struct lttng_ht *agent_apps_ht_by_sock = NULL;
/*
- * Whether sessiond is ready for commands/notification channel/health check
+ * The initialization of the session daemon is done in multiple phases.
+ *
+ * While all threads are launched near-simultaneously, only some of them
+ * are needed to ensure the session daemon can start to respond to client
* requests.
- * NR_LTTNG_SESSIOND_READY must match the number of calls to
- * sessiond_notify_ready().
+ *
+ * There are two important guarantees that we wish to offer with respect
+ * to the initialisation of the session daemon:
+ * - When the daemonize/background launcher process exits, the sessiond
+ * is fully able to respond to client requests,
+ * - Auto-loaded sessions are visible to clients.
+ *
+ * In order to achieve this, a number of support threads have to be launched
+ * to allow the "client" thread to function properly. Moreover, since the
+ * "load session" thread needs the client thread, we must provide a way
+ * for the "load session" thread to know that the "client" thread is up
+ * and running.
+ *
+ * Hence, the support threads decrement the lttng_sessiond_ready counter
+ * while the "client" threads waits for it to reach 0. Once the "client" thread
+ * unblocks, it posts the message_thread_ready semaphore which allows the
+ * "load session" thread to progress.
+ *
+ * This implies that the "load session" thread is the last to be initialized
+ * and will explicitly call sessiond_signal_parents(), which signals the parents
+ * that the session daemon is fully initialized.
+ *
+ * The four (4) support threads are:
+ * - agent_thread
+ * - notification_thread
+ * - rotation_thread
+ * - health_thread
*/
-#define NR_LTTNG_SESSIOND_READY 6
-int lttng_sessiond_ready = NR_LTTNG_SESSIOND_READY;
+#define NR_LTTNG_SESSIOND_SUPPORT_THREADS 4
+int lttng_sessiond_ready = NR_LTTNG_SESSIOND_SUPPORT_THREADS;
int sessiond_check_thread_quit_pipe(int fd, uint32_t events)
{
/* Notify parents that we are ready for cmd and health check */
LTTNG_HIDDEN
-void sessiond_notify_ready(void)
+void sessiond_signal_parents(void)
{
- if (uatomic_sub_return(<tng_sessiond_ready, 1) == 0) {
- /*
- * Notify parent pid that we are ready to accept command
- * for client side. This ppid is the one from the
- * external process that spawned us.
- */
- if (config.sig_parent) {
- kill(ppid, SIGUSR1);
- }
+ /*
+ * Notify parent pid that we are ready to accept command
+ * for client side. This ppid is the one from the
+ * external process that spawned us.
+ */
+ if (config.sig_parent) {
+ kill(ppid, SIGUSR1);
+ }
- /*
- * Notify the parent of the fork() process that we are
- * ready.
- */
- if (config.daemonize || config.background) {
- kill(child_ppid, SIGUSR1);
- }
+ /*
+ * Notify the parent of the fork() process that we are
+ * ready.
+ */
+ if (config.daemonize || config.background) {
+ kill(child_ppid, SIGUSR1);
}
}
+LTTNG_HIDDEN
+void sessiond_notify_ready(void)
+{
+ /*
+ * This memory barrier is paired with the one performed by
+ * the client thread after it has seen that 'lttng_sessiond_ready' is 0.
+ *
+ * The purpose of these memory barriers is to ensure that all
+ * initialization operations of the various threads that call this
+ * function to signal that they are ready are commited/published
+ * before the client thread can see the 'lttng_sessiond_ready' counter
+ * reach 0.
+ *
+ * Note that this could be a 'write' memory barrier, but a full barrier
+ * is used in case the code using this utility changes. The performance
+ * implications of this choice are minimal since this is a slow path.
+ */
+ cmm_smp_mb();
+ uatomic_sub(<tng_sessiond_ready, 1);
+}
+
static
int __sessiond_set_thread_pollset(struct lttng_poll_event *events, size_t size,
int *a_pipe)
*
* Useful for CPU hotplug feature.
