[lttng-dev] [MI RFC 2/3] Mi: support for command list

Simon Marchi simon.marchi at polymtl.ca
Mon Apr 7 11:36:20 EDT 2014


A small thing I just noticed. In the MI version of list, the attribute
used to show if a session is started is <enabled>. In the CLI, the
terms active/inactive are used. It might be a good idea to be
consistent.

Other small stuff below.

On 6 April 2014 15:30, Jonathan Rajotte <jonathan.r.julien at gmail.com> wrote:
> Signed-off-by: Jonathan Rajotte <jonathan.r.julien at gmail.com>
> ---
>  src/bin/lttng/commands/list.c | 888 ++++++++++++++++++++++++++++++++++++------
>  src/common/mi-lttng.c         | 685 +++++++++++++++++++++++++++++++-
>  src/common/mi-lttng.h         | 299 +++++++++++++-
>  3 files changed, 1735 insertions(+), 137 deletions(-)
>
> diff --git a/src/bin/lttng/commands/list.c b/src/bin/lttng/commands/list.c
> index bbd674c..a0d0e4c 100644
> --- a/src/bin/lttng/commands/list.c
> +++ b/src/bin/lttng/commands/list.c
> @@ -23,6 +23,8 @@
>  #include <string.h>
>  #include <assert.h>
>
> +#include <common/mi-lttng.h>
> +
>  #include "../command.h"
>
>  static int opt_userspace;
> @@ -48,6 +50,7 @@ enum {
>  };
>
>  static struct lttng_handle *handle;
> +static struct mi_writer *writer;
>
>  static struct poptOption long_options[] = {
>         /* longName, shortName, argInfo, argPtr, value, descrip, argDesc */
> @@ -148,89 +151,6 @@ static const char *snapshot_string(int value)
>         }
>  }
>
> -static
> -const char *enabled_string(int value)
> -{
> -       switch (value) {
> -       case 0: return " [disabled]";
> -       case 1: return " [enabled]";
> -       case -1: return "";
> -       default: return NULL;
> -       }
> -}
> -
> -static
> -const char *filter_string(int value)
> -{
> -       switch (value) {
> -       case 1: return " [with filter]";
> -       default: return "";
> -       }
> -}
> -
> -static
> -const char *exclusion_string(int value)
> -{
> -       switch (value) {
> -       case 1: return " [has exclusions]";
> -       default: return "";
> -       }
> -}
> -
> -static const char *loglevel_string(int value)
> -{
> -       switch (value) {
> -       case -1:
> -               return "";
> -       case LTTNG_LOGLEVEL_EMERG:
> -               return "TRACE_EMERG";
> -       case LTTNG_LOGLEVEL_ALERT:
> -               return "TRACE_ALERT";
> -       case LTTNG_LOGLEVEL_CRIT:
> -               return "TRACE_CRIT";
> -       case LTTNG_LOGLEVEL_ERR:
> -               return "TRACE_ERR";
> -       case LTTNG_LOGLEVEL_WARNING:
> -               return "TRACE_WARNING";
> -       case LTTNG_LOGLEVEL_NOTICE:
> -               return "TRACE_NOTICE";
> -       case LTTNG_LOGLEVEL_INFO:
> -               return "TRACE_INFO";
> -       case LTTNG_LOGLEVEL_DEBUG_SYSTEM:
> -               return "TRACE_DEBUG_SYSTEM";
> -       case LTTNG_LOGLEVEL_DEBUG_PROGRAM:
> -               return "TRACE_DEBUG_PROGRAM";
> -       case LTTNG_LOGLEVEL_DEBUG_PROCESS:
> -               return "TRACE_DEBUG_PROCESS";
> -       case LTTNG_LOGLEVEL_DEBUG_MODULE:
> -               return "TRACE_DEBUG_MODULE";
> -       case LTTNG_LOGLEVEL_DEBUG_UNIT:
> -               return "TRACE_DEBUG_UNIT";
> -       case LTTNG_LOGLEVEL_DEBUG_FUNCTION:
> -               return "TRACE_DEBUG_FUNCTION";
> -       case LTTNG_LOGLEVEL_DEBUG_LINE:
> -               return "TRACE_DEBUG_LINE";
> -       case LTTNG_LOGLEVEL_DEBUG:
> -               return "TRACE_DEBUG";
> -       default:
> -               return "<<UNKNOWN>>";
> -       }
> -}
> -
> -static const char *logleveltype_string(enum lttng_loglevel_type value)
> -{
> -       switch (value) {
> -       case LTTNG_EVENT_LOGLEVEL_ALL:
> -               return ":";
> -       case LTTNG_EVENT_LOGLEVEL_RANGE:
> -               return " <=";
> -       case LTTNG_EVENT_LOGLEVEL_SINGLE:
> -               return " ==";
> -       default:
> -               return " <<TYPE UNKN>>";
> -       }
> -}
> -
>  /*
>   * Pretty print single event.
>   */
> @@ -446,6 +366,118 @@ error:
>  }
>
>  /*
> + * Machine interface
> + * Ask session daemon for all user space tracepoints available and print them
> + *
> + * print_domain 0-> do not print domains and domain element
> + *                  (used when mi_list_jul_ust_events is nested under a domain)
> + *              else print the domains and domain element
> + */
> +static int mi_list_jul_ust_events(enum lttng_domain_type type, int print_domain)
> +{
> +       int ret, i, size;
> +       struct lttng_domain domain;
> +       struct lttng_handle *handle;
> +       struct lttng_event *event_list;
> +       pid_t cur_pid = 0;
> +       char *cmdline = NULL;
> +       int pid_element_open = 0;
> +
> +       memset(&domain, 0, sizeof(domain));
> +
> +       domain.type = type;
> +
> +       handle = lttng_create_handle(NULL, &domain);
> +       if (handle == NULL) {
> +               ret = -LTTNG_ERR_NOMEM;
> +               goto end;
> +       }
> +
> +       size = lttng_list_tracepoints(handle, &event_list);
> +       if (size < 0) {
> +               if (LTTNG_DOMAIN_UST) {
> +                       ERR("Unable to list UST events: %s", lttng_strerror(size));
> +               } else if (LTTNG_DOMAIN_JUL) {
> +                       ERR("Unable to list JUL events: %s", lttng_strerror(size));
> +               }
> +               lttng_destroy_handle(handle);
> +               return size;
> +       }
> +
> +       if (print_domain) {
> +               /* Open domains element */
> +               ret = mi_lttng_domains_open(writer);
> +               if (ret) {
> +                       goto end;
> +               }
> +
> +               /* Write domain */
> +               ret = mi_lttng_domain(writer, &domain, 1);
> +               if (ret) {
> +                       goto end;
> +               }
> +       }
> +
> +       /* Open pids element */
> +       ret = mi_lttng_pids_open(writer);
> +       if (ret) {
> +               goto end;
> +       }
> +
> +       for (i = 0; i < size; i++) {
> +               if (cur_pid != event_list[i].pid) {
> +                       if (pid_element_open) {
> +                               /* Close the previous envents and  pid element */
> +                               ret = mi_lttng_close_multi_element(writer, 2);
> +                               if (ret) {
> +                                       goto end;
> +                               }
> +                               pid_element_open = !pid_element_open;
> +                       }
> +
> +                       cur_pid = event_list[i].pid;
> +                       cmdline = get_cmdline_by_pid(cur_pid);
> +
> +                       if (!pid_element_open) {
> +                               /* Open and write a pid elemen */
> +                               ret = mi_lttng_pid(writer, cur_pid, cmdline, 1);
> +                               if (ret) {
> +                                       goto end;
> +                               }
> +
> +                               /* Open events element */
> +                               ret = mi_lttng_events_open(writer);
> +                               if (ret) {
> +                                       goto end;
> +                               }
> +
> +                               pid_element_open = !pid_element_open;
> +                       }
> +                       free(cmdline);
> +               }
> +
> +               /* Write an event */
> +               ret = mi_lttng_event(writer, &event_list[i], 0);
> +               if (ret) {
> +                       goto end;
> +               }
> +       }
> +
> +
> +       /* Close pids */
> +       ret = mi_lttng_writer_close_element(writer);
> +
> +       if (print_domain) {
> +               /* Close domain, domains */
> +               ret = mi_lttng_close_multi_element(writer, 2);
> +       }
> +end:
> +       free(event_list);
> +       lttng_destroy_handle(handle);
> +       return ret;
> +}
> +
> +/*
>   * Ask session daemon for all user space tracepoint fields available.
