-/*
- * 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)
-{
- int i, ret, pollfd, err = -1;
- ssize_t size_ret;
- uint32_t revents, nb_fd;
- struct lttng_poll_event events;
-
- DBG("[thread] Manage application started");
-
- rcu_register_thread();
- rcu_thread_online();
-
- health_register(health_sessiond, HEALTH_SESSIOND_TYPE_APP_MANAGE);
-
- if (testpoint(sessiond_thread_manage_apps)) {
- goto error_testpoint;
- }
-
- health_code_update();
-
- ret = sessiond_set_thread_pollset(&events, 2);
- if (ret < 0) {
- goto error_poll_create;
- }
-
- ret = lttng_poll_add(&events, apps_cmd_pipe[0], LPOLLIN | LPOLLRDHUP);
- if (ret < 0) {
- goto error;
- }
-
- if (testpoint(sessiond_thread_manage_apps_before_loop)) {
- goto error;
- }
-
- health_code_update();
-
- while (1) {
- DBG("Apps thread polling");
-
- /* Inifinite blocking call, waiting for transmission */
- restart:
- health_poll_entry();
- ret = lttng_poll_wait(&events, -1);
- DBG("Apps thread return from poll on %d fds",
- LTTNG_POLL_GETNB(&events));
- health_poll_exit();
- if (ret < 0) {
- /*
- * Restart interrupted system call.
- */
- if (errno == EINTR) {
- goto restart;
- }
- goto error;
- }
-
- nb_fd = ret;
-
- for (i = 0; i < nb_fd; i++) {
- /* Fetch once the poll data */
- revents = LTTNG_POLL_GETEV(&events, i);
- pollfd = LTTNG_POLL_GETFD(&events, i);
-
- health_code_update();
-
- if (!revents) {
- /* No activity for this FD (poll implementation). */
- continue;
- }
-
- /* Thread quit pipe has been closed. Killing thread. */
- ret = sessiond_check_thread_quit_pipe(pollfd, revents);
- if (ret) {
- err = 0;
- goto exit;
- }
-
- /* Inspect the apps cmd pipe */
- if (pollfd == apps_cmd_pipe[0]) {
- if (revents & LPOLLIN) {
- int sock;
-
- /* Empty pipe */
- size_ret = lttng_read(apps_cmd_pipe[0], &sock, sizeof(sock));
- if (size_ret < sizeof(sock)) {
- PERROR("read apps cmd pipe");
- goto error;
- }
-
- health_code_update();
-
- /*
- * Since this is a command socket (write then read),
- * we only monitor the error events of the socket.
- */
- ret = lttng_poll_add(&events, sock,
- LPOLLERR | LPOLLHUP | LPOLLRDHUP);
- if (ret < 0) {
- goto error;
- }
-
- DBG("Apps with sock %d added to poll set", sock);
- } else if (revents & (LPOLLERR | LPOLLHUP | LPOLLRDHUP)) {
- ERR("Apps command pipe error");
- goto error;
- } else {
- ERR("Unknown poll events %u for sock %d", revents, pollfd);
- goto error;
- }
- } else {
- /*
- * At this point, we know that a registered application made
- * the event at poll_wait.
- */
- if (revents & (LPOLLERR | LPOLLHUP | LPOLLRDHUP)) {
- /* Removing from the poll set */
- ret = lttng_poll_del(&events, pollfd);
- if (ret < 0) {
- goto error;
- }
-
- /* Socket closed on remote end. */
- ust_app_unregister(pollfd);
- } else {
- ERR("Unexpected poll events %u for sock %d", revents, pollfd);
- goto error;
- }
- }
-
- health_code_update();
- }
- }
-
-exit:
-error:
- lttng_poll_clean(&events);
-error_poll_create:
-error_testpoint:
- utils_close_pipe(apps_cmd_pipe);
- apps_cmd_pipe[0] = apps_cmd_pipe[1] = -1;
-
- /*
- * We don't clean the UST app hash table here since already registered
- * applications can still be controlled so let them be until the session
- * daemon dies or the applications stop.
- */
-
- if (err) {
- health_error();
- ERR("Health error occurred in %s", __func__);
- }
- health_unregister(health_sessiond);
- DBG("Application communication apps thread cleanup complete");
- rcu_thread_offline();
- rcu_unregister_thread();
- return NULL;
-}
-