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 | LPOLLRDHUP);
  62         if (ret < 0) {
  63                 goto error;
  64         }
  65
  66         ret = lttng_poll_add(&events, thread_quit_pipe_fd, LPOLLIN);
  67         if (ret < 0) {
  68                 goto error;
  69         }
  70
  71         health_code_update();
  72
  73         while (1) {
  74                 DBG3("[ust-thread] Manage notify polling");
  75
  76                 /* Inifinite blocking call, waiting for transmission */
  77 restart:
  78                 health_poll_entry();
  79                 ret = lttng_poll_wait(&events, -1);
  80                 DBG3("[ust-thread] Manage notify return from poll on %d fds",
  81                                 LTTNG_POLL_GETNB(&events));
  82                 health_poll_exit();
  83                 if (ret < 0) {
  84                         /*
  85                          * Restart interrupted system call.
  86                          */
  87                         if (errno == EINTR) {
  88                                 goto restart;
  89                         }
  90                         goto error;
  91                 }
  92
  93                 nb_fd = ret;
  94
  95                 for (i = 0; i < nb_fd; i++) {
  96                         health_code_update();
  97
  98                         /* Fetch once the poll data */
  99                         const auto revents = LTTNG_POLL_GETEV(&events, i);
 100                         const auto pollfd = LTTNG_POLL_GETFD(&events, i);
 101
 102                         /* Activity on thread quit pipe, exiting. */
 103                         if (pollfd == thread_quit_pipe_fd) {
 104                                 DBG("Activity on thread quit pipe");
 105                                 err = 0;
 106                                 goto exit;
 107                         }
 108
 109                         if (pollfd == notifiers->apps_cmd_notify_pipe_read_fd) {
 110                                 /* Inspect the apps cmd pipe */
 111                                 int sock;
 112
 113                                 if (revents & LPOLLIN) {
 114                                         /* Get socket from dispatch thread. */
 115                                         size_ret = lttng_read(notifiers->apps_cmd_notify_pipe_read_fd,
 116                                                         &sock, sizeof(sock));
 117                                         if (size_ret < sizeof(sock)) {
 118                                                 PERROR("read apps notify pipe");
 119                                                 goto error;
 120                                         }
 121                                         health_code_update();
 122
 123                                         ret = lttng_poll_add(&events, sock, LPOLLIN | LPOLLRDHUP);
 124                                         if (ret < 0) {
 125                                                 /*
 126                                                  * It's possible we've reached the max poll fd allowed.
 127                                                  * Let's close the socket but continue normal execution.
 128                                                  */
 129                                                 ret = close(sock);
 130                                                 if (ret) {
 131                                                         PERROR("close notify socket %d", sock);
 132                                                 }
 133                                                 lttng_fd_put(LTTNG_FD_APPS, 1);
 134                                                 continue;
 135                                         }
 136                                         DBG3("UST thread notify added sock %d to pollset", sock);
 137                                 } else if (revents & (LPOLLERR | LPOLLHUP | LPOLLRDHUP)) {
 138                                         ERR("Apps notify command pipe error");
 139                                         goto error;
 140                                 } else {
 141                                         ERR("Unexpected poll events %u for sock %d", revents, pollfd);
 142                                         goto error;
 143                                 }
 144                         } else {
 145                                 /*
 146                                  * At this point, we know that a registered application
 147                                  * triggered the event.
 148                                  */
 149                                 if (revents & (LPOLLIN | LPOLLPRI)) {
 150                                         ret = ust_app_recv_notify(pollfd);
 151                                         if (ret < 0) {
 152                                                 /* Removing from the poll set */
 153                                                 ret = lttng_poll_del(&events, pollfd);
 154                                                 if (ret < 0) {
 155                                                         goto error;
 156                                                 }
 157
 158                                                 /* The socket is closed after a grace period here. */
 159                                                 ust_app_notify_sock_unregister(pollfd);
 160                                         }
 161                                 } else if (revents & (LPOLLERR | LPOLLHUP | LPOLLRDHUP)) {
 162                                         /* Removing from the poll set */
 163                                         ret = lttng_poll_del(&events, pollfd);
 164                                         if (ret < 0) {
 165                                                 goto error;
 166                                         }
 167
 168                                         /* The socket is closed after a grace period here. */
 169                                         ust_app_notify_sock_unregister(pollfd);
 170                                 } else {
 171                                         ERR("Unexpected poll events %u for sock %d", revents, pollfd);
 172                                         goto error;
 173                                 }
 174                                 health_code_update();
 175                         }
 176                 }
 177         }
 178
 179 exit:
 180 error:
 181         lttng_poll_clean(&events);
 182 error_poll_create:
 183 error_testpoint:
 184
 185         DBG("Application notify communication apps thread cleanup complete");
 186         if (err) {
 187                 health_error();
 188                 ERR("Health error occurred in %s", __func__);
 189         }
 190         health_unregister(the_health_sessiond);
 191         rcu_thread_offline();
 192         rcu_unregister_thread();
 193         return NULL;
 194 }
 195
 196 static bool shutdown_application_notification_thread(void *data)
 197 {
 198         struct thread_notifiers *notifiers = (thread_notifiers *) data;
 199         const int write_fd = lttng_pipe_get_writefd(notifiers->quit_pipe);
 200
 201         return notify_thread_pipe(write_fd) == 1;
 202 }
 203
 204 static void cleanup_application_notification_thread(void *data)
 205 {
 206         struct thread_notifiers *notifiers = (thread_notifiers *) data;
 207
 208         lttng_pipe_destroy(notifiers->quit_pipe);
 209         free(notifiers);
 210 }
 211
 212 bool launch_application_notification_thread(int apps_cmd_notify_pipe_read_fd)
 213 {
 214         struct lttng_thread *thread;
 215         struct thread_notifiers *notifiers;
 216         struct lttng_pipe *quit_pipe;
 217
 218         notifiers = zmalloc<thread_notifiers>();
 219         if (!notifiers) {
 220                 goto error_alloc;
 221         }
 222         notifiers->apps_cmd_notify_pipe_read_fd = apps_cmd_notify_pipe_read_fd;
 223
 224         quit_pipe = lttng_pipe_open(FD_CLOEXEC);
 225         if (!quit_pipe) {
 226                 goto error;
 227         }
 228         notifiers->quit_pipe = quit_pipe;
 229
 230         thread = lttng_thread_create("Application notification",
 231                         thread_application_notification,
 232                         shutdown_application_notification_thread,
 233                         cleanup_application_notification_thread,
 234                         notifiers);
 235         if (!thread) {
 236                 goto error;
 237         }
 238         lttng_thread_put(thread);
 239         return true;
 240 error:
 241         cleanup_application_notification_thread(notifiers);
 242 error_alloc:
 243         return false;
 244 }