>   */
>  static int list_ust_event_fields(void)
> @@ -514,6 +546,144 @@ error:
>  }
>
>  /*
> + * Machine interface
> + * List all ust event with their fields
> + */
> +static int mi_list_ust_event_fields(void)
> +{
> +       int ret, i, size;
> +       struct lttng_domain domain;
> +       struct lttng_handle *handle;
> +       struct lttng_event_field *event_field_list;
> +       pid_t cur_pid = 0;
> +       char *cmdline = NULL;
> +       int pid_element_open = 0;
> +       int event_element_open = 0;
> +
> +       struct lttng_event cur_event;
> +
> +       memset(&domain, 0, sizeof(domain));
> +       memset(&cur_event, 0, sizeof(cur_event));
> +
> +       domain.type = LTTNG_DOMAIN_UST;
> +
> +       handle = lttng_create_handle(NULL, &domain);
> +       if (handle == NULL) {
> +               ret = -LTTNG_ERR_NOMEM;
> +               goto end;
> +       }
> +
> +       size = lttng_list_tracepoint_fields(handle, &event_field_list);
> +       if (size < 0) {
> +               ERR("Unable to list UST event fields: %s", lttng_strerror(size));
> +               lttng_destroy_handle(handle);
> +               return size;
> +       }
> +
> +       /* Open domains element */
> +       ret = mi_lttng_domains_open(writer);
> +       if (ret) {
> +               goto end;
> +       }
> +
> +       /* Write domain */
> +       ret = mi_lttng_domain(writer, &domain, 1);
> +
> +       /* Open pids element */
> +       ret = mi_lttng_pids_open(writer);
> +       if (ret) {
> +               goto end;
> +       }
> +
> +
> +       for (i = 0; i < size; i++) {
> +               if (cur_pid != event_field_list[i].event.pid) {
> +                       if (pid_element_open) {
> +                               if (event_element_open) {
> +                                       /* Close the previous fields element
> +                                        * and the previous event
> +                                        */
> +                                       ret = mi_lttng_close_multi_element(writer, 2);
> +                                       if (ret) {
> +                                               goto end;
> +                                       }
> +                                       event_element_open = !event_element_open ;
> +                               }
> +                               /* Close the previous events, pid element */
> +                               ret = mi_lttng_close_multi_element(writer, 2);
> +                               if (ret) {
> +                                       goto end;
> +                               }
> +                               pid_element_open = !pid_element_open;
> +                       }
> +
> +                       cur_pid = event_field_list[i].event.pid;
> +                       cmdline = get_cmdline_by_pid(cur_pid);
> +                       if (!pid_element_open) {
> +                               /* Open and write a pid elemen */
> +                               ret = mi_lttng_pid(writer, cur_pid, cmdline, 1);
> +                               if (ret) {
> +                                       goto end;
> +                               }
> +
> +                               /* Open events element */
> +                               ret = mi_lttng_events_open(writer);
> +                               if (ret) {
> +                                       goto end;
> +                               }
> +                               pid_element_open = !pid_element_open;
> +                       }
> +                       free(cmdline);
> +                       /* Wipe current event since we are about to print a new PID. */
> +                       memset(&cur_event, 0, sizeof(cur_event));
> +               }
> +
> +               if (strcmp(cur_event.name, event_field_list[i].event.name) != 0) {
> +                       if (event_element_open) {
> +                               /* Close the previous fields element and the previous event */
> +                               ret = mi_lttng_close_multi_element(writer, 2);
> +                               if (ret) {
> +                                       goto end;
> +                               }
> +                               event_element_open = !event_element_open ;
> +                       }
> +
> +                       memcpy(&cur_event, &event_field_list[i].event,
> +                                       sizeof(cur_event));
> +
> +                       if (!event_element_open) {
> +                               /* Open and write the event */
> +                               ret = mi_lttng_event(writer, &cur_event, 1);
> +                               if (ret) {
> +                                       goto end;
> +                               }
> +
> +                               /* Open a fields element */
> +                               ret = mi_lttng_event_fields_open(writer);
> +                               if (ret) {
> +                                       goto end;
> +                               }
> +                               event_element_open = !event_element_open ;
> +                       }
> +               }
> +
> +               /* Print the event_field */
> +               ret = mi_lttng_event_field(writer, &event_field_list[i]);
> +               if (ret) {
> +                       goto end;
> +               }
> +       }
> +
> +       /* Close pids, domain, domains */
> +       ret = mi_lttng_close_multi_element(writer, 3);
> +
> +end:
> +       free(event_field_list);
> +       lttng_destroy_handle(handle);
> +       return ret;
> +}
> +
> +/*
>   * Ask for all trace events in the kernel and pretty print them.
>   */
>  static int list_kernel_events(void)
> @@ -560,6 +730,71 @@ error:
>  }
>
>  /*
> + * Machine interface
> + * Ask for all trace events in the kernel
> + */
> +static int mi_list_kernel_events(void)
> +{
> +       int ret, i, size;
> +       struct lttng_domain domain;
> +       struct lttng_handle *handle;
> +       struct lttng_event *event_list;
> +
> +       memset(&domain, 0, sizeof(domain));
> +
> +       domain.type = LTTNG_DOMAIN_KERNEL;
> +
> +       handle = lttng_create_handle(NULL, &domain);
> +       if (handle == NULL) {
> +               ret = -LTTNG_ERR_NOMEM;
> +               goto end;
> +       }
> +
> +       size = lttng_list_tracepoints(handle, &event_list);
> +       if (size < 0) {
> +               ERR("Unable to list kernel events: %s", lttng_strerror(size));
> +               lttng_destroy_handle(handle);
> +               return size;
> +       }
> +
> +       /* Open domains element */
> +       ret = mi_lttng_domains_open(writer);
> +       if (ret) {
> +               goto end;
> +       }
> +
> +       /* Write domain */
> +       ret = mi_lttng_domain(writer, &domain, 1);
> +       if (ret) {
> +               goto end;
> +       }
> +
> +       /* Open events */
> +       ret = mi_lttng_events_open(writer);
> +       if (ret) {
> +               goto end;
> +       }
> +
> +       for (i = 0; i < size; i++) {
> +               mi_lttng_event(writer, &event_list[i], 0);
> +               if (ret) {
> +                       goto end;
> +               }
> +       }
> +
> +       /* close events, domain and domains */
> +       ret = mi_lttng_close_multi_element(writer, 3);
> +       if (ret) {
> +               goto end;
> +       }
> +
> +end:
> +       free(event_list);
> +       lttng_destroy_handle(handle);
> +       return ret;
> +}
> +
> +/*
>   * List JUL events for a specific session using the handle.
>   *
>   * Return CMD_SUCCESS on success else a negative value.
> @@ -598,6 +833,43 @@ error:
>  }
>
>  /*
> + * Machine Interface
> + * List JUL events for a specific session using the handle.
> + */
> +static int mi_list_session_jul_events(void)
> +{
> +       int ret, count, i;
> +       struct lttng_event *events = NULL;
> +
> +       count = lttng_list_events(handle, "", &events);
> +       if (count < 0) {
> +               ret = count;
> +               ERR("%s", lttng_strerror(ret));
> +               goto end;
> +       }
> +
> +       /* Open events element */
> +       ret = mi_lttng_events_open(writer);
> +       if (ret) {
> +               goto end;
> +       }
> +
> +       for (i = 0; i < count; i++) {
> +               ret = mi_lttng_event(writer, &events[i], 0);
> +               if (ret) {
> +                       goto end;
> +               }
> +       }
> +
> +       /* Close events element */
> +       ret = mi_lttng_writer_close_element(writer);
> +
> +end:
> +       free(events);
> +       return ret;
> +}
> +
> +/*
>   * List events of channel of session and domain.
>   */
>  static int list_events(const char *channel_name)
> @@ -633,6 +905,43 @@ error:
>  }
>
>  /*
> + * Machine interface
> + * List events of channel of session and domain.
> + */
> +static int mi_list_events(const char *channel_name)
> +{
> +       int ret, count, i;
> +       struct lttng_event *events = NULL;
> +
> +       count = lttng_list_events(handle, channel_name, &events);
> +       if (count < 0) {
> +               ret = count;
> +               ERR("%s", lttng_strerror(ret));
> +               goto end;
> +       }
> +
> +       /* Open events element */
> +       ret = mi_lttng_events_open(writer);
> +       if (ret) {
> +               goto end;
> +       }
> +
> +       for (i = 0; i < count; i++) {
> +               ret = mi_lttng_event(writer, &events[i], 0);
> +               if (ret) {
> +                       goto end;
> +               }
> +       }
> +
> +       /* Close events element */
> +       ret = mi_lttng_writer_close_element(writer);
> +
> +end:
> +       free(events);
> +       return ret;
> +}
> +
> +/*
>   * Pretty print channel
>   */
>  static void print_channel(struct lttng_channel *channel)
> @@ -724,13 +1033,92 @@ error_channels:
>  }
>
>  /*
> + * Machine interface
> + * List channel(s) of session and domain.
