[ltt-dev] [UST PATCH] Re-write ustcomm parts of UST

David Goulet david.goulet at polymtl.ca
Thu Sep 23 17:55:57 EDT 2010


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Hey Nils,

I'll check carefully this patch tomorrow but until that time we might consider
this for a communication protocol. Since TCF is using JSON protocol, we can use
that for UST. We have a LTTng and UST TCF agent so unifying everything would be
ideal.

As Mathieu suggest, and it was brought up at the CDT Summit this week, is that
we should *not* be dependent on the TCF JSON library and consider using the
libjson (http://oss.metaparadigm.com/json-c/) or our own implementation.

Cheers
David

On 10-09-23 06:13 AM, Nils Carlson wrote:
> This is a very big patch, and so it requires a bit of explaining.
> 
> This patch is a step on the way of accomplishing serveral goals I have in this
> area:
> 
> 1. Use enums for commands and eliminate text-based commands. This does not mean
>    that we will stop processing strings for trace/channel and marker names;
>    just that the long series of if statements with token and string matching
>    will be replaced with a switch statement. To this end I have created a
>    ustcomm_header struct that contains the length of the data-field and some
>    other fields. This allows us to first receive the header, allocate memory
>    for the data and then receive the data; eliminating all scanning of messages.
> 
> 2. Reduce the complexity of the implementation. To put it simply, I don't like
>    callbacks. They reduce transparency and make it difficult to follow the
>    flow of the code; so I have eliminated multipoll replacing it with a normal
>    epoll. I have also replaced almost all the different server, connection and
>    source structs with one, called ustcomm_sock.
> 
> 3. Make ustd scale better. Currently ustd scales terribly. We allocate one
>    thread per-cpu per-channel per-process, five applications each with three
>    channels on a four cpu machine leads to 5*3*4=60 threads. Part of the reason
>    for this multitude of threads was that we used a ustcomm_request call
>    (consisting of a send and a receive) to wait for a subbuffer to be written.
>    The sequence for a subbuffer to be written was as follows:
> 
>       Ustd calls send with a 'get_subbuffer' command, and then recv in one of
>       the threads and hangs on the recv on the socket.
> 
>       Upon filling the subbuffer the traced app writes '1' to a pipe.
> 
>       The ust_thread inside the app which was listening to the other end of the
>       pipe wakes up when the '1' is written. The callback from multipoll calls
>       a send which sends a reply to the ustd thread over the socket.
> 
>       The ustd thread wakes up and reads the message, continuing along in its
>       execution.
> 
>    I replace this with a bit of a different mechanism, which should allow us
>    to eventually reduce the number of threads to one per cpu:
> 
>       Ustd requests a buffer_fd which causes the ustd_thread inside the app
>       to send the file-descriptor for the read en of the pipe to ustd.
> 
>       The ustd thread now does a read on the pipe, halting its execution until
>       the app fills the subbuffer and writes '1' to the pipe, waking up the ustd
>       thread.
> 
>       Ustd now makes the 'get_subbuffer' call which the ust_thread inside the
>       app responds to with information about the subbuffer. Writes it and then
>       goes back to the read call, hanging on the pipe.
> 
>    So we are still stuck on the multitude of threads, but we are in much better
>    position to move forward. Replacing the read with an epoll statement and then
>    pointing the epoll event data at the buffer struct containing the current
>    buffer to whitch the pipe belongs should be relatively easy. We can then
>    instead of spawning a new thread for each buffer just allocate the
>    buffer_info struct and assign it to one of the per-cpu threads in ustd to
>    poll on.
> 
> 4. Replace poll with epoll which scales better, especially for
>    events << (nr of fds). This is complete.
> 
> 5. Allow UST to handle arbitrarily long unix socket names. This is done by
>    carefull allocation of the socketaddr_un struct with a dynamic length.
>    Truncating is ugly and dangerous.
> 
> There is a lot of work still left to be done. This is only the first of a
> number of patches that I expect in this area. If someone feels like tackling
> ustd head on to reduce the number of threads that would be great.
> 
> I have kept Pierre-Marc's form of error handling for the I/O wrapping functions
> because I want to propagate return codes up to the apps that are using them
> so they can close file-descriptors and free associated resources. If somebody
> knows of a better approach please make yourself heard.
> 
> Signed-off-by: Nils Carlson <nils.carlson at ericsson.com>
> ---
>  include/ust/ustd.h     |   12 +-
>  libust/buffers.h       |    5 +
>  libust/tracectl.c      |  474 ++++++++++++++----------
>  libustcmd/ustcmd.c     |   15 +-
>  libustcomm/Makefile.am |    5 +-
>  libustcomm/multipoll.c |  130 -------
>  libustcomm/multipoll.h |   44 ---
>  libustcomm/ustcomm.c   |  969 +++++++++++++++++++-----------------------------
>  libustcomm/ustcomm.h   |   83 ++---
>  libustd/libustd.c      |  277 ++++++++++-----
>  10 files changed, 902 insertions(+), 1112 deletions(-)
>  delete mode 100644 libustcomm/multipoll.c
>  delete mode 100644 libustcomm/multipoll.h
> 
> diff --git a/include/ust/ustd.h b/include/ust/ustd.h
> index 5fec7f9..7ce063f 100644
> --- a/include/ust/ustd.h
> +++ b/include/ust/ustd.h
> @@ -29,16 +29,18 @@
>  #include <pthread.h>
>  #include <dirent.h>
>  #include <ust/kcompat/kcompat.h>
> +#include <urcu/list.h>
>  
>  #define USTD_DEFAULT_TRACE_PATH "/tmp/usttrace"
>  
> -struct ustcomm_connection;
> -struct ustcomm_ustd;
> +struct ustcomm_sock;
>  
>  struct buffer_info {
>  	const char *name;
>  	pid_t pid;
> -	struct ustcomm_connection *conn;
> +	int app_sock;
> +	/* The pipe file descriptor */
> +	int pipe_fd;
>  
>  	int shmid;
>  	int bufstruct_shmid;
> @@ -73,7 +75,9 @@ struct libustd_instance {
>  	struct libustd_callbacks *callbacks;
>  	int quit_program;
>  	int is_init;
> -	struct ustcomm_ustd *comm;
> +	struct list_head connections;
> +	int epoll_fd;
> +	struct ustcomm_sock *listen_sock;
>  	char *sock_path;
>  	pthread_mutex_t mutex;
>  	int active_buffers;
> diff --git a/libust/buffers.h b/libust/buffers.h
> index 3044500..a2ad83e 100644
> --- a/libust/buffers.h
> +++ b/libust/buffers.h
> @@ -82,6 +82,11 @@ struct ust_buffer {
>  	int data_ready_fd_write;
>  	/* the reading end of the pipe */
>  	int data_ready_fd_read;
> +	/*
> +	 * List of buffers with an open pipe, used for fork and forced subbuffer
> +	 * switch.
> +	 */
> +	struct list_head open_buffers_list;
>  
>  	unsigned int finalized;
>  //ust//	struct timer_list switch_timer; /* timer for periodical switch */
> diff --git a/libust/tracectl.c b/libust/tracectl.c
> index 60c375b..3472ca9 100644
> --- a/libust/tracectl.c
> +++ b/libust/tracectl.c
> @@ -26,13 +26,15 @@
>  #include <stdint.h>
>  #include <pthread.h>
>  #include <signal.h>
> +#include <sys/epoll.h>
> +#include <sys/time.h>
>  #include <sys/types.h>
>  #include <sys/socket.h>
> -#include <sys/un.h>
>  #include <fcntl.h>
>  #include <poll.h>
>  #include <regex.h>
>  #include <urcu/uatomic_arch.h>
> +#include <urcu/list.h>
>  
>  #include <ust/marker.h>
>  #include <ust/tracepoint.h>
> @@ -42,7 +44,6 @@
>  #include "ustcomm.h"
>  #include "buffers.h"
>  #include "marker-control.h"
> -#include "multipoll.h"
>  
>  #define USTSIGNAL SIGIO
>  
> @@ -55,50 +56,18 @@
>   */
>  s64 pidunique = -1LL;
>  
> -extern struct chan_info_struct chan_infos[];
> +static int epoll_fd;
> +static struct ustcomm_sock *listen_sock;
>  
> -struct list_head blocked_consumers = LIST_HEAD_INIT(blocked_consumers);
> +extern struct chan_info_struct chan_infos[];
>  
> -static struct ustcomm_app ustcomm_app;
> +static struct list_head open_buffers_list = LIST_HEAD_INIT(open_buffers_list);
>  
> -struct tracecmd { /* no padding */
> -	uint32_t size;
> -	uint16_t command;
> -};
> +static struct list_head ust_socks = LIST_HEAD_INIT(ust_socks);
>  
>  /* volatile because shared between the listener and the main thread */
>  int buffers_to_export = 0;
>  
> -struct trctl_msg {
> -	/* size: the size of all the fields except size itself */
> -	uint32_t size;
> -	uint16_t type;
> -	/* Only the necessary part of the payload is transferred. It
> -         * may even be none of it.
> -         */
> -	char payload[94];
> -};
> -
> -struct consumer_channel {
> -	int fd;
> -	struct ltt_channel_struct *chan;
> -};
> -
> -struct blocked_consumer {
> -	int fd_consumer;
> -	int fd_producer;
> -	int tmp_poll_idx;
> -
> -	/* args to ustcomm_send_reply */
> -	struct ustcomm_server server;
> -	struct ustcomm_source src;
> -
> -	/* args to ust_buffers_get_subbuf */
> -	struct ust_buffer *buf;
> -
> -	struct list_head list;
> -};
> -
>  static long long make_pidunique(void)
>  {
>  	s64 retval;
> @@ -122,7 +91,12 @@ static void print_markers(FILE *fp)
>  	marker_iter_start(&iter);
>  
>  	while (iter.marker) {
> -		fprintf(fp, "marker: %s/%s %d \"%s\" %p\n", iter.marker->channel, iter.marker->name, (int)imv_read(iter.marker->state), iter.marker->format, iter.marker->location);
> +		fprintf(fp, "marker: %s/%s %d \"%s\" %p\n",
> +			iter.marker->channel,
> +			iter.marker->name,
> +			(int)imv_read(iter.marker->state),
> +			iter.marker->format,
> +			iter.marker->location);
>  		marker_iter_next(&iter);
>  	}
>  	unlock_markers();
> @@ -143,8 +117,6 @@ static void print_trace_events(FILE *fp)
>  	unlock_trace_events();
>  }
>  
> -static int init_socket(void);
> -
>  /* Ask the daemon to collect a trace called trace_name and being
>   * produced by this pid.
