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_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                 DBG3("[ht-thread] Polling on %d fds.",
  65                         LTTNG_POLL_GETNB(&events));
  66
  67                 /* Inifinite blocking call, waiting for transmission */
  68 restart:
  69                 health_poll_entry();
  70                 ret = lttng_poll_wait(&events, -1);
  71                 health_poll_exit();
  72                 if (ret < 0) {
  73                         /*
  74                          * Restart interrupted system call.
  75                          */
  76                         if (errno == EINTR) {
  77                                 goto restart;
  78                         }
  79                         goto error;
  80                 }
  81
  82                 nb_fd = ret;
  83
  84                 for (i = 0; i < nb_fd; i++) {
  85                         struct lttng_ht *ht;
  86
  87                         health_code_update();
  88
  89                         /* Fetch once the poll data */
  90                         revents = LTTNG_POLL_GETEV(&events, i);
  91                         pollfd = LTTNG_POLL_GETFD(&events, i);
  92
  93                         /* Thread quit pipe has been closed. Killing thread. */
  94                         ret = sessiond_check_thread_quit_pipe(pollfd, revents);
  95                         if (ret) {
  96                                 err = 0;
  97                                 goto exit;
  98                         }
  99                         assert(pollfd == ht_cleanup_pipe[0]);
 100
 101                         if (revents & (LPOLLERR | LPOLLHUP | LPOLLRDHUP)) {
 102                                 ERR("ht cleanup pipe error");
 103                                 goto error;
 104                         } else if (!(revents & LPOLLIN)) {
 105                                 /* No POLLIN and not a catched error, stop the thread. */
 106                                 ERR("ht cleanup failed. revent: %u", revents);
 107                                 goto error;
 108                         }
 109
 110                         /* Get socket from dispatch thread. */
 111                         size_ret = lttng_read(ht_cleanup_pipe[0], &ht,
 112                                         sizeof(ht));
 113                         if (size_ret < sizeof(ht)) {
 114                                 PERROR("ht cleanup notify pipe");
 115                                 goto error;
 116                         }
 117                         health_code_update();
 118                         /*
 119                          * The whole point of this thread is to call
 120                          * lttng_ht_destroy from a context that is NOT:
 121                          * 1) a read-side RCU lock,
 122                          * 2) a call_rcu thread.
 123                          */
 124                         lttng_ht_destroy(ht);
 125
 126                         health_code_update();
 127                 }
 128         }
 129
 130 exit:
 131 error:
 132         lttng_poll_clean(&events);
 133 error_poll_create:
 134 error_testpoint:
 135         utils_close_pipe(ht_cleanup_pipe);
 136         ht_cleanup_pipe[0] = ht_cleanup_pipe[1] = -1;
 137         DBG("[ust-thread] cleanup complete.");
 138         if (err) {
 139                 health_error();
 140                 ERR("Health error occurred in %s", __func__);
 141         }
 142         health_unregister(health_sessiond);
 143         rcu_thread_offline();
 144         rcu_unregister_thread();
 145         return NULL;
 146 }