src/bin/lttng-sessiond/ht-cleanup.c

   1 /*
   2  * Copyright (C) 2013 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License, version 2 only,
   6  * as published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  11  * GNU General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public License along
  14  * with this program; if not, write to the Free Software Foundation, Inc.,
  15  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  16  */
  17
  18 #define _GNU_SOURCE
  19 #define _LGPL_SOURCE
  20 #include <assert.h>
  21
  22 #include <common/hashtable/hashtable.h>
  23 #include <common/common.h>
  24 #include <common/utils.h>
  25
  26 #include "lttng-sessiond.h"
  27 #include "health-sessiond.h"
  28 #include "testpoint.h"
  29
  30 void *thread_ht_cleanup(void *data)
  31 {
  32         int ret, i, pollfd, err = -1;
  33         ssize_t size_ret;
  34         uint32_t revents, nb_fd;
  35         struct lttng_poll_event events;
  36
  37         DBG("[ht-thread] startup.");
  38
  39         rcu_register_thread();
  40         rcu_thread_online();
  41
  42         health_register(health_sessiond, HEALTH_SESSIOND_TYPE_HT_CLEANUP);
  43
  44         if (testpoint(sessiond_thread_ht_cleanup)) {
  45                 DBG("[ht-thread] testpoint.");
  46                 goto error_testpoint;
  47         }
  48
  49         health_code_update();
  50
  51         ret = sessiond_set_ht_cleanup_thread_pollset(&events, 2);
  52         if (ret < 0) {
  53                 DBG("[ht-thread] sessiond_set_ht_cleanup_thread_pollset error %d.", ret);
  54                 goto error_poll_create;
  55         }
  56
  57         /* Add pipe to the pollset. */
  58         ret = lttng_poll_add(&events, ht_cleanup_pipe[0], LPOLLIN | LPOLLERR);
  59         if (ret < 0) {
  60                 DBG("[ht-thread] lttng_poll_add error %d.", ret);
  61                 goto error;
  62         }
  63
  64         health_code_update();
  65
  66         while (1) {
  67                 int handled_event;
  68
  69                 DBG3("[ht-thread] Polling on %d fds.",
  70                         LTTNG_POLL_GETNB(&events));
  71
  72                 /* Inifinite blocking call, waiting for transmission */
  73 restart:
  74                 handled_event = 0;
  75                 health_poll_entry();
  76                 ret = lttng_poll_wait(&events, -1);
  77                 health_poll_exit();
  78                 if (ret < 0) {
  79                         /*
  80                          * Restart interrupted system call.
  81                          */
  82                         if (errno == EINTR) {
  83                                 goto restart;
  84                         }
  85                         goto error;
  86                 }
  87
  88                 nb_fd = ret;
  89
  90                 for (i = 0; i < nb_fd; i++) {
  91                         struct lttng_ht *ht;
  92
  93                         health_code_update();
  94
  95                         /* Fetch once the poll data */
  96                         revents = LTTNG_POLL_GETEV(&events, i);
  97                         pollfd = LTTNG_POLL_GETFD(&events, i);
  98
  99                         if (!revents) {
 100                                 /* No activity for this FD (poll implementation). */
 101                                 continue;
 102                         }
 103
 104                         if (pollfd != ht_cleanup_pipe[0]) {
 105                                 continue;
 106                         }
 107
 108                         if (revents & (LPOLLERR | LPOLLHUP | LPOLLRDHUP)) {
 109                                 ERR("ht cleanup pipe error");
 110                                 goto error;
 111                         } else if (!(revents & LPOLLIN)) {
 112                                 /* No POLLIN and not a catched error, stop the thread. */
 113                                 ERR("ht cleanup failed. revent: %u", revents);
 114                                 goto error;
 115                         }
 116
 117                         /* Get socket from dispatch thread. */
 118                         size_ret = lttng_read(ht_cleanup_pipe[0], &ht,
 119                                         sizeof(ht));
 120                         if (size_ret < sizeof(ht)) {
 121                                 PERROR("ht cleanup notify pipe");
 122                                 goto error;
 123                         }
 124                         health_code_update();
 125                         /*
 126                          * The whole point of this thread is to call
 127                          * lttng_ht_destroy from a context that is NOT:
 128                          * 1) a read-side RCU lock,
 129                          * 2) a call_rcu thread.
 130                          */
 131                         lttng_ht_destroy(ht);
 132
 133                         health_code_update();
 134                 }
 135
 136                 /* Only check cleanup quit when no more work to do. */
 137                 if (handled_event) {
 138                         continue;
 139                 }
 140
 141                 for (i = 0; i < nb_fd; i++) {
 142                         health_code_update();
 143
 144                         /* Fetch once the poll data */
 145                         revents = LTTNG_POLL_GETEV(&events, i);
 146                         pollfd = LTTNG_POLL_GETFD(&events, i);
 147
 148                         if (!revents) {
 149                                 /* No activity for this FD (poll implementation). */
 150                                 continue;
 151                         }
 152
 153                         if (pollfd == ht_cleanup_pipe[0]) {
 154                                 continue;
 155                         }
 156
 157                         /* Thread quit pipe has been closed. Killing thread. */
 158                         ret = sessiond_check_ht_cleanup_quit(pollfd, revents);
 159                         if (ret) {
 160                                 err = 0;
 161                                 DBG("[ht-cleanup] quit.");
 162                                 goto exit;
 163                         }
 164                 }
 165         }
 166
 167 exit:
 168 error:
 169         lttng_poll_clean(&events);
 170 error_poll_create:
 171 error_testpoint:
 172         DBG("[ht-cleanup] Thread terminates.");
 173         if (err) {
 174                 health_error();
 175                 ERR("Health error occurred in %s", __func__);
 176         }
 177         health_unregister(health_sessiond);
 178         rcu_thread_offline();
 179         rcu_unregister_thread();
 180         return NULL;
 181 }