> + *
> + * If channel_name is NULL, all channels are listed.
> + */
> +static int mi_list_channels(const char *channel_name)
> +{
> +       int count, i, ret;
> +       unsigned int chan_found = 0;
> +       struct lttng_channel *channels = NULL;
> +
> +       count = lttng_list_channels(handle, &channels);
> +       if (count < 0) {
> +               switch (-count) {
> +               case LTTNG_ERR_KERN_CHAN_NOT_FOUND:
> +                       /* When printing mi this is not an error
> +                        * but an empty channels element */
> +                       count = 0;
> +                       break;
> +               default:
> +                       /* We had a real error */
> +                       ret = count;
> +                       ERR("%s", lttng_strerror(ret));
> +                       goto error_channels;
> +                       break;
> +               }
> +       }
> +
> +       /* Open channels element */
> +       ret = mi_lttng_channels_open(writer);
> +       if (ret) {
> +               goto error;
> +       }
> +
> +       for (i = 0; i < count; i++) {
> +               if (channel_name != NULL) {
> +                       if (strncmp(channels[i].name, channel_name, NAME_MAX) == 0) {
> +                               chan_found = 1;
> +                       } else {
> +                               continue;
> +                       }
> +               }
> +
> +               /* Write channel element  and leave it open */
> +               ret = mi_lttng_channel(writer, &channels[i], 1);
> +
> +               /* Listing events per channel */
> +               ret = mi_list_events(channels[i].name);
> +               if (ret) {
> +                       goto error;
> +               }
> +
> +               /* Closing the channel element we opened earlier */
> +               ret = mi_lttng_writer_close_element(writer);
> +               if (ret) {
> +                       goto error;
> +               }
> +
> +               if (chan_found) {
> +                       break;
> +               }
> +       }
> +
> +       /* Close channels element */
> +       ret = mi_lttng_writer_close_element(writer);
> +       if (ret) {
> +               goto error;
> +       }
> +
> +
> +error:
> +       free(channels);
> +
> +error_channels:
> +       return ret;
> +}
> +
> +/*
>   * List available tracing session. List only basic information.
>   *
>   * If session_name is NULL, all sessions are listed.
>   */
>  static int list_sessions(const char *session_name)
>  {
> -       int ret, count, i;
> +       int ret = CMD_SUCCESS;
> +       int count, i;
>         unsigned int session_found = 0;
>         struct lttng_session *sessions;
>
> @@ -749,25 +1137,25 @@ static int list_sessions(const char *session_name)
>                 MSG("Available tracing sessions:");
>         }
>
> +
>         for (i = 0; i < count; i++) {
>                 if (session_name != NULL) {
>                         if (strncmp(sessions[i].name, session_name, NAME_MAX) == 0) {
>                                 session_found = 1;
> -                               MSG("Tracing session %s: [%s%s]", session_name,
> -                                               active_string(sessions[i].enabled),
> -                                               snapshot_string(sessions[i].snapshot_mode));
> -                               MSG("%sTrace path: %s\n", indent4, sessions[i].path);
> +                                       MSG("Tracing session %s: [%s%s]", session_name,
> +                                                       active_string(sessions[i].enabled),
> +                                                       snapshot_string(sessions[i].snapshot_mode));
> +                                       MSG("%sTrace path: %s\n", indent4, sessions[i].path);
>                                 break;
>                         }
>                 } else {
> -                       MSG("  %d) %s (%s) [%s%s]", i + 1, sessions[i].name, sessions[i].path,
> -                                       active_string(sessions[i].enabled),
> -                                       snapshot_string(sessions[i].snapshot_mode));
> +                               MSG("  %d) %s (%s) [%s%s]", i + 1,
> +                                               sessions[i].name, sessions[i].path,
> +                                               active_string(sessions[i].enabled),
> +                                               snapshot_string(sessions[i].snapshot_mode));
>                 }
>         }
>
> -       free(sessions);
> -
>         if (!session_found && session_name != NULL) {
>                 ERR("Session '%s' not found", session_name);
>                 ret = CMD_ERROR;
> @@ -778,10 +1166,97 @@ static int list_sessions(const char *session_name)
>                 MSG("\nUse lttng list <session_name> for more details");
>         }
>
> +error:
> +       free(sessions);
>  end:
> -       return CMD_SUCCESS;
> +       return ret;
> +}
>
> -error:
> +/*
> + * Machine interface
> + * Find the session with session_name as name
> + * and print his informations.
> + */
> +static int mi_list_session(const char *session_name)
> +{
> +       int ret, count, i;
> +       struct lttng_session *sessions;
> +       unsigned int session_found = 0;
> +
> +       count = lttng_list_sessions(&sessions);
> +       if (count < 0) {
> +               ret = count;
> +               ERR("%s", lttng_strerror(ret));
> +               goto end;
> +       }
> +
> +       if (session_name == NULL) {
> +               ret = -LTTNG_ERR_SESS_NOT_FOUND;
> +               goto end;
> +       }
> +
> +       for (i = 0; i < count; i++) {
> +                       if (strncmp(sessions[i].name, session_name, NAME_MAX) == 0) {
> +                               /* We need to left it unclosed to append other informations

left it -> leave it

I would also say unclosed -> open.

> +                                * like domain, channel, events etc.*/
> +                               session_found = 1;
> +                               ret = mi_lttng_session(writer, &sessions[i], 1);
> +                               if (ret) {
> +                                       goto end;
> +                               }
> +                               break;
> +                       }
> +       }
> +
> +       if (!session_found) {
> +               ERR("Session not found");
> +               ret = -LTTNG_ERR_SESS_NOT_FOUND;
> +               goto end;
> +       }
> +
> +end:
> +       free(sessions);
> +       return ret;
> +}
> +
> +/*
> + * Machine interface
> + * List all availables session
> + */
> +static int mi_list_sessions()
> +{
> +       int ret, count, i;
> +       struct lttng_session *sessions;
> +
> +       count = lttng_list_sessions(&sessions);
> +       if (count < 0) {
> +               ret = count;
> +               ERR("%s", lttng_strerror(ret));
> +               goto end;
> +       }
> +
> +       /* Opening sessions element */
> +       ret = mi_lttng_sessions_open(writer);
> +       if (ret) {
> +               goto end;
> +       }
> +
> +       /* Listing sessions */
> +       for (i = 0; i < count; i++) {
> +               ret = mi_lttng_session(writer, &sessions[i], 0);
> +               if (ret) {
> +                       goto end;
> +               }
> +       }
> +
> +       /* Closing sessions element */
> +       ret = mi_lttng_writer_close_element(writer);
> +       if (ret) {
> +               goto end;
> +       }
> +
> +end:
> +       free(sessions);
>         return ret;
>  }
>
> @@ -829,6 +1304,39 @@ error:
>  }
>
>  /*
> + * Machine Interface
> + * list available domain(s) for a session.