>   *
> @@ -179,7 +151,8 @@ static void inform_consumer_daemon(const char *trace_name)
>  				}
>  				result = ustcomm_request_consumer(pid, buf);
>  				if (result == -1) {
> -					WARN("Failed to request collection for channel %s. Is the daemon available?", trace->channels[i].channel_name);
> +					WARN("Failed to request collection for channel %s. Is the daemon available?",
> +					     trace->channels[i].channel_name);
>  					/* continue even if fail */
>  				}
>  				free(buf);
> @@ -192,74 +165,6 @@ static void inform_consumer_daemon(const char *trace_name)
>  	ltt_unlock_traces();
>  }
>  
> -int process_blkd_consumer_act(void *priv, int fd, short events)
> -{
> -	int result;
> -	long consumed_old = 0;
> -	char *reply;
> -	struct blocked_consumer *bc = (struct blocked_consumer *) priv;
> -	char inbuf;
> -
> -	result = read(bc->fd_producer, &inbuf, 1);
> -	if (result == -1) {
> -		PERROR("read");
> -		return -1;
> -	}
> -	if (result == 0) {
> -		int res;
> -		DBG("listener: got messsage that a buffer ended");
> -
> -		res = close(bc->fd_producer);
> -		if (res == -1) {
> -			PERROR("close");
> -		}
> -
> -		list_del(&bc->list);
> -
> -		result = ustcomm_send_reply(&bc->server, "END", &bc->src);
> -		if (result < 0) {
> -			ERR("ustcomm_send_reply failed");
> -			return -1;
> -		}
> -
> -		return 0;
> -	}
> -
> -	result = ust_buffers_get_subbuf(bc->buf, &consumed_old);
> -	if (result == -EAGAIN) {
> -		WARN("missed buffer?");
> -		return 0;
> -	} else if (result < 0) {
> -		ERR("ust_buffers_get_subbuf: error: %s", strerror(-result));
> -	}
> -	if (asprintf(&reply, "%s %ld", "OK", consumed_old) < 0) {
> -               ERR("process_blkd_consumer_act : asprintf failed (OK %ld)",
> -		   consumed_old);
> -               return -1;
> -	}
> -	result = ustcomm_send_reply(&bc->server, reply, &bc->src);
> -	if (result < 0) {
> -		ERR("ustcomm_send_reply failed");
> -		free(reply);
> -		return -1;
> -	}
> -	free(reply);
> -
> -	list_del(&bc->list);
> -
> -	return 0;
> -}
> -
> -void blocked_consumers_add_to_mp(struct mpentries *ent)
> -{
> -	struct blocked_consumer *bc;
> -
> -	list_for_each_entry(bc, &blocked_consumers, list) {
> -		multipoll_add(ent, bc->fd_producer, POLLIN, process_blkd_consumer_act, bc, NULL);
> -	}
> -
> -}
> -
>  void seperate_channel_cpu(const char *channel_and_cpu, char **channel, int *cpu)
>  {
>  	const char *sep;
> @@ -279,7 +184,7 @@ void seperate_channel_cpu(const char *channel_and_cpu, char **channel, int *cpu)
>  	}
>  }
>  
> -static int do_cmd_get_shmid(const char *recvbuf, struct ustcomm_source *src)
> +static int do_cmd_get_shmid(const char *recvbuf, int sock)
>  {
>  	int retval = 0;
>  	struct ust_trace *trace;
> @@ -333,7 +238,7 @@ static int do_cmd_get_shmid(const char *recvbuf, struct ustcomm_source *src)
>  				goto free_short_chan_name;
>  			}
>  
> -			result = ustcomm_send_reply(&ustcomm_app.server, reply, src);
> +			result = ustcomm_send_reply(reply, sock);
>  			if (result) {
>  				ERR("ustcomm_send_reply failed");
>  				free(reply);
> @@ -359,7 +264,7 @@ static int do_cmd_get_shmid(const char *recvbuf, struct ustcomm_source *src)
>  	return retval;
>  }
>  
> -static int do_cmd_get_n_subbufs(const char *recvbuf, struct ustcomm_source *src)
> +static int do_cmd_get_n_subbufs(const char *recvbuf, int sock)
>  {
>  	int retval = 0;
>  	struct ust_trace *trace;
> @@ -411,7 +316,7 @@ static int do_cmd_get_n_subbufs(const char *recvbuf, struct ustcomm_source *src)
>  				goto free_short_chan_name;
>  			}
>  
> -			result = ustcomm_send_reply(&ustcomm_app.server, reply, src);
> +			result = ustcomm_send_reply(reply, sock);
>  			if (result) {
>  				ERR("ustcomm_send_reply failed");
>  				free(reply);
> @@ -435,7 +340,7 @@ static int do_cmd_get_n_subbufs(const char *recvbuf, struct ustcomm_source *src)
>  	return retval;
>  }
>  
> -static int do_cmd_get_subbuf_size(const char *recvbuf, struct ustcomm_source *src)
> +static int do_cmd_get_subbuf_size(const char *recvbuf, int sock)
>  {
>  	int retval = 0;
>  	struct ust_trace *trace;
> @@ -487,7 +392,7 @@ static int do_cmd_get_subbuf_size(const char *recvbuf, struct ustcomm_source *sr
>  				goto free_short_chan_name;
>  			}
>  
> -			result = ustcomm_send_reply(&ustcomm_app.server, reply, src);
> +			result = ustcomm_send_reply(reply, sock);
>  			if (result) {
>  				ERR("ustcomm_send_reply failed");
>  				free(reply);
> @@ -524,7 +429,7 @@ static unsigned int pow2_higher_or_eq(unsigned int v)
>  		return retval<<1;
>  }
>  
> -static int do_cmd_set_subbuf_size(const char *recvbuf, struct ustcomm_source *src)
> +static int do_cmd_set_subbuf_size(const char *recvbuf, int sock)
>  {
>  	char *channel_slash_size;
>  	char *ch_name = NULL;
> @@ -581,7 +486,7 @@ static int do_cmd_set_subbuf_size(const char *recvbuf, struct ustcomm_source *sr
>  	return retval;
>  }
>  
> -static int do_cmd_set_subbuf_num(const char *recvbuf, struct ustcomm_source *src)
> +static int do_cmd_set_subbuf_num(const char *recvbuf, int sock)
>  {
>  	char *channel_slash_num;
>  	char *ch_name = NULL;
> @@ -638,7 +543,102 @@ static int do_cmd_set_subbuf_num(const char *recvbuf, struct ustcomm_source *src
>  	return retval;
>  }
>  
> -static int do_cmd_get_subbuffer(const char *recvbuf, struct ustcomm_source *src)
> +static int do_cmd_get_subbuffer(const char *recvbuf, int sock)
> +{
> +	int retval = 0, found = 0;;
> +	int i, ch_cpu, result;
> +	long consumed_old = 0;
> +	struct ust_trace *trace;
> +	char trace_name[] = "auto";
> +	char *channel_and_cpu;
> +	char *ch_name;
> +
> +	DBG("get_subbuf");
> +
> +	channel_and_cpu = nth_token(recvbuf, 1);
> +	if(channel_and_cpu == NULL) {
> +		ERR("cannot parse channel");
> +		retval = -1;
> +		goto end;
> +	}
> +
> +	seperate_channel_cpu(channel_and_cpu, &ch_name, &ch_cpu);
> +	if(ch_cpu == -1) {
> +		ERR("problem parsing channel name");
> +		retval = -1;
> +		goto free_short_chan_name;
> +	}
> +
> +	ltt_lock_traces();
> +	trace = _ltt_trace_find(trace_name);
> +
> +	if(trace == NULL) {
> +		int result;
> +
> +		DBG("Cannot find trace. It was likely destroyed by the user.");
> +		result = ustcomm_send_reply("NOTFOUND", sock);
> +		if(result) {
> +			ERR("ustcomm_send_reply failed");
> +			retval = -1;
> +			goto unlock_traces;
> +		}
> +
> +		goto unlock_traces;
> +	}
> +
> +	for(i=0; i<trace->nr_channels; i++) {
> +		struct ust_channel *channel = &trace->channels[i];
> +
> +		if(!strcmp(trace->channels[i].channel_name, ch_name)) {
> +			struct ust_buffer *buf = channel->buf[ch_cpu];
> +			char *reply;
> +
> +			found = 1;
> +
> +			result = ust_buffers_get_subbuf(buf, &consumed_old);
> +			if(result == -EAGAIN) {
> +				WARN("missed buffer?");
> +				return 0;
> +			} else if (result < 0) {
> +				ERR("ust_buffers_get_subbuf: error: %s", strerror(-result));
> +			}
> +			if (asprintf(&reply, "%s %ld", "OK", consumed_old) < 0) {
> +				ERR("process_blkd_consumer_act : asprintf failed (OK %ld)",
> +				    consumed_old);
> +				return -1;
> +			}
> +			result = ustcomm_send_reply(reply, sock);
> +			if (result < 0) {
> +				ERR("ustcomm_send_reply failed");
> +				free(reply);
> +				return -1;
> +			}
> +			free(reply);
> +
> +			break;
> +		}
> +	}
> +	if(found == 0) {
> +		result = ustcomm_send_reply("NOTFOUND", sock);
> +		if (result <= 0) {
> +			ERR("ustcomm_send_reply failed");
> +			return -1;
> +		}
> +		ERR("unable to find channel");
> +	}
> +
> +	unlock_traces:
> +	ltt_unlock_traces();
> +
> +	free_short_chan_name:
> +	free(ch_name);
> +
> +	end:
> +	return retval;
> +}
> +
> +
> +static int do_cmd_get_buffer_fd(const char *recvbuf, int sock)
>  {
>  	int retval = 0;
>  	struct ust_trace *trace;
> @@ -648,8 +648,9 @@ static int do_cmd_get_subbuffer(const char *recvbuf, struct ustcomm_source *src)
>  	int found = 0;
>  	char *ch_name;
>  	int ch_cpu;
> +	struct ustcomm_header header;
>  
> -	DBG("get_subbuf");
> +	DBG("get_buffer_fd");
>  
>  	channel_and_cpu = nth_token(recvbuf, 1);
>  	if (channel_and_cpu == NULL) {
> @@ -672,7 +673,7 @@ static int do_cmd_get_subbuffer(const char *recvbuf, struct ustcomm_source *src)
>  		int result;
>  
>  		DBG("Cannot find trace. It was likely destroyed by the user.");
> -		result = ustcomm_send_reply(&ustcomm_app.server, "NOTFOUND", src);
> +		result = ustcomm_send_reply("NOTFOUND", sock);
>  		if (result) {
>  			ERR("ustcomm_send_reply failed");
>  			retval = -1;
> @@ -687,22 +688,16 @@ static int do_cmd_get_subbuffer(const char *recvbuf, struct ustcomm_source *src)
>  
>  		if (!strcmp(trace->channels[i].channel_name, ch_name)) {
>  			struct ust_buffer *buf = channel->buf[ch_cpu];
> -			struct blocked_consumer *bc;
>  
>  			found = 1;
>  
> -			bc = (struct blocked_consumer *) zmalloc(sizeof(struct blocked_consumer));
> -			if (bc == NULL) {
> -				ERR("zmalloc returned NULL");
> +			header.size = 0;
> +			header.fd_included = 1;
> +			if (ustcomm_send_fd(sock, &header, NULL,
> +					    &buf->data_ready_fd_read) <= 0) {
> +				ERR("ustcomm_send_fd failed\n");
>  				goto unlock_traces;
>  			}
> -			bc->fd_consumer = src->fd;
> -			bc->fd_producer = buf->data_ready_fd_read;
> -			bc->buf = buf;
> -			bc->src = *src;
> -			bc->server = ustcomm_app.server;
> -
> -			list_add(&bc->list, &blocked_consumers);
>  
>  			/* Being here is the proof the daemon has mapped the buffer in its
>  			 * memory. We may now decrement buffers_to_export.
> @@ -712,6 +707,10 @@ static int do_cmd_get_subbuffer(const char *recvbuf, struct ustcomm_source *src)
>  				STORE_SHARED(buffers_to_export, LOAD_SHARED(buffers_to_export)-1);
>  			}
>  
> +			/* The buffer has been exported, ergo, we can add it to the
> +			 * list of open buffers
> +			 */
> +			list_add(&buf->open_buffers_list, &open_buffers_list);
>  			break;
>  		}
>  	}
> @@ -729,7 +728,7 @@ static int do_cmd_get_subbuffer(const char *recvbuf, struct ustcomm_source *src)
>  	return retval;
>  }
>  
> -static int do_cmd_put_subbuffer(const char *recvbuf, struct ustcomm_source *src)
> +static int do_cmd_put_subbuffer(const char *recvbuf, int sock)
>  {
>  	int retval = 0;
>  	struct ust_trace *trace;
> @@ -779,7 +778,7 @@ static int do_cmd_put_subbuffer(const char *recvbuf, struct ustcomm_source *src)
>  
>  	if (trace == NULL) {
>  		DBG("Cannot find trace. It was likely destroyed by the user.");
> -		result = ustcomm_send_reply(&ustcomm_app.server, "NOTFOUND", src);
> +		result = ustcomm_send_reply("NOTFOUND", sock);
>  		if (result) {
>  			ERR("ustcomm_send_reply failed");
>  			retval = -1;
> @@ -814,7 +813,7 @@ static int do_cmd_put_subbuffer(const char *recvbuf, struct ustcomm_source *src)
>  				}
>  			}
>  
> -			result = ustcomm_send_reply(&ustcomm_app.server, reply, src);
> +			result = ustcomm_send_reply(reply, sock);
>  			if (result) {
>  				ERR("ustcomm_send_reply failed");
>  				free(reply);
> @@ -845,26 +844,26 @@ static int do_cmd_put_subbuffer(const char *recvbuf, struct ustcomm_source *src)
>  
>  static void listener_cleanup(void *ptr)
>  {
> -	ustcomm_fini_app(&ustcomm_app, 0);
> +	ustcomm_del_named_sock(listen_sock, 0);
>  }
>  
>  static void do_cmd_force_switch()
>  {
> -	struct blocked_consumer *bc;
> +	struct ust_buffer *buf;
>  
> -	list_for_each_entry(bc, &blocked_consumers, list) {
> -		ltt_force_switch(bc->buf, FORCE_FLUSH);
> +	list_for_each_entry(buf, &open_buffers_list,
> +			    open_buffers_list) {
> +		ltt_force_switch(buf, FORCE_FLUSH);
>  	}
>  }
>  
> -int process_client_cmd(char *recvbuf, struct ustcomm_source *src)
> +static int process_client_cmd(char *recvbuf, int sock)
>  {
>  	int result;
