace_end(struct liblttd_instance *instance)
> > > +{
> > > +	struct liblttd_callbacks *callbacks = instance->callbacks;
> > > +	struct liblttdutils_data *data = callbacks->user_data;
> > > +
> > > +	free(data);
> > > +	free(callbacks);
> > > +}
> > > +
> > > +struct liblttd_callbacks* liblttdutils_local_new_callbacks(char* trace_name,
> > > +	int append_mode, int verbose_mode)
> > > +{
> > > +	struct liblttdutils_data *data;
> > > +	struct liblttd_callbacks *callbacks;
> > > +
> > > +	if(!trace_name) return NULL;
> > > +
> > > +	data = malloc(sizeof(struct liblttdutils_data));
> > > +
> > > +	strncpy(data->path_trace, trace_name, PATH_MAX-1);
> > > +	data->path_trace_len = strlen(data->path_trace);
> > > +	data->end_path_trace = data->path_trace + data->path_trace_len;
> > > +	data->append_mode = append_mode;
> > > +	data->verbose_mode = verbose_mode;
> > > +
> > > +	callbacks = malloc(sizeof(struct liblttd_callbacks));
> > > +
> > > +	callbacks->on_open_channel = liblttdutils_local_on_open_channel;
> > > +	callbacks->on_close_channel = liblttdutils_local_on_close_channel;
> > > +	callbacks->on_new_channels_folder = liblttdutils_local_on_new_channels_folder;
> > > +	callbacks->on_read_subbuffer = liblttdutils_local_on_read_subbuffer;
> > > +	callbacks->on_trace_end = liblttdutils_local_on_trace_end;
> > > +	callbacks->on_new_thread = liblttdutils_local_on_new_thread;
> > > +	callbacks->on_close_thread = liblttdutils_local_on_close_thread;
> > > +	callbacks->user_data = data;
> > > +
> > > +	return callbacks;
> > > +}
> > > +
> > > diff --git a/liblttd/liblttdutils.h b/liblttd/liblttdutils.h
> > > new file mode 100644
> > > index 0000000..78439d2
> > > --- /dev/null
> > > +++ b/liblttd/liblttdutils.h
> > > @@ -0,0 +1,38 @@
> > > +/* liblttdutils header file
> > > + *
> > > + * Copyright 2010-
> > > + *		 Oumarou Dicko <oumarou.dicko at polymtl.ca>
> > > + *		 Michael Sills-Lavoie <michael.sills-lavoie at polymtl.ca>
> > > + *
> > > + * This program is free software; you can redistribute it and/or modify
> > > + * it under the terms of the GNU General Public License as published by
> > > + * the Free Software Foundation; either version 2 of the License, or
> > > + * (at your option) any later version.
> > > + *
> > > + * This program is distributed in the hope that it will be useful,
> > > + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> > > + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	See the
> > > + * GNU General Public License for more details.
> > > + *
> > > + */
> > > +
> > > +#ifndef _LIBLTTDUTILS_H
> > > +#define _LIBLTTDUTILS_H
> > > +
> > > +#include "liblttd.h"
> > > +
> > > +/**
> > > + * liblttdutils_new_callbacks - Is a utility function called to create a new
> > > + * callbacks struct used by liblttd to write trace data to the disk.
> > > + *
> > > + * @trace_name: Directory name of the trace to write to. It will be created.
> > > + * @append_mode: Append to a possibly existing trace.
> > > + * @verbose_mode: Verbose mode.
> > > + *
> > > + * Returns the callbacks if the function succeeds else NULL.
> > > + */
> > > +struct liblttd_callbacks* liblttdutils_local_new_callbacks(char* trace_name,
> > > +	int append_mode, int verbose_mode);
> > > +
> > > +#endif /*_LIBLTTDUTILS_H */
> > > +
> > > diff --git a/lttd/lttd.c b/lttd/lttd.c
> > > index d3c12d5..b43b637 100644
> > > --- a/lttd/lttd.c
> > > +++ b/lttd/lttd.c
> > > @@ -8,6 +8,8 @@
> > >   * CPU hot-plugging is supported using inotify.
