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 #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 "ust-thread.h"
  27 #include "health-sessiond.h"
  28 #include "testpoint.h"
  29
  30 /*
  31  * This thread manage application notify communication.
  32  */
  33 void *ust_thread_manage_notify(void *data)
  34 {
  35         int i, ret, pollfd, err = -1;
  36         ssize_t size_ret;
  37         uint32_t revents, nb_fd;
  38         struct lttng_poll_event events;
  39
  40         DBG("[ust-thread] Manage application notify command");
  41
  42         rcu_register_thread();
  43         rcu_thread_online();
  44
  45         health_register(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 = sessiond_set_thread_pollset(&events, 2);
  55         if (ret < 0) {
  56                 goto error_poll_create;
  57         }
  58
  59         /* Add notify pipe to the pollset. */
  60         ret = lttng_poll_add(&events, apps_cmd_notify_pipe[0], LPOLLIN | LPOLLERR);
  61         if (ret < 0) {
  62                 goto error;
  63         }
  64
  65         health_code_update();
  66
  67         while (1) {
  68                 DBG3("[ust-thread] Manage notify polling");
  69
  70                 /* Inifinite blocking call, waiting for transmission */
  71 restart:
  72                 health_poll_entry();
  73                 ret = lttng_poll_wait(&events, -1);
  74                 DBG3("[ust-thread] Manage notify return from poll on %d fds",
  75                                 LTTNG_POLL_GETNB(&events));
  76                 health_poll_exit();
  77                 if (ret < 0) {
  78                         /*
  79                          * Restart interrupted system call.
  80                          */
  81                         if (errno == EINTR) {
  82                                 goto restart;
  83                         }
  84                         goto error;
  85                 }
  86
  87                 nb_fd = ret;
  88
  89                 for (i = 0; i < nb_fd; i++) {
  90                         health_code_update();
  91
  92                         /* Fetch once the poll data */
  93                         revents = LTTNG_POLL_GETEV(&events, i);
  94                         pollfd = LTTNG_POLL_GETFD(&events, i);
  95
  96                         if (!revents) {
  97                                 /* No activity for this FD (poll implementation). */
  98                                 continue;
  99                         }
 100
 101                         /* Thread quit pipe has been closed. Killing thread. */
 102                         ret = sessiond_check_thread_quit_pipe(pollfd, revents);
 103                         if (ret) {
 104                                 err = 0;
 105                                 goto exit;
 106                         }
 107
 108                         /* Inspect the apps cmd pipe */
 109                         if (pollfd == apps_cmd_notify_pipe[0]) {
 110                                 int sock;
 111
 112                                 if (revents & (LPOLLERR | LPOLLHUP | LPOLLRDHUP)) {
 113                                         ERR("Apps notify command pipe error");
 114                                         goto error;
 115                                 } else if (!(revents & LPOLLIN)) {
 116                                         /* No POLLIN and not a catched error, stop the thread. */
 117                                         ERR("Notify command pipe failed. revent: %u", revents);
 118                                         goto error;
 119                                 }
 120
 121                                 /* Get socket from dispatch thread. */
 122                                 size_ret = lttng_read(apps_cmd_notify_pipe[0],
 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 {
 146                                 /*
 147                                  * At this point, we know that a registered application
 148                                  * triggered the event.
 149                                  */
 150                                 if (revents & (LPOLLERR | LPOLLHUP | LPOLLRDHUP)) {
 151                                         /* Removing from the poll set */
 152                                         ret = lttng_poll_del(&events, pollfd);
 153                                         if (ret < 0) {
 154                                                 goto error;
 155                                         }
 156
 157                                         /* The socket is closed after a grace period here. */
 158                                         ust_app_notify_sock_unregister(pollfd);
 159                                 } else if (revents & (LPOLLIN | LPOLLPRI)) {
 160                                         ret = ust_app_recv_notify(pollfd);
 161                                         if (ret < 0) {
 162                                                 /*
 163                                                  * If the notification failed either the application is
 164                                                  * dead or an internal error happened. In both cases,
 165                                                  * we can only continue here. If the application is
 166                                                  * dead, an unregistration will follow or else the
 167                                                  * application will notice that we are not responding
 168                                                  * on that socket and will close it.
 169                                                  */
 170                                                 continue;
 171                                         }
 172                                 } else {
 173                                         ERR("Unknown poll events %u for sock %d", revents, pollfd);
 174                                         continue;
 175                                 }
 176                                 health_code_update();
 177                         }
 178                 }
 179         }
 180
 181 exit:
 182 error:
 183         lttng_poll_clean(&events);
 184 error_poll_create:
 185 error_testpoint:
 186         utils_close_pipe(apps_cmd_notify_pipe);
 187         apps_cmd_notify_pipe[0] = apps_cmd_notify_pipe[1] = -1;
 188         DBG("Application notify communication apps thread cleanup complete");
 189         if (err) {
 190                 health_error();
 191                 ERR("Health error occurred in %s", __func__);
 192         }
 193         health_unregister(health_sessiond);
 194         rcu_thread_offline();
 195         rcu_unregister_thread();
 196         return NULL;
 197 }