> + */
> +static int mi_list_domains(const char *session_name)
> +{
> +       int i, count, ret;
> +       struct lttng_domain *domains = NULL;
> +
> +       /* Open domains element */
> +       ret = mi_lttng_domains_open(writer);
> +       if (ret) {
> +               goto end;
> +       }
> +
> +       count = lttng_list_domains(session_name, &domains);
> +       if (count < 0) {
> +               ret = count;
> +               ERR("%s", lttng_strerror(ret));
> +               goto end;
> +       }
> +
> +       for (i = 0; i < count; i++) {
> +               ret = mi_lttng_domain(writer, &domains[i] , 0);
> +       }
> +
> +       /* Closing domains element */
> +       ret = mi_lttng_writer_close_element(writer);
> +end:
> +       free(domains);
> +       return ret;
> +}
> +
> +/*
>   * The 'list <options>' first level command
>   */
>  int cmd_list(int argc, const char **argv)
> @@ -850,13 +1358,6 @@ int cmd_list(int argc, const char **argv)
>         pc = poptGetContext(NULL, argc, argv, long_options, 0);
>         poptReadDefaultConfig(pc, 0);
>
> -       /* TODO: mi support */
> -       if (lttng_opt_mi) {
> -               ret = -LTTNG_ERR_MI_NOT_IMPLEMENTED;
> -               ERR("mi option not supported");
> -               goto end;
> -       }
> -
>         while ((opt = poptGetNextOpt(pc)) != -1) {
>                 switch (opt) {
>                 case OPT_HELP:
> @@ -875,6 +1376,29 @@ int cmd_list(int argc, const char **argv)
>                 }
>         }
>
> +       /* Mi check */
> +       if (lttng_opt_mi) {
> +               writer = mi_lttng_writer_create(fileno(stdout), lttng_opt_mi);
> +               if (!writer) {
> +                       ret = -LTTNG_ERR_NOMEM;
> +                       goto end;
> +               }
> +
> +               /* Open command element */
> +               ret = mi_lttng_writer_command_open(writer,
> +                               mi_lttng_element_command_list);
> +               if (ret) {
> +                       goto end;
> +               }
> +
> +               /* Open output element */
> +               ret = mi_lttng_writer_open_element(writer,
> +                               mi_lttng_element_command_output);
> +               if (ret) {
> +                       goto end;
> +               }
> +       }
> +
>         /* Get session name (trailing argument) */
>         session_name = poptGetArg(pc);
>         DBG2("Session name: %s", session_name);
> @@ -899,53 +1423,111 @@ int cmd_list(int argc, const char **argv)
>
>         if (session_name == NULL) {
>                 if (!opt_kernel && !opt_userspace && !opt_jul) {
> -                       ret = list_sessions(NULL);
> -                       if (ret != 0) {
> +                       if (lttng_opt_mi) {
> +                               ret = mi_list_sessions();
> +                       } else {
> +                               ret = list_sessions(NULL);
> +                       }
> +                       if (ret) {
>                                 goto end;
>                         }
>                 }
>                 if (opt_kernel) {
> -                       ret = list_kernel_events();
> -                       if (ret < 0) {
> -                               ret = CMD_ERROR;
> +                       if (lttng_opt_mi) {
> +                               ret = mi_list_kernel_events();
> +                       } else {
> +                               ret = list_kernel_events();
> +                       }
> +                       if (ret) {
>                                 goto end;
>                         }
>                 }
>                 if (opt_userspace) {
>                         if (opt_fields) {
> -                               ret = list_ust_event_fields();
> +                               if (lttng_opt_mi) {
> +                                       ret = mi_list_ust_event_fields();
> +                               } else {
> +                                       ret = list_ust_event_fields();
> +                               }
>                         } else {
> -                               ret = list_ust_events();
> +                               if (lttng_opt_mi) {
> +                                       ret = mi_list_jul_ust_events(LTTNG_DOMAIN_UST, 1);
> +                               } else {
> +                                       ret = list_ust_events();
> +                               }
>                         }
> -                       if (ret < 0) {
> -                               ret = CMD_ERROR;
> +                       if (ret) {
>                                 goto end;
>                         }
>                 }
>                 if (opt_jul) {
> -                       ret = list_jul_events();
> -                       if (ret < 0) {
> -                               ret = CMD_ERROR;
> +                       if (lttng_opt_mi) {
> +                               ret = mi_list_jul_ust_events(LTTNG_DOMAIN_JUL, 1);
> +                       } else {
> +                               ret = list_jul_events();
> +                       }
> +                       if (ret) {
>                                 goto end;
>                         }
>                 }
>         } else {
>                 /* List session attributes */
> -               ret = list_sessions(session_name);
> -               if (ret != 0) {
> +               if (lttng_opt_mi) {
> +                       /* Open element sessions
> +                        * Present for xml consistency */
> +                       ret = mi_lttng_sessions_open(writer);
> +                       if (ret) {
> +                               goto end;
> +                       }
> +
> +                       /* MI: the ouptut of list_sessions is an unclosed session element */
> +                       ret = mi_list_session(session_name);
> +               } else {
> +                       ret = list_sessions(session_name);
> +               }
> +               if (ret) {
>                         goto end;
>                 }
>
>                 /* Domain listing */
>                 if (opt_domain) {
> -                       ret = list_domains(session_name);
> +                       if (lttng_opt_mi) {
> +                               ret = mi_list_domains(session_name);
> +                       } else {
> +                               ret = list_domains(session_name);
> +                       }
>                         goto end;
>                 }
>
> +               /* Channel listing */
>                 if (opt_kernel || opt_userspace) {
> -                       /* Channel listing */
> -                       ret = list_channels(opt_channel);
> -                       if (ret < 0) {
> +                       if (lttng_opt_mi) {
> +                               /* Add of domains and domain element for xml
> +                                * consistency and validation
> +                                */
> +                               ret = mi_lttng_domains_open(writer);
> +                               if (ret) {
> +                                       goto end;
> +                               }
> +
> +                               /* Open domain and leave it open for
> +                                * nested channels printing */
> +                               ret = mi_lttng_domain(writer, &domain, 1);
> +                               if (ret) {
> +                                       goto end;
> +                               }
> +
> +                               ret = mi_list_channels(opt_channel);
> +                               if (ret) {
> +                                       goto end;
> +                               }
> +
> +                               /* Close domain and domain element */
> +                               ret = mi_lttng_close_multi_element(writer, 2);
> +                       } else {
> +                               ret = list_channels(opt_channel);
> +                       }
> +                       if (ret) {
>                                 goto end;
>                         }
>                 } else {
> @@ -959,6 +1541,13 @@ int cmd_list(int argc, const char **argv)
>                                 goto end;
>                         }
>
> +                       if (lttng_opt_mi) {
> +                               ret = mi_lttng_domains_open(writer);
> +                               if (ret) {
> +                                       goto end;
> +                               }
> +                       }
> +
>                         for (i = 0; i < nb_domain; i++) {
>                                 switch (domains[i].type) {
>                                 case LTTNG_DOMAIN_KERNEL:
> @@ -978,6 +1567,13 @@ int cmd_list(int argc, const char **argv)
>                                         break;
