Clean-up: use a define for support thread count
[lttng-tools.git] / src / bin / lttng-sessiond / main.c
index 968fec84a1d6bc80299cbbcd0aa2241de84f5012..f9b41d2707bd26aff4f95a72aa1885d2f2f09280 100644 (file)
 #include "load-session-thread.h"
 #include "notification-thread.h"
 #include "notification-thread-commands.h"
-#include "syscall.h"
+#include "rotation-thread.h"
+#include "lttng-syscall.h"
 #include "agent.h"
 #include "ht-cleanup.h"
 #include "sessiond-config.h"
+#include "sessiond-timer.h"
 
 static const char *help_msg =
 #ifdef LTTNG_EMBED_HELP
@@ -94,6 +96,9 @@ static int lockfile_fd = -1;
 /* Set to 1 when a SIGUSR1 signal is received. */
 static int recv_child_signal;
 
+static struct lttng_kernel_tracer_version kernel_tracer_version;
+static struct lttng_kernel_tracer_abi_version kernel_tracer_abi_version;
+
 /*
  * Consumer daemon specific control data. Every value not initialized here is
  * set to 0 by the static definition.
@@ -103,6 +108,7 @@ static struct consumer_data kconsumer_data = {
        .err_sock = -1,
        .cmd_sock = -1,
        .channel_monitor_pipe = -1,
+       .channel_rotate_pipe = -1,
        .pid_mutex = PTHREAD_MUTEX_INITIALIZER,
        .lock = PTHREAD_MUTEX_INITIALIZER,
        .cond = PTHREAD_COND_INITIALIZER,
@@ -113,6 +119,7 @@ static struct consumer_data ustconsumer64_data = {
        .err_sock = -1,
        .cmd_sock = -1,
        .channel_monitor_pipe = -1,
+       .channel_rotate_pipe = -1,
        .pid_mutex = PTHREAD_MUTEX_INITIALIZER,
        .lock = PTHREAD_MUTEX_INITIALIZER,
        .cond = PTHREAD_COND_INITIALIZER,
@@ -123,6 +130,7 @@ static struct consumer_data ustconsumer32_data = {
        .err_sock = -1,
        .cmd_sock = -1,
        .channel_monitor_pipe = -1,
+       .channel_rotate_pipe = -1,
        .pid_mutex = PTHREAD_MUTEX_INITIALIZER,
        .lock = PTHREAD_MUTEX_INITIALIZER,
        .cond = PTHREAD_COND_INITIALIZER,
@@ -202,6 +210,8 @@ static pthread_t ht_cleanup_thread;
 static pthread_t agent_reg_thread;
 static pthread_t load_session_thread;
 static pthread_t notification_thread;
+static pthread_t rotation_thread;
+static pthread_t timer_thread;
 
 /*
  * UST registration command queue. This queue is tied with a futex and uses a N
@@ -282,17 +292,48 @@ struct load_session_thread_data *load_info;
 /* Notification thread handle. */
 struct notification_thread_handle *notification_thread_handle;
 
+/* Rotation thread handle. */
+struct rotation_thread_handle *rotation_thread_handle;
+
 /* Global hash tables */
 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                4
-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)
 {
@@ -301,28 +342,36 @@ 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(&lttng_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(&lttng_sessiond_ready, 1);
+}
+
 static
 int __sessiond_set_thread_pollset(struct lttng_poll_event *events, size_t size,
                int *a_pipe)
@@ -468,6 +517,24 @@ static void close_consumer_sockets(void)
                        PERROR("UST consumerd64 channel monitor pipe close");
                }
        }
+       if (kconsumer_data.channel_rotate_pipe >= 0) {
+               ret = close(kconsumer_data.channel_rotate_pipe);
+               if (ret < 0) {
+                       PERROR("kernel consumer channel rotate pipe close");
+               }
+       }
+       if (ustconsumer32_data.channel_rotate_pipe >= 0) {
+               ret = close(ustconsumer32_data.channel_rotate_pipe);
+               if (ret < 0) {
+                       PERROR("UST consumerd32 channel rotate pipe close");
+               }
+       }
+       if (ustconsumer64_data.channel_rotate_pipe >= 0) {
+               ret = close(ustconsumer64_data.channel_rotate_pipe);
+               if (ret < 0) {
+                       PERROR("UST consumerd64 channel rotate pipe close");
+               }
+       }
 }
 
