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

   1 /*
   2  * Copyright (C) 2013 - David Goulet <dgoulet@efficios.com>
   3  *
   4  * This program is free software; you can redistribute it and/or modify it
   5  * under the terms of the GNU General Public License, version 2 only, as
   6  * published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful, but WITHOUT
   9  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  10  * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
  11  * more details.
  12  *
  13  * You should have received a copy of the GNU General Public License along with
  14  * this program; if not, write to the Free Software Foundation, Inc., 51
  15  * Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  16  */
  17
  18 #define _LGPL_SOURCE
  19 #include <assert.h>
  20
  21 #include <common/common.h>
  22 #include <common/utils.h>
  23
  24 #include "fd-limit.h"
  25 #include "lttng-sessiond.h"
  26 #include "notify-apps.h"
  27 #include "health-sessiond.h"
  28 #include "testpoint.h"
  29 #include "utils.h"
  30 #include "thread.h"
  31
  32 struct thread_notifiers {
  33         struct lttng_pipe *quit_pipe;
  34         int apps_cmd_notify_pipe_read_fd;
  35 };
  36
  37 /*
  38  * This thread manage application notify communication.
  39  */
  40 static void *thread_application_notification(void *data)
  41 {
  42         int i, ret, pollfd, err = -1;
  43         ssize_t size_ret;
  44         uint32_t revents, nb_fd;
  45         struct lttng_poll_event events;
  46         struct thread_notifiers *notifiers = data;
  47         const int quit_pipe_read_fd = lttng_pipe_get_readfd(notifiers->quit_pipe);
  48
  49         DBG("[ust-thread] Manage application notify command");
  50
  51         rcu_register_thread();
  52         rcu_thread_online();
  53
  54         health_register(health_sessiond,
  55                 HEALTH_SESSIOND_TYPE_APP_MANAGE_NOTIFY);
  56
  57         if (testpoint(sessiond_thread_app_manage_notify)) {
  58                 goto error_testpoint;
  59         }
  60
  61         health_code_update();
  62
  63         ret = lttng_poll_create(&events, 2, LTTNG_CLOEXEC);
  64         if (ret < 0) {
  65                 goto error_poll_create;
  66         }
  67
  68         /* Add notify pipe to the pollset. */
  69         ret = lttng_poll_add(&events, notifiers->apps_cmd_notify_pipe_read_fd,
  70                         LPOLLIN | LPOLLERR | LPOLLHUP | LPOLLRDHUP);
  71         if (ret < 0) {
  72                 goto error;
  73         }
  74
  75         ret = lttng_poll_add(&events, quit_pipe_read_fd,
  76                         LPOLLIN | LPOLLERR);
  77         if (ret < 0) {
  78                 goto error;
  79         }
  80
  81         health_code_update();
  82
  83         while (1) {
  84                 DBG3("[ust-thread] Manage notify polling");
  85
  86                 /* Inifinite blocking call, waiting for transmission */
  87 restart:
  88                 health_poll_entry();
  89                 ret = lttng_poll_wait(&events, -1);
  90                 DBG3("[ust-thread] Manage notify return from poll on %d fds",
  91                                 LTTNG_POLL_GETNB(&events));
  92                 health_poll_exit();
  93                 if (ret < 0) {
  94                         /*
  95                          * Restart interrupted system call.
  96                          */
  97                         if (errno == EINTR) {
  98                                 goto restart;
  99                         }
 100                         goto error;
 101                 }
 102
 103                 nb_fd = ret;
 104
 105                 for (i = 0; i < nb_fd; i++) {
 106                         health_code_update();
 107
 108                         /* Fetch once the poll data */
 109                         revents = LTTNG_POLL_GETEV(&events, i);
 110                         pollfd = LTTNG_POLL_GETFD(&events, i);
 111
 112                         /* Thread quit pipe has been closed. Killing thread. */
 113                         if (pollfd == quit_pipe_read_fd) {
 114                                 err = 0;
 115                                 goto exit;
 116                         } else if (pollfd == notifiers->apps_cmd_notify_pipe_read_fd) {
 117                                 /* Inspect the apps cmd pipe */
 118                                 int sock;
 119
 120                                 if (revents & LPOLLIN) {
 121                                         /* Get socket from dispatch thread. */
 122                                         size_ret = lttng_read(notifiers->apps_cmd_notify_pipe_read_fd,
 123                                                         &sock, sizeof(sock));
 124                                         if (size_ret < sizeof(sock)) {
 125                                                 PERROR("read apps notify pipe");
 126                                                 goto error;
 127                                         }
 128                                         health_code_update();
 129
 130                                         ret = lttng_poll_add(&events, sock,
 131                                                         LPOLLIN | LPOLLERR | LPOLLHUP | LPOLLRDHUP);
 132                                         if (ret < 0) {
 133                                                 /*
 134                                                  * It's possible we've reached the max poll fd allowed.
