src/bin/lttng-sessiond/notify-apps.cpp

   1 /*
   2  * Copyright (C) 2013 David Goulet <dgoulet@efficios.com>
   3  *
   4  * SPDX-License-Identifier: GPL-2.0-only
   5  *
   6  */
   7
   8 #define _LGPL_SOURCE
   9
  10 #include <common/common.hpp>
  11 #include <common/utils.hpp>
  12
  13 #include "fd-limit.hpp"
  14 #include "lttng-sessiond.hpp"
  15 #include "notify-apps.hpp"
  16 #include "health-sessiond.hpp"
  17 #include "testpoint.hpp"
  18 #include "utils.hpp"
  19 #include "thread.hpp"
  20
  21 namespace {
  22 struct thread_notifiers {
  23         struct lttng_pipe *quit_pipe;
  24         int apps_cmd_notify_pipe_read_fd;
  25 };
  26 } /* namespace */
  27
  28 /*
  29  * This thread manage application notify communication.
  30  */
  31 static void *thread_application_notification(void *data)
  32 {
  33         int i, ret, pollfd, err = -1;
  34         ssize_t size_ret;
  35         uint32_t revents, nb_fd;
  36         struct lttng_poll_event events;
  37         struct thread_notifiers *notifiers = (thread_notifiers *) data;
  38         const int quit_pipe_read_fd = lttng_pipe_get_readfd(notifiers->quit_pipe);
  39
  40         DBG("[ust-thread] Manage application notify command");
  41
  42         rcu_register_thread();
  43         rcu_thread_online();
  44
  45         health_register(the_health_sessiond,
  46                         HEALTH_SESSIOND_TYPE_APP_MANAGE_NOTIFY);
  47
  48         if (testpoint(sessiond_thread_app_manage_notify)) {
  49                 goto error_testpoint;
  50         }
  51
  52         health_code_update();
  53
  54         ret = lttng_poll_create(&events, 2, LTTNG_CLOEXEC);
  55         if (ret < 0) {
  56                 goto error_poll_create;
  57         }
  58
  59         /* Add notify pipe to the pollset. */
  60         ret = lttng_poll_add(&events, notifiers->apps_cmd_notify_pipe_read_fd,
  61                         LPOLLIN | LPOLLERR | LPOLLHUP | LPOLLRDHUP);
  62         if (ret < 0) {
  63                 goto error;
  64         }
  65
  66         ret = lttng_poll_add(&events, quit_pipe_read_fd,
  67                         LPOLLIN | LPOLLERR);
  68         if (ret < 0) {
  69                 goto error;
  70         }
  71
  72         health_code_update();
  73
  74         while (1) {
  75                 DBG3("[ust-thread] Manage notify polling");
  76
  77                 /* Inifinite blocking call, waiting for transmission */
  78 restart:
  79                 health_poll_entry();
  80                 ret = lttng_poll_wait(&events, -1);
  81                 DBG3("[ust-thread] Manage notify return from poll on %d fds",
  82                                 LTTNG_POLL_GETNB(&events));
  83                 health_poll_exit();
  84                 if (ret < 0) {
  85                         /*
  86                          * Restart interrupted system call.
  87                          */
  88                         if (errno == EINTR) {
  89                                 goto restart;
  90                         }
  91                         goto error;
  92                 }
  93
  94                 nb_fd = ret;
  95
  96                 for (i = 0; i < nb_fd; i++) {
  97                         health_code_update();
  98
  99                         /* Fetch once the poll data */
 100                         revents = LTTNG_POLL_GETEV(&events, i);
 101                         pollfd = LTTNG_POLL_GETFD(&events, i);
 102
 103                         /* Thread quit pipe has been closed. Killing thread. */
 104                         if (pollfd == quit_pipe_read_fd) {
 105                                 err = 0;
 106                                 goto exit;
 107                         } else if (pollfd == notifiers->apps_cmd_notify_pipe_read_fd) {
 108                                 /* Inspect the apps cmd pipe */
 109                                 int sock;
 110
 111                                 if (revents & LPOLLIN) {
 112                                         /* Get socket from dispatch thread. */
 113                                         size_ret = lttng_read(notifiers->apps_cmd_notify_pipe_read_fd,
 114                                                         &sock, sizeof(sock));
 115                                         if (size_ret < sizeof(sock)) {
 116                                                 PERROR("read apps notify pipe");
 117                                                 goto error;
 118                                         }
 119                                         health_code_update();
 120
 121                                         ret = lttng_poll_add(&events, sock,
 122                                                         LPOLLIN | LPOLLERR | LPOLLHUP | LPOLLRDHUP);
 123                                         if (ret < 0) {
 124                                                 /*
 125                                                  * It's possible we've reached the max poll fd allowed.