 /*
@@ -564,7 +631,8 @@ static void sessiond_cleanup(void)
                /* Cleanup ALL session */
                cds_list_for_each_entry_safe(sess, stmp,
                                &session_list_ptr->head, list) {
-                       cmd_destroy_session(sess, kernel_poll_pipe[1]);
+                       cmd_destroy_session(sess, kernel_poll_pipe[1],
+                                       notification_thread_handle);
                }
        }
 
@@ -599,21 +667,6 @@ static void sessiond_cleanup(void)
                free(load_info);
        }
 
-       /*
-        * Cleanup lock file by deleting it and finaly closing it which will
-        * release the file system lock.
-        */
-       if (lockfile_fd >= 0) {
-               ret = remove(config.lock_file_path.value);
-               if (ret < 0) {
-                       PERROR("remove lock file");
-               }
-               ret = close(lockfile_fd);
-               if (ret < 0) {
-                       PERROR("close lock file");
-               }
-       }
-
        /*
         * We do NOT rmdir rundir because there are other processes
         * using it, for instance lttng-relayd, which can start in
@@ -843,7 +896,7 @@ static int update_kernel_stream(struct consumer_data *consumer_data, int fd)
                        cds_lfht_for_each_entry(ksess->consumer->socks->ht,
                                        &iter.iter, socket, node.node) {
                                pthread_mutex_lock(socket->lock);
-                               ret = kernel_consumer_send_channel_stream(socket,
+                               ret = kernel_consumer_send_channel_streams(socket,
                                                channel, ksess,
                                                session->output_traces ? 1 : 0);
                                pthread_mutex_unlock(socket->lock);
@@ -1263,19 +1316,28 @@ restart:
        health_code_update();
 
        /*
-        * Transfer the write-end of the channel monitoring pipe to the
-        * by issuing a SET_CHANNEL_MONITOR_PIPE command.
+        * Transfer the write-end of the channel monitoring and rotate pipe
+        * to the consumer by issuing a SET_CHANNEL_MONITOR_PIPE and
+        * SET_CHANNEL_ROTATE_PIPE commands.
         */
        cmd_socket_wrapper = consumer_allocate_socket(&consumer_data->cmd_sock);
        if (!cmd_socket_wrapper) {
                goto error;
        }
+       cmd_socket_wrapper->lock = &consumer_data->lock;
 
        ret = consumer_send_channel_monitor_pipe(cmd_socket_wrapper,
                        consumer_data->channel_monitor_pipe);
        if (ret) {
                goto error;
        }
+
+       ret = consumer_send_channel_rotate_pipe(cmd_socket_wrapper,
+                       consumer_data->channel_rotate_pipe);
+       if (ret) {
+               goto error;
+       }
+
        /* Discard the socket wrapper as it is no longer needed. */
        consumer_destroy_socket(cmd_socket_wrapper);
        cmd_socket_wrapper = NULL;
@@ -1445,7 +1507,17 @@ error_poll:
 }
 
 /*
- * This thread manage application communication.
+ * This thread receives application command sockets (FDs) on the
+ * apps_cmd_pipe and waits (polls) on them until they are closed
+ * or an error occurs.
+ *
+ * At that point, it flushes the data (tracing and metadata) associated
+ * with this application and tears down ust app sessions and other
+ * associated data structures through ust_app_unregister().
+ *
+ * Note that this thread never sends commands to the applications
+ * through the command sockets; it merely listens for hang-ups
+ * and errors on those sockets and cleans-up as they occur.
  */
 static void *thread_manage_apps(void *data)
 {
@@ -2440,33 +2512,30 @@ static pid_t spawn_consumerd(struct consumer_data *consumer_data)
                        break;
                case LTTNG_CONSUMER64_UST:
                {
-                       char *tmpnew = NULL;
-
                        if (config.consumerd64_lib_dir.value) {
                                char *tmp;
                                size_t tmplen;
+                               char *tmpnew;
 
