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                 goto error_testpoint;
  46         }
  47
  48         health_code_update();
  49
  50         ret = sessiond_set_ht_cleanup_thread_pollset(&events, 2);
  51         if (ret < 0) {
  52                 goto error_poll_create;
  53         }
  54
  55         /* Add pipe to the pollset. */
  56         ret = lttng_poll_add(&events, ht_cleanup_pipe[0], LPOLLIN | LPOLLERR);
  57         if (ret < 0) {
  58                 goto error;
  59         }
  60
  61         health_code_update();
  62
  63         while (1) {
  64                 int handled_event;
  65
  66                 DBG3("[ht-thread] Polling on %d fds.",
  67                         LTTNG_POLL_GETNB(&events));
  68
  69                 /* Inifinite blocking call, waiting for transmission */
  70 restart:
  71                 handled_event = 0;
  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                         struct lttng_ht *ht;
  89
  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 (pollfd != ht_cleanup_pipe[0]) {
  97                                 continue;
  98                         }
  99
 100                         if (revents & (LPOLLERR | LPOLLHUP | LPOLLRDHUP)) {
 101                                 ERR("ht cleanup pipe error");
 102                                 goto error;
 103                         } else if (!(revents & LPOLLIN)) {
 104                                 /* No POLLIN and not a catched error, stop the thread. */
 105                                 ERR("ht cleanup failed. revent: %u", revents);
 106                                 goto error;
 107                         }
 108
 109                         /* Get socket from dispatch thread. */
 110                         size_ret = lttng_read(ht_cleanup_pipe[0], &ht,
 111                                         sizeof(ht));
 112                         if (size_ret < sizeof(ht)) {
 113                                 PERROR("ht cleanup notify pipe");
 114                                 goto error;
 115                         }
 116                         health_code_update();
 117                         /*
 118                          * The whole point of this thread is to call
 119                          * lttng_ht_destroy from a context that is NOT:
 120                          * 1) a read-side RCU lock,
 121                          * 2) a call_rcu thread.
 122                          */
 123                         lttng_ht_destroy(ht);
 124
 125                         health_code_update();
 126                 }
 127
 128                 /* Only check cleanup quit when no more work to do. */
 129                 if (handled_event) {
 130                         continue;
 131                 }
 132
 133                 for (i = 0; i < nb_fd; i++) {
 134                         health_code_update();
 135
 136                         /* Fetch once the poll data */
 137                         revents = LTTNG_POLL_GETEV(&events, i);
 138                         pollfd = LTTNG_POLL_GETFD(&events, i);
 139
 140                         if (pollfd == ht_cleanup_pipe[0]) {
 141                                 continue;
 142                         }
 143
 144                         /* Thread quit pipe has been closed. Killing thread. */
 145                         ret = sessiond_check_ht_cleanup_quit(pollfd, revents);
 146                         if (ret) {
 147                                 err = 0;
 148                                 goto exit;
 149                         }
 150                 }
 151         }
 152
 153 exit:
 154 error:
 155         lttng_poll_clean(&events);
 156 error_poll_create:
 157 error_testpoint:
 158         DBG("[ht-cleanup] Thread terminates.");
 159         if (err) {
 160                 health_error();
 161                 ERR("Health error occurred in %s", __func__);
 162         }
 163         health_unregister(health_sessiond);
 164         rcu_thread_offline();
 165         rcu_unregister_thread();
 166         return NULL;
 167 }