> > >   *
> > >   * Copyright 2009-2010 - Mathieu Desnoyers <mathieu.desnoyers at efficios.com>
> > > + * Copyright 2010 - Michael Sills-Lavoie <michael.sills-lavoie at polymtl.ca>
> > > + * Copyright 2010 - Oumarou Dicko <oumarou.dicko at polymtl.ca>
> > >   *
> > >   * This program is free software; you can redistribute it and/or modify
> > >   * it under the terms of the GNU General Public License as published by
> > > @@ -22,6 +24,7 @@
> > >   * You should have received a copy of the GNU General Public License along
> > >   * with this program; if not, write to the Free Software Foundation, Inc.,
> > >   * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
> > > + *
> > >   */
> > >  
> > >  #ifdef HAVE_CONFIG_H
> > > @@ -33,23 +36,14 @@
> > >  
> > >  #include <stdio.h>
> > >  #include <stdlib.h>
> > > -#include <string.h>
> > >  #include <signal.h>
> > >  #include <errno.h>
> > > -#include <fcntl.h>
> > > -#include <dirent.h>
> > > -#include <sys/stat.h>
> > >  
> > >  #include <liblttd/liblttd.h>
> > > +#include <liblttd/liblttdutils.h>
> > >  
> > > -struct lttd_channel_data {
> > > -	int trace;
> > > -};
> > > +struct liblttd_instance* instance;
> > >  
> > > -struct liblttd_instance *instance;
> > > -static char		path_trace[PATH_MAX];
> > > -static char		*end_path_trace;
> > > -static int		path_trace_len = 0;
> > >  static char		*trace_name = NULL;
> > >  static char		*channel_name = NULL;
> > >  static int		daemon_mode = 0;
> > > @@ -59,13 +53,6 @@ static int		dump_flight_only = 0;
> > >  static int		dump_normal_only = 0;
> > >  static int		verbose_mode = 0;
> > >  
> > > -static __thread int thread_pipe[2];
> > > -
> > > -#define printf_verbose(fmt, args...) \
> > > -  do {                               \
> > > -    if (verbose_mode)                \
> > > -      printf(fmt, ##args);           \
> > > -  } while (0)
> > >  
> > >  /* Args :
> > >   *
> > > @@ -195,152 +182,11 @@ static void handler(int signo)
> > >  	liblttd_stop_instance(instance);
> > >  }
> > >  
> > > -int lttd_on_open_channel(struct liblttd_callbacks *data, struct fd_pair *pair, char *relative_channel_path)
> > > -{
> > > -	int open_ret = 0;
> > > -	int ret;
> > > -	struct stat stat_buf;
> > > -	struct lttd_channel_data *channel_data;
> > > -
> > > -	pair->user_data = malloc(sizeof(struct lttd_channel_data));
> > > -	channel_data = pair->user_data;
> > > -
> > > -	strncpy(end_path_trace, relative_channel_path, PATH_MAX - path_trace_len);
> > > -	printf_verbose("Creating trace file %s\n", path_trace);
> > > -
> > > -	ret = stat(path_trace, &stat_buf);
> > > -	if(ret == 0) {
> > > -		if(append_mode) {
> > > -			printf_verbose("Appending to file %s as requested\n",
> > > -				path_trace);
> > > -
> > > -			channel_data->trace = open(path_trace, O_WRONLY, S_IRWXU|S_IRWXG|S_IRWXO);
> > > -			if(channel_data->trace == -1) {
> > > -				perror(path_trace);
> > > -				open_ret = -1;
> > > -				goto end;
> > > -			}
> > > -			ret = lseek(channel_data->trace, 0, SEEK_END);
> > > -			if (ret < 0) {
> > > -				perror(path_trace);
> > > -				open_ret = -1;
> > > -				close(channel_data->trace);
> > > -				goto end;
> > > -			}
> > > -		} else {
> > > -			printf("File %s exists, cannot open. Try append mode.\n", path_trace);
> > > -			open_ret = -1;
> > > -			goto end;
> > > -		}
> > > -	} else {
> > > -		if(errno == ENOENT) {
> > > -			channel_data->trace = open(path_trace, O_WRONLY|O_CREAT|O_EXCL, S_IRWXU|S_IRWXG|S_IRWXO);
> > > -			if(channel_data->trace == -1) {
> > > -				perror(path_trace);
> > > -				open_ret = -1;
> > > -				goto end;
> > > -			}
> > > -		}
> > > -	}
> > > -
> > > -end:
> > > -	return open_ret;
> > > -
> > > -}
> > > -
> > > -int lttd_on_close_channel(struct liblttd_callbacks *data, struct fd_pair *pair)
> > > -{
> > > -	int ret;
> > > -	ret = close(((struct lttd_channel_data *)(pair->user_data))->trace);
> > > -	free(pair->user_data);
> > > -	return ret;
> > > -}
> > > -
> > > -int lttd_on_new_channels_folder(struct liblttd_callbacks *data, char *relative_folder_path)