                                tmp = lttng_secure_getenv("LD_LIBRARY_PATH");
                                if (!tmp) {
                                        tmp = "";
                                }
-                               tmplen = strlen("LD_LIBRARY_PATH=")
-                                       + strlen(config.consumerd64_lib_dir.value) + 1 /* : */ + strlen(tmp);
+                               tmplen = strlen(config.consumerd64_lib_dir.value) + 1 /* : */ + strlen(tmp);
                                tmpnew = zmalloc(tmplen + 1 /* \0 */);
                                if (!tmpnew) {
                                        ret = -ENOMEM;
                                        goto error;
                                }
-                               strcpy(tmpnew, "LD_LIBRARY_PATH=");
                                strcat(tmpnew, config.consumerd64_lib_dir.value);
                                if (tmp[0] != '\0') {
                                        strcat(tmpnew, ":");
                                        strcat(tmpnew, tmp);
                                }
-                               ret = putenv(tmpnew);
+                               ret = setenv("LD_LIBRARY_PATH", tmpnew, 1);
+                               free(tmpnew);
                                if (ret) {
                                        ret = -errno;
-                                       free(tmpnew);
                                        goto error;
                                }
                        }
@@ -2476,38 +2545,34 @@ static pid_t spawn_consumerd(struct consumer_data *consumer_data)
                                        "--consumerd-err-sock", consumer_data->err_unix_sock_path,
                                        "--group", config.tracing_group_name.value,
                                        NULL);
-                       free(tmpnew);
                        break;
                }
                case LTTNG_CONSUMER32_UST:
                {
-                       char *tmpnew = NULL;
-
                        if (config.consumerd32_lib_dir.value) {
                                char *tmp;
                                size_t tmplen;
+                               char *tmpnew;
 
                                tmp = lttng_secure_getenv("LD_LIBRARY_PATH");
                                if (!tmp) {
                                        tmp = "";
                                }
-                               tmplen = strlen("LD_LIBRARY_PATH=")
-                                       + strlen(config.consumerd32_lib_dir.value) + 1 /* : */ + strlen(tmp);
+                               tmplen = strlen(config.consumerd32_lib_dir.value) + 1 /* : */ + strlen(tmp);
                                tmpnew = zmalloc(tmplen + 1 /* \0 */);
                                if (!tmpnew) {
                                        ret = -ENOMEM;
                                        goto error;
                                }
-                               strcpy(tmpnew, "LD_LIBRARY_PATH=");
                                strcat(tmpnew, config.consumerd32_lib_dir.value);
                                if (tmp[0] != '\0') {
                                        strcat(tmpnew, ":");
                                        strcat(tmpnew, tmp);
                                }
-                               ret = putenv(tmpnew);
+                               ret = setenv("LD_LIBRARY_PATH", tmpnew, 1);
+                               free(tmpnew);
                                if (ret) {
                                        ret = -errno;
-                                       free(tmpnew);
                                        goto error;
                                }
                        }
@@ -2517,7 +2582,6 @@ static pid_t spawn_consumerd(struct consumer_data *consumer_data)
                                        "--consumerd-err-sock", consumer_data->err_unix_sock_path,
                                        "--group", config.tracing_group_name.value,
                                        NULL);
-                       free(tmpnew);
                        break;
                }
                default:
@@ -2618,7 +2682,8 @@ static int init_kernel_tracer(void)
        }
 
        /* Validate kernel version */
-       ret = kernel_validate_version(kernel_tracer_fd);
+       ret = kernel_validate_version(kernel_tracer_fd, &kernel_tracer_version,
+                       &kernel_tracer_abi_version);
        if (ret < 0) {
                goto error_version;
        }
@@ -2825,20 +2890,6 @@ static int create_kernel_session(struct ltt_session *session)
                goto error;
        }
 
-       /* Create directory(ies) on local filesystem. */
-       if (session->kernel_session->consumer->type == CONSUMER_DST_LOCAL &&
-                       strlen(session->kernel_session->consumer->dst.trace_path) > 0) {
-               ret = run_as_mkdir_recursive(
-                               session->kernel_session->consumer->dst.trace_path,
-                               S_IRWXU | S_IRWXG, session->uid, session->gid);
-               if (ret < 0) {
-                       if (errno != EEXIST) {
-                               ERR("Trace directory creation error");
-                               goto error;
-                       }
-               }
-       }
-
        session->kernel_session->uid = session->uid;
        session->kernel_session->gid = session->gid;
        session->kernel_session->output_traces = session->output_traces;
@@ -2874,6 +2925,22 @@ static unsigned int lttng_sessions_count(uid_t uid, gid_t gid)
        return i;
 }
 