>                                 }
>
> +                               if (lttng_opt_mi) {
> +                                       ret = mi_lttng_domain(writer, &domains[i], 1);
> +                                       if (ret) {
> +                                               goto end;
> +                                       }
> +                               }
> +
>                                 /* Clean handle before creating a new one */
>                                 if (handle) {
>                                         lttng_destroy_handle(handle);
> @@ -990,22 +1586,66 @@ int cmd_list(int argc, const char **argv)
>                                 }
>
>                                 if (domains[i].type == LTTNG_DOMAIN_JUL) {
> -                                       ret = list_session_jul_events();
> -                                       if (ret < 0) {
> +                                       if (lttng_opt_mi) {
> +                                               ret = mi_list_session_jul_events();
> +                                       } else {
> +                                               ret = list_session_jul_events();
> +                                       }
> +                                       if (ret) {
>                                                 goto end;
>                                         }
>                                         continue;
>                                 }
>
> -                               ret = list_channels(opt_channel);
> -                               if (ret < 0) {
> +                               if (lttng_opt_mi) {
> +                                       ret = mi_list_channels(opt_channel);
> +                               } else {
> +                                       ret = list_channels(opt_channel);
> +                               }
> +                               if (ret) {
> +                                       goto end;
> +                               }
> +
> +                               if (lttng_opt_mi) {
> +                                       /* Close domain element */
> +                                       ret = mi_lttng_writer_close_element(writer);
> +                                       if (ret) {
> +                                               goto end;
> +                                       }
> +                               }
> +
> +                       }
> +                       if (lttng_opt_mi) {
> +                               /* Close the domains, session and sessions element */
> +                               ret = mi_lttng_close_multi_element(writer, 3);
> +                               if (ret) {
>                                         goto end;
>                                 }
>                         }
>                 }
>         }
>
> +       /* Mi closing */
> +       if (lttng_opt_mi) {
> +               /* Close  output element */
> +               ret = mi_lttng_writer_close_element(writer);
> +               if (ret) {
> +                       goto end;
> +               }
> +
> +               /* Command element close */
> +               ret = mi_lttng_writer_command_close(writer);
> +               if (ret) {
> +                       goto end;
> +               }
> +       }
>  end:
> +       /* Mi clean-up */
> +       if (writer && mi_lttng_writer_destroy(writer)) {
> +               /* Preserve original error code */
> +               ret = ret ? ret : LTTNG_ERR_MI_IO_FAIL;
> +       }
> +
>         free(domains);
>         if (handle) {
>                 lttng_destroy_handle(handle);
> diff --git a/src/common/mi-lttng.c b/src/common/mi-lttng.c
> index bbec2c5..19af444 100644
> --- a/src/common/mi-lttng.c
> +++ b/src/common/mi-lttng.c
> @@ -16,10 +16,13 @@
>   * Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
>   */
>
> +
>  #include <include/config.h>
>  #include <common/config/config.h>
>  #include "mi-lttng.h"
>
> +#include <assert.h>
> +
>  /* Strings related to command */
>  const char * const mi_lttng_element_command = "command";
>  const char * const mi_lttng_element_command_version = "version";
> @@ -37,6 +40,159 @@ const char * const mi_lttng_element_version_license = "license";
>  const char * const mi_lttng_element_version_patch_level = "patchLevel";
>  const char * const mi_lttng_element_version_description = "description";
>
> +/* Strings related to pid */
> +const char * const mi_lttng_element_pids = "pids";
> +const char * const mi_lttng_element_pid = "pid";
> +const char * const mi_lttng_element_pid_id = "id";
> +
> +/* String related to a lttng_event_field */
> +const char * const mi_lttng_element_event_field = "event_field";
> +const char * const mi_lttng_element_event_fields = "event_fields";
> +
> +/* General elements of mi_lttng */
> +const char * const mi_lttng_element_type_other = "OTHER";
> +const char * const mi_lttng_element_type_integer = "INTEGER";
> +const char * const mi_lttng_element_type_enum = "ENUM";
> +const char * const mi_lttng_element_type_float = "FLOAT";
> +const char * const mi_lttng_element_type_string = "STRING";
> +const char * const mi_lttng_element_nowrite = "nowrite";
> +
> +const char * const mi_lttng_element_empty = "";
> +
> +const char *enabled_string(int value)
> +{
> +       switch (value) {
> +       case 0: return " [disabled]";
> +       case 1: return " [enabled]";
> +       case -1: return "";
> +       default: return NULL;
> +       }
> +}
> +
> +const char *filter_string(int value)
> +{
> +       switch (value) {
> +       case 1: return " [with filter]";
> +       default: return "";
> +       }
> +}
> +
> +const char *exclusion_string(int value)
> +{
> +       switch (value) {
> +       case 1: return " [has exclusions]";
> +       default: return "";
> +       }
> +}
> +
> +const char *loglevel_string(int value)
> +{
> +       switch (value) {
> +       case -1:
> +               return "";
> +       case LTTNG_LOGLEVEL_EMERG:
> +               return "TRACE_EMERG";
> +       case LTTNG_LOGLEVEL_ALERT:
> +               return "TRACE_ALERT";
> +       case LTTNG_LOGLEVEL_CRIT:
> +               return "TRACE_CRIT";
> +       case LTTNG_LOGLEVEL_ERR:
> +               return "TRACE_ERR";
> +       case LTTNG_LOGLEVEL_WARNING:
> +               return "TRACE_WARNING";
> +       case LTTNG_LOGLEVEL_NOTICE:
> +               return "TRACE_NOTICE";
> +       case LTTNG_LOGLEVEL_INFO:
> +               return "TRACE_INFO";
> +       case LTTNG_LOGLEVEL_DEBUG_SYSTEM:
> +               return "TRACE_DEBUG_SYSTEM";
> +       case LTTNG_LOGLEVEL_DEBUG_PROGRAM:
> +               return "TRACE_DEBUG_PROGRAM";
> +       case LTTNG_LOGLEVEL_DEBUG_PROCESS:
> +               return "TRACE_DEBUG_PROCESS";
> +       case LTTNG_LOGLEVEL_DEBUG_MODULE:
> +               return "TRACE_DEBUG_MODULE";
> +       case LTTNG_LOGLEVEL_DEBUG_UNIT:
> +               return "TRACE_DEBUG_UNIT";
> +       case LTTNG_LOGLEVEL_DEBUG_FUNCTION:
> +               return "TRACE_DEBUG_FUNCTION";
> +       case LTTNG_LOGLEVEL_DEBUG_LINE:
> +               return "TRACE_DEBUG_LINE";
> +       case LTTNG_LOGLEVEL_DEBUG:
> +               return "TRACE_DEBUG";
> +       default:
> +               return "UNKNOWN";
> +       }
> +}
> +
> +const char *logleveltype_string(enum lttng_loglevel_type value)
> +{
> +       switch (value) {
> +       case LTTNG_EVENT_LOGLEVEL_ALL:
> +               return ":";
> +       case LTTNG_EVENT_LOGLEVEL_RANGE:
> +               return " <=";
> +       case LTTNG_EVENT_LOGLEVEL_SINGLE:
> +               return " ==";
> +       default:
> +               return " TYPE UNKN";
> +       }
> +}
> +
> +const char *eventtype_string(enum lttng_event_type value)
> +{
> +       switch (value) {
> +       case LTTNG_EVENT_ALL:
> +               return config_event_type_all;
> +               break;
> +       case LTTNG_EVENT_TRACEPOINT:
> +               return config_event_type_tracepoint;
> +               break;
> +       case LTTNG_EVENT_PROBE:
> +               return config_event_type_probe;
> +               break;
> +       case LTTNG_EVENT_FUNCTION:
> +               return config_event_type_function;
> +               break;
> +       case LTTNG_EVENT_FUNCTION_ENTRY:
> +               return config_event_type_function_entry;
> +               break;
> +       case LTTNG_EVENT_SYSCALL:
> +               return config_event_type_syscall;
> +               break;
> +       case LTTNG_EVENT_NOOP:
> +               return config_event_type_noop;
> +               break;
> +       default:
> +               return mi_lttng_element_empty;
> +               break;
> +       }
> +}
> +
> +const char *eventfieldtype_string(enum lttng_event_field_type val)
> +{
> +       const char *ret;
> +
> +       switch (val) {
> +       case(LTTNG_EVENT_FIELD_INTEGER):
> +               ret = mi_lttng_element_type_integer;
> +               break;