>  	char trace_name[] = "auto";
>  	char trace_type[] = "ustrelay";
>  	int len;
>  
> -	DBG("received a message! it's: %s", recvbuf);
>  	len = strlen(recvbuf);
>  
>  	if (!strcmp(recvbuf, "print_markers")) {
> @@ -878,7 +877,7 @@ int process_client_cmd(char *recvbuf, struct ustcomm_source *src)
>  		print_markers(fp);
>  		fclose(fp);
>  
> -		result = ustcomm_send_reply(&ustcomm_app.server, ptr, src);
> +		result = ustcomm_send_reply(ptr, sock);
>  
>  		free(ptr);
>  	} else if (!strcmp(recvbuf, "print_trace_events")) {
> @@ -897,7 +896,7 @@ int process_client_cmd(char *recvbuf, struct ustcomm_source *src)
>  		print_trace_events(fp);
>  		fclose(fp);
>  
> -		result = ustcomm_send_reply(&ustcomm_app.server, ptr, src);
> +		result = ustcomm_send_reply(ptr, sock);
>  		if (result < 0) {
>  			ERR("list_trace_events failed");
>  			return -1;
> @@ -1002,11 +1001,11 @@ int process_client_cmd(char *recvbuf, struct ustcomm_source *src)
>  			return -1;
>  		}
>  	} else if (nth_token_is(recvbuf, "get_shmid", 0) == 1) {
> -		do_cmd_get_shmid(recvbuf, src);
> +		do_cmd_get_shmid(recvbuf, sock);
>  	} else if (nth_token_is(recvbuf, "get_n_subbufs", 0) == 1) {
> -		do_cmd_get_n_subbufs(recvbuf, src);
> +		do_cmd_get_n_subbufs(recvbuf, sock);
>  	} else if (nth_token_is(recvbuf, "get_subbuf_size", 0) == 1) {
> -		do_cmd_get_subbuf_size(recvbuf, src);
> +		do_cmd_get_subbuf_size(recvbuf, sock);
>  	} else if (nth_token_is(recvbuf, "load_probe_lib", 0) == 1) {
>  		char *libfile;
>  
> @@ -1016,13 +1015,17 @@ int process_client_cmd(char *recvbuf, struct ustcomm_source *src)
>  
>  		free(libfile);
>  	} else if (nth_token_is(recvbuf, "get_subbuffer", 0) == 1) {
> -		do_cmd_get_subbuffer(recvbuf, src);
> -	} else if (nth_token_is(recvbuf, "put_subbuffer", 0) == 1) {
> -		do_cmd_put_subbuffer(recvbuf, src);
> +		do_cmd_get_subbuffer(recvbuf, sock);
> +	}
> +	else if(nth_token_is(recvbuf, "get_buffer_fd", 0) == 1) {
> +		do_cmd_get_buffer_fd(recvbuf, sock);
> +	}
> +	else if(nth_token_is(recvbuf, "put_subbuffer", 0) == 1) {
> +		do_cmd_put_subbuffer(recvbuf, sock);
>  	} else if (nth_token_is(recvbuf, "set_subbuf_size", 0) == 1) {
> -		do_cmd_set_subbuf_size(recvbuf, src);
> +		do_cmd_set_subbuf_size(recvbuf, sock);
>  	} else if (nth_token_is(recvbuf, "set_subbuf_num", 0) == 1) {
> -		do_cmd_set_subbuf_num(recvbuf, src);
> +		do_cmd_set_subbuf_num(recvbuf, sock);
>  	} else if (nth_token_is(recvbuf, "enable_marker", 0) == 1) {
>  		char *channel_slash_name = nth_token(recvbuf, 1);
>  		char *channel_name = NULL;
> @@ -1074,7 +1077,7 @@ int process_client_cmd(char *recvbuf, struct ustcomm_source *src)
>  			goto next_cmd;
>  		}
>  
> -		result = ustcomm_send_reply(&ustcomm_app.server, reply, src);
> +		result = ustcomm_send_reply(reply, sock);
>  		if (result) {
>  			ERR("listener: get_pidunique: ustcomm_send_reply failed");
>  			goto next_cmd;
> @@ -1089,10 +1092,10 @@ int process_client_cmd(char *recvbuf, struct ustcomm_source *src)
>  				    SOCK_DIR);
>  				goto next_cmd;
>  			}
> -			result = ustcomm_send_reply(&ustcomm_app.server, reply, src);
> +			result = ustcomm_send_reply(reply, sock);
>  			free(reply);
>  		} else {
> -			result = ustcomm_send_reply(&ustcomm_app.server, reply, src);
> +			result = ustcomm_send_reply(reply, sock);
>  		}
>  		if (result)
>  			ERR("ustcomm_send_reply failed");
> @@ -1112,28 +1115,54 @@ next_cmd:
>  	return 0;
>  }
>  
> +
> +
> +
> +#define MAX_EVENTS 10
> +
> +
> +
>  void *listener_main(void *p)
>  {
> -	int result;
> +	struct ustcomm_sock *epoll_sock;
> +	struct epoll_event events[MAX_EVENTS];
> +	struct sockaddr addr;
> +	int accept_fd, nfds, result, i, addr_size;
>  
>  	DBG("LISTENER");
>  
>  	pthread_cleanup_push(listener_cleanup, NULL);
>  
> -	for (;;) {
> -		struct mpentries mpent;
> -
> -		multipoll_init(&mpent);
> -
> -		blocked_consumers_add_to_mp(&mpent);
> -		ustcomm_mp_add_app_clients(&mpent, &ustcomm_app, process_client_cmd);
> -
> -		result = multipoll_poll(&mpent, -1);
> -		if (result == -1) {
> -			ERR("error in multipoll_poll");
> +	for(;;) {
> +		nfds = epoll_wait(epoll_fd, events, MAX_EVENTS, -1);
> +		if (nfds == -1) {
> +			ERR("epoll_wait");
> +			continue;
>  		}
>  
> -		multipoll_destroy(&mpent);
> +		for (i = 0; i < nfds; i++) {
> +			epoll_sock = (struct ustcomm_sock *)events[i].data.ptr;
> +			if (epoll_sock == listen_sock) {
> +				addr_size = sizeof(struct sockaddr);
> +				accept_fd = accept(epoll_sock->fd,
> +						   &addr,
> +						   (socklen_t *)&addr_size);
> +				if (accept_fd == -1) {
> +					ERR("accept failed\n");
> +				}
> +				ustcomm_init_sock(accept_fd, epoll_fd,
> +						 &ust_socks);
> +			} else {
> +				char *msg = NULL;
> +				result = recv_message_conn(epoll_sock->fd, &msg);
> +				if (result == 0) {
> +					ustcomm_del_sock(epoll_sock, 0);
> +				} else if (msg) {
> +					process_client_cmd(msg, epoll_sock->fd);
> +					free(msg);
> +				}
> +			}
> +		}
>  	}
>  
>  	pthread_cleanup_pop(1);
> @@ -1183,11 +1212,6 @@ void create_listener(void)
>  	}
>  }
>  
> -static int init_socket(void)
> -{
> -	return ustcomm_init_app(getpid(), &ustcomm_app);
> -}
> -
>  #define AUTOPROBE_DISABLED      0
>  #define AUTOPROBE_ENABLE_ALL    1
>  #define AUTOPROBE_ENABLE_REGEX  2
> @@ -1225,6 +1249,41 @@ static void auto_probe_connect(struct marker *m)
>  
>  }
>  
> +static struct ustcomm_sock * init_app_socket(int epoll_fd)
> +{
> +	char *name;
> +	int result;
> +	struct ustcomm_sock *sock;
> +
> +	result = asprintf(&name, "%s/%d", SOCK_DIR, (int)getpid());
> +	if (result < 0) {
> +		ERR("string overflow allocating socket name, "
> +		    "UST thread bailing");
> +		return NULL;
> +	}
> +
> +	result = ensure_dir_exists(SOCK_DIR);
> +	if (result == -1) {
> +		ERR("Unable to create socket directory %s, UST thread bailing",
> +		    SOCK_DIR);
> +		goto free_name;
> +	}
> +
> +	sock = ustcomm_init_named_socket(name, epoll_fd);
> +	if (!sock) {
> +		ERR("Error initializing named socket (%s). Check that directory"
> +		    "exists and that it is writable. UST thread bailing", name);
> +		goto free_name;
> +	}
> +
> +	free(name);
> +	return sock;
> +
> +free_name:
> +	free(name);
> +	return NULL;
> +}
> +
>  static void __attribute__((constructor)) init()
>  {
>  	int result;
> @@ -1242,9 +1301,18 @@ static void __attribute__((constructor)) init()
>  
>  	DBG("Tracectl constructor");
>  
> -	result = init_socket();
> -	if (result == -1) {
> -		ERR("init_socket error");
> +	/* Set up epoll */
> +	epoll_fd = epoll_create(MAX_EVENTS);
> +	if (epoll_fd == -1) {
> +		ERR("epoll_create failed, tracing shutting down");
> +		return;
> +	}
> +
> +	/* Create the socket */
> +	listen_sock = init_app_socket(epoll_fd);
> +	if (!listen_sock) {
> +		ERR("failed to create application socket,"
> +		    " tracing shutting down");
>  		return;
>  	}
>  
> @@ -1451,13 +1519,6 @@ static int trace_recording(void)
>  	return retval;
>  }
>  
> -#if 0
> -static int have_consumer(void)
> -{
> -	return !list_empty(&blocked_consumers);
> -}
> -#endif
> -
>  int restarting_usleep(useconds_t usecs)
>  {
>          struct timespec tv; 
> @@ -1545,8 +1606,8 @@ void ust_potential_exec(void)
>  
>  static void ust_fork(void)
>  {
> -	struct blocked_consumer *bc;
> -	struct blocked_consumer *deletable_bc = NULL;
> +	struct ust_buffer *buf, *buf_tmp;
> +	struct ustcomm_sock *sock, *sock_tmp;
>  	int result;
>  
>  	/* FIXME: technically, the locks could have been taken before the fork */
> @@ -1557,26 +1618,47 @@ static void ust_fork(void)
>  
>  	ltt_trace_stop("auto");
>  	ltt_trace_destroy("auto", 1);
> -	/* Delete all active connections */
> -	ustcomm_close_all_connections(&ustcomm_app.server);
> +	/* Delete all active connections, but leave them in the epoll set */
> +	list_for_each_entry_safe(sock, sock_tmp, &ust_socks, list) {
> +		ustcomm_del_sock(sock, 1);
> +	}
>  
>  	/* Delete all blocked consumers */
> -	list_for_each_entry(bc, &blocked_consumers, list) {
> -		result = close(bc->fd_producer);
> -		if (result == -1) {
> +	list_for_each_entry_safe(buf, buf_tmp, &open_buffers_list,
> +				 open_buffers_list) {
> +		result = close(buf->data_ready_fd_read);
> +		if(result == -1) {
>  			PERROR("close");
>  		}
> -		free(deletable_bc);
> -		deletable_bc = bc;
> -		list_del(&bc->list);
> +		result = close(buf->data_ready_fd_write);
> +		if(result == -1) {
> +			PERROR("close");
> +		}
> +		list_del(&buf->open_buffers_list);
>  	}
>  
> -	/* free app, keeping socket file */
> -	ustcomm_fini_app(&ustcomm_app, 1);
> +	/* Clean up the listener socket and epoll, keeping the scoket file */
> +	ustcomm_del_named_sock(listen_sock, 1);
> +	close(epoll_fd);
>  
> +	/* Re-start the launch sequence */
>  	STORE_SHARED(buffers_to_export, 0);
>  	have_listener = 0;
> -	init_socket();
> +
> +	/* Set up epoll */
> +	epoll_fd = epoll_create(MAX_EVENTS);
> +	if (epoll_fd == -1) {
> +		ERR("epoll_create failed, tracing shutting down");
> +		return;
> +	}
> +
> +	/* Create the socket */
> +	listen_sock = init_app_socket(epoll_fd);
> +	if (!listen_sock) {
> +		ERR("failed to create application socket,"
> +		    " tracing shutting down");
> +		return;
> +	}
>  	create_listener();
>  	ltt_trace_setup("auto");
>  	result = ltt_trace_set_type("auto", "ustrelay");
> diff --git a/libustcmd/ustcmd.c b/libustcmd/ustcmd.c
> index c512320..ac90f6c 100644
> --- a/libustcmd/ustcmd.c
> +++ b/libustcmd/ustcmd.c
> @@ -52,7 +52,12 @@ pid_t *ustcmd_get_online_pids(void)
>  			!!strcmp(dirent->d_name, "ustd")) {
>  
>  			sscanf(dirent->d_name, "%u", (unsigned int *) &ret[i]);
> -			if (pid_is_online(ret[i])) {
> +			/* FIXME: Here we previously called pid_is_online, which
> +			 * always returned 1, now I replaced it with just 1.
> +			 * We need to figure out an intelligent way of solving
> +			 * this, maybe connect-disconnect.
> +			 */
> +			if (1) {
>  				ret_size += sizeof(pid_t);
>  				ret = (pid_t *) realloc(ret, ret_size);
>  				++i;
> @@ -592,17 +597,17 @@ int ustcmd_force_switch(pid_t pid)
>  
>  int ustcmd_send_cmd(const char *cmd, const pid_t pid, char **reply)
>  {
> -	struct ustcomm_connection conn;
> +	int app_fd;
>  	int retval;
>  
> -	if (ustcomm_connect_app(pid, &conn)) {
> +	if (ustcomm_connect_app(pid, &app_fd)) {
>  		ERR("could not connect to PID %u", (unsigned int) pid);
>  		return -1;
>  	}
>  
> -	retval = ustcomm_send_request(&conn, cmd, reply);
> +	retval = ustcomm_send_request(app_fd, cmd, reply);
>  
> -	ustcomm_close_app(&conn);
> +	close(app_fd);
>  
>  	return retval;
>  }
> diff --git a/libustcomm/Makefile.am b/libustcomm/Makefile.am
> index 2672071..3ae96d5 100644
> --- a/libustcomm/Makefile.am
> +++ b/libustcomm/Makefile.am
> @@ -4,8 +4,7 @@ AM_CFLAGS = -fno-strict-aliasing
>  noinst_LTLIBRARIES = libustcomm.la
>  libustcomm_la_SOURCES = \
>  	ustcomm.h \
> -	ustcomm.c \
> -	multipoll.h \
> -	multipoll.c
> +	ustcomm.c
> +
>  libustcomm_la_LDFLAGS = -no-undefined -static
>  libustcomm_la_CFLAGS = -DUST_COMPONENT="libustcomm" -fPIC -fno-strict-aliasing
> diff --git a/libustcomm/multipoll.c b/libustcomm/multipoll.c
> deleted file mode 100644
> index 80426e3..0000000
> --- a/libustcomm/multipoll.c
> +++ /dev/null
> @@ -1,130 +0,0 @@
> -/*
> - * multipoll.c
> - *
> - * Copyright (C) 2010 - Pierre-Marc Fournier (pierre-marc dot fournier at polymtl dot ca)
> - *
> - * This library is free software; you can redistribute it and/or
> - * modify it under the terms of the GNU Lesser General Public
> - * License as published by the Free Software Foundation; either
> - * version 2.1 of the License, or (at your option) any later version.
