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