> +       case(LTTNG_EVENT_FIELD_ENUM):
> +               ret = mi_lttng_element_type_enum;
> +               break;
> +       case(LTTNG_EVENT_FIELD_FLOAT):
> +               ret = mi_lttng_element_type_float;
> +               break;
> +       case(LTTNG_EVENT_FIELD_STRING):
> +               ret = mi_lttng_element_type_string;
> +               break;
> +       default:
> +               ret = mi_lttng_element_type_other;
> +               break;
> +       }
> +       return ret;
> +}
> +
>  LTTNG_HIDDEN
>  struct mi_writer *mi_lttng_writer_create(int fd_output, int mi_output_type)
>  {
> @@ -119,6 +275,25 @@ int mi_lttng_writer_close_element(struct mi_writer *writer)
>  }
>
>  LTTNG_HIDDEN
> +int mi_lttng_close_multi_element(struct mi_writer *writer,
> +               unsigned int nb_element)
> +{
> +       int ret, i;
> +       if (nb_element < 1) {
> +               ret = 0;
> +               goto end;
> +       }
> +       for (i = 0; i < nb_element; i++) {
> +               ret = mi_lttng_writer_close_element(writer);
> +               if (ret) {
> +                       goto end;
> +               }
> +       }
> +end:
> +       return ret;
> +}
> +
> +LTTNG_HIDDEN
>  int mi_lttng_writer_write_element_unsigned_int(struct mi_writer *writer,
>                 const char *element_name, uint64_t value)
>  {
> @@ -226,12 +401,20 @@ end:
>  }
>
>  LTTNG_HIDDEN
> +int mi_lttng_sessions_open(struct mi_writer *writer)
> +{
> +       return mi_lttng_writer_open_element(writer, config_element_sessions);
> +}
> +
> +LTTNG_HIDDEN
>  int mi_lttng_session(struct mi_writer *writer,
>                 struct lttng_session *session, int is_open)
>  {
>         int ret;
>
> -       /* open sessions element */
> +       assert(session);
> +
> +       /* Open sessions element */
>         ret = mi_lttng_writer_open_element(writer,
>                         config_element_session);
>         if (ret) {
> @@ -245,28 +428,28 @@ int mi_lttng_session(struct mi_writer *writer,
>                 goto end;
>         }
>
> -       /* path */
> +       /* Path */
>         ret = mi_lttng_writer_write_element_string(writer,
>                         config_element_path, session->path);
>         if (ret) {
>                 goto end;
>         }
>
> -       /* enabled ? */
> -       ret = mi_lttng_writer_write_element_unsigned_int(writer,
> +       /* Enabled ? */
> +       ret = mi_lttng_writer_write_element_bool(writer,
>                         config_element_enabled, session->enabled);
>         if (ret) {
>                 goto end;
>         }
>
> -       /* snapshot mode */
> +       /* Snapshot mode */
>         ret = mi_lttng_writer_write_element_unsigned_int(writer,
>                         config_element_snapshot_mode, session->snapshot_mode);
>         if (ret) {
>                 goto end;
>         }
>
> -       /* live timer interval in usec */
> +       /* Live timer interval in usec */
>         ret = mi_lttng_writer_write_element_unsigned_int(writer,
>                         config_element_live_timer_interval,
>                         session->live_timer_interval);
> @@ -282,3 +465,493 @@ end:
>         return ret;
>
>  }
> +
> +LTTNG_HIDDEN
> +int mi_lttng_domains_open(struct mi_writer *writer)
> +{
> +       return mi_lttng_writer_open_element(writer, config_element_domains);
> +}
> +
> +LTTNG_HIDDEN
> +int mi_lttng_domain(struct mi_writer *writer,
> +               struct lttng_domain *domain, int is_open)
> +{
> +       int ret = 0;
> +       const char *str_domain;
> +       const char *str_buffer;
> +
> +       assert(domain);
> +
> +       /* Open domain element */
> +       ret = mi_lttng_writer_open_element(writer, config_element_domain);
> +       if (ret) {
> +               goto end;
> +       }
> +
> +       /* Type
> +        * Note: This is a *duplicate* of get_domain_str from bin/lttng/utils.c
> +        */
> +       switch (domain->type) {
> +       case LTTNG_DOMAIN_KERNEL:
> +               str_domain = config_domain_type_kernel;
> +               break;
> +       case LTTNG_DOMAIN_UST:
> +               str_domain = config_domain_type_ust;
> +               break;
> +       case LTTNG_DOMAIN_JUL:
> +               str_domain = config_domain_type_jul;
> +               break;
> +       default:
> +               /* Should not have an unknown domain */
> +               assert(0);
> +       }
> +
> +       ret = mi_lttng_writer_write_element_string(writer, config_element_type,
> +                       str_domain);
> +       if (ret) {
> +               goto end;
> +       }
> +
> +       /* Buffer Type */
> +       switch (domain->buf_type) {
> +       case LTTNG_BUFFER_PER_PID:
> +               str_buffer = config_buffer_type_per_pid;
> +               break;
> +       case LTTNG_BUFFER_PER_UID:
> +               str_buffer = config_buffer_type_per_uid;
> +               break;
> +       case LTTNG_BUFFER_GLOBAL:
> +               str_buffer = config_buffer_type_global;
> +               break;
> +       default:
> +               /* Shoul not have an unknow buffer type */
> +               assert(0);
> +       }
> +
> +       ret = mi_lttng_writer_write_element_string(writer,
> +                       config_element_buffer_type, str_buffer);
> +       if (ret) {
> +               goto end;
> +       }
> +
> +       /* TODO: attr... not sure how to use the union.... */
> +
> +       if (!is_open) {
> +               /* Closing domain element */
> +               ret = mi_lttng_writer_close_element(writer);
> +       }
> +
> +end:
> +       return ret;
> +
> +}
> +
> +LTTNG_HIDDEN
> +int mi_lttng_channels_open(struct mi_writer *writer)
> +{
> +       return mi_lttng_writer_open_element(writer, config_element_channels);
> +}
> +
> +LTTNG_HIDDEN
> +int mi_lttng_channel(struct mi_writer *writer,
> +               struct lttng_channel *channel, int is_open)
> +{
> +       int ret = 0;
> +
> +       assert(channel);
> +
> +       /* Opening channel element */
> +       ret = mi_lttng_writer_open_element(writer, config_element_channel);
> +       if (ret) {
> +               goto end;
> +       }
> +       /* Name */
> +       ret = mi_lttng_writer_write_element_string(writer, config_element_name,
> +                       channel->name);
> +       if (ret) {
> +               goto end;
> +       }
> +
> +       /* Enabled ? */
> +       ret = mi_lttng_writer_write_element_bool(writer,
> +                       config_element_enabled, channel->enabled);
> +       if (ret) {
> +               goto end;
> +       }
> +
> +       /* Attribute */
> +       ret = mi_lttng_channel_attr(writer, &channel->attr);
> +       if (ret) {
> +               goto end;
> +       }
> +
> +       if (!is_open) {
> +               /* Closing channel element */
> +               ret = mi_lttng_writer_close_element(writer);
> +               if (ret) {
> +                       goto end;
> +               }
> +       }
> +end:
> +       return ret;
> +}
> +
> +LTTNG_HIDDEN
> +int mi_lttng_channel_attr(struct mi_writer *writer,
> +               struct lttng_channel_attr *attr)
> +{
> +       int ret = 0;
> +
> +       assert(attr);
> +
> +       /* Opening Attributes */
> +       ret = mi_lttng_writer_open_element(writer, config_element_attributes);
> +       if (ret) {
> +               goto end;
> +       }
> +
> +       /* Overwrite */
> +       ret = mi_lttng_writer_write_element_string(writer,
> +               config_element_overwrite_mode,
> +               attr->overwrite ? config_overwrite_mode_overwrite :
> +                       config_overwrite_mode_discard);
> +       if (ret) {
> +               goto end;
> +       }
> +
> +       /* Sub buffer size in byte */
> +       ret = mi_lttng_writer_write_element_unsigned_int(writer,
> +               config_element_subbuf_size, attr->subbuf_size);
> +       if (ret) {
> +               goto end;
> +       }
> +
> +       /* Number of sub buffer (power of two) */
> +       ret = mi_lttng_writer_write_element_unsigned_int(writer,
> +               config_element_num_subbuf,
> +               attr->num_subbuf);
> +       if (ret) {
> +               goto end;
> +       }
> +
> +       /* Switch timer interval in usec */
> +       ret = mi_lttng_writer_write_element_unsigned_int(writer,
> +               config_element_switch_timer_interval,
> +               attr->switch_timer_interval);
> +       if (ret) {
> +               goto end;
> +       }
> +
> +       /* Read timer interval in usec */
> +       ret = mi_lttng_writer_write_element_unsigned_int(writer,
> +               config_element_read_timer_interval,
> +               attr->read_timer_interval);
> +       if (ret) {
> +               goto end;
> +       }
> +
> +       /* Event output */
> +       ret = mi_lttng_writer_write_element_string(writer,
> +               config_element_output_type,
> +               attr->output == LTTNG_EVENT_SPLICE ?