> - *
> - * This library 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
> - * Lesser General Public License for more details.
> - *
> - * You should have received a copy of the GNU Lesser General Public
> - * License along with this library; if not, write to the Free Software
> - * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301 USA
> - */
> -
> -/* Multipoll is a framework to poll on several file descriptors and to call
> - * a specific callback depending on the fd that had activity.
> - */
> -
> -#include <poll.h>
> -#include <stdlib.h>
> -#include "multipoll.h"
> -#include "usterr.h"
> -
> -#define INITIAL_N_AVAIL 16
> -
> -/* multipoll_init
> - *
> - * Initialize an mpentries struct, which is initially empty of any fd.
> - */
> -
> -int multipoll_init(struct mpentries *ent)
> -{
> -	ent->n_used = 0;
> -	ent->n_avail = INITIAL_N_AVAIL;
> -
> -	ent->pollfds = (struct pollfd *) zmalloc(sizeof(struct pollfd) * INITIAL_N_AVAIL);
> -	ent->extras = (struct pollfd_extra *) zmalloc(sizeof(struct pollfd_extra) * INITIAL_N_AVAIL);
> -
> -	return 0;
> -}
> -
> -/* multipoll_destroy: free a struct mpentries
> - */
> -
> -int multipoll_destroy(struct mpentries *ent)
> -{
> -	int i;
> -
> -	for(i=0; i<ent->n_used; i++) {
> -		if(ent->extras[i].destroy_priv) {
> -			ent->extras[i].destroy_priv(ent->extras[i].priv);
> -		}
> -	}
> -
> -	free(ent->pollfds);
> -	free(ent->extras);
> -
> -	return 0;
> -}
> -
> -/* multipoll_add
> - *
> - * Add a file descriptor to be waited on in a struct mpentries.
> - *
> - * @ent: the struct mpentries to add an fd to
> - * @fd: the fd to wait on
> - * @events: a mask of the types of events to wait on, see the poll(2) man page
> - * @func: the callback function to be called if there is activity on the fd
> - * @priv: the private pointer to pass to func
> - * @destroy_priv: a callback to destroy the priv pointer when the mpentries
> -                  is destroyed; may be NULL
> - */
> -
> -int multipoll_add(struct mpentries *ent, int fd, short events, int (*func)(void *priv, int fd, short events), void *priv, int (*destroy_priv)(void *))
> -{
> -	int cur;
> -
> -	if(ent->n_used == ent->n_avail) {
> -		ent->n_avail *= 2;
> -		ent->pollfds = (struct pollfd *) realloc(ent->pollfds, sizeof(struct pollfd) * ent->n_avail);
> -		ent->extras = (struct pollfd_extra *) realloc(ent->extras, sizeof(struct pollfd_extra) * ent->n_avail);
> -	}
> -
> -	cur = ent->n_used;
> -	ent->n_used++;
> -
> -	ent->pollfds[cur].fd = fd;
> -	ent->pollfds[cur].events = events;
> -	ent->extras[cur].func = func;
> -	ent->extras[cur].priv = priv;
> -	ent->extras[cur].destroy_priv = destroy_priv;
> -
> -	return 0;
> -}
> -
> -/* multipoll_poll: do the actual poll on a struct mpentries
> - *
> - * File descriptors should have been already added with multipoll_add().
> - *
> - * A struct mpentries may be reused for multiple multipoll_poll calls.
> - *
> - * @ent: the struct mpentries to poll on.
> - * @timeout: the timeout after which to return if there was no activity.
> - */
> -
> -int multipoll_poll(struct mpentries *ent, int timeout)
> -{
> -	int result;
> -	int i;
> -
> -	result = poll(ent->pollfds, ent->n_used, timeout);
> -	if(result == -1) {
> -		PERROR("poll");
> -		return -1;
> -	}
> -
> -	for(i=0; i<ent->n_used; i++) {
> -		if(ent->pollfds[i].revents) {
> -			ent->extras[i].func(ent->extras[i].priv, ent->pollfds[i].fd, ent->pollfds[i].revents);
> -		}
> -	}
> -
> -	return 0;
> -}
> diff --git a/libustcomm/multipoll.h b/libustcomm/multipoll.h
> deleted file mode 100644
> index 8a0124f..0000000
> --- a/libustcomm/multipoll.h
> +++ /dev/null
> @@ -1,44 +0,0 @@
> -/*
> - * multipoll.h
> - *
> - * Copyright (C) 2010 - Pierre-Marc Fournier (pierre-marc dot fournier at polymtl dot ca)
> - *
> - * This library is free software; you can redistribute it and/or
> - * modify it under the terms of the GNU Lesser General Public
> - * License as published by the Free Software Foundation; either
> - * version 2.1 of the License, or (at your option) any later version.
> - *
> - * This library 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
> - * Lesser General Public License for more details.
> - *
> - * You should have received a copy of the GNU Lesser General Public
> - * License along with this library; if not, write to the Free Software
> - * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301 USA
> - */
> -
> -#ifndef UST_MULTIPOLL_H
> -#define UST_MULTIPOLL_H
> -
> -struct pollfd_extra {
> -	int (*func)(void *priv, int fd, short events);
> -	void *priv;
> -
> -	int (*destroy_priv)(void *priv);
> -};
> -
> -struct mpentries {
> -	struct pollfd *pollfds;
> -	struct pollfd_extra *extras;
> -
> -	int n_used;
> -	int n_avail;
> -};
> -
> -extern int multipoll_init(struct mpentries *ent);
> -extern int multipoll_add(struct mpentries *ent, int fd, short events, int (*func)(void *priv, int fd, short events), void *priv, int (*destroy_priv)(void *));
> -extern int multipoll_destroy(struct mpentries *ent);
> -extern int multipoll_poll(struct mpentries *ent, int timeout);
> -
> -#endif /* UST_MULTIPOLL_H */
> diff --git a/libustcomm/ustcomm.c b/libustcomm/ustcomm.c
> index 567c5d1..d55ac4c 100644
> --- a/libustcomm/ustcomm.c
> +++ b/libustcomm/ustcomm.c
> @@ -25,6 +25,7 @@
>  #include <sys/un.h>
>  #include <unistd.h>
>  #include <poll.h>
> +#include <sys/epoll.h>
>  #include <sys/stat.h>
>  
>  #include <stdio.h>
> @@ -35,9 +36,6 @@
>  #include "ustcomm.h"
>  #include "usterr.h"
>  #include "share.h"
> -#include "multipoll.h"
> -
> -#define UNIX_PATH_MAX 108
>  
>  static int mkdir_p(const char *path, mode_t mode)
>  {
> @@ -91,430 +89,450 @@ static int mkdir_p(const char *path, mode_t mode)
>  	return retval;
>  }
>  
> -static int signal_process(pid_t pid)
> +static struct sockaddr_un * create_sock_addr(const char *name,
> +					     size_t *sock_addr_size)
>  {
> -	return 0;
> -}
> +	struct sockaddr_un * addr;
> +	size_t alloc_size;
>  
> -void ustcomm_init_connection(struct ustcomm_connection *conn)
> -{
> -	conn->recv_buf = NULL;
> -	conn->recv_buf_size = 0;
> -	conn->recv_buf_alloc = 0;
> -}
> +	alloc_size = (size_t) (((struct sockaddr_un *) 0)->sun_path) +
> +		strlen(name) + 1;
>  
> -int pid_is_online(pid_t pid) {
> -	return 1;
> -}
> +	addr = malloc(alloc_size);
> +	if (addr < 0) {
> +		ERR("allocating addr failed");
> +		return NULL;
> +	}
>  
> -/* Send a message
> - *
> - * @fd: file descriptor to send to
> - * @msg: a null-terminated string containing the message to send
> - *
> - * Return value:
> - * -1: error
> - * 0: connection closed
> - * 1: success
> - */
> +	addr->sun_family = AF_UNIX;
> +	strcpy(addr->sun_path, name);
> +
> +	*sock_addr_size = alloc_size;
> +
> +	return addr;
> +}
>  
> -static int send_message_fd(int fd, const char *msg)
> +struct ustcomm_sock * ustcomm_init_sock(int fd, int epoll_fd,
> +					struct list_head *list)
>  {
> -	int result;
> +	struct epoll_event ev;
> +	struct ustcomm_sock *sock;
>  
> -	/* Send including the final \0 */
> -	result = patient_send(fd, msg, strlen(msg)+1, MSG_NOSIGNAL);
> -	if(result == -1) {
> -		if(errno != EPIPE)
> -			PERROR("send");
> -		return -1;
> +	sock = malloc(sizeof(struct ustcomm_sock));
> +	if (!sock) {
> +		perror("malloc: couldn't allocate ustcomm_sock");
> +		return NULL;
>  	}
> -	else if(result == 0) {
> -		return 0;
> +
> +	ev.events = EPOLLIN;
> +	ev.data.ptr = sock;
> +	sock->fd = fd;
> +
> +	if (epoll_ctl(epoll_fd, EPOLL_CTL_ADD, sock->fd, &ev) == -1) {
> +		perror("epoll_ctl: failed to add socket\n");
> +		free(sock);
> +		return NULL;
>  	}
>  
> -	DBG("sent message \"%s\"", msg);
> -	return 1;
> +	sock->epoll_fd = epoll_fd;
> +	if (list) {
> +		list_add(&sock->list, list);
> +	} else {
> +		INIT_LIST_HEAD(&sock->list);
> +	}
> +
> +	return sock;
>  }
>  
> -/* Called by an app to ask the consumer daemon to connect to it. */
> +void ustcomm_del_sock(struct ustcomm_sock *sock, int keep_in_epoll)
> +{
> +	list_del(&sock->list);
> +	if (!keep_in_epoll) {
> +		if (epoll_ctl(sock->epoll_fd, EPOLL_CTL_DEL, sock->fd, NULL) == -1) {
> +			PERROR("epoll_ctl: failed to delete socket");
> +		}
> +	}
> +	close(sock->fd);
> +	free(sock);
> +}
>  
> -int ustcomm_request_consumer(pid_t pid, const char *channel)
> +struct ustcomm_sock * ustcomm_init_named_socket(const char *name,
> +						int epoll_fd)
>  {
> -	char path[UNIX_PATH_MAX];
>  	int result;
> -	char *msg=NULL;
> -	int retval = 0;
> -	struct ustcomm_connection conn;
> -	char *explicit_daemon_socket_path;
> +	int fd;
> +	size_t sock_addr_size;
> +	struct sockaddr_un * addr;
> +	struct ustcomm_sock *sock;
>  
> -	explicit_daemon_socket_path = getenv("UST_DAEMON_SOCKET");
> -	if(explicit_daemon_socket_path) {
> -		/* user specified explicitly a socket path */
> -		result = snprintf(path, UNIX_PATH_MAX, "%s", explicit_daemon_socket_path);
> -	}
> -	else {
> -		/* just use the default path */
> -		result = snprintf(path, UNIX_PATH_MAX, "%s/ustd", SOCK_DIR);
> +	fd = socket(PF_UNIX, SOCK_STREAM, 0);
> +	if(fd == -1) {
> +		PERROR("socket");
> +		return NULL;
>  	}
>  
> -	if(result >= UNIX_PATH_MAX) {
> -		ERR("string overflow allocating socket name");
> -		return -1;
> +	addr = create_sock_addr(name, &sock_addr_size);
> +	if (addr == NULL) {
> +		ERR("allocating addr, UST thread bailing");
> +		goto close_sock;
>  	}
>  
> -	if (asprintf(&msg, "collect %d %s", pid, channel) < 0) {
> -		ERR("ustcomm_request_consumer : asprintf failed (collect %d/%s)",
> -		    pid, channel);
> -		return -1;
> +	result = access(name, F_OK);
> +	if(result == 0) {
> +		/* file exists */
> +		result = unlink(name);
> +		if(result == -1) {
> +			PERROR("unlink of socket file");
> +			goto free_addr;
> +		}
> +		DBG("socket already exists; overwriting");
>  	}
>  
> -	/* don't signal it because it's the daemon */
> -	result = ustcomm_connect_path(path, &conn, -1);
> +	result = bind(fd, (struct sockaddr *)addr, sock_addr_size);
>  	if(result == -1) {
> -		WARN("ustcomm_connect_path failed");
> -		retval = -1;
> -		goto del_string;
> +		PERROR("bind");
> +		goto free_addr;
>  	}
>  
> -	result = ustcomm_send_request(&conn, msg, NULL);
> +	result = listen(fd, 1);
>  	if(result == -1) {
> -		WARN("ustcomm_send_request failed");
> -		retval = -1;
> -		goto disconnect;
> +		PERROR("listen");
> +		goto free_addr;
>  	}
>  
> -	disconnect:
> -	ustcomm_disconnect(&conn);
> -	del_string:
> -	free(msg);
> +	sock = ustcomm_init_sock(fd, epoll_fd,
> +				 NULL);
> +	if (!sock) {
> +		ERR("failed to create ustcomm_sock");
> +		goto free_addr;
> +	}
>  
> -	return retval;
> -}
> +	free(addr);
>  
> -/* returns 1 to indicate a message was received
> - * returns 0 to indicate no message was received (end of stream)
> - * returns -1 to indicate an error
> - */
> +	return sock;
>  
> -#define RECV_INCREMENT 1000
> -#define RECV_INITIAL_BUF_SIZE 10
> +free_addr:
> +	free(addr);
> +close_sock:
> +	close(fd);
>  
> -static int recv_message_fd(int fd, char **recv_buf, int *recv_buf_size, int *recv_buf_alloc, char **msg)
> +	return NULL;
> +}
> +