+/*
+ * Check if the current kernel tracer supports the session rotation feature.
+ * Return 1 if it does, 0 otherwise.
+ */
+static int check_rotate_compatible(void)
+{
+       int ret = 1;
+
+       if (kernel_tracer_version.major != 2 || kernel_tracer_version.minor < 11) {
+               DBG("Kernel tracer version is not compatible with the rotation feature");
+               ret = 0;
+       }
+
+       return ret;
+}
+
 /*
  * Process the command requested by the lttng client within the command
  * context structure. This function make sure that the return structure (llm)
@@ -2918,6 +2985,12 @@ static int process_client_msg(struct command_ctx *cmd_ctx, int sock,
        case LTTNG_REGENERATE_STATEDUMP:
        case LTTNG_REGISTER_TRIGGER:
        case LTTNG_UNREGISTER_TRIGGER:
+       case LTTNG_ROTATE_SESSION:
+       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:
                need_domain = 0;
                break;
        default:
@@ -2960,6 +3033,10 @@ static int process_client_msg(struct command_ctx *cmd_ctx, int sock,
        case LTTNG_LIST_SYSCALLS:
        case LTTNG_LIST_TRACKER_PIDS:
        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:
                break;
        default:
                /* Setup lttng message with no payload */
@@ -3651,6 +3728,20 @@ error_add_context:
        }
        case LTTNG_START_TRACE:
        {
+               /*
+                * On the first start, if we have a kernel session and we have
+                * enabled time or size-based rotations, we have to make sure
+                * the kernel tracer supports it.
+                */
+               if (!cmd_ctx->session->has_been_started && \
+                               cmd_ctx->session->kernel_session && \
+                               (cmd_ctx->session->rotate_timer_period || \
+                                       cmd_ctx->session->rotate_size) && \
+                               !check_rotate_compatible()) {
+                       DBG("Kernel tracer version is not compatible with the rotation feature");
+                       ret = LTTNG_ERR_ROTATION_WRONG_VERSION;
+                       goto error;
+               }
                ret = cmd_start_trace(cmd_ctx->session);
                break;
        }
@@ -3702,7 +3793,8 @@ error_add_context:
        }
        case LTTNG_DESTROY_SESSION:
        {
-               ret = cmd_destroy_session(cmd_ctx->session, kernel_poll_pipe[1]);
+               ret = cmd_destroy_session(cmd_ctx->session, kernel_poll_pipe[1],
+                               notification_thread_handle);
 
                /* Set session to NULL so we do not unlock it after free. */
                cmd_ctx->session = NULL;
@@ -4048,6 +4140,141 @@ error_add_context:
                                notification_thread_handle);
                break;
        }
+       case LTTNG_ROTATE_SESSION:
+       {
+               struct lttng_rotate_session_return rotate_return;
+
+               DBG("Client rotate session \"%s\"", cmd_ctx->session->name);
+
+               memset(&rotate_return, 0, sizeof(rotate_return));
+               if (cmd_ctx->session->kernel_session && !check_rotate_compatible()) {
+                       DBG("Kernel tracer version is not compatible with the rotation feature");
+                       ret = LTTNG_ERR_ROTATION_WRONG_VERSION;
+                       goto error;
+               }
+
+               ret = cmd_rotate_session(cmd_ctx->session, &rotate_return);
+               if (ret < 0) {
+                       ret = -ret;
+                       goto error;
+               }
+
+               ret = setup_lttng_msg_no_cmd_header(cmd_ctx, &rotate_return,
+                               sizeof(rotate_return));
+               if (ret < 0) {
+                       ret = -ret;
+                       goto error;
+               }
+
+               ret = LTTNG_OK;
+               break;
+       }
+       case LTTNG_ROTATION_GET_INFO:
+       {
+               struct lttng_rotation_get_info_return get_info_return;
+
+               memset(&get_info_return, 0, sizeof(get_info_return));
+               ret = cmd_rotate_get_info(cmd_ctx->session, &get_info_return,
+                               cmd_ctx->lsm->u.get_rotation_info.rotation_id);
+               if (ret < 0) {
+                       ret = -ret;
+                       goto error;
+               }
+
+               ret = setup_lttng_msg_no_cmd_header(cmd_ctx, &get_info_return,
+                               sizeof(get_info_return));
+               if (ret < 0) {
+                       ret = -ret;
+                       goto error;
+               }
+
+               ret = LTTNG_OK;
+               break;
+       }
+       case LTTNG_SESSION_GET_CURRENT_OUTPUT:
+       {
+               struct lttng_session_get_current_output_return output_return;
+
+               memset(&output_return, 0, sizeof(output_return));
+               ret = cmd_session_get_current_output(cmd_ctx->session,
+                               &output_return);
+               if (ret < 0) {
+                       ret = -ret;
+                       goto error;
+               }
+
+               ret = setup_lttng_msg_no_cmd_header(cmd_ctx, &output_return,
+                               sizeof(output_return));
+               if (ret < 0) {
+                       ret = -ret;
+                       goto error;
+               }
+
+               ret = LTTNG_OK;
+               break;
+       }
+       case LTTNG_ROTATION_SET_SCHEDULE:
+       {
+               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;
+               }
+
+               ret = cmd_rotation_set_schedule(cmd_ctx->session,
+                               cmd_ctx->lsm->u.rotate_setup.timer_us,
+                               cmd_ctx->lsm->u.rotate_setup.size,
+                               notification_thread_handle);
+               if (ret != LTTNG_OK) {
+                       goto error;
+               }
+
+               break;
+       }
+       case LTTNG_ROTATION_SCHEDULE_GET_TIMER_PERIOD:
+       {
+               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);
+               if (ret < 0) {
+                       ret = -ret;
+                       goto error;
+               }
+
+               ret = LTTNG_OK;
+               break;
+       }
        default:
                ret = LTTNG_ERR_UND;
                break;
@@ -4304,13 +4531,41 @@ static void *thread_manage_clients(void *data)
                goto error;
        }
 