 135                                                  * Let's close the socket but continue normal execution.
 136                                                  */
 137                                                 ret = close(sock);
 138                                                 if (ret) {
 139                                                         PERROR("close notify socket %d", sock);
 140                                                 }
 141                                                 lttng_fd_put(LTTNG_FD_APPS, 1);
 142                                                 continue;
 143                                         }
 144                                         DBG3("UST thread notify added sock %d to pollset", sock);
 145                                 } else if (revents & (LPOLLERR | LPOLLHUP | LPOLLRDHUP)) {
 146                                         ERR("Apps notify command pipe error");
 147                                         goto error;
 148                                 } else {
 149                                         ERR("Unexpected poll events %u for sock %d", revents, pollfd);
 150                                         goto error;
 151                                 }
 152                         } else {
 153                                 /*
 154                                  * At this point, we know that a registered application
 155                                  * triggered the event.
 156                                  */
 157                                 if (revents & (LPOLLIN | LPOLLPRI)) {
 158                                         ret = ust_app_recv_notify(pollfd);
 159                                         if (ret < 0) {
 160                                                 /* Removing from the poll set */
 161                                                 ret = lttng_poll_del(&events, pollfd);
 162                                                 if (ret < 0) {
 163                                                         goto error;
 164                                                 }
 165
 166                                                 /* The socket is closed after a grace period here. */
 167                                                 ust_app_notify_sock_unregister(pollfd);
 168                                         }
 169                                 } else if (revents & (LPOLLERR | LPOLLHUP | LPOLLRDHUP)) {
 170                                         /* Removing from the poll set */
 171                                         ret = lttng_poll_del(&events, pollfd);
 172                                         if (ret < 0) {
 173                                                 goto error;
 174                                         }
 175
 176                                         /* The socket is closed after a grace period here. */
 177                                         ust_app_notify_sock_unregister(pollfd);
 178                                 } else {
 179                                         ERR("Unexpected poll events %u for sock %d", revents, pollfd);
 180                                         goto error;
 181                                 }
 182                                 health_code_update();
 183                         }
 184                 }
 185         }
 186
 187 exit:
 188 error:
 189         lttng_poll_clean(&events);
 190 error_poll_create:
 191 error_testpoint:
 192
 193         DBG("Application notify communication apps thread cleanup complete");
 194         if (err) {
 195                 health_error();
 196                 ERR("Health error occurred in %s", __func__);
 197         }
 198         health_unregister(health_sessiond);
 199         rcu_thread_offline();
 200         rcu_unregister_thread();
 201         return NULL;
 202 }
 203
 204 static bool shutdown_application_notification_thread(void *data)
 205 {
 206         struct thread_notifiers *notifiers = data;
 207         const int write_fd = lttng_pipe_get_writefd(notifiers->quit_pipe);
 208
 209         return notify_thread_pipe(write_fd) == 1;
 210 }
 211
 212 static void cleanup_application_notification_thread(void *data)
 213 {
 214         struct thread_notifiers *notifiers = data;
 215
 216         lttng_pipe_destroy(notifiers->quit_pipe);
 217         free(notifiers);
 218 }
 219
 220 bool launch_application_notification_thread(int apps_cmd_notify_pipe_read_fd)
 221 {
 222         struct lttng_thread *thread;
 223         struct thread_notifiers *notifiers;
 224         struct lttng_pipe *quit_pipe;
 225
 226         notifiers = zmalloc(sizeof(*notifiers));
 227         if (!notifiers) {
 228                 goto error_alloc;
 229         }
 230         notifiers->apps_cmd_notify_pipe_read_fd = apps_cmd_notify_pipe_read_fd;
 231
 232         quit_pipe = lttng_pipe_open(FD_CLOEXEC);
 233         if (!quit_pipe) {
 234                 goto error;
 235         }
 236         notifiers->quit_pipe = quit_pipe;
 237
 238         thread = lttng_thread_create("Application notification",
 239                         thread_application_notification,
 240                         shutdown_application_notification_thread,
 241                         cleanup_application_notification_thread,
 242                         notifiers);
 243         if (!thread) {
 244                 goto error;
 245         }
 246         lttng_thread_put(thread);
 247         return true;
 248 error:
 249         cleanup_application_notification_thread(notifiers);
 250 error_alloc:
 251         return false;
 252 }