> > > -{
> > > -	int ret;
> > > -	int open_ret = 0;
> > > -
> > > -	strncpy(end_path_trace, relative_folder_path, PATH_MAX - path_trace_len);
> > > -	printf_verbose("Creating trace subdirectory %s\n", path_trace);
> > > -
> > > -	ret = mkdir(path_trace, S_IRWXU|S_IRWXG|S_IRWXO);
> > > -	if(ret == -1) {
> > > -		if(errno != EEXIST) {
> > > -			perror(path_trace);
> > > -			open_ret = -1;
> > > -			goto end;
> > > -		}
> > > -	}
> > > -
> > > -end:
> > > -	return open_ret;
> > > -}
> > > -
> > > -int lttd_on_read_subbuffer(struct liblttd_callbacks *data, struct fd_pair *pair, unsigned int len)
> > > -{
> > > -	long ret;
> > > -	off_t offset = 0;
> > > -
> > > -	while (len > 0) {
> > > -		printf_verbose("splice chan to pipe offset %lu\n",
> > > -			(unsigned long)offset);
> > > -		ret = splice(pair->channel, &offset, thread_pipe[1], NULL,
> > > -			len, SPLICE_F_MOVE | SPLICE_F_MORE);
> > > -		printf_verbose("splice chan to pipe ret %ld\n", ret);
> > > -		if (ret < 0) {
> > > -			perror("Error in relay splice");
> > > -			goto write_error;
> > > -		}
> > > -		ret = splice(thread_pipe[0], NULL,
> > > -			((struct lttd_channel_data *)(pair->user_data))->trace,
> > > -			NULL, ret, SPLICE_F_MOVE | SPLICE_F_MORE);
> > > -		printf_verbose("splice pipe to file %ld\n", ret);
> > > -		if (ret < 0) {
> > > -			perror("Error in file splice");
> > > -			goto write_error;
> > > -		}
> > > -		len -= ret;
> > > -	}
> > > -
> > > -write_error:
> > > -	return ret;
> > > -}
> > > -
> > > -int lttd_on_new_thread(struct liblttd_callbacks *data, unsigned long thread_num)
> > > -{
> > > -	int ret;
> > > -	ret = pipe(thread_pipe);
> > > -	if (ret < 0) {
> > > -		perror("Error creating pipe");
> > > -		return ret;
> > > -	}
> > > -	return 0;
> > > -}
> > > -
> > > -int lttd_on_close_thread(struct liblttd_callbacks *data, unsigned long thread_num)
> > > -{
> > > -	close(thread_pipe[0]);	/* close read end */
> > > -	close(thread_pipe[1]);	/* close write end */
> > > -	return 0;
> > > -}
> > > -
> > >  int main(int argc, char ** argv)
> > >  {
> > >  	int ret = 0;
> > >  	struct sigaction act;
> > >  
> > > -	struct liblttd_callbacks callbacks = {
> > > -		lttd_on_open_channel,
> > > -		lttd_on_close_channel,
> > > -		lttd_on_new_channels_folder,
> > > -		lttd_on_read_subbuffer,
> > > -		NULL,
> > > -		lttd_on_new_thread,
> > > -		lttd_on_close_thread,
> > > -		NULL
> > > -	};
> > > -
> > >  	ret = parse_arguments(argc, argv);
> > >  
> > >  	if(ret != 0) show_arguments();
> > > @@ -368,12 +214,13 @@ int main(int argc, char ** argv)
> > >  			exit(-1);
> > >  		}
> > >  	}
> > > -	strncpy(path_trace, trace_name, PATH_MAX-1);
> > > -	path_trace_len = strlen(path_trace);
> > > -	end_path_trace = path_trace + path_trace_len;
> > >  
> > > -	instance = liblttd_new_instance(&callbacks, channel_name, num_threads,
> > > +	struct liblttd_callbacks* callbacks = liblttdutils_local_new_callbacks(
> > > +		trace_name, append_mode, verbose_mode);
> > > +
> > > +	instance = liblttd_new_instance(callbacks, channel_name, num_threads,
> > >  		dump_flight_only, dump_normal_only, verbose_mode);
> > > +
> > >  	if(!instance) {
> > >  		perror("An error occured while creating the liblttd instance");
> > >  		return ret;
> > 
> > 
> > -- 
> > Mathieu Desnoyers
> > Operating System Efficiency R&D Consultant
> > EfficiOS Inc.
> > http://www.efficios.com
> > 
> > _______________________________________________
> > ltt-dev mailing list
> > ltt-dev at lists.casi.polymtl.ca
> > http://lists.casi.polymtl.ca/cgi-bin/mailman/listinfo/ltt-dev
> > 
> 
> -- 
> Mathieu Desnoyers
> Operating System Efficiency R&D Consultant
> EfficiOS Inc.
> http://www.efficios.com
> 
> _______________________________________________
> ltt-dev mailing list
> ltt-dev at lists.casi.polymtl.ca
> http://lists.casi.polymtl.ca/cgi-bin/mailman/listinfo/ltt-dev
> 

-- 
Mathieu Desnoyers
Operating System Efficiency R&D Consultant
EfficiOS Inc.
http://www.efficios.com




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