> +               config_output_type_splice : config_output_type_mmap);
> +       if (ret) {
> +               goto end;
> +       }
> +
> +       /* Tracefile size in bytes */
> +       ret = mi_lttng_writer_write_element_unsigned_int(writer,
> +               config_element_tracefile_size, attr->tracefile_size);
> +       if (ret) {
> +               goto end;
> +       }
> +
> +       /* Count of tracefiles */
> +       ret = mi_lttng_writer_write_element_unsigned_int(writer,
> +               config_element_tracefile_count,
> +               attr->tracefile_count);
> +       if (ret) {
> +               goto end;
> +       }
> +
> +       /* Live timer interval in usec*/
> +       ret = mi_lttng_writer_write_element_unsigned_int(writer,
> +               config_element_live_timer_interval,
> +               attr->live_timer_interval);
> +       if (ret) {
> +               goto end;
> +       }
> +
> +       /* Closing attributes */
> +       ret = mi_lttng_writer_close_element(writer);
> +       if (ret) {
> +               goto end;
> +       }
> +end:
> +       return ret;
> +
> +}
> +
> +LTTNG_HIDDEN
> +int mi_lttng_event_common_attributes(struct mi_writer *writer,
> +               struct lttng_event *event)
> +{
> +       int ret;
> +
> +       /* Open event element */
> +       ret = mi_lttng_writer_open_element(writer, config_element_event);
> +       if (ret) {
> +               goto end;
> +       }
> +
> +       /* event name */
> +       ret = mi_lttng_writer_write_element_string(writer,
> +                       config_element_name, event->name);
> +       if (ret) {
> +               goto end;
> +       }
> +
> +       /* event type */
> +       ret = mi_lttng_writer_write_element_string(writer,
> +                       config_element_type, eventtype_string(event->type));
> +       if (ret) {
> +               goto end;
> +       }
> +
> +       /* is event enabled */
> +       ret = mi_lttng_writer_write_element_string(writer,
> +                       config_element_enabled, enabled_string(event->enabled));
> +       if (ret) {
> +               goto end;
> +       }
> +
> +       /* event filter */
> +       ret = mi_lttng_writer_write_element_string(writer,
> +                       config_element_filter, filter_string(event->filter));
> +
> +end:
> +       return ret;
> +}
> +
> +LTTNG_HIDDEN
> +int mi_lttng_event_tracepoint_loglevel(struct mi_writer *writer,
> +               struct lttng_event *event)
> +{
> +       int ret;
> +
> +       /* event loglevel */
> +       ret = mi_lttng_writer_write_element_string(writer,
> +                       config_element_loglevel, loglevel_string(event->loglevel));
> +       if (ret) {
> +               goto end;
> +       }
> +
> +       /* event exclusion filter */
> +       ret = mi_lttng_writer_write_element_string(writer,
> +                       config_element_exclusion, exclusion_string(event->exclusion));
> +       if (ret) {
> +               goto end;
> +       }
> +
> +end:
> +       return ret;
> +}
> +
> +LTTNG_HIDDEN
> +int mi_lttng_event_tracepoint_no_loglevel(struct mi_writer *writer,
> +               struct lttng_event *event)
> +{
> +       /* event exclusion filter */
> +       return mi_lttng_writer_write_element_string(writer,
> +                       config_element_exclusion, exclusion_string(event->exclusion));
> +}
> +
> +LTTNG_HIDDEN
> +int mi_lttng_event_function_probe(struct mi_writer *writer,
> +               struct lttng_event *event)
> +{
> +       int ret;
> +
> +       if (event->attr.probe.addr != 0) {
> +               /* event probe address */
> +               ret = mi_lttng_writer_write_element_unsigned_int(writer,
> +                               config_element_address, event->attr.probe.addr);
> +               if (ret) {
> +                       goto end;
> +               }
> +       } else {
> +               /* event probe offset */
> +               ret = mi_lttng_writer_write_element_unsigned_int(writer,
> +                               config_element_offset, event->attr.probe.offset);
> +               if (ret) {
> +                       goto end;
> +               }
> +
> +               /* event probe symbol_name */
> +               ret = mi_lttng_writer_write_element_string(writer,
> +                               config_element_symbol_name, event->attr.probe.symbol_name);
> +               if (ret) {
> +                       goto end;
> +               }
> +       }
> +end:
> +       return ret;
> +}
> +
> +LTTNG_HIDDEN
> +int mi_lttng_event_function_entry(struct mi_writer *writer,
> +               struct lttng_event *event)
> +{
> +       /* event probe symbol_name */
> +       return mi_lttng_writer_write_element_string(writer,
> +                       config_element_symbol_name, event->attr.ftrace.symbol_name);
> +}
> +
> +LTTNG_HIDDEN
> +int mi_lttng_events_open(struct mi_writer *writer)
> +{
> +       return mi_lttng_writer_open_element(writer, config_element_events);
> +}
> +
> +LTTNG_HIDDEN
> +int mi_lttng_event(struct mi_writer *writer,
> +               struct lttng_event *event, int is_open)
> +{
> +       int ret;
> +
> +       ret = mi_lttng_event_common_attributes(writer, event);
> +       if (ret) {
> +               goto end;
> +       }
> +
> +       switch (event->type) {
> +       case LTTNG_EVENT_ALL:
> +               /* We should never have "all" events in list. */
> +               assert(0);
> +               break;
> +       case LTTNG_EVENT_TRACEPOINT:
> +       {
> +               if (event->loglevel != -1) {
> +                       ret = mi_lttng_event_tracepoint_loglevel(writer, event);
> +               } else {
> +                       ret = mi_lttng_event_tracepoint_no_loglevel(writer, event);
> +               }
> +               break;
> +       }
> +       case LTTNG_EVENT_PROBE:
> +               ret = mi_lttng_event_function_probe(writer, event);
> +               break;
> +       case LTTNG_EVENT_FUNCTION_ENTRY:
> +               ret = mi_lttng_event_function_entry(writer, event);
> +               break;
> +       default:
> +               break;
> +       }
> +
> +       if (!is_open) {
> +               ret = mi_lttng_writer_close_element(writer);
> +       }
> +
> +end:
> +       return ret;
> +}
> +
> +LTTNG_HIDDEN
> +int mi_lttng_pids_open(struct mi_writer *writer)
> +{
> +       return mi_lttng_writer_open_element(writer, mi_lttng_element_pids);
> +}
> +
> +LTTNG_HIDDEN
> +int mi_lttng_pid(struct mi_writer *writer, pid_t pid , const char *cmdline,
> +               int is_open)
> +{
> +       int ret;
> +
> +       /* Open element pid */
> +       ret = mi_lttng_writer_open_element(writer, mi_lttng_element_pid);
> +       if (ret) {
> +               goto end;
> +       }
> +
> +       /* Writing pid number */
> +       ret = mi_lttng_writer_write_element_signed_int(writer,
> +                       mi_lttng_element_pid_id, (int)pid);
> +       if (ret) {
> +               goto end;
> +       }
> +
> +       /* Writing name of the process */
> +       ret = mi_lttng_writer_write_element_string(writer, config_element_name,
> +                       cmdline);
> +       if (ret) {
> +               goto end;
> +       }
> +
> +       if (!is_open) {
> +               /* Closing Pid */
> +               ret = mi_lttng_writer_close_element(writer);
> +       }
> +
> +end:
> +       return ret;
> +}
> +
> +LTTNG_HIDDEN
> +int mi_lttng_event_fields_open(struct mi_writer *writer)
> +{
> +       return mi_lttng_writer_open_element(writer, mi_lttng_element_event_fields);
> +}
> +
> +LTTNG_HIDDEN
> +int mi_lttng_event_field(struct mi_writer *writer,
> +               struct lttng_event_field *field)
> +{
> +       int ret;
> +
> +       if (!field->field_name[0]) {
> +               /* To Review: not sure if legal david ?
> +                * how should this be handle ?
> +                */
> +               ret = 0;
> +               goto end;
> +       }
> +
> +       /* Open field */
> +       ret = mi_lttng_writer_open_element(writer, mi_lttng_element_event_field);
> +       if (ret) {
> +               goto end;
> +       }
> +
> +       if (!field->field_name[0]) {
> +               goto close;
> +       }
> +
> +       /* Name */
> +       ret = mi_lttng_writer_write_element_string(writer, config_element_name,
> +                       field->field_name);
> +       if (ret) {
> +               goto end;
> +       }
> +
> +       /* Type */
> +       ret = mi_lttng_writer_write_element_string(writer, config_element_type,
> +                       eventfieldtype_string(field->type));
> +       if (ret) {
> +               goto end;
> +       }
> +
> +       /* nowrite  */
> +       ret = mi_lttng_writer_write_element_signed_int(writer,
> +                       mi_lttng_element_nowrite, field->nowrite);
> +       if (ret) {
> +               goto end;
> +       }
> +
> +close:
> +       /* Close field element */
> +       ret = mi_lttng_writer_close_element(writer);
> +
> +end:
> +       return ret;
> +}
> diff --git a/src/common/mi-lttng.h b/src/common/mi-lttng.h
> index 69ec0f5..33b5547 100644
> --- a/src/common/mi-lttng.h
> +++ b/src/common/mi-lttng.h
> @@ -63,6 +63,31 @@ const char * const mi_lttng_element_version_license;
>  const char * const mi_lttng_element_version_patch_level;
>  const char * const mi_lttng_element_version_description;
>
> +/* String related to a lttng_event_field */
> +const char * const mi_lttng_element_event_field;
> +const char * const mi_lttng_element_event_fields;
> +
> +/* Strings related to pid */
> +const char * const mi_lttng_element_pids;
> +const char * const mi_lttng_element_pid;
> +const char * const mi_lttng_element_pid_id;
> +
> +/* General element of mi_lttng */
> +const char * const mi_lttng_element_type_other;
> +const char * const mi_lttng_element_type_integer;
> +const char * const mi_lttng_element_type_enum;
> +const char * const mi_lttng_element_type_float;
> +const char * const mi_lttng_element_type_string;
> +const char * const mi_lttng_element_nowrite;
> +
> +/* Utility string function  */
> +const char *enabled_string(int value);
> +const char *filter_string(int value);
> +const char *exclusion_string(int value);
> +const char *loglevel_string(int value);
> +const char *logleveltype_string(enum lttng_loglevel_type value);
> +const char *eventfieldtype_string(enum lttng_event_field_type value);
> +
>  /*
>   * Create an instance of a machine interface writer.
>   *
> @@ -130,6 +155,19 @@ int mi_lttng_writer_open_element(struct mi_writer *writer,
>  int mi_lttng_writer_close_element(struct mi_writer *writer);
>
>  /*
> + * Close multiple element .