> +void ustcomm_del_named_sock(struct ustcomm_sock *sock,
> +			    int keep_socket_file)
>  {
> -	int result;
> +	int result, fd;
> +	struct stat st;
> +	struct sockaddr dummy;
> +	struct sockaddr_un *sockaddr = NULL;
> +	int alloc_size;
>  
> -	/* 1. Check if there is a message in the buf */
> -	/* 2. If not, do:
> -           2.1 receive chunk and put it in buffer
> -	   2.2 process full message if there is one
> -	   -- while no message arrived
> -	*/
> +	fd = sock->fd;
>  
> -	for(;;) {
> -		int i;
> -		int nulfound = 0;
> +	if(!keep_socket_file) {
>  
> -		/* Search for full message in buffer */
> -		for(i=0; i<*recv_buf_size; i++) {
> -			if((*recv_buf)[i] == '\0') {
> -				nulfound = 1;
> -				break;
> -			}
> +		/* Get the socket name */
> +		alloc_size = sizeof(dummy);
> +		if (getsockname(fd, &dummy, (socklen_t *)&alloc_size) < 0) {
> +			PERROR("getsockname failed");
> +			return;
>  		}
>  
> -		/* Process found message */
> -		if(nulfound == 1) {
> -			char *newbuf;
> -
> -			if(i == 0) {
> -				/* problem */
> -				WARN("received empty message");
> -			}
> -			*msg = strndup(*recv_buf, i);
> -
> -			/* Remove processed message from buffer */
> -			newbuf = (char *) malloc(*recv_buf_size - (i+1));
> -			memcpy(newbuf, *recv_buf + (i+1), *recv_buf_size - (i+1));
> -			free(*recv_buf);
> -			*recv_buf = newbuf;
> -			*recv_buf_size -= (i+1);
> -			*recv_buf_alloc -= (i+1);
> -
> -			return 1;
> +		sockaddr = malloc(alloc_size);
> +		if (!sockaddr) {
> +			ERR("failed to allocate sockaddr");
> +			return;
>  		}
>  
> -		/* Receive a chunk from the fd */
> -		if(*recv_buf_alloc - *recv_buf_size < RECV_INCREMENT) {
> -			*recv_buf_alloc += RECV_INCREMENT - (*recv_buf_alloc - *recv_buf_size);
> -			*recv_buf = (char *) realloc(*recv_buf, *recv_buf_alloc);
> +		if (getsockname(fd, sockaddr, (socklen_t *)&alloc_size) < 0) {
> +			PERROR("getsockname failed");
> +			goto free_sockaddr;
>  		}
>  
> -		result = recv(fd, *recv_buf+*recv_buf_size, RECV_INCREMENT, 0);
> +		/* Destroy socket */
> +		result = stat(sockaddr->sun_path, &st);
>  		if(result == -1) {
> -			if(errno == ECONNRESET) {
> -				*recv_buf_size = 0;
> -				return 0;
> -			}
> -			else if(errno == EINTR) {
> -				return -1;
> -			}
> -			else {
> -				PERROR("recv");
> -				return -1;
> -			}
> +			PERROR("stat (%s)", sockaddr->sun_path);
> +			goto free_sockaddr;
>  		}
> -		if(result == 0) {
> -			return 0;
> +
> +		/* Paranoid check before deleting. */
> +		result = S_ISSOCK(st.st_mode);
> +		if(!result) {
> +			ERR("The socket we are about to delete is not a socket.");
> +			goto free_sockaddr;
>  		}
> -		*recv_buf_size += result;
>  
> -		/* Go back to the beginning to check if there is a full message in the buffer */
> +		result = unlink(sockaddr->sun_path);
> +		if(result == -1) {
> +			PERROR("unlink");
> +		}
>  	}
>  
> -	DBG("received message \"%s\"", *recv_buf);
> +	ustcomm_del_sock(sock, keep_socket_file);
>  
> -	return 1;
> +free_sockaddr:
> +	free(sockaddr);
>  
>  }
>  
> -static int recv_message_conn(struct ustcomm_connection *conn, char **msg)
> -{
> -	return recv_message_fd(conn->fd, &conn->recv_buf, &conn->recv_buf_size, &conn->recv_buf_alloc, msg);
> -}
>  
> -int ustcomm_send_reply(struct ustcomm_server *server, char *msg, struct ustcomm_source *src)
> +/* Called by an app to ask the consumer daemon to connect to it. */
> +
> +int ustcomm_request_consumer(pid_t pid, const char *channel)
>  {
> -	int result;
> +	int result, daemon_fd;
> +	int retval = 0;
> +	char *msg=NULL;
> +	char *explicit_daemon_socket_path, *daemon_path;
>  
> -	result = send_message_fd(src->fd, msg);
> -	if(result < 0) {
> -		ERR("error in send_message_fd");
> +	explicit_daemon_socket_path = getenv("UST_DAEMON_SOCKET");
> +	if (explicit_daemon_socket_path) {
> +		/* user specified explicitly a socket path */
> +		result = asprintf(&daemon_path, "%s", explicit_daemon_socket_path);
> +	} else {
> +		/* just use the default path */
> +		result = asprintf(&daemon_path, "%s/ustd", SOCK_DIR);
> +	}
> +	if (result == -1) {
> +		ERR("string overflow allocating socket name");
>  		return -1;
>  	}
>  
> -	return 0;
> -} 
> -
> -/* Called after a fork. */
> +	if (asprintf(&msg, "collect %d %s", pid, channel) < 0) {
> +		ERR("ustcomm_request_consumer : asprintf failed (collect %d/%s)",
> +		    pid, channel);
> +		retval = -1;
> +		goto free_daemon_path;
> +	}
>  
> -int ustcomm_close_all_connections(struct ustcomm_server *server)
> -{
> -	struct ustcomm_connection *conn;
> -	struct ustcomm_connection *deletable_conn = NULL;
> +	result = ustcomm_connect_path(daemon_path, &daemon_fd);
> +	if (result == -1) {
> +		WARN("ustcomm_connect_path failed, daemon_path: %s",
> +		     daemon_path);
> +		retval = -1;
> +		goto del_string;
> +	}
>  
> -	list_for_each_entry(conn, &server->connections, list) {
> -		free(deletable_conn);
> -		deletable_conn = conn;
> -		ustcomm_close_app(conn);
> -		list_del(&conn->list);
> +	result = ustcomm_send_request(daemon_fd, msg, NULL);
> +	if (result == -1) {
> +		WARN("ustcomm_send_request failed, daemon path: %s",
> +		     daemon_path);
> +		retval = -1;
>  	}
>  
> -	return 0;
> +	close(daemon_fd);
> +del_string:
> +	free(msg);
> +free_daemon_path:
> +	free(daemon_path);
> +
> +	return retval;
>  }
>  
> -/* @timeout: max blocking time in milliseconds, -1 means infinity
> - *
> - * returns 1 to indicate a message was received
> - * returns 0 to indicate no message was received
> +/* returns 1 to indicate a message was received
> + * returns 0 to indicate no message was received (end of stream)
>   * returns -1 to indicate an error
>   */
> -
> -int ustcomm_recv_message(struct ustcomm_server *server, char **msg, struct ustcomm_source *src, int timeout)
> +int ustcomm_recv_fd(int sock,
> +		    struct ustcomm_header *header,
> +		    char **data, int *fd)
>  {
> -	struct pollfd *fds;
> -	struct ustcomm_connection **conn_table;
> -	struct ustcomm_connection *conn;
>  	int result;
>  	int retval;
> -
> -	for(;;) {
> -		int idx = 0;
> -		int n_fds = 1;
> -
> -		list_for_each_entry(conn, &server->connections, list) {
> -			n_fds++;
> -		}
> -
> -		fds = (struct pollfd *) zmalloc(n_fds * sizeof(struct pollfd));
> -		if(fds == NULL) {
> -			ERR("zmalloc returned NULL");
> +	struct ustcomm_header peek_header;
> +	struct iovec iov[2];
> +	struct msghdr msg;
> +	struct cmsghdr *cmsg;
> +	char buf[CMSG_SPACE(sizeof(int))];
> +
> +	result = recv(sock, &peek_header, sizeof(peek_header),
> +		      MSG_PEEK | MSG_WAITALL);
> +	if (result <= 0) {
> +		if(errno == ECONNRESET) {
> +			return 0;
> +		} else if (errno == EINTR) {
> +			return -1;
> +		} else if (result < 0) {
> +			PERROR("recv");
>  			return -1;
>  		}
> +		return 0;
> +	}
>  
> -		conn_table = (struct ustcomm_connection **) zmalloc(n_fds * sizeof(struct ustcomm_connection *));
> -		if(conn_table == NULL) {
> -			ERR("zmalloc returned NULL");
> -			retval = -1;
> -			goto free_fds_return;
> -		}
> +	memset(&msg, 0, sizeof(msg));
>  
> -		/* special idx 0 is for listening socket */
> -		fds[idx].fd = server->listen_fd;
> -		fds[idx].events = POLLIN;
> -		idx++;
> +	iov[0].iov_base = (char *)header;
> +	iov[0].iov_len = sizeof(struct ustcomm_header);
>  
> -		list_for_each_entry(conn, &server->connections, list) {
> -			fds[idx].fd = conn->fd;
> -			fds[idx].events = POLLIN;
> -			conn_table[idx] = conn;
> -			idx++;
> -		}
> +	msg.msg_iov = iov;
> +	msg.msg_iovlen = 1;
>  
> -		result = poll(fds, n_fds, timeout);
> -		if(result == -1 && errno == EINTR) {
> -			/* That's ok. ustd receives signals to notify it must shutdown. */
> -			retval = -1;
> -			goto free_conn_table_return;
> -		}
> -		else if(result == -1) {
> -			PERROR("poll");
> -			retval = -1;
> -			goto free_conn_table_return;
> +	if (peek_header.size) {
> +		if (peek_header.size < 0 || peek_header.size > 100) {
> +			WARN("big peek header! %d", peek_header.size);
>  		}
> -		else if(result == 0) {
> -			retval = 0;
> -			goto free_conn_table_return;
> +		*data = malloc(peek_header.size);
> +		if (!*data) {
> +			ERR("failed to allocate space for message");
>  		}
>  
> -		if(fds[0].revents) {
> -			struct ustcomm_connection *newconn;
> -			int newfd;
> +		iov[1].iov_base = (char *)*data;
> +		iov[1].iov_len = peek_header.size;
>  
> -			result = newfd = accept(server->listen_fd, NULL, NULL);
> -			if(result == -1) {
> -				PERROR("accept");
> -				retval = -1;
> -				goto free_conn_table_return;
> -			}
> +		msg.msg_iovlen++;
> +	}
>  
> -			newconn = (struct ustcomm_connection *) zmalloc(sizeof(struct ustcomm_connection));
> -			if(newconn == NULL) {
> -				ERR("zmalloc returned NULL");
> -				return -1;
> -			}
> +	if (fd && peek_header.fd_included) {
> +		msg.msg_control = buf;
> +		msg.msg_controllen = sizeof(buf);
> +	}
>  
> -			ustcomm_init_connection(newconn);
> -			newconn->fd = newfd;
> +	result = recvmsg(sock, &msg,
> +			 MSG_WAITALL);
>  
> -			list_add(&newconn->list, &server->connections);
> +	if (result <= 0) {
> +		if(errno == ECONNRESET) {
> +			retval = 0;
> +		} else if (errno == EINTR) {
> +			retval = -1;
> +		} else if (result < 0) {
> +			PERROR("recv");
> +			retval = -1;
> +		} else {
> +			retval = 0;
>  		}
> -
> -		for(idx=1; idx<n_fds; idx++) {
> -			if(fds[idx].revents) {
> -				retval = recv_message_conn(conn_table[idx], msg);
> -				if(src)
> -					src->fd = fds[idx].fd;
> -
> -				if(retval == 0) {
> -					/* connection finished */
> -					list_for_each_entry(conn, &server->connections, list) {
> -						if(conn->fd == fds[idx].fd) {
> -							ustcomm_close_app(conn);
> -							list_del(&conn->list);
> -							free(conn);
> -							break;
> -						}
> -					}
> -				}
> -				else {
> -					goto free_conn_table_return;
> -				}
> +		free(*data);
> +		return retval;
> +	}
> +
> +	if (fd && peek_header.fd_included) {
> +		cmsg = CMSG_FIRSTHDR(&msg);
> +		result = 0;
> +		while (cmsg != NULL) {
> +			if (cmsg->cmsg_level == SOL_SOCKET
> +			    && cmsg->cmsg_type  == SCM_RIGHTS) {
> +				*fd = *(int *) CMSG_DATA(cmsg);
> +				result = 1;
> +				break;
>  			}
> +			cmsg = CMSG_NXTHDR(&msg, cmsg);
> +		}
> +		if (!result) {
> +			ERR("Failed to receive file descriptor\n");
>  		}
> -
> -		free(fds);
> -		free(conn_table);
>  	}
>  
> -free_conn_table_return:
> -	free(conn_table);
> -free_fds_return:
> -	free(fds);
> -	return retval;
> +	return 1;
>  }
>  
> -int ustcomm_ustd_recv_message(struct ustcomm_ustd *ustd, char **msg, struct ustcomm_source *src, int timeout)
> +int ustcomm_recv(int sock,
> +		 struct ustcomm_header *header,
> +		 char **data)
>  {
> -	return ustcomm_recv_message(&ustd->server, msg, src, timeout);
> +	return ustcomm_recv_fd(sock, header, data, NULL);
>  }
>  
> -int ustcomm_app_recv_message(struct ustcomm_app *app, char **msg, struct ustcomm_source *src, int timeout)
> +
> +int recv_message_conn(int sock, char **msg)
>  {
> -	return ustcomm_recv_message(&app->server, msg, src, timeout);
> -}
> +	struct ustcomm_header header;
>  
> -/* This removes src from the list of active connections of app.
