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, err = -1;
  34         ssize_t size_ret;
  35         uint32_t nb_fd;
  36         struct lttng_poll_event events;
  37         struct thread_notifiers *notifiers = (thread_notifiers *) data;
  38         const auto thread_quit_pipe_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, thread_quit_pipe_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                         const auto revents = LTTNG_POLL_GETEV(&events, i);
 101                         const auto pollfd = LTTNG_POLL_GETFD(&events, i);
 102
 103                         /* Activity on thread quit pipe, exiting. */
 104                         if (pollfd == thread_quit_pipe_fd) {
 105                                 DBG("Activity on thread quit pipe");
 106                                 err = 0;
 107                                 goto exit;
 108                         }
 109
 110                         if (pollfd == notifiers->apps_cmd_notify_pipe_read_fd) {
 111                                 /* Inspect the apps cmd pipe */
 112                                 int sock;
 113
 114                                 if (revents & LPOLLIN) {
 115                                         /* Get socket from dispatch thread. */
 116                                         size_ret = lttng_read(notifiers->apps_cmd_notify_pipe_read_fd,
 117                                                         &sock, sizeof(sock));
 118                                         if (size_ret < sizeof(sock)) {
 119                                                 PERROR("read apps notify pipe");
 120                                                 goto error;
 121                                         }
 122                                         health_code_update();
 123
 124                                         ret = lttng_poll_add(&events, sock,
 125                                                         LPOLLIN | LPOLLERR | LPOLLHUP | LPOLLRDHUP);
 126                                         if (ret < 0) {
 127                                                 /*
 128                                                  * It's possible we've reached the max poll fd allowed.
 129                                                  * Let's close the socket but continue normal execution.
 130                                                  */
 131                                                 ret = close(sock);
 132                                                 if (ret) {
 133                                                         PERROR("close notify socket %d", sock);
 134                                                 }
 135                                                 lttng_fd_put(LTTNG_FD_APPS, 1);
 136                                                 continue;
 137                                         }
 138                                         DBG3("UST thread notify added sock %d to pollset", sock);
 139                                 } else if (revents & (LPOLLERR | LPOLLHUP | LPOLLRDHUP)) {
 140                                         ERR("Apps notify command pipe error");
 141                                         goto error;
 142                                 } else {
 143                                         ERR("Unexpected poll events %u for sock %d", revents, pollfd);
 144                                         goto error;
 145                                 }
 146                         } else {
 147                                 /*
 148                                  * At this point, we know that a registered application
 149                                  * triggered the event.
 150                                  */
 151                                 if (revents & (LPOLLIN | LPOLLPRI)) {
 152                                         ret = ust_app_recv_notify(pollfd);
 153                                         if (ret < 0) {
 154                                                 /* Removing from the poll set */
 155                                                 ret = lttng_poll_del(&events, pollfd);
 156                                                 if (ret < 0) {
 157                                                         goto error;
 158                                                 }
 159
 160                                                 /* The socket is closed after a grace period here. */
 161                                                 ust_app_notify_sock_unregister(pollfd);
 162                                         }
 163                                 } else if (revents & (LPOLLERR | LPOLLHUP | LPOLLRDHUP)) {
 164                                         /* Removing from the poll set */
 165                                         ret = lttng_poll_del(&events, pollfd);
 166                                         if (ret < 0) {
 167                                                 goto error;
 168                                         }
 169
 170                                         /* The socket is closed after a grace period here. */
 171                                         ust_app_notify_sock_unregister(pollfd);
 172                                 } else {
 173                                         ERR("Unexpected poll events %u for sock %d", revents, pollfd);
 174                                         goto error;
 175                                 }
 176                                 health_code_update();
 177                         }
 178                 }
 179         }
 180
 181 exit:
 182 error:
 183         lttng_poll_clean(&events);
 184 error_poll_create:
 185 error_testpoint:
 186
 187         DBG("Application notify communication apps thread cleanup complete");
 188         if (err) {
 189                 health_error();
 190                 ERR("Health error occurred in %s", __func__);
 191         }
 192         health_unregister(the_health_sessiond);
 193         rcu_thread_offline();
 194         rcu_unregister_thread();
 195         return NULL;
 196 }
 197
 198 static bool shutdown_application_notification_thread(void *data)
 199 {
 200         struct thread_notifiers *notifiers = (thread_notifiers *) data;
 201         const int write_fd = lttng_pipe_get_writefd(notifiers->quit_pipe);
 202
 203         return notify_thread_pipe(write_fd) == 1;
 204 }
 205
 206 static void cleanup_application_notification_thread(void *data)
 207 {
 208         struct thread_notifiers *notifiers = (thread_notifiers *) data;
 209
 210         lttng_pipe_destroy(notifiers->quit_pipe);
 211         free(notifiers);
 212 }
 213
 214 bool launch_application_notification_thread(int apps_cmd_notify_pipe_read_fd)
 215 {
 216         struct lttng_thread *thread;
 217         struct thread_notifiers *notifiers;
 218         struct lttng_pipe *quit_pipe;
 219
 220         notifiers = zmalloc<thread_notifiers>();
 221         if (!notifiers) {
 222                 goto error_alloc;
 223         }
 224         notifiers->apps_cmd_notify_pipe_read_fd = apps_cmd_notify_pipe_read_fd;
 225
 226         quit_pipe = lttng_pipe_open(FD_CLOEXEC);
 227         if (!quit_pipe) {
 228                 goto error;
 229         }
 230         notifiers->quit_pipe = quit_pipe;
 231
 232         thread = lttng_thread_create("Application notification",
 233                         thread_application_notification,
 234                         shutdown_application_notification_thread,
 235                         cleanup_application_notification_thread,
 236                         notifiers);
 237         if (!thread) {
 238                 goto error;
 239         }
 240         lttng_thread_put(thread);
 241         return true;
 242 error:
 243         cleanup_application_notification_thread(notifiers);
 244 error_alloc:
 245         return false;
 246 }