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.h"
  27
  28 /*
  29  * This thread manage application notify communication.
  30  */
  31 void *ust_thread_manage_notify(void *data)
  32 {
  33         int i, ret, pollfd, err = -1;
  34         uint32_t revents, nb_fd;
  35         struct lttng_poll_event events;
  36
  37         DBG("[ust-thread] Manage application notify command");
  38
  39         rcu_register_thread();
  40         rcu_thread_online();
  41
  42         health_register(HEALTH_TYPE_APP_MANAGE_NOTIFY);
  43
  44         health_code_update();
  45
  46         ret = sessiond_set_thread_pollset(&events, 2);
  47         if (ret < 0) {
  48                 goto error_poll_create;
  49         }
  50
  51         /* Add notify pipe to the pollset. */
  52         ret = lttng_poll_add(&events, apps_cmd_notify_pipe[0], LPOLLIN | LPOLLERR);
  53         if (ret < 0) {
  54                 goto error;
  55         }
  56
  57         health_code_update();
  58
  59         while (1) {
  60                 DBG3("[ust-thread] Manage notify polling on %d fds",
  61                                 LTTNG_POLL_GETNB(&events));
  62
  63                 /* Inifinite blocking call, waiting for transmission */
  64 restart:
  65                 health_poll_entry();
  66                 ret = lttng_poll_wait(&events, -1);
  67                 health_poll_exit();
  68                 if (ret < 0) {
  69                         /*
  70                          * Restart interrupted system call.
  71                          */
  72                         if (errno == EINTR) {
  73                                 goto restart;
  74                         }
  75                         goto error;
  76                 }
  77
  78                 nb_fd = ret;
  79
  80                 for (i = 0; i < nb_fd; i++) {
  81                         health_code_update();
  82
  83                         /* Fetch once the poll data */
  84                         revents = LTTNG_POLL_GETEV(&events, i);
  85                         pollfd = LTTNG_POLL_GETFD(&events, i);
  86
  87                         /* Thread quit pipe has been closed. Killing thread. */
  88                         ret = sessiond_check_thread_quit_pipe(pollfd, revents);
  89                         if (ret) {
  90                                 err = 0;
  91                                 goto exit;
  92                         }
  93
  94                         /* Inspect the apps cmd pipe */
  95                         if (pollfd == apps_cmd_notify_pipe[0]) {
  96                                 int sock;
  97
  98                                 if (revents & (LPOLLERR | LPOLLHUP | LPOLLRDHUP)) {
  99                                         ERR("Apps notify command pipe error");
 100                                         goto error;
 101                                 } else if (!(revents & LPOLLIN)) {
 102                                         /* No POLLIN and not a catched error, stop the thread. */
 103                                         ERR("Notify command pipe failed. revent: %u", revents);
 104                                         goto error;
 105                                 }
 106
 107                                 do {
 108                                         /* Get socket from dispatch thread. */
 109                                         ret = read(apps_cmd_notify_pipe[0], &sock, sizeof(sock));
 110                                 } while (ret < 0 && errno == EINTR);
 111                                 if (ret < 0 || ret < sizeof(sock)) {
 112                                         PERROR("read apps notify pipe");
 113                                         goto error;
 114                                 }
 115                                 health_code_update();
 116
 117                                 ret = lttng_poll_add(&events, sock,
 118                                                 LPOLLIN | LPOLLERR | LPOLLHUP | LPOLLRDHUP);
 119                                 if (ret < 0) {
 120                                         /*
 121                                          * It's possible we've reached the max poll fd allowed.
 122                                          * Let's close the socket but continue normal execution.
 123                                          */
 124                                         ret = close(sock);
 125                                         if (ret) {
 126                                                 PERROR("close notify socket %d", sock);
 127                                         }
 128                                         lttng_fd_put(LTTNG_FD_APPS, 1);
 129                                         continue;
 130                                 }
 131                                 DBG3("UST thread notify added sock %d to pollset", sock);
 132                         } else {
 133                                 /*
 134                                  * At this point, we know that a registered application
 135                                  * triggered the event.
 136                                  */
 137                                 if (revents & (LPOLLERR | LPOLLHUP | LPOLLRDHUP)) {
 138                                         /* Removing from the poll set */
 139                                         ret = lttng_poll_del(&events, pollfd);
 140                                         if (ret < 0) {
 141                                                 goto error;
 142                                         }
 143
 144                                         /* The socket is closed after a grace period here. */
 145                                         ust_app_notify_sock_unregister(pollfd);
 146                                 } else if (revents & (LPOLLIN | LPOLLPRI)) {
 147                                         ret = ust_app_recv_notify(pollfd);
 148                                         if (ret < 0) {
 149                                                 /*
 150                                                  * If the notification failed either the application is
 151                                                  * dead or an internal error happened. In both cases,
 152                                                  * we can only continue here. If the application is
 153                                                  * dead, an unregistration will follow or else the
 154                                                  * application will notice that we are not responding
 155                                                  * on that socket and will close it.
 156                                                  */
 157                                                 continue;
 158                                         }
 159                                 } else {
 160                                         ERR("Unknown poll events %u for sock %d", revents, pollfd);
 161                                         continue;
 162                                 }
 163                                 health_code_update();
 164                         }
 165                 }
 166         }
 167
 168 exit:
 169 error:
 170         lttng_poll_clean(&events);
 171 error_poll_create:
 172         utils_close_pipe(apps_cmd_notify_pipe);
 173         apps_cmd_notify_pipe[0] = apps_cmd_notify_pipe[1] = -1;
 174         DBG("Application notify communication apps thread cleanup complete");
 175         if (err) {
 176                 health_error();
 177                 ERR("Health error occurred in %s", __func__);
 178         }
 179         health_unregister();
 180         rcu_thread_offline();
 181         rcu_unregister_thread();
 182         return NULL;
 183 }