> - */
> +	return ustcomm_recv(sock, &header, msg);
> +}
>  
> -int ustcomm_app_detach_client(struct ustcomm_app *app, struct ustcomm_source *src)
> +int ustcomm_send_fd(int sock,
> +		    const struct ustcomm_header *header,
> +		    const char *data,
> +		    int *fd)
>  {
> -	struct ustcomm_server *server = (struct ustcomm_server *)app;
> -	struct ustcomm_connection *conn;
> +	struct iovec iov[2];
> +	struct msghdr msg;
> +	int result;
> +	struct cmsghdr *cmsg;
> +	char buf[CMSG_SPACE(sizeof(int))];
> +
> +	memset(&msg, 0, sizeof(msg));
> +
> +	iov[0].iov_base = (char *)header;
> +	iov[0].iov_len = sizeof(struct ustcomm_header);
> +
> +	msg.msg_iov = iov;
> +	msg.msg_iovlen = 1;
> +
> +	if (header->size) {
> +		iov[1].iov_base = (char *)data;
> +		iov[1].iov_len = header->size;
> +
> +		msg.msg_iovlen++;
>  
> -	list_for_each_entry(conn, &server->connections, list) {
> -		if(conn->fd == src->fd) {
> -			list_del(&conn->list);
> -			goto found;
> -		}
>  	}
>  
> -	return -1;
> -found:
> -	return src->fd;
> +	if (fd && header->fd_included) {
> +		msg.msg_control = buf;
> +		msg.msg_controllen = sizeof(buf);
> +		cmsg = CMSG_FIRSTHDR(&msg);
> +		cmsg->cmsg_level = SOL_SOCKET;
> +		cmsg->cmsg_type = SCM_RIGHTS;
> +		cmsg->cmsg_len = CMSG_LEN(sizeof(int));
> +		*(int *) CMSG_DATA(cmsg) = *fd;
> +		msg.msg_controllen = cmsg->cmsg_len;
> +	}
> +
> +	result = sendmsg(sock, &msg, MSG_NOSIGNAL);
> +	if (result < 0 && errno != EPIPE) {
> +		PERROR("sendmsg failed");
> +	}
> +	return result;
>  }
>  
> -static int init_named_socket(const char *name, char **path_out)
> +int ustcomm_send(int sock,
> +		 const struct ustcomm_header *header,
> +		 const char *data)
>  {
> -	int result;
> -	int fd;
> +	return ustcomm_send_fd(sock, header, data, NULL);
> +}
>  
> -	struct sockaddr_un addr;
> -	
> -	result = fd = socket(PF_UNIX, SOCK_STREAM, 0);
> -	if(result == -1) {
> -		PERROR("socket");
> -		return -1;
> -	}
> +int ustcomm_send_reply(char *msg, int sock)
> +{
> +	int result;
> +	struct ustcomm_header header;
>  
> -	addr.sun_family = AF_UNIX;
> +	memset(&header, 0, sizeof(header));
>  
> -	strncpy(addr.sun_path, name, UNIX_PATH_MAX);
> -	addr.sun_path[UNIX_PATH_MAX-1] = '\0';
> +	header.size = strlen(msg) + 1;
>  
> -	result = access(name, F_OK);
> -	if(result == 0) {
> -		/* file exists */
> -		result = unlink(name);
> -		if(result == -1) {
> -			PERROR("unlink of socket file");
> -			goto close_sock;
> -		}
> -		DBG("socket already exists; overwriting");
> +	result = ustcomm_send(sock, &header, msg);
> +	if(result < 0) {
> +		ERR("error in ustcomm_send");
> +		return result;
>  	}
>  
> -	result = bind(fd, (struct sockaddr *)&addr, sizeof(addr));
> -	if(result == -1) {
> -		PERROR("bind");
> -		goto close_sock;
> -	}
> +	return 0;
> +}
>  
> -	result = listen(fd, 1);
> -	if(result == -1) {
> -		PERROR("listen");
> -		goto close_sock;
> -	}
> +int ustcomm_send_req(int sock,
> +		     const struct ustcomm_header *req_header,
> +		     const char *data,
> +		     char **response)
> +{
> +	int result;
> +	struct ustcomm_header res_header;
>  
> -	if(path_out) {
> -		*path_out = strdup(addr.sun_path);
> +	result = ustcomm_send(sock, req_header, data);
> +	if ( result <= 0) {
> +		return result;
>  	}
>  
> -	return fd;
> +	if (!response) {
> +		return 1;
> +	}
>  
> -	close_sock:
> -	close(fd);
> +	return ustcomm_recv(sock,
> +			    &res_header,
> +			    response);
>  
> -	return -1;
>  }
>  
>  /*
> @@ -527,27 +545,17 @@ static int init_named_socket(const char *name, char **path_out)
>   * ECONNRESET, which is normal when the application dies.
>   */
>  
> -int ustcomm_send_request(struct ustcomm_connection *conn, const char *req, char **reply)
> +int ustcomm_send_request(int sock, const char *req, char **reply)
>  {
> -	int result;
> +	struct ustcomm_header req_header;
>  
> -	/* Send including the final \0 */
> -	result = send_message_fd(conn->fd, req);
> -	if(result != 1)
> -		return result;
> +	req_header.size = strlen(req) + 1;
>  
> -	if(!reply)
> -		return 1;
> +	return ustcomm_send_req(sock,
> +				&req_header,
> +				req,
> +				reply);
>  
> -	result = recv_message_conn(conn, reply);
> -	if(result == -1) {
> -		return -1;
> -	}
> -	else if(result == 0) {
> -		return 0;
> -	}
> -	
> -	return 1;
>  }
>  
>  /* Return value:
> @@ -555,52 +563,45 @@ int ustcomm_send_request(struct ustcomm_connection *conn, const char *req, char
>   * -1: error
>   */
>  
> -int ustcomm_connect_path(const char *path, struct ustcomm_connection *conn, pid_t signalpid)
> +int ustcomm_connect_path(const char *name, int *connection_fd)
>  {
> -	int fd;
> -	int result;
> -	struct sockaddr_un addr;
> +	int result, fd;
> +	size_t sock_addr_size;
> +	struct sockaddr_un *addr;
>  
> -	ustcomm_init_connection(conn);
> -
> -	result = fd = socket(PF_UNIX, SOCK_STREAM, 0);
> -	if(result == -1) {
> +	fd = socket(PF_UNIX, SOCK_STREAM, 0);
> +	if(fd == -1) {
>  		PERROR("socket");
>  		return -1;
>  	}
>  
> -	addr.sun_family = AF_UNIX;
> -
> -	result = snprintf(addr.sun_path, UNIX_PATH_MAX, "%s", path);
> -	if(result >= UNIX_PATH_MAX) {
> -		ERR("string overflow allocating socket name");
> -		return -1;
> -	}
> -
> -	if(signalpid >= 0) {
> -		result = signal_process(signalpid);
> -		if(result == -1) {
> -			ERR("could not signal process");
> -			return -1;
> -		}
> +	addr = create_sock_addr(name, &sock_addr_size);
> +	if (addr == NULL) {
> +		ERR("allocating addr failed");
> +		goto close_sock;
>  	}
>  
> -	result = connect(fd, (struct sockaddr *)&addr, sizeof(addr));
> +	result = connect(fd, (struct sockaddr *)addr, sock_addr_size);
>  	if(result == -1) {
> -		PERROR("connect (path=%s)", path);
> -		return -1;
> +		PERROR("connect (path=%s)", name);
> +		goto free_sock_addr;
>  	}
>  
> -	conn->fd = fd;
> +	*connection_fd = fd;
> +
> +	free(addr);
>  
>  	return 0;
> -}
>  
> -int ustcomm_disconnect(struct ustcomm_connection *conn)
> -{
> -	return close(conn->fd);
> +free_sock_addr:
> +	free(addr);
> +close_sock:
> +	close(fd);
> +
> +	return -1;
>  }
>  
> +
>  /* Open a connection to a traceable app.
>   *
>   * Return value:
> @@ -608,35 +609,30 @@ int ustcomm_disconnect(struct ustcomm_connection *conn)
>   * -1: error
>   */
>  
> -int ustcomm_connect_app(pid_t pid, struct ustcomm_connection *conn)
> +int ustcomm_connect_app(pid_t pid, int *app_fd)
>  {
>  	int result;
> -	char path[UNIX_PATH_MAX];
> -
> +	int retval = 0;
> +	char *name;
>  
> -	result = snprintf(path, UNIX_PATH_MAX, "%s/%d", SOCK_DIR, pid);
> -	if(result >= UNIX_PATH_MAX) {
> -		ERR("string overflow allocating socket name");
> +	result = asprintf(&name, "%s/%d", SOCK_DIR, pid);
> +	if (result < 0) {
> +		ERR("failed to allocate socket name");
>  		return -1;
>  	}
>  
> -	return ustcomm_connect_path(path, conn, pid);
> -}
> -
> -/* Close a connection to a traceable app. It frees the
> - * resources. It however does not free the
> - * ustcomm_connection itself.
> - */
> +	result = ustcomm_connect_path(name, app_fd);
> +	if (result < 0) {
> +		ERR("failed to connect to app");
> +		retval = -1;
> +	}
>  
> -int ustcomm_close_app(struct ustcomm_connection *conn)
> -{
> -	close(conn->fd);
> -	free(conn->recv_buf);
> +	free(name);
>  
> -	return 0;
> +	return retval;
>  }
>  
> -static int ensure_dir_exists(const char *dir)
> +int ensure_dir_exists(const char *dir)
>  {
>  	struct stat st;
>  	int result;
> @@ -663,139 +659,10 @@ static int ensure_dir_exists(const char *dir)
>  	return 0;
>  }
>  
> -/* Called by an application to initialize its server so daemons can
> - * connect to it.
> - */
> -
> -int ustcomm_init_app(pid_t pid, struct ustcomm_app *handle)
> -{
> -	int result;
> -	char *name;
> -
> -	result = asprintf(&name, "%s/%d", SOCK_DIR, (int)pid);
> -	if(result >= UNIX_PATH_MAX) {
> -		ERR("string overflow allocating socket name");
> -		return -1;
> -	}
> -
> -	result = ensure_dir_exists(SOCK_DIR);
> -	if(result == -1) {
> -		ERR("Unable to create socket directory %s", SOCK_DIR);
> -		return -1;
> -	}
> -
> -	handle->server.listen_fd = init_named_socket(name, &(handle->server.socketpath));
> -	if(handle->server.listen_fd < 0) {
> -		ERR("Error initializing named socket (%s). Check that directory exists and that it is writable.", name);
> -		goto free_name;
> -	}
> -	free(name);
> -
> -	INIT_LIST_HEAD(&handle->server.connections);
> -
> -	return 0;
> -
> -free_name:
> -	free(name);
> -	return -1;
> -}
> -
>  /* Used by the daemon to initialize its server so applications
>   * can connect to it.
>   */
>  
> -int ustcomm_init_ustd(struct ustcomm_ustd *handle, const char *sock_path)
> -{
> -	char *name;
> -	int retval = 0;
> -
> -	if(sock_path) {
> -		if (asprintf(&name, "%s", sock_path) < 0) {
> -			ERR("ustcomm_init_ustd : asprintf failed (sock_path %s)",
> -			    sock_path);
> -			return -1;
> -		}
> -	}
> -	else {
> -		int result;
> -
> -		/* Only check if socket dir exists if we are using the default directory */
> -		result = ensure_dir_exists(SOCK_DIR);
> -		if(result == -1) {
> -			ERR("Unable to create socket directory %s", SOCK_DIR);
> -			return -1;
> -		}
> -
> -		if (asprintf(&name, "%s/%s", SOCK_DIR, "ustd") < 0) {
> -			ERR("ustcomm_init_ustd : asprintf failed (%s/ustd)",
> -			    SOCK_DIR);
> -			return -1;
> -		}
> -	}
> -
> -	handle->server.listen_fd = init_named_socket(name, &handle->server.socketpath);
> -	if(handle->server.listen_fd < 0) {
> -		ERR("error initializing named socket at %s", name);
> -		retval = -1;
> -		goto free_name;
> -	}
> -
> -	INIT_LIST_HEAD(&handle->server.connections);
> -
> -free_name:
> -	free(name);
> -
> -	return retval;
> -}
> -
> -static void ustcomm_fini_server(struct ustcomm_server *server, int keep_socket_file)
> -{
> -	int result;
> -	struct stat st;
> -
> -	if(!keep_socket_file) {
> -		/* Destroy socket */
> -		result = stat(server->socketpath, &st);
> -		if(result == -1) {
> -			PERROR("stat (%s)", server->socketpath);
> -			return;
> -		}
> -
> -		/* Paranoid check before deleting. */
> -		result = S_ISSOCK(st.st_mode);
> -		if(!result) {
> -			ERR("The socket we are about to delete is not a socket.");
> -			return;
> -		}
> -
> -		result = unlink(server->socketpath);
> -		if(result == -1) {
> -			PERROR("unlink");
> -		}
> -	}
> -
> -	free(server->socketpath);
> -
> -	result = close(server->listen_fd);
> -	if(result == -1) {
> -		PERROR("close");
> -		return;
> -	}
> -}
> -
> -/* Free a traceable application server */
> -
> -void ustcomm_fini_app(struct ustcomm_app *handle, int keep_socket_file)
> -{
> -	ustcomm_fini_server(&handle->server, keep_socket_file);
> -}
> -
> -/* Free a ustd server */
> -
> -void ustcomm_fini_ustd(struct ustcomm_ustd *handle)
> -{
> -	ustcomm_fini_server(&handle->server, 0);
> -}
>  
>  static const char *find_tok(const char *str)
>  {
> @@ -884,89 +751,3 @@ char *nth_token(const char *str, int tok_no)
>  
>  	return retval;
>  }
> -
> -/* Callback from multipoll.