*/
-static int update_kernel_stream(struct consumer_data *consumer_data, int fd)
+static int update_kernel_stream(int fd)
{
int ret = 0;
struct ltt_session *session;
* New CPU detected by the kernel. Adding kernel stream to
* kernel session and updating the kernel consumer
*/
- ret = update_kernel_stream(&kconsumer_data, pollfd);
+ ret = update_kernel_stream(pollfd);
if (ret < 0) {
continue;
}
case LTTNG_ROTATION_GET_INFO:
case LTTNG_SESSION_GET_CURRENT_OUTPUT:
case LTTNG_ROTATION_SET_SCHEDULE:
- case LTTNG_ROTATION_SCHEDULE_GET_TIMER_PERIOD:
- case LTTNG_ROTATION_SCHEDULE_GET_SIZE:
+ case LTTNG_SESSION_LIST_ROTATION_SCHEDULES:
need_domain = 0;
break;
default:
case LTTNG_DATA_PENDING:
case LTTNG_ROTATE_SESSION:
case LTTNG_ROTATION_GET_INFO:
- case LTTNG_ROTATION_SCHEDULE_GET_TIMER_PERIOD:
- case LTTNG_ROTATION_SCHEDULE_GET_SIZE:
+ case LTTNG_SESSION_LIST_ROTATION_SCHEDULES:
break;
default:
/* Setup lttng message with no payload */
}
case LTTNG_ROTATION_SET_SCHEDULE:
{
+ bool set_schedule;
+ enum lttng_rotation_schedule_type schedule_type;
+ uint64_t value;
+
if (cmd_ctx->session->kernel_session && !check_rotate_compatible()) {
DBG("Kernel tracer version does not support session rotations");
ret = LTTNG_ERR_ROTATION_WRONG_VERSION;
goto error;
}
+ set_schedule = cmd_ctx->lsm->u.rotation_set_schedule.set == 1;
+ schedule_type = (enum lttng_rotation_schedule_type) cmd_ctx->lsm->u.rotation_set_schedule.type;
+ value = cmd_ctx->lsm->u.rotation_set_schedule.value;
+
ret = cmd_rotation_set_schedule(cmd_ctx->session,
- cmd_ctx->lsm->u.rotate_setup.timer_us,
- cmd_ctx->lsm->u.rotate_setup.size,
+ set_schedule,
+ schedule_type,
+ value,
notification_thread_handle);
if (ret != LTTNG_OK) {
goto error;
break;
}
- case LTTNG_ROTATION_SCHEDULE_GET_TIMER_PERIOD:
+ case LTTNG_SESSION_LIST_ROTATION_SCHEDULES:
{
- struct lttng_rotation_schedule_get_timer_period *get_timer;
-
- get_timer = zmalloc(sizeof(struct lttng_rotation_schedule_get_timer_period));
- if (!get_timer) {
- ret = ENOMEM;
- goto error;
- }
- get_timer->rotate_timer = cmd_ctx->session->rotate_timer_period;
-
- ret = setup_lttng_msg_no_cmd_header(cmd_ctx, get_timer,
- sizeof(struct lttng_rotation_schedule_get_timer_period));
- free(get_timer);
- if (ret < 0) {
- ret = -ret;
- goto error;
- }
-
- ret = LTTNG_OK;
- break;
- }
- case LTTNG_ROTATION_SCHEDULE_GET_SIZE:
- {
- struct lttng_rotation_schedule_get_size *get_size;
-
- get_size = zmalloc(sizeof(struct lttng_rotation_schedule_get_size));
- if (!get_size) {
- ret = ENOMEM;
- goto error;
- }
- get_size->rotate_size = cmd_ctx->session->rotate_size;
-
- ret = setup_lttng_msg_no_cmd_header(cmd_ctx, get_size,
- sizeof(struct lttng_rotation_schedule_get_size));
- free(get_size);
+ struct lttng_session_list_schedules_return schedules = {
+ .periodic.set = !!cmd_ctx->session->rotate_timer_period,
+ .periodic.value = cmd_ctx->session->rotate_timer_period,
+ .size.set = !!cmd_ctx->session->rotate_size,
+ .size.value = cmd_ctx->session->rotate_size,
+ };
+
+ ret = setup_lttng_msg_no_cmd_header(cmd_ctx, &schedules,
+ sizeof(schedules));
if (ret < 0) {
ret = -ret;
goto error;
goto error;
}
- sessiond_notify_ready();
-
ret = sem_post(&load_info->message_thread_ready);
if (ret) {
PERROR("sem_post message_thread_ready");
goto exit;
}
}
+ /*
+ * This barrier is paired with the one in sessiond_notify_ready() to
+ * ensure that loads accessing data initialized by the other threads,
+ * on which this thread was waiting, are not performed before this point.
+ *
+ * Note that this could be a 'read' memory barrier, but a full barrier
+ * is used in case the code changes. The performance implications of
+ * this choice are minimal since this is a slow path.
+ */
+ cmm_smp_mb();
/* This testpoint is after we signal readiness to the parent. */
if (testpoint(sessiond_thread_manage_clients)) {
health_code_update();
while (1) {
+ const struct cmd_completion_handler *cmd_completion_handler;
+
DBG("Accepting client command ...");
/* Inifinite blocking call, waiting for transmission */
continue;
}
+ cmd_completion_handler = cmd_pop_completion_handler();
+ if (cmd_completion_handler) {
+ enum lttng_error_code completion_code;
+
+ completion_code = cmd_completion_handler->run(
+ cmd_completion_handler->data);
+ if (completion_code != LTTNG_OK) {
+ clean_command_ctx(&cmd_ctx);
+ continue;
+ }
+ }
+
health_code_update();
DBG("Sending response (size: %d, retcode: %s (%d))",
goto exit_set_signal_handler;
}
+ /*
+ * Init config from environment variables.
+ * Command line option override env configuration per-doc. Do env first.
+ */
+ sessiond_config_apply_env_config(&config);
+
/*
* Parse arguments and load the daemon configuration file.
*
goto exit_options;
}
- /* Init config from environment variables. */
- sessiond_config_apply_env_config(&config);
-
/*
* Resolve all paths received as arguments, configuration option, or
* through environment variable as absolute paths. This is necessary
projects / lttng-tools.git / blobdiff