#include "agent.h"
#include "ht-cleanup.h"
#include "sessiond-config.h"
+#include "clear.h"
static const char *help_msg =
#ifdef LTTNG_EMBED_HELP
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 three (3) support threads are:
+ * - agent_thread
+ * - notification_thread
+ * - health_thread
*/
-#define NR_LTTNG_SESSIOND_READY 5
-int lttng_sessiond_ready = NR_LTTNG_SESSIOND_READY;
+int lttng_sessiond_ready = 3;
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)
+{
+ /*
+ * The _return variant is used since the implied memory barriers are
+ * required.
+ */
+ (void) uatomic_sub_return(<tng_sessiond_ready, 1);
+}
+
static
int __sessiond_set_thread_pollset(struct lttng_poll_event *events, size_t size,
int *a_pipe)
*/
utils_close_pipe(thread_quit_pipe);
- /*
- * If config.pid_file_path.value is undefined, the default file will be
- * wiped when removing the rundir.
- */
- if (config.pid_file_path.value) {
- ret = remove(config.pid_file_path.value);
- if (ret < 0) {
- PERROR("remove pidfile %s", config.pid_file_path.value);
- }
+ ret = remove(config.pid_file_path.value);
+ if (ret < 0) {
+ PERROR("remove pidfile %s", config.pid_file_path.value);
}
DBG("Removing sessiond and consumerd content of directory %s",
} else if (stat(INSTALL_BIN_PATH "/" DEFAULT_CONSUMERD_FILE, &st) == 0) {
DBG3("Found location #2");
consumer_to_use = INSTALL_BIN_PATH "/" DEFAULT_CONSUMERD_FILE;
- } else if (stat(config.consumerd32_bin_path.value, &st) == 0) {
+ } else if (config.consumerd32_bin_path.value &&
+ stat(config.consumerd32_bin_path.value, &st) == 0) {
DBG3("Found location #3");
consumer_to_use = config.consumerd32_bin_path.value;
} else {
case LTTNG_REGENERATE_STATEDUMP:
case LTTNG_REGISTER_TRIGGER:
case LTTNG_UNREGISTER_TRIGGER:
+ case LTTNG_CLEAR_SESSION:
need_domain = 0;
break;
default:
notification_thread_handle);
break;
}
+ case LTTNG_CLEAR_SESSION:
+ {
+ ret = cmd_clear_session(cmd_ctx->session);
+ if (ret != LTTNG_OK) {
+ goto error;
+ }
+ break;
+ }
default:
ret = LTTNG_ERR_UND;
break;
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)) {
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