-       sessiond_notify_ready();
        ret = sem_post(&load_info->message_thread_ready);
        if (ret) {
                PERROR("sem_post message_thread_ready");
                goto error;
        }
 
+       /*
+        * Wait until all support threads are initialized before accepting
+        * commands.
+        */
+       while (uatomic_read(&lttng_sessiond_ready) != 0) {
+               fd_set read_fds;
+               struct timeval timeout;
+
+               FD_ZERO(&read_fds);
+               FD_SET(thread_quit_pipe[0], &read_fds);
+               memset(&timeout, 0, sizeof(timeout));
+               timeout.tv_usec = 1000;
+
+               /*
+                * If a support thread failed to launch, it may signal that
+                * we must exit and the sessiond would never be marked as
+                * "ready".
+                *
+                * The timeout is set to 1ms, which serves as a way to
+                * pace down this check.
+                */
+               ret = select(thread_quit_pipe[0] + 1, &read_fds, NULL, NULL,
+                               &timeout);
+               if (ret > 0 || (ret < 0 && errno != EINTR)) {
+                       goto exit;
+               }
+               cmm_smp_rmb();
+       }
+
        /* This testpoint is after we signal readiness to the parent. */
        if (testpoint(sessiond_thread_manage_clients)) {
                goto error;
@@ -4723,7 +4978,7 @@ static int set_option(int opt, const char *arg, const char *optname)
        } else if (string_match(optname, "no-kernel")) {
                config.no_kernel = true;
        } else if (string_match(optname, "quiet") || opt == 'q') {
-               lttng_opt_quiet = true;
+               config.quiet = true;
        } else if (string_match(optname, "verbose") || opt == 'v') {
                /* Verbose level can increase using multiple -v */
                if (arg) {
@@ -4842,8 +5097,8 @@ static int set_option(int opt, const char *arg, const char *optname)
                                ERR("Port overflow in --agent-tcp-port parameter: %s", arg);
                                return -1;
                        }
-                       config.agent_tcp_port = (uint32_t) v;
-                       DBG3("Agent TCP port set to non default: %u", config.agent_tcp_port);
+                       config.agent_tcp_port.begin = config.agent_tcp_port.end = (int) v;
+                       DBG3("Agent TCP port set to non default: %i", (int) v);
                }
        } else if (string_match(optname, "load") || opt == 'l') {
                if (!arg || *arg == '\0') {
@@ -5126,18 +5381,57 @@ end:
        return ret;
 }
 
+/*
+ * Create lockfile using the rundir and return its fd.
+ */
+static int create_lockfile(void)
+{
+        return utils_create_lock_file(config.lock_file_path.value);
+}
+
 /*
  * Check if the global socket is available, and if a daemon is answering at the
  * other side. If yes, error is returned.
+ *
+ * Also attempts to create and hold the lock file.
  */
 static int check_existing_daemon(void)
 {
+       int ret = 0;
+
        /* Is there anybody out there ? */
        if (lttng_session_daemon_alive()) {
-               return -EEXIST;
+               ret = -EEXIST;
+               goto end;
        }
 
-       return 0;
+       lockfile_fd = create_lockfile();
+       if (lockfile_fd < 0) {
+               ret = -EEXIST;
+               goto end;
+       }
+end:
+       return ret;
+}
+
+static void sessiond_cleanup_lock_file(void)
+{
+       int ret;
+
+       /*
+        * Cleanup lock file by deleting it and finaly closing it which will
+        * release the file system lock.
+        */
+       if (lockfile_fd >= 0) {
+               ret = remove(config.lock_file_path.value);
+               if (ret < 0) {
+                       PERROR("remove lock file");
+               }
+               ret = close(lockfile_fd);
+               if (ret < 0) {
+                       PERROR("close lock file");
+               }
+       }
 }
 
