src/bin/lttng-sessiond/ust-thread.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 #define _GNU_SOURCE
  18 #include <assert.h>
  19
  20 #include <common/common.h>
  21 #include <common/utils.h>
  22
  23 #include "fd-limit.h"
  24 #include "lttng-sessiond.h"
  25 #include "ust-thread.h"
  26 #include "health-sessiond.h"
  27 #include "testpoint.h"
  28
  29 /*
  30  * This thread manage application notify communication.
  31  */
  32 void *ust_thread_manage_notify(void *data)
  33 {
  34         int i, ret, pollfd, err = -1;
  35         ssize_t size_ret;
  36         uint32_t revents, nb_fd;
  37         struct lttng_poll_event events;
  38
  39         DBG("[ust-thread] Manage application notify command");
  40
  41         rcu_register_thread();
  42         rcu_thread_online();
  43
  44         health_register(health_sessiond,
  45                 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 = sessiond_set_thread_pollset(&events, 2);
  54         if (ret < 0) {
  55                 goto error_poll_create;
  56         }
  57
  58         /* Add notify pipe to the pollset. */
  59         ret = lttng_poll_add(&events, apps_cmd_notify_pipe[0], LPOLLIN | LPOLLERR);
  60         if (ret < 0) {
  61                 goto error;
  62         }
  63
  64         health_code_update();
  65
  66         while (1) {
  67                 DBG3("[ust-thread] Manage notify polling on %d fds",
  68                                 LTTNG_POLL_GETNB(&events));
  69
  70                 /* Inifinite blocking call, waiting for transmission */
  71 restart:
  72                 health_poll_entry();
  73                 ret = lttng_poll_wait(&events, -1);
  74                 health_poll_exit();
  75                 if (ret < 0) {
  76                         /*
  77                          * Restart interrupted system call.
  78                          */
  79                         if (errno == EINTR) {
  80                                 goto restart;
  81                         }
  82                         goto error;
  83                 }
  84
  85                 nb_fd = ret;
  86
  87                 for (i = 0; i < nb_fd; i++) {
  88                         health_code_update();
  89
  90                         /* Fetch once the poll data */
  91                         revents = LTTNG_POLL_GETEV(&events, i);
  92                         pollfd = LTTNG_POLL_GETFD(&events, i);
  93
  94                         /* Thread quit pipe has been closed. Killing thread. */
  95                         ret = sessiond_check_thread_quit_pipe(pollfd, revents);
  96                         if (ret) {
  97                                 err = 0;
  98                                 goto exit;
  99                         }
 100
 101                         /* Inspect the apps cmd pipe */
 102                         if (pollfd == apps_cmd_notify_pipe[0]) {
 103                                 int sock;
 104
 105                                 if (revents & (LPOLLERR | LPOLLHUP | LPOLLRDHUP)) {
 106                                         ERR("Apps notify command pipe error");
 107                                         goto error;
 108                                 } else if (!(revents & LPOLLIN)) {
 109                                         /* No POLLIN and not a catched error, stop the thread. */
 110                                         ERR("Notify command pipe failed. revent: %u", revents);
 111                                         goto error;
 112                                 }
 113
 114                                 /* Get socket from dispatch thread. */
 115                                 size_ret = lttng_read(apps_cmd_notify_pipe[0],
 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,
 124                                                 LPOLLIN | LPOLLERR | LPOLLHUP | LPOLLRDHUP);
 125                                 if (ret < 0) {
 126                                         /*
 127                                          * It's possible we've reached the max poll fd allowed.
 128                                          * Let's close the socket but continue normal execution.
 129                                          */
 130                                         ret = close(sock);
 131                                         if (ret) {
 132                                                 PERROR("close notify socket %d", sock);
 133                                         }
 134                                         lttng_fd_put(LTTNG_FD_APPS, 1);
 135                                         continue;
 136                                 }
 137                                 DBG3("UST thread notify added sock %d to pollset", sock);
 138                         } else {
 139                                 /*
 140                                  * At this point, we know that a registered application
 141                                  * triggered the event.
 142                                  */
 143                                 if (revents & (LPOLLERR | LPOLLHUP | LPOLLRDHUP)) {
 144                                         /* Removing from the poll set */
 145                                         ret = lttng_poll_del(&events, pollfd);
 146                                         if (ret < 0) {
 147                                                 goto error;
 148                                         }
 149
 150                                         /* The socket is closed after a grace period here. */
 151                                         ust_app_notify_sock_unregister(pollfd);
 152                                 } else if (revents & (LPOLLIN | LPOLLPRI)) {
 153                                         ret = ust_app_recv_notify(pollfd);
 154                                         if (ret < 0) {
 155                                                 /*
 156                                                  * If the notification failed either the application is
 157                                                  * dead or an internal error happened. In both cases,
 158                                                  * we can only continue here. If the application is
 159                                                  * dead, an unregistration will follow or else the
 160                                                  * application will notice that we are not responding
 161                                                  * on that socket and will close it.
 162                                                  */
 163                                                 continue;
 164                                         }
 165                                 } else {
 166                                         ERR("Unknown poll events %u for sock %d", revents, pollfd);
 167                                         continue;
 168                                 }
 169                                 health_code_update();
 170                         }
 171                 }
 172         }
 173
 174 exit:
 175 error:
 176         lttng_poll_clean(&events);
 177 error_poll_create:
 178 error_testpoint:
 179         utils_close_pipe(apps_cmd_notify_pipe);
 180         apps_cmd_notify_pipe[0] = apps_cmd_notify_pipe[1] = -1;
 181         DBG("Application notify communication apps thread cleanup complete");
 182         if (err) {
 183                 health_error();
 184                 ERR("Health error occurred in %s", __func__);
 185         }
 186         health_unregister(health_sessiond);
 187         rcu_thread_offline();
 188         rcu_unregister_thread();
 189         return NULL;
 190 }