> - * Receive a new connection on the listening socket.
> - */
> -
> -static int process_mp_incoming_conn(void *priv, int fd, short events)
> -{
> -	struct ustcomm_connection *newconn;
> -	struct ustcomm_server *server = (struct ustcomm_server *) priv;
> -	int newfd;
> -	int result;
> -
> -	result = newfd = accept(server->listen_fd, NULL, NULL);
> -	if(result == -1) {
> -		PERROR("accept");
> -		return -1;
> -	}
> -
> -	newconn = (struct ustcomm_connection *) zmalloc(sizeof(struct ustcomm_connection));
> -	if(newconn == NULL) {
> -		ERR("zmalloc returned NULL");
> -		return -1;
> -	}
> -
> -	ustcomm_init_connection(newconn);
> -	newconn->fd = newfd;
> -
> -	list_add(&newconn->list, &server->connections);
> -
> -	return 0;
> -}
> -
> -/* Callback from multipoll.
> - * Receive a message on an existing connection.
> - */
> -
> -static int process_mp_conn_msg(void *priv, int fd, short revents)
> -{
> -	struct ustcomm_multipoll_conn_info *mpinfo = (struct ustcomm_multipoll_conn_info *) priv;
> -	int result;
> -	char *msg;
> -	struct ustcomm_source src;
> -
> -	if(revents) {
> -		src.fd = fd;
> -
> -		result = recv_message_conn(mpinfo->conn, &msg);
> -		if(result == -1) {
> -			ERR("error in recv_message_conn");
> -		}
> -
> -		else if(result == 0) {
> -			/* connection finished */
> -			ustcomm_close_app(mpinfo->conn);
> -			list_del(&mpinfo->conn->list);
> -			free(mpinfo->conn);
> -		}
> -		else {
> -			mpinfo->cb(msg, &src);
> -			free(msg);
> -		}
> -	}
> -
> -	return 0;
> -}
> -
> -int free_ustcomm_client_poll(void *data)
> -{
> -	free(data);
> -	return 0;
> -}
> -
> -void ustcomm_mp_add_app_clients(struct mpentries *ent, struct ustcomm_app *app, int (*cb)(char *recvbuf, struct ustcomm_source *src))
> -{
> -	struct ustcomm_connection *conn;
> -
> -	/* add listener socket */
> -	multipoll_add(ent, app->server.listen_fd, POLLIN, process_mp_incoming_conn, &app->server, NULL);
> -
> -	list_for_each_entry(conn, &app->server.connections, list) {
> -		struct ustcomm_multipoll_conn_info *mpinfo = (struct ustcomm_multipoll_conn_info *) zmalloc(sizeof(struct ustcomm_multipoll_conn_info));
> -		mpinfo->conn = conn;
> -		mpinfo->cb = cb;
> -		multipoll_add(ent, conn->fd, POLLIN, process_mp_conn_msg, mpinfo, free_ustcomm_client_poll);
> -	}
> -}
> diff --git a/libustcomm/ustcomm.h b/libustcomm/ustcomm.h
> index f96ca16..f3c07b6 100644
> --- a/libustcomm/ustcomm.h
> +++ b/libustcomm/ustcomm.h
> @@ -23,73 +23,62 @@
>  #include <urcu/list.h>
>  
>  #include <ust/kcompat/kcompat.h>
> -#include "multipoll.h"
>  
>  #define SOCK_DIR "/tmp/ust-app-socks"
>  #define UST_SIGNAL SIGIO
>  
> -struct ustcomm_connection {
> +struct ustcomm_sock {
>  	struct list_head list;
>  	int fd;
> -	/* Data that has not yet been consumed: */
> -	char *recv_buf;
> -	int recv_buf_size;
> -	int recv_buf_alloc;
> +	int epoll_fd;
>  };
>  
> -/* ustcomm_server must be shallow-copyable */
> -struct ustcomm_server {
> -	/* the "server" socket for serving the external requests */
> -	int listen_fd;
> -	char *socketpath;
> -
> -	struct list_head connections;
> -};
> -
> -struct ustcomm_ustd {
> -	struct ustcomm_server server;
> +struct ustcomm_header {
> +	int type;
> +	long size;
> +	int command;
> +	int response;
> +	int fd_included;
>  };
>  
> -struct ustcomm_app {
> -	struct ustcomm_server server;
> -};
>  
> -/* ustcomm_source must be shallow-copyable */
> -struct ustcomm_source {
> -	int fd;
> -	void *priv;
> -};
> +//int send_message_pid(pid_t pid, const char *msg, char **reply);
>  
> -struct ustcomm_multipoll_conn_info {
> -	struct ustcomm_connection *conn;
> -	int (*cb)(char *msg, struct ustcomm_source *src);
> -};
> +/* Ensure directory existence, usefull for unix sockets */
> +extern int ensure_dir_exists(const char *dir);
>  
> -//int send_message_pid(pid_t pid, const char *msg, char **reply);
> -extern int ustcomm_request_consumer(pid_t pid, const char *channel);
> +/* Create and delete sockets */
> +extern struct ustcomm_sock * ustcomm_init_sock(int fd, int epoll_fd,
> +					       struct list_head *list);
> +extern void ustcomm_del_sock(struct ustcomm_sock *sock, int keep_in_epoll);
>  
> -extern int ustcomm_ustd_recv_message(struct ustcomm_ustd *ustd, char **msg, struct ustcomm_source *src, int timeout);
> -extern int ustcomm_app_recv_message(struct ustcomm_app *app, char **msg, struct ustcomm_source *src, int timeout);
> +/* Create and delete named sockets */
> +extern struct ustcomm_sock * ustcomm_init_named_socket(const char *name,
> +						       int epoll_fd);
> +extern void ustcomm_del_named_sock(struct ustcomm_sock *sock,
> +				   int keep_socket_file);
>  
> -extern int ustcomm_init_app(pid_t pid, struct ustcomm_app *handle);
> -extern void ustcomm_fini_app(struct ustcomm_app *handle, int keep_socket_file);
> -extern void ustcomm_fini_ustd(struct ustcomm_ustd *handle);
> +/* Send and receive functions for file descriptors */
> +extern int ustcomm_send_fd(int sock, const struct ustcomm_header *header,
> +			   const char *data, int *fd);
> +extern int ustcomm_recv_fd(int sock, struct ustcomm_header *header,
> +			   char **data, int *fd);
>  
> -extern int ustcomm_init_ustd(struct ustcomm_ustd *handle, const char *sock_path);
> +/* Normal send and receive functions */
> +extern int ustcomm_send(int sock, const struct ustcomm_header *header,
> +			const char *data);
> +extern int ustcomm_recv(int sock, struct ustcomm_header *header,
> +			char **data);
>  
> -extern int ustcomm_connect_app(pid_t pid, struct ustcomm_connection *conn);
> -extern int ustcomm_close_app(struct ustcomm_connection *conn);
> -extern int ustcomm_connect_path(const char *path, struct ustcomm_connection *conn, pid_t signalpid);
> -extern int ustcomm_send_request(struct ustcomm_connection *conn, const char *req, char **reply);
> -extern int ustcomm_send_reply(struct ustcomm_server *server, char *msg, struct ustcomm_source *src);
> -extern int ustcomm_disconnect(struct ustcomm_connection *conn);
> -extern int ustcomm_close_all_connections(struct ustcomm_server *server);
> -extern void ustcomm_mp_add_app_clients(struct mpentries *ent, struct ustcomm_app *app, int (*cb)(char *recvbuf, struct ustcomm_source *src));
>  
> +extern int ustcomm_request_consumer(pid_t pid, const char *channel);
> +extern int ustcomm_connect_app(pid_t pid, int *app_fd);
> +extern int ustcomm_connect_path(const char *path, int *connection_fd);
> +extern int ustcomm_send_request(int sock, const char *req, char **reply);
> +extern int ustcomm_send_reply(char *msg, int sock);
> +extern int recv_message_conn(int sock, char **msg);
>  extern int nth_token_is(const char *str, const char *token, int tok_no);
>  
>  extern char *nth_token(const char *str, int tok_no);
>  
> -extern int pid_is_online(pid_t);
> -
>  #endif /* USTCOMM_H */
> diff --git a/libustd/libustd.c b/libustd/libustd.c
> index 999e4da..cb5b123 100644
> --- a/libustd/libustd.c
> +++ b/libustd/libustd.c
> @@ -18,7 +18,10 @@
>  
>  #define _GNU_SOURCE
>  
> +#include <sys/epoll.h>
>  #include <sys/shm.h>
> +#include <sys/types.h>
> +#include <sys/stat.h>
>  #include <unistd.h>
>  #include <pthread.h>
>  #include <signal.h>
> @@ -64,7 +67,8 @@ int get_subbuffer(struct buffer_info *buf)
>  		retval = -1;
>  		goto end;
>  	}
> -	result = ustcomm_send_request(buf->conn, send_msg, &received_msg);
> +
> +	result = ustcomm_send_request(buf->app_sock, send_msg, &received_msg);
>  	if((result == -1 && (errno == ECONNRESET || errno == EPIPE)) || result == 0) {
>  		DBG("app died while being traced");
>  		retval = GET_SUBBUF_DIED;
> @@ -84,20 +88,14 @@ int get_subbuffer(struct buffer_info *buf)
>  		goto end_rep;
>  	}
>  
> -	if(!strcmp(rep_code, "OK")) {
> +	if (!strcmp(rep_code, "OK")) {
>  		DBG("got subbuffer %s", buf->name);
>  		retval = GET_SUBBUF_OK;
> -	}
> -	else if(nth_token_is(received_msg, "END", 0) == 1) {
> -		retval = GET_SUBBUF_DONE;
> -		goto end_rep;
> -	}
> -	else if(!strcmp(received_msg, "NOTFOUND")) {
> +	} else if(!strcmp(received_msg, "NOTFOUND")) {
>  		DBG("For buffer %s, the trace was not found. This likely means it was destroyed by the user.", buf->name);
>  		retval = GET_SUBBUF_DIED;
>  		goto end_rep;
> -	}
> -	else {
> +	} else {
>  		DBG("error getting subbuffer %s", buf->name);
>  		retval = -1;
>  	}
> @@ -129,7 +127,7 @@ int put_subbuffer(struct buffer_info *buf)
>  		retval = -1;
>  		goto end;
>  	}
> -	result = ustcomm_send_request(buf->conn, send_msg, &received_msg);
> +	result = ustcomm_send_request(buf->app_sock, send_msg, &received_msg);
>  	if(result < 0 && (errno == ECONNRESET || errno == EPIPE)) {
>  		retval = PUT_SUBBUF_DIED;
>  		goto end;
> @@ -200,6 +198,7 @@ struct buffer_info *connect_buffer(struct libustd_instance *instance, pid_t pid,
>  	char *received_msg;
>  	int result;
>  	struct shmid_ds shmds;
> +	struct ustcomm_header header;
>  
>  	buf = (struct buffer_info *) zmalloc(sizeof(struct buffer_info));
>  	if(buf == NULL) {
> @@ -207,18 +206,12 @@ struct buffer_info *connect_buffer(struct libustd_instance *instance, pid_t pid,
>  		return NULL;
>  	}
>  
> -	buf->conn = malloc(sizeof(struct ustcomm_connection));
> -	if(buf->conn == NULL) {
> -		ERR("add_buffer: insufficient memory");
> -		free(buf);
> -		return NULL;
> -	}
> -
>  	buf->name = bufname;
>  	buf->pid = pid;
>  
> +	/* FIXME: Fix all the freeing and exit sequence from this functions */
>  	/* connect to app */
> -	result = ustcomm_connect_app(buf->pid, buf->conn);
> +	result = ustcomm_connect_app(buf->pid, &buf->app_sock);
>  	if(result) {
>  		WARN("unable to connect to process, it probably died before we were able to connect");
>  		return NULL;
> @@ -229,7 +222,7 @@ struct buffer_info *connect_buffer(struct libustd_instance *instance, pid_t pid,
>  		ERR("connect_buffer : asprintf failed (get_pidunique)");
>  		return NULL;
>  	}
> -	result = ustcomm_send_request(buf->conn, send_msg, &received_msg);
> +	result = ustcomm_send_request(buf->app_sock, send_msg, &received_msg);
>  	free(send_msg);
>  	if(result == -1) {
>  		ERR("problem in ustcomm_send_request(get_pidunique)");
> @@ -253,7 +246,7 @@ struct buffer_info *connect_buffer(struct libustd_instance *instance, pid_t pid,
>  		    buf->name);
>  		return NULL;
>  	}
> -	result = ustcomm_send_request(buf->conn, send_msg, &received_msg);