 /*
@@ -5396,23 +5690,6 @@ static int write_pidfile(void)
         return utils_create_pid_file(getpid(), config.pid_file_path.value);
 }
 
-/*
- * Create lockfile using the rundir and return its fd.
- */
-static int create_lockfile(void)
-{
-        return utils_create_lock_file(config.lock_file_path.value);
-}
-
-/*
- * Write agent TCP port using the rundir.
- */
-static int write_agent_port(void)
-{
-       return utils_create_pid_file(config.agent_tcp_port,
-                       config.agent_port_file_path.value);
-}
-
 static int set_clock_plugin_env(void)
 {
        int ret = 0;
@@ -5442,6 +5719,48 @@ end:
        return ret;
 }
 
+static
+struct rotation_thread_timer_queue *create_rotate_timer_queue(void)
+{
+       struct rotation_thread_timer_queue *queue = NULL;
+
+       queue = zmalloc(sizeof(struct rotation_thread_timer_queue));
+       if (!queue) {
+               PERROR("Failed to allocate timer rotate queue");
+               goto end;
+       }
+
+       queue->event_pipe = lttng_pipe_open(FD_CLOEXEC | O_NONBLOCK);
+       CDS_INIT_LIST_HEAD(&queue->list);
+       pthread_mutex_init(&queue->lock, NULL);
+
+end:
+       return queue;
+}
+
+static
+void destroy_rotate_timer_queue(struct rotation_thread_timer_queue *queue)
+{
+       struct sessiond_rotation_timer *node, *tmp_node;
+
+       if (!queue) {
+               return;
+       }
+
+       lttng_pipe_destroy(queue->event_pipe);
+
+       pthread_mutex_lock(&queue->lock);
+       /* Empty wait queue. */
+       cds_list_for_each_entry_safe(node, tmp_node, &queue->list, head) {
+               cds_list_del(&node->head);
+               free(node);
+       }
+       pthread_mutex_unlock(&queue->lock);
+
+       pthread_mutex_destroy(&queue->lock);
+       free(queue);
+}
+
 /*
  * main
  */
@@ -5453,7 +5772,16 @@ int main(int argc, char **argv)
        struct lttng_pipe *ust32_channel_monitor_pipe = NULL,
                        *ust64_channel_monitor_pipe = NULL,
                        *kernel_channel_monitor_pipe = NULL;
-       bool notification_thread_running = false;
+       bool notification_thread_launched = false;
+       bool rotation_thread_launched = false;
+       bool timer_thread_launched = false;
+       struct lttng_pipe *ust32_channel_rotate_pipe = NULL,
+                       *ust64_channel_rotate_pipe = NULL,
+                       *kernel_channel_rotate_pipe = NULL;
+       struct timer_thread_parameters timer_thread_ctx;
+       /* Queue of rotation jobs populated by the sessiond-timer. */
+       struct rotation_thread_timer_queue *rotation_timer_queue = NULL;
+       sem_t notification_thread_ready;
 
        init_kernel_workarounds();
 
@@ -5464,6 +5792,11 @@ int main(int argc, char **argv)
                goto exit_set_signal_handler;
        }
 
+       if (sessiond_timer_signal_init()) {
+               retval = -1;
+               goto exit_set_signal_handler;
+       }
+
        page_size = sysconf(_SC_PAGESIZE);
        if (page_size < 0) {
                PERROR("sysconf _SC_PAGESIZE");
@@ -5524,6 +5857,18 @@ int main(int argc, char **argv)
 
        sessiond_config_log(&config);
 
+       if (create_lttng_rundir()) {
+               retval = -1;
+               goto exit_options;
+       }
+
+       /* Abort launch if a session daemon is already running. */
+       if (check_existing_daemon()) {
+               ERR("A session daemon is already running.");
+               retval = -1;
+               goto exit_options;
+       }
+
        /* Daemonize */
        if (config.daemonize || config.background) {
                int i;
@@ -5538,9 +5883,12 @@ int main(int argc, char **argv)
                /*
                 * We are in the child. Make sure all other file descriptors are
                 * closed, in case we are called with more opened file
-                * descriptors than the standard ones.
+                * descriptors than the standard ones and the lock file.
                 */
                for (i = 3; i < sysconf(_SC_OPEN_MAX); i++) {
+                       if (i == lockfile_fd) {
+                               continue;
+                       }
                        (void) close(i);
                }
        }
@@ -5579,12 +5927,6 @@ int main(int argc, char **argv)
 