> + *
> + * writer An instance of a machine interface writer.
> + *
> + * nb_element
> + *
> + * Returns zero if the XML document could be closed cleanly.
> + * Negative values indicate an error.
> + */
> +int mi_lttng_close_multi_element(struct mi_writer *writer,
> +               unsigned int nb_element);
> +
> +/*
>   * Write an element of type unsigned int.
>   *
>   * writer An instance of a machine interface writer.
> @@ -207,24 +245,271 @@ int mi_lttng_version(struct mi_writer *writer, struct mi_lttng_version *version,
>                 const char *lttng_description, const char *lttng_license);
>
>  /*
> + * Machine interface: open a sessions element.
> + *
> + * writer An instance of a machine interface writer
> + *
> + * Returns zero if the element's value could be written.
> + * Negative values indicate an error.
> + */
> +int mi_lttng_sessions_open(struct mi_writer *writer);
> +
> +/*
>   * Machine interface of struct session.
>   *
>   * writer An instance of a machine interface writer
>   *
>   * session An instance of a session
>   *
> - * isOpen Define if we close the session element
> - *        This should be use carefully and the client
> - *        need to close the session element.
> - *        Use case: nested addition information on a session
> + * is_open Define if we close the session element
> + *         This should be used carefully and the client
> + *         need to close the session element.
> + *         Use case: nested addtionnal information on a session
>   *                  ex: domain,channel event.
> - *        0-> False
> - *        1-> True
> + *         0-> False
> + *         1-> True
>   *
>   * Returns zero if the element's value could be written.
>   * Negative values indicate an error.
>   */
>  int mi_lttng_session(struct mi_writer *writer,
> -               struct lttng_session *session, int isOpen);
> +               struct lttng_session *session, int is_open);
> +
> +/*
> + * Machine interface: open a domains element.
> + *
> + * writer An instance of a machine interface writer
> + *
> + * Returns zero if the element's value could be written.
> + * Negative values indicate an error.
> + */
> +int mi_lttng_domains_open(struct mi_writer *writer);
> +
> +/*
> + * Machine interface of struct domain.
> + *
> + * writer An instance of a machine interface writer
> + *
> + * domain An instance of a domain
> + *
> + * is_open Define if we close the domain element
> + *         This should be used carefully and the client
> + *         need to close the domain element.
> + *         Use case: nested addition information on a domain
> + *                  ex: channel event.
> + *         0-> False
> + *         1-> True
> + *
> + * Returns zero if the element's value could be written.
> + * Negative values indicate an error.
> + */
> +int mi_lttng_domain(struct mi_writer *writer,
> +               struct lttng_domain *domain, int is_open);
> +
> +/*
> + * Machine interface: open a channels element.
> + *
> + * writer An instance of a machine interface writer
> + *
> + * Returns zero if the element's value could be written.
> + * Negative values indicate an error.
> + */
> +int mi_lttng_channels_open(struct mi_writer *writer);
> +
> +/*
> + * Machine interface of struct channel.
> + *
> + * writer An instance of a machine interface writer
> + *
> + * channel An instance of a channel
> + *
> + * is_open Define if we close the channel element
> + *         This should be used carefully and the client
> + *         need to close the channel element.
> + *         Use case: nested addition information on a domain
> + *                  ex: channel event.
> + *         0-> False
> + *         1-> True
> + *
> + * Returns zero if the element's value could be written.
> + * Negative values indicate an error.
> + */
> +int mi_lttng_channel(struct mi_writer *writer,
> +               struct lttng_channel *channel, int is_open);
> +
> +/*
> + * Machine interface of struct channel_attr.
> + *
> + * writer An instance of a machine interface writer
> + *
> + * attr An instance of a channel_attr struct
> + *
> + * Returns zero if the element's value could be written.
> + * Negative values indicate an error.
> + */
> +int mi_lttng_channel_attr(struct mi_writer *writer,
> +               struct lttng_channel_attr *attr);
> +
> +/*
> +* Machine interface for event common attribute.
> +*
> +* writer An instance of a mi writer.
> +*
> +* event single trace event.
> +*
> +* The common attribute are:
> +* - mi event element
> +* - event name
> +* - event type
> +* - enabled tag
> +* - event filter
> +*
> +* Returns zero if the element's value could be written.
> +* Negative values indicate an error.
> +*/
> +int mi_lttng_event_common_attributes(struct mi_writer *writer,
> +               struct lttng_event *event);
> +
> +/*
> + * Machine interface for kernel tracepoint event with a loglevel.
> + *
> + * writer An instance of a mi writer.
> + *
> + * event single trace event.
> + *
> + * Returns zero if the element's value could be written.
> + * Negative values indicate an error.
> + */
> +int mi_lttng_event_tracepoint_loglevel(struct mi_writer *writer,
> +               struct lttng_event *event);
> +
> +/*
> + * Machine interface for kernel tracepoint event with no loglevel.
> + *
> + * writer An instance of a mi writer.
> + *
> + * event single trace event.
> + *
> + * Returns zero if the element's value could be written.
> + * Negative values indicate an error.
> + */
> +int mi_lttng_event_tracepoint_no_loglevel(struct mi_writer *writer,
> +               struct lttng_event *event);
> +
> +/*
> + * Machine interface for kernel function and probe event.
> + *
> + * writer An instance of a mi writer.
> + *
> + * event single trace event.
> + *
> + * Returns zero if the element's value could be written.
> + * Negative values indicate an error.
> + */
> +int mi_lttng_event_function_probe(struct mi_writer *writer,
> +               struct lttng_event *event);
> +
> +/*
> + * Machine interface for kernel function entry event.
> + *
> + * writer An instance of a mi writer.
> + *
> + * event single trace event.
> + *
> + * Returns zero if the element's value could be written.
> + * Negative values indicate an error.
> + */
> +int mi_lttng_event_function_entry(struct mi_writer *writer,
> +               struct lttng_event *event);
> +
> +/*
> + * Machine interface: open an events element.
> + *
> + * writer An instance of a machine interface writer
> + *
> + * Returns zero if the element's value could be written.
> + * Negative values indicate an error.
> + */
> +int mi_lttng_events_open(struct mi_writer *writer);
> +
> +/*
> + * Machine interface for printing an event.
> + * The trace event type currently supported are:
> + *  TRACEPOINT,
> + *  PROBE,
> + *  FUNCTION,
> + *  FUNCTION_ENTRY,
> + *  SYSCALL
> + *
> + * writer An instance of a mi writer.
> + *
> + * event single trace event.
> + *
> + * is_open Define if we close the event element
> + *         This should be used carefully and the client
> + *         need to close the event element.
> + *         Use case: nested additional information
> + *         0-> False
> + *         1-> True
> + *
> + * Returns zero if the element's value could be written.
> + * Negative values indicate an error.
> + */
> +int mi_lttng_event(struct mi_writer *writer, struct lttng_event *event,
> +               int is_open);
> +
> +/*
> + * Machine interface for struct lttng_event_field .
> + *
> + * writer An instance of a mi writer.
> + *
> + * field An event_field instance.
> + *
> + * Returns zero if the element's value could be written.
> + * Negative values indicate an error.
> + */
> +int mi_lttng_event_field(struct mi_writer *writer,
> +               struct lttng_event_field *field);
> +
> +/*
> + * Machine interface: open a event_fields element.
> + *
> + * writer An instance of a machine interface writer
> + *
> + * Returns zero if the element's value could be written.
> + * Negative values indicate an error.
> + */
> +int mi_lttng_event_fields_open(struct mi_writer *writer);
> +
> +/*
> + * Machine interface: open a pids element.
> + *
> + * writer An instance of a machine interface writer
> + *
> + * Returns zero if the element's value could be written.
> + * Negative values indicate an error.
> + */
> +int mi_lttng_pids_open(struct mi_writer *writer);
> +
> +/*
> + * Machine interface of a pid.
> + *
> + * writer An instance of a machine interface writer
> + *
> + * pid A pid
> + *
> + * is_open Define if we close the pid element
> + *         This should be used carefully and the client
> + *         need to close the pid element.
> + *         Use case: nested addition information on a domain
> + *                  ex: channel event.
> + *         0-> False
> + *         1-> True
> + *
> + * Returns zero if the element's value could be written.
> + * Negative values indicate an error.
> + */
> +int mi_lttng_pid(struct mi_writer *writer, pid_t pid , const char *cmdline,
> +               int is_open);
>
>  #endif /* _MI_LTTNG_H */
> --
> 1.8.3.2
>
>
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> lttng-dev at lists.lttng.org
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