X-Git-Url: http://git.efficios.com/?p=lttng-tools.git;a=blobdiff_plain;f=src%2Fbin%2Flttng-sessiond%2Fcmd.c;h=7f05655ecd7371a60c6fc3b5b9e1bd9eef768f84;hp=8c51037b6c8a4613eea1b4f6d9da2c6f86e2a2e5;hb=17dd12323bbd9f979e5b3886f979a1e02e2dcbe6;hpb=3044f922f5125b490a1815d5913f8b9d00e21e9a diff --git a/src/bin/lttng-sessiond/cmd.c b/src/bin/lttng-sessiond/cmd.c index 8c51037b6..7f05655ec 100644 --- a/src/bin/lttng-sessiond/cmd.c +++ b/src/bin/lttng-sessiond/cmd.c @@ -21,6 +21,7 @@ #include #include #include +#include #include #include @@ -37,6 +38,7 @@ #include #include #include +#include #include #include "channel.h" @@ -59,6 +61,30 @@ #include "cmd.h" +/* Sleep for 100ms between each check for the shm path's deletion. */ +#define SESSION_DESTROY_SHM_PATH_CHECK_DELAY_US 100000 + +static enum lttng_error_code wait_on_path(void *path); + +/* + * Command completion handler that is used by the destroy command + * when a session that has a non-default shm_path is being destroyed. + * + * See comment in cmd_destroy_session() for the rationale. + */ +static struct destroy_completion_handler { + struct cmd_completion_handler handler; + char shm_path[member_sizeof(struct ltt_session, shm_path)]; +} destroy_completion_handler = { + .handler = { + .run = wait_on_path, + .data = destroy_completion_handler.shm_path + }, + .shm_path = { 0 }, +}; + +static struct cmd_completion_handler *current_completion_handler; + /* * Used to keep a unique index for each relayd socket created where this value * is associated with streams on the consumer so it can match the right relayd @@ -1153,7 +1179,7 @@ static int start_kernel_session(struct ltt_kernel_session *ksess, int wpipe) } /* Quiescent wait after starting trace */ - kernel_wait_quiescent(kernel_tracer_fd); + kernel_wait_quiescent(wpipe); ksess->active = 1; @@ -3030,6 +3056,59 @@ int cmd_destroy_session(struct ltt_session *session, int wpipe, PERROR("write kernel poll pipe"); } + if (session->shm_path[0]) { + /* + * When a session is created with an explicit shm_path, + * the consumer daemon will create its shared memory files + * at that location and will *not* unlink them. This is normal + * as the intention of that feature is to make it possible + * to retrieve the content of those files should a crash occur. + * + * To ensure the content of those files can be used, the + * sessiond daemon will replicate the content of the metadata + * cache in a metadata file. + * + * On clean-up, it is expected that the consumer daemon will + * unlink the shared memory files and that the session daemon + * will unlink the metadata file. Then, the session's directory + * in the shm path can be removed. + * + * Unfortunately, a flaw in the design of the sessiond's and + * consumerd's tear down of channels makes it impossible to + * determine when the sessiond _and_ the consumerd have both + * destroyed their representation of a channel. For one, the + * unlinking, close, and rmdir happen in deferred 'call_rcu' + * callbacks in both daemons. + * + * However, it is also impossible for the sessiond to know when + * the consumer daemon is done destroying its channel(s) since + * it occurs as a reaction to the closing of the channel's file + * descriptor. There is no resulting communication initiated + * from the consumerd to the sessiond to confirm that the + * operation is completed (and was successful). + * + * Until this is all fixed, the session daemon checks for the + * removal of the session's shm path which makes it possible + * to safely advertise a session as having been destroyed. + * + * Prior to this fix, it was not possible to reliably save + * a session making use of the --shm-path option, destroy it, + * and load it again. This is because the creation of the + * session would fail upon seeing the session's shm path + * already in existence. + * + * Note that none of the error paths in the check for the + * directory's existence return an error. This is normal + * as there isn't much that can be done. The session will + * be destroyed properly, except that we can't offer the + * guarantee that the same session can be re-created. + */ + current_completion_handler = &destroy_completion_handler.handler; + ret = lttng_strncpy(destroy_completion_handler.shm_path, + session->shm_path, + sizeof(destroy_completion_handler.shm_path)); + assert(!ret); + } ret = session_destroy(session); return ret; @@ -4482,6 +4561,14 @@ int cmd_rotate_session(struct ltt_session *session, session->current_archive_id++; session->rotate_pending = true; session->rotation_state = LTTNG_ROTATION_STATE_ONGOING; + ret = notification_thread_command_session_rotation_ongoing( + notification_thread_handle, + session->name, session->uid, session->gid, + session->current_archive_id); + if (ret != LTTNG_OK) { + ERR("Failed to notify notification thread that a session rotation is ongoing for session %s", + session->name); + } /* * Create the path name for the next chunk. @@ -4594,13 +4681,29 @@ int cmd_rotate_session(struct ltt_session *session, * session_list locks. */ if (!session->kernel_session && !ust_active) { + struct lttng_trace_archive_location *location; + + session->rotate_pending = false; + session->rotation_state = LTTNG_ROTATION_STATE_COMPLETED; ret = rename_complete_chunk(session, now); if (ret < 0) { ERR("Failed to rename completed rotation chunk"); goto end; } - session->rotate_pending = false; - session->rotation_state = LTTNG_ROTATION_STATE_COMPLETED; + + /* Ownership of location is transferred. */ + location = session_get_trace_archive_location(session); + ret = notification_thread_command_session_rotation_completed( + notification_thread_handle, + session->name, + session->uid, + session->gid, + session->current_archive_id, + location); + if (ret != LTTNG_OK) { + ERR("Failed to notify notification thread that rotation is complete for session %s", + session->name); + } } } @@ -4721,15 +4824,19 @@ end: * Command LTTNG_ROTATION_SET_SCHEDULE from the lttng-ctl library. * * Configure the automatic rotation parameters. - * Set to -1ULL to disable them. + * 'activate' to true means activate the rotation schedule type with 'new_value'. + * 'activate' to false means deactivate the rotation schedule and validate that + * 'new_value' has the same value as the currently active value. * - * Return 0 on success or else an LTTNG_ERR code. + * Return 0 on success or else a positive LTTNG_ERR code. */ int cmd_rotation_set_schedule(struct ltt_session *session, - uint64_t timer_us, uint64_t size, + bool activate, enum lttng_rotation_schedule_type schedule_type, + uint64_t new_value, struct notification_thread_handle *notification_thread_handle) { int ret; + uint64_t *parameter_value; assert(session); @@ -4737,71 +4844,117 @@ int cmd_rotation_set_schedule(struct ltt_session *session, if (session->live_timer || session->snapshot_mode || !session->output_traces) { + DBG("Failing ROTATION_SET_SCHEDULE command as the rotation feature is not available for this session"); ret = LTTNG_ERR_ROTATION_NOT_AVAILABLE; goto end; } - /* Trying to override an already active timer. */ - if (timer_us && timer_us != -1ULL && session->rotate_timer_period) { - ret = LTTNG_ERR_ROTATION_TIMER_SET; + switch (schedule_type) { + case LTTNG_ROTATION_SCHEDULE_TYPE_SIZE_THRESHOLD: + parameter_value = &session->rotate_size; + break; + case LTTNG_ROTATION_SCHEDULE_TYPE_PERIODIC: + parameter_value = &session->rotate_timer_period; + if (new_value >= UINT_MAX) { + DBG("Failing ROTATION_SET_SCHEDULE command as the value requested for a periodic rotation schedule is invalid: %" PRIu64 " > %u (UINT_MAX)", + new_value, UINT_MAX); + ret = LTTNG_ERR_INVALID; + goto end; + } + break; + default: + WARN("Failing ROTATION_SET_SCHEDULE command on unknown schedule type"); + ret = LTTNG_ERR_INVALID; goto end; - /* Trying to disable an inactive timer. */ - } else if (timer_us == -1ULL && !session->rotate_timer_period) { - ret = LTTNG_ERR_ROTATION_NO_TIMER_SET; + } + + /* Improper use of the API. */ + if (new_value == -1ULL) { + WARN("Failing ROTATION_SET_SCHEDULE command as the value requested is -1"); + ret = LTTNG_ERR_INVALID; goto end; } - if (size && size != -1ULL && session->rotate_size) { - ret = LTTNG_ERR_ROTATION_SIZE_SET; + /* + * As indicated in struct ltt_session's comments, a value of == 0 means + * this schedule rotation type is not in use. + * + * Reject the command if we were asked to activate a schedule that was + * already active. + */ + if (activate && *parameter_value != 0) { + DBG("Failing ROTATION_SET_SCHEDULE (activate) command as the schedule is already active"); + ret = LTTNG_ERR_ROTATION_SCHEDULE_SET; goto end; - } else if (size == -1ULL && !session->rotate_size) { - ret = LTTNG_ERR_ROTATION_NO_SIZE_SET; + } + + /* + * Reject the command if we were asked to deactivate a schedule that was + * not active. + */ + if (!activate && *parameter_value == 0) { + DBG("Failing ROTATION_SET_SCHEDULE (deactivate) command as the schedule is already inactive"); + ret = LTTNG_ERR_ROTATION_SCHEDULE_NOT_SET; goto end; } - if (timer_us && !session->rotate_timer_period) { - if (timer_us > UINT_MAX) { - ret = LTTNG_ERR_INVALID; - goto end; - } + /* + * Reject the command if we were asked to deactivate a schedule that + * doesn't exist. + */ + if (!activate && *parameter_value != new_value) { + DBG("Failing ROTATION_SET_SCHEDULE (deactivate) command as an inexistant schedule was provided"); + ret = LTTNG_ERR_ROTATION_SCHEDULE_NOT_SET; + goto end; + } - session->rotate_timer_period = timer_us; - /* - * Only start the timer if the session is active, otherwise - * it will be started when the session starts. - */ - if (session->active) { - ret = sessiond_rotate_timer_start(session, timer_us); + *parameter_value = activate ? new_value : 0; + + switch (schedule_type) { + case LTTNG_ROTATION_SCHEDULE_TYPE_PERIODIC: + if (activate && session->active) { + /* + * Only start the timer if the session is active, + * otherwise it will be started when the session starts. + */ + ret = sessiond_rotate_timer_start(session, new_value); if (ret) { - ERR("Failed to enable rotate timer"); + ERR("Failed to enable session rotation timer in ROTATION_SET_SCHEDULE command"); + ret = LTTNG_ERR_UNK; + goto end; + } + } else { + ret = sessiond_rotate_timer_stop(session); + if (ret) { + ERR("Failed to disable session rotation timer in ROTATION_SET_SCHEDULE command"); ret = LTTNG_ERR_UNK; goto end; } } - } else if (timer_us == -1ULL && session->rotate_timer_period > 0) { - sessiond_rotate_timer_stop(session); - session->rotate_timer_period = 0; - } - - if (size > 0) { - if (size == -1ULL) { - ret = unsubscribe_session_consumed_size_rotation(session, - notification_thread_handle); + break; + case LTTNG_ROTATION_SCHEDULE_TYPE_SIZE_THRESHOLD: + if (activate) { + ret = subscribe_session_consumed_size_rotation(session, + new_value, notification_thread_handle); if (ret) { + ERR("Failed to enable consumed-size notification in ROTATION_SET_SCHEDULE command"); ret = LTTNG_ERR_UNK; goto end; } - session->rotate_size = 0; } else { - ret = subscribe_session_consumed_size_rotation(session, - size, notification_thread_handle); + ret = unsubscribe_session_consumed_size_rotation(session, + notification_thread_handle); if (ret) { - PERROR("Subscribe to session usage"); + ERR("Failed to disable consumed-size notification in ROTATION_SET_SCHEDULE command"); ret = LTTNG_ERR_UNK; goto end; } - session->rotate_size = size; + } + break; + default: + /* Would have been caught before. */ + abort(); } ret = LTTNG_OK; @@ -4864,6 +5017,49 @@ end: return ret; } +/* Wait for a given path to be removed before continuing. */ +static enum lttng_error_code wait_on_path(void *path_data) +{ + const char *shm_path = path_data; + + DBG("Waiting for the shm path at %s to be removed before completing session destruction", + shm_path); + while (true) { + int ret; + struct stat st; + + ret = stat(shm_path, &st); + if (ret) { + if (errno != ENOENT) { + PERROR("stat() returned an error while checking for the existence of the shm path"); + } else { + DBG("shm path no longer exists, completing the destruction of session"); + } + break; + } else { + if (!S_ISDIR(st.st_mode)) { + ERR("The type of shm path %s returned by stat() is not a directory; aborting the wait for shm path removal", + shm_path); + break; + } + } + usleep(SESSION_DESTROY_SHM_PATH_CHECK_DELAY_US); + } + return LTTNG_OK; +} + +/* + * Returns a pointer to a handler to run on completion of a command. + * Returns NULL if no handler has to be run for the last command executed. + */ +const struct cmd_completion_handler *cmd_pop_completion_handler(void) +{ + struct cmd_completion_handler *handler = current_completion_handler; + + current_completion_handler = NULL; + return handler; +} + /* * Init command subsystem. */