 126                                                  * Let's close the socket but continue normal execution.
 127                                                  */
 128                                                 ret = close(sock);
 129                                                 if (ret) {
 130                                                         PERROR("close notify socket %d", sock);
 131                                                 }
 132                                                 lttng_fd_put(LTTNG_FD_APPS, 1);
 133                                                 continue;
 134                                         }
 135                                         DBG3("UST thread notify added sock %d to pollset", sock);
 136                                 } else if (revents & (LPOLLERR | LPOLLHUP | LPOLLRDHUP)) {
 137                                         ERR("Apps notify command pipe error");
 138                                         goto error;
 139                                 } else {
 140                                         ERR("Unexpected poll events %u for sock %d", revents, pollfd);
 141                                         goto error;
 142                                 }
 143                         } else {
 144                                 /*
 145                                  * At this point, we know that a registered application
 146                                  * triggered the event.
 147                                  */
 148                                 if (revents & (LPOLLIN | LPOLLPRI)) {
 149                                         ret = ust_app_recv_notify(pollfd);
 150                                         if (ret < 0) {
 151                                                 /* Removing from the poll set */
 152                                                 ret = lttng_poll_del(&events, pollfd);
 153                                                 if (ret < 0) {
 154                                                         goto error;
 155                                                 }
 156
 157                                                 /* The socket is closed after a grace period here. */
 158                                                 ust_app_notify_sock_unregister(pollfd);
 159                                         }
 160                                 } else if (revents & (LPOLLERR | LPOLLHUP | LPOLLRDHUP)) {
 161                                         /* Removing from the poll set */
 162                                         ret = lttng_poll_del(&events, pollfd);
 163                                         if (ret < 0) {
 164                                                 goto error;
 165                                         }
 166
 167                                         /* The socket is closed after a grace period here. */
 168                                         ust_app_notify_sock_unregister(pollfd);
 169                                 } else {
 170                                         ERR("Unexpected poll events %u for sock %d", revents, pollfd);
 171                                         goto error;
 172                                 }
 173                                 health_code_update();
 174                         }
 175                 }
 176         }
 177
 178 exit:
 179 error:
 180         lttng_poll_clean(&events);
 181 error_poll_create:
 182 error_testpoint:
 183
 184         DBG("Application notify communication apps thread cleanup complete");
 185         if (err) {
 186                 health_error();
 187                 ERR("Health error occurred in %s", __func__);
 188         }
 189         health_unregister(the_health_sessiond);
 190         rcu_thread_offline();
 191         rcu_unregister_thread();
 192         return NULL;
 193 }
 194
 195 static bool shutdown_application_notification_thread(void *data)
 196 {
 197         struct thread_notifiers *notifiers = (thread_notifiers *) data;
 198         const int write_fd = lttng_pipe_get_writefd(notifiers->quit_pipe);
 199
 200         return notify_thread_pipe(write_fd) == 1;
 201 }
 202
 203 static void cleanup_application_notification_thread(void *data)
 204 {
 205         struct thread_notifiers *notifiers = (thread_notifiers *) data;
 206
 207         lttng_pipe_destroy(notifiers->quit_pipe);
 208         free(notifiers);
 209 }
 210
 211 bool launch_application_notification_thread(int apps_cmd_notify_pipe_read_fd)
 212 {
 213         struct lttng_thread *thread;
 214         struct thread_notifiers *notifiers;
 215         struct lttng_pipe *quit_pipe;
 216
 217         notifiers = zmalloc<thread_notifiers>();
 218         if (!notifiers) {
 219                 goto error_alloc;
 220         }
 221         notifiers->apps_cmd_notify_pipe_read_fd = apps_cmd_notify_pipe_read_fd;
 222
 223         quit_pipe = lttng_pipe_open(FD_CLOEXEC);
 224         if (!quit_pipe) {
 225                 goto error;
 226         }
 227         notifiers->quit_pipe = quit_pipe;
 228
 229         thread = lttng_thread_create("Application notification",
 230                         thread_application_notification,
 231                         shutdown_application_notification_thread,
 232                         cleanup_application_notification_thread,
 233                         notifiers);
 234         if (!thread) {
 235                 goto error;
 236         }
 237         lttng_thread_put(thread);
 238         return true;
 239 error:
 240         cleanup_application_notification_thread(notifiers);
 241 error_alloc:
 242         return false;
 243 }