        /* Check if daemon is UID = 0 */
        is_root = !getuid();
-
-       if (create_lttng_rundir()) {
-               retval = -1;
-               goto exit_init_data;
-       }
-
        if (is_root) {
                /* Create global run dir with root access */
 
@@ -5601,12 +5943,19 @@ int main(int argc, char **argv)
                        retval = -1;
                        goto exit_init_data;
                }
-       }
-
-       lockfile_fd = create_lockfile();
-       if (lockfile_fd < 0) {
-               retval = -1;
-               goto exit_init_data;
+               kernel_channel_rotate_pipe = lttng_pipe_open(0);
+               if (!kernel_channel_rotate_pipe) {
+                       ERR("Failed to create kernel consumer channel rotate pipe");
+                       retval = -1;
+                       goto exit_init_data;
+               }
+               kconsumer_data.channel_rotate_pipe =
+                               lttng_pipe_release_writefd(
+                                       kernel_channel_rotate_pipe);
+               if (kconsumer_data.channel_rotate_pipe < 0) {
+                       retval = -1;
+                       goto exit_init_data;
+               }
        }
 
        /* Set consumer initial state */
@@ -5625,6 +5974,30 @@ int main(int argc, char **argv)
                retval = -1;
                goto exit_init_data;
        }
+       ust32_channel_rotate_pipe = lttng_pipe_open(0);
+       if (!ust32_channel_rotate_pipe) {
+               ERR("Failed to create 32-bit user space consumer channel rotate pipe");
+               retval = -1;
+               goto exit_init_data;
+       }
+       ustconsumer32_data.channel_rotate_pipe = lttng_pipe_release_writefd(
+                       ust32_channel_rotate_pipe);
+       if (ustconsumer32_data.channel_rotate_pipe < 0) {
+               retval = -1;
+               goto exit_init_data;
+       }
+
+       /*
+        * The rotation_timer_queue structure is shared between the sessiond timer
+        * thread and the rotation thread. The main() keeps the ownership and
+        * destroys it when both threads have quit.
+        */
+       rotation_timer_queue = create_rotate_timer_queue();
+       if (!rotation_timer_queue) {
+               retval = -1;
+               goto exit_init_data;
+       }
+       timer_thread_ctx.rotation_timer_queue = rotation_timer_queue;
 
        ust64_channel_monitor_pipe = lttng_pipe_open(0);
        if (!ust64_channel_monitor_pipe) {
@@ -5638,16 +6011,15 @@ int main(int argc, char **argv)
                retval = -1;
                goto exit_init_data;
        }
-
-       /*
-        * See if daemon already exist.
-        */
-       if (check_existing_daemon()) {
-               ERR("Already running daemon.\n");
-               /*
-                * We do not goto exit because we must not cleanup()
-                * because a daemon is already running.
-                */
+       ust64_channel_rotate_pipe = lttng_pipe_open(0);
+       if (!ust64_channel_rotate_pipe) {
+               ERR("Failed to create 64-bit user space consumer channel rotate pipe");
+               retval = -1;
+               goto exit_init_data;
+       }
+       ustconsumer64_data.channel_rotate_pipe = lttng_pipe_release_writefd(
+                       ust64_channel_rotate_pipe);
+       if (ustconsumer64_data.channel_rotate_pipe < 0) {
                retval = -1;
                goto exit_init_data;
        }
@@ -5779,12 +6151,6 @@ int main(int argc, char **argv)
                retval = -1;
                goto exit_init_data;
        }
-       ret = write_agent_port();
-       if (ret) {
-               ERR("Error in write_agent_port");
-               retval = -1;
-               goto exit_init_data;
-       }
 
        /* Initialize communication library */
        lttcomm_init();
@@ -5807,11 +6173,19 @@ int main(int argc, char **argv)
                goto exit_health;
        }
 