> +	result = ustcomm_send_request(buf->app_sock, send_msg, &received_msg);
>  	free(send_msg);
>  	if(result == -1) {
>  		ERR("problem in ustcomm_send_request(get_shmid)");
> @@ -277,7 +270,7 @@ struct buffer_info *connect_buffer(struct libustd_instance *instance, pid_t pid,
>  		    buf->name);
>  		return NULL;
>  	}
> -	result = ustcomm_send_request(buf->conn, send_msg, &received_msg);
> +	result = ustcomm_send_request(buf->app_sock, send_msg, &received_msg);
>  	free(send_msg);
>  	if(result == -1) {
>  		ERR("problem in ustcomm_send_request(g_n_subbufs)");
> @@ -301,7 +294,7 @@ struct buffer_info *connect_buffer(struct libustd_instance *instance, pid_t pid,
>  		    buf->name);
>  		return NULL;
>  	}
> -	result = ustcomm_send_request(buf->conn, send_msg, &received_msg);
> +	result = ustcomm_send_request(buf->app_sock, send_msg, &received_msg);
>  	free(send_msg);
>  	if(result == -1) {
>  		ERR("problem in ustcomm_send_request(get_subbuf_size)");
> @@ -342,6 +335,32 @@ struct buffer_info *connect_buffer(struct libustd_instance *instance, pid_t pid,
>  	}
>  	buf->memlen = shmds.shm_segsz;
>  
> +	/* get buffer pipe fd */
> +	memset(&header, 0, sizeof(header));
> +	if (asprintf(&send_msg, "get_buffer_fd %s", buf->name) < 0) {
> +		ERR("connect_buffer : asprintf failed (get_buffer_fd %s)",
> +		    buf->name);
> +		return NULL;
> +	}
> +	header.size = strlen(send_msg) + 1;
> +	result = ustcomm_send(buf->app_sock, &header, send_msg);
> +	free(send_msg);
> +	if (result <= 0) {
> +		ERR("ustcomm_send failed.");
> +		return NULL;
> +	}
> +	result = ustcomm_recv_fd(buf->app_sock, &header, NULL, &buf->pipe_fd);
> +	if (result <= 0) {
> +		ERR("ustcomm_recv_fd failed");
> +		return NULL;
> +	} else {
> +		struct stat temp;
> +		fstat(buf->pipe_fd, &temp);
> +		if (!S_ISFIFO(temp.st_mode)) {
> +			ERR("Didn't receive a fifo from the app");
> +			return NULL;
> +		}
> +	}
>  	if(instance->callbacks->on_open_buffer)
>  		instance->callbacks->on_open_buffer(instance->callbacks, buf);
>  
> @@ -361,7 +380,7 @@ static void destroy_buffer(struct libustd_callbacks *callbacks,
>  {
>  	int result;
>  
> -	result = ustcomm_close_app(buf->conn);
> +	result = close(buf->app_sock);
>  	if(result == -1) {
>  		WARN("problem calling ustcomm_close_app");
>  	}
> @@ -379,28 +398,31 @@ static void destroy_buffer(struct libustd_callbacks *callbacks,
>  	if(callbacks->on_close_buffer)
>  		callbacks->on_close_buffer(callbacks, buf);
>  
> -	free(buf->conn);
>  	free(buf);
>  }
>  
>  int consumer_loop(struct libustd_instance *instance, struct buffer_info *buf)
>  {
> -	int result;
> +	int result, read_result;
> +	char read_buf;
>  
>  	pthread_cleanup_push(decrement_active_buffers, instance);
>  
>  	for(;;) {
> +		read_result = read(buf->pipe_fd, &read_buf, 1);
>  		/* get the subbuffer */
> -		result = get_subbuffer(buf);
> -		if(result == -1) {
> -			ERR("error getting subbuffer");
> -			continue;
> -		}
> -		else if(result == GET_SUBBUF_DONE) {
> -			/* this is done */
> -			break;
> -		}
> -		else if(result == GET_SUBBUF_DIED) {
> +		if (read_result == 1) {
> +			result = get_subbuffer(buf);
> +			if(result == -1) {
> +				ERR("error getting subbuffer");
> +				continue;
> +			} else if (result == GET_SUBBUF_DIED) {
> +				finish_consuming_dead_subbuffer(instance->callbacks, buf);
> +				break;
> +			}
> +		} else if ((read_result == -1 && (errno == ECONNRESET || errno == EPIPE)) ||
> +			   result == 0) {
> +			DBG("App died while being traced");
>  			finish_consuming_dead_subbuffer(instance->callbacks, buf);
>  			break;
>  		}
> @@ -541,64 +563,86 @@ int start_consuming_buffer(
>  
>  	return 0;
>  }
> +static void process_client_cmd(char *recvbuf, struct libustd_instance *instance)
> +{
> +	if(!strncmp(recvbuf, "collect", 7)) {
> +		pid_t pid;
> +		char *bufname;
> +		int result;
> +
> +		result = sscanf(recvbuf, "%*s %d %50as", &pid, &bufname);
> +		if (result != 2) {
> +			ERR("parsing error: %s", recvbuf);
> +			goto free_bufname;
> +		}
> +
> +		result = start_consuming_buffer(instance, pid, bufname);
> +		if (result < 0) {
> +			ERR("error in add_buffer");
> +			goto free_bufname;
> +		}
> +
> +	free_bufname:
> +		free(bufname);
> +	} else if(!strncmp(recvbuf, "exit", 4)) {
> +		/* Only there to force poll to return */
> +	} else {
> +		WARN("unknown command: %s", recvbuf);
> +	}
> +}
> +
> +#define MAX_EVENTS 10
>  
>  int libustd_start_instance(struct libustd_instance *instance)
>  {
> -	int result;
> -	int timeout = -1;
> +	struct ustcomm_sock *epoll_sock;
> +	struct epoll_event events[MAX_EVENTS];
> +	struct sockaddr addr;
> +	int result, epoll_fd, accept_fd, nfds, i, addr_size, timeout;
>  
>  	if(!instance->is_init) {
>  		ERR("libustd instance not initialized");
>  		return 1;
>  	}
> +	epoll_fd = instance->epoll_fd;
> +
> +	timeout = -1;
>  
>  	/* app loop */
>  	for(;;) {
> -		char *recvbuf;
> -
> -		/* check for requests on our public socket */
> -		result = ustcomm_ustd_recv_message(instance->comm, &recvbuf, NULL, timeout);
> -		if(result == -1 && errno == EINTR) {
> +		nfds = epoll_wait(epoll_fd, events, MAX_EVENTS, timeout);
> +		if (nfds == -1 && errno == EINTR) {
>  			/* Caught signal */
> +		} else if (nfds == -1) {
> +			ERR("epoll_wait");
>  		}
> -		else if(result == -1) {
> -			ERR("error in ustcomm_ustd_recv_message");
> -			goto loop_end;
> -		}
> -		else if(result > 0) {
> -			if(!strncmp(recvbuf, "collect", 7)) {
> -				pid_t pid;
> -				char *bufname;
> -				int result;
> -
> -				result = sscanf(recvbuf, "%*s %d %50as", &pid, &bufname);
> -				if(result != 2) {
> -					ERR("parsing error: %s", recvbuf);
> -					goto free_bufname;
> -				}
>  
> -				result = start_consuming_buffer(instance, pid, bufname);
> -				if(result < 0) {
> -					ERR("error in add_buffer");
> -					goto free_bufname;
> +		for (i = 0; i < nfds; ++i) {
> +			epoll_sock = (struct ustcomm_sock *)events[i].data.ptr;
> +			if (epoll_sock == instance->listen_sock) {
> +				addr_size = sizeof(struct sockaddr);
> +				accept_fd = accept(epoll_sock->fd,
> +						   &addr,
> +						   (socklen_t *)&addr_size);
> +				if (accept_fd == -1) {
> +					ERR("accept failed\n");
> +				}
> +				ustcomm_init_sock(accept_fd, epoll_fd,
> +						 &instance->connections);
> +			} else {
> +				char *msg = NULL;
> +				result = recv_message_conn(epoll_sock->fd, &msg);
> +				if (result == 0) {
> +					ustcomm_del_sock(epoll_sock, 0);
> +				} else if (msg) {
> +					process_client_cmd(msg, instance);
> +					free(msg);
>  				}
>  
> -				free_bufname:
> -				free(bufname);
> -			}
> -			else if(!strncmp(recvbuf, "exit", 4)) {
> -				/* Only there to force poll to return */
> -			}
> -			else {
> -				WARN("unknown command: %s", recvbuf);
>  			}
> -
> -			free(recvbuf);
>  		}
>  
> -		loop_end:
> -
> -		if(instance->quit_program) {
> +		if (instance->quit_program) {
>  			pthread_mutex_lock(&instance->mutex);
>  			if(instance->active_buffers == 0) {
>  				pthread_mutex_unlock(&instance->mutex);
> @@ -617,14 +661,16 @@ int libustd_start_instance(struct libustd_instance *instance)
>  	return 0;
>  }
>  
> +/* FIXME: threads and connections !? */
>  void libustd_delete_instance(struct libustd_instance *instance)
>  {
> -	if(instance->is_init)
> -		ustcomm_fini_ustd(instance->comm);
> +	if (instance->is_init) {
> +		ustcomm_del_named_sock(instance->listen_sock, 0);
> +		close(instance->epoll_fd);
> +	}
>  
>  	pthread_mutex_destroy(&instance->mutex);
>  	free(instance->sock_path);
> -	free(instance->comm);
>  	free(instance);
>  }
>  
> @@ -669,17 +715,13 @@ int libustd_stop_instance(struct libustd_instance *instance, int send_msg)
>  	return 0;
>  }
>  
> -struct libustd_instance *libustd_new_instance(
> -	struct libustd_callbacks *callbacks, char *sock_path)
> +struct libustd_instance
> +*libustd_new_instance(struct libustd_callbacks *callbacks,
> +		      char *sock_path)
>  {
>  	struct libustd_instance *instance =
>  		zmalloc(sizeof(struct libustd_instance));
> -	if(!instance)
> -		return NULL;
> -
> -	instance->comm = malloc(sizeof(struct ustcomm_ustd));
> -	if(!instance->comm) {
> -		free(instance);
> +	if(!instance) {
>  		return NULL;
>  	}
>  
> @@ -689,18 +731,75 @@ struct libustd_instance *libustd_new_instance(
>  	instance->active_buffers = 0;
>  	pthread_mutex_init(&instance->mutex, NULL);
>  
> -	if(sock_path)
> +	if (sock_path) {
>  		instance->sock_path = strdup(sock_path);
> -	else
> +	} else {
>  		instance->sock_path = NULL;
> +	}
>  
>  	return instance;
>  }
>  
> +static int init_ustd_socket(struct libustd_instance *instance)
> +{
> +	char *name;
> +
> +	if (instance->sock_path) {
> +		if (asprintf(&name, "%s", instance->sock_path) < 0) {
> +			ERR("ustcomm_init_ustd : asprintf failed (sock_path %s)",
> +			    instance->sock_path);
> +			return -1;
> +		}
> +	} else {
> +		int result;
> +
> +		/* Only check if socket dir exists if we are using the default directory */
> +		result = ensure_dir_exists(SOCK_DIR);
> +		if (result == -1) {
> +			ERR("Unable to create socket directory %s", SOCK_DIR);
> +			return -1;
> +		}
> +
> +		if (asprintf(&name, "%s/%s", SOCK_DIR, "ustd") < 0) {
> +			ERR("ustcomm_init_ustd : asprintf failed (%s/ustd)",
> +			    SOCK_DIR);
> +			return -1;
> +		}
> +	}
> +
> +	/* Set up epoll */
> +	instance->epoll_fd = epoll_create(MAX_EVENTS);
> +	if (instance->epoll_fd == -1) {
> +		ERR("epoll_create failed, start instance bailing");
> +		goto free_name;
> +	}
> +
> +	/* Create the named socket */
> +	instance->listen_sock = ustcomm_init_named_socket(name,
> +							  instance->epoll_fd);
> +	if(!instance->listen_sock) {
> +		ERR("error initializing named socket at %s", name);
> +		goto close_epoll;
> +	}
> +
> +	INIT_LIST_HEAD(&instance->connections);
> +
> +	free(name);
> +
> +	return 0;
> +
> +close_epoll:
> +	close(instance->epoll_fd);
> +free_name:
> +	free(name);
> +
> +	return -1;
> +}
> +
>  int libustd_init_instance(struct libustd_instance *instance)
>  {
>  	int result;
> -	result = ustcomm_init_ustd(instance->comm, instance->sock_path);
> +	result = init_ustd_socket(instance);
>  	if(result == -1) {
>  		ERR("failed to initialize socket");
>  		return 1;

- -- 
David Goulet
LTTng project, DORSAL Lab.

1024D/16BD8563
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