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 "fd-limit.hpp"
  11 #include "health-sessiond.hpp"
  12 #include "lttng-sessiond.hpp"
  13 #include "notify-apps.hpp"
  14 #include "testpoint.hpp"
  15 #include "thread.hpp"
  16 #include "utils.hpp"
  17
  18 #include <common/common.hpp>
  19 #include <common/utils.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, HEALTH_SESSIOND_TYPE_APP_MANAGE_NOTIFY);
  46
  47         if (testpoint(sessiond_thread_app_manage_notify)) {
  48                 goto error_testpoint;
  49         }
  50
  51         health_code_update();
  52
  53         ret = lttng_poll_create(&events, 2, LTTNG_CLOEXEC);
  54         if (ret < 0) {
  55                 goto error_poll_create;
  56         }
  57
  58         /* Add notify pipe to the pollset. */
  59         ret = lttng_poll_add(
  60                 &events, notifiers->apps_cmd_notify_pipe_read_fd, LPOLLIN | LPOLLRDHUP);
  61         if (ret < 0) {
  62                 goto error;
  63         }
  64
  65         ret = lttng_poll_add(&events, thread_quit_pipe_fd, LPOLLIN);
  66         if (ret < 0) {
  67                 goto error;
  68         }
  69
  70         health_code_update();
  71
  72         while (true) {
  73                 DBG3("[ust-thread] Manage notify polling");
  74
  75                 /* Inifinite blocking call, waiting for transmission */
  76         restart:
  77                 health_poll_entry();
  78                 ret = lttng_poll_wait(&events, -1);
  79                 DBG3("[ust-thread] Manage notify return from poll on %d fds",
  80                      LTTNG_POLL_GETNB(&events));
  81                 health_poll_exit();
  82                 if (ret < 0) {
  83                         /*
  84                          * Restart interrupted system call.
  85                          */
  86                         if (errno == EINTR) {
  87                                 goto restart;
  88                         }
  89                         goto error;
  90                 }
  91
  92                 nb_fd = ret;
  93
  94                 for (i = 0; i < nb_fd; i++) {
  95                         health_code_update();
  96
  97                         /* Fetch once the poll data */
  98                         const auto revents = LTTNG_POLL_GETEV(&events, i);
  99                         const auto pollfd = LTTNG_POLL_GETFD(&events, i);
 100
 101                         /* Activity on thread quit pipe, exiting. */
 102                         if (pollfd == thread_quit_pipe_fd) {
 103                                 DBG("Activity on thread quit pipe");
 104                                 err = 0;
 105                                 goto exit;
 106                         }
 107
 108                         if (pollfd == notifiers->apps_cmd_notify_pipe_read_fd) {
 109                                 /* Inspect the apps cmd pipe */
 110                                 int sock;
 111
 112                                 if (revents & LPOLLIN) {
 113                                         /* Get socket from dispatch thread. */
 114                                         size_ret =
 115                                                 lttng_read(notifiers->apps_cmd_notify_pipe_read_fd,
 116                                                            &sock,
 117                                                            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, LPOLLIN | LPOLLRDHUP);
 125                                         if (ret < 0) {
 126                                                 /*
 127                                                  * It's possible we've reached the max poll fd
 128                                                  * allowed. Let's close the socket but continue
 129                                                  * 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",
 144                                             revents,
 145                                             pollfd);
 146                                         goto error;
 147                                 }
 148                         } else {
 149                                 /*
 150                                  * At this point, we know that a registered application
 151                                  * triggered the event.
 152                                  */
 153                                 if (revents & (LPOLLIN | LPOLLPRI)) {
 154                                         ret = ust_app_recv_notify(pollfd);
 155                                         if (ret < 0) {
 156                                                 /* Removing from the poll set */
 157                                                 ret = lttng_poll_del(&events, pollfd);
 158                                                 if (ret < 0) {
 159                                                         goto error;
 160                                                 }
 161
 162                                                 /* The socket is closed after a grace period here.
 163                                                  */
 164                                                 ust_app_notify_sock_unregister(pollfd);
 165                                         }
 166                                 } else if (revents & (LPOLLERR | LPOLLHUP | LPOLLRDHUP)) {
 167                                         /* Removing from the poll set */
 168                                         ret = lttng_poll_del(&events, pollfd);
 169                                         if (ret < 0) {
 170                                                 goto error;
 171                                         }
 172
 173                                         /* The socket is closed after a grace period here. */
 174                                         ust_app_notify_sock_unregister(pollfd);
 175                                 } else {
 176                                         ERR("Unexpected poll events %u for sock %d",
 177                                             revents,
 178                                             pollfd);
 179                                         goto error;
 180                                 }
 181                                 health_code_update();
 182                         }
 183                 }
 184         }
 185
 186 exit:
 187 error:
 188         lttng_poll_clean(&events);
 189 error_poll_create:
 190 error_testpoint:
 191
 192         DBG("Application notify communication apps thread cleanup complete");
 193         if (err) {
 194                 health_error();
 195                 ERR("Health error occurred in %s", __func__);
 196         }
 197         health_unregister(the_health_sessiond);
 198         rcu_thread_offline();
 199         rcu_unregister_thread();
 200         return nullptr;
 201 }
 202
 203 static bool shutdown_application_notification_thread(void *data)
 204 {
 205         struct thread_notifiers *notifiers = (thread_notifiers *) data;
 206         const int write_fd = lttng_pipe_get_writefd(notifiers->quit_pipe);
 207
 208         return notify_thread_pipe(write_fd) == 1;
 209 }
 210
 211 static void cleanup_application_notification_thread(void *data)
 212 {
 213         struct thread_notifiers *notifiers = (thread_notifiers *) data;
 214
 215         lttng_pipe_destroy(notifiers->quit_pipe);
 216         free(notifiers);
 217 }
 218
 219 bool launch_application_notification_thread(int apps_cmd_notify_pipe_read_fd)
 220 {
 221         struct lttng_thread *thread;
 222         struct thread_notifiers *notifiers;
 223         struct lttng_pipe *quit_pipe;
 224
 225         notifiers = zmalloc<thread_notifiers>();
 226         if (!notifiers) {
 227                 goto error_alloc;
 228         }
 229         notifiers->apps_cmd_notify_pipe_read_fd = apps_cmd_notify_pipe_read_fd;
 230
 231         quit_pipe = lttng_pipe_open(FD_CLOEXEC);
 232         if (!quit_pipe) {
 233                 goto error;
 234         }
 235         notifiers->quit_pipe = quit_pipe;
 236
 237         thread = lttng_thread_create("Application notification",
 238                                      thread_application_notification,
 239                                      shutdown_application_notification_thread,
 240                                      cleanup_application_notification_thread,
 241                                      notifiers);
 242         if (!thread) {
 243                 goto error;
 244         }
 245         lttng_thread_put(thread);
 246         return true;
 247 error:
 248         cleanup_application_notification_thread(notifiers);
 249 error_alloc:
 250         return false;
 251 }