+       /*
+        * The rotation thread needs the notification thread to be ready before
+        * creating the rotate_notification_channel, so we use this semaphore as
+        * a rendez-vous point.
+        */
+       sem_init(&notification_thread_ready, 0, 0);
+
        /* notification_thread_data acquires the pipes' read side. */
        notification_thread_handle = notification_thread_handle_create(
                        ust32_channel_monitor_pipe,
                        ust64_channel_monitor_pipe,
-                       kernel_channel_monitor_pipe);
+                       kernel_channel_monitor_pipe,
+                       &notification_thread_ready);
        if (!notification_thread_handle) {
                retval = -1;
                ERR("Failed to create notification thread shared data");
@@ -5829,7 +6203,47 @@ int main(int argc, char **argv)
                stop_threads();
                goto exit_notification;
        }
-       notification_thread_running = true;
+       notification_thread_launched = true;
+
+       /* Create timer thread. */
+       ret = pthread_create(&timer_thread, default_pthread_attr(),
+                       sessiond_timer_thread, &timer_thread_ctx);
+       if (ret) {
+               errno = ret;
+               PERROR("pthread_create timer");
+               retval = -1;
+               stop_threads();
+               goto exit_notification;
+       }
+       timer_thread_launched = true;
+
+       /* rotation_thread_data acquires the pipes' read side. */
+       rotation_thread_handle = rotation_thread_handle_create(
+                       ust32_channel_rotate_pipe,
+                       ust64_channel_rotate_pipe,
+                       kernel_channel_rotate_pipe,
+                       thread_quit_pipe[0],
+                       rotation_timer_queue,
+                       notification_thread_handle,
+                       &notification_thread_ready);
+       if (!rotation_thread_handle) {
+               retval = -1;
+               ERR("Failed to create rotation thread shared data");
+               stop_threads();
+               goto exit_rotation;
+       }
+
+       /* Create rotation thread. */
+       ret = pthread_create(&rotation_thread, default_pthread_attr(),
+                       thread_rotation, rotation_thread_handle);
+       if (ret) {
+               errno = ret;
+               PERROR("pthread_create rotation");
+               retval = -1;
+               stop_threads();
+               goto exit_rotation;
+       }
+       rotation_thread_launched = true;
 
        /* Create thread to manage the client socket */
        ret = pthread_create(&client_thread, default_pthread_attr(),
@@ -5997,7 +6411,9 @@ exit_dispatch:
        }
 
 exit_client:
+exit_rotation:
 exit_notification:
+       sem_destroy(&notification_thread_ready);
        ret = pthread_join(health_thread, &status);
        if (ret) {
                errno = ret;
@@ -6033,7 +6449,7 @@ exit_init_data:
         * of the active session and channels at the moment of the teardown.
         */
        if (notification_thread_handle) {
-               if (notification_thread_running) {
+               if (notification_thread_launched) {
                        notification_thread_command_quit(
                                        notification_thread_handle);
                        ret = pthread_join(notification_thread, &status);
@@ -6046,6 +6462,34 @@ exit_init_data:
                notification_thread_handle_destroy(notification_thread_handle);
        }
 
+       if (rotation_thread_handle) {
+               if (rotation_thread_launched) {
+                       ret = pthread_join(rotation_thread, &status);
+                       if (ret) {
+                               errno = ret;
+                               PERROR("pthread_join rotation thread");
+                               retval = -1;
+                       }
+               }
+               rotation_thread_handle_destroy(rotation_thread_handle);
+       }
+
+       if (timer_thread_launched) {
+               kill(getpid(), LTTNG_SESSIOND_SIG_EXIT);
+               ret = pthread_join(timer_thread, &status);
+               if (ret) {
+                       errno = ret;
+                       PERROR("pthread_join timer thread");
+                       retval = -1;
+               }
+       }
+
+       /*
+        * After the rotation and timer thread have quit, we can safely destroy
+        * the rotation_timer_queue.
+        */
+       destroy_rotate_timer_queue(rotation_timer_queue);
+
        rcu_thread_offline();
        rcu_unregister_thread();
 
@@ -6056,6 +6500,9 @@ exit_init_data:
        lttng_pipe_destroy(ust32_channel_monitor_pipe);
        lttng_pipe_destroy(ust64_channel_monitor_pipe);
        lttng_pipe_destroy(kernel_channel_monitor_pipe);
+       lttng_pipe_destroy(ust32_channel_rotate_pipe);
+       lttng_pipe_destroy(ust64_channel_rotate_pipe);
+       lttng_pipe_destroy(kernel_channel_rotate_pipe);
 exit_ht_cleanup:
 
        health_app_destroy(health_sessiond);
@@ -6063,6 +6510,7 @@ exit_health_sessiond_cleanup:
 exit_create_run_as_worker_cleanup:
 
 exit_options:
+       sessiond_cleanup_lock_file();
        sessiond_cleanup_options();
 
 exit_set_signal_handler:
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