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 #include <assert.h>
  20
  21 #include <common/hashtable/hashtable.h>
  22 #include <common/common.h>
  23 #include <common/utils.h>
  24
  25 #include "lttng-sessiond.h"
  26 #include "health.h"
  27
  28 void *thread_ht_cleanup(void *data)
  29 {
  30         int ret, i, pollfd, err = -1;
  31         uint32_t revents, nb_fd;
  32         struct lttng_poll_event events;
  33
  34         DBG("[ht-thread] startup.");
  35
  36         rcu_register_thread();
  37         rcu_thread_online();
  38
  39         health_register(HEALTH_TYPE_HT_CLEANUP);
  40
  41         health_code_update();
  42
  43         ret = sessiond_set_thread_pollset(&events, 2);
  44         if (ret < 0) {
  45                 goto error_poll_create;
  46         }
  47
  48         /* Add pipe to the pollset. */
  49         ret = lttng_poll_add(&events, ht_cleanup_pipe[0], LPOLLIN | LPOLLERR);
  50         if (ret < 0) {
  51                 goto error;
  52         }
  53
  54         health_code_update();
  55
  56         while (1) {
  57                 DBG3("[ht-thread] Polling on %d fds.",
  58                         LTTNG_POLL_GETNB(&events));
  59
  60                 /* Inifinite blocking call, waiting for transmission */
  61 restart:
  62                 health_poll_entry();
  63                 ret = lttng_poll_wait(&events, -1);
  64                 health_poll_exit();
  65                 if (ret < 0) {
  66                         /*
  67                          * Restart interrupted system call.
  68                          */
  69                         if (errno == EINTR) {
  70                                 goto restart;
  71                         }
  72                         goto error;
  73                 }
  74
  75                 nb_fd = ret;
  76
  77                 for (i = 0; i < nb_fd; i++) {
  78                         struct lttng_ht *ht;
  79
  80                         health_code_update();
  81
  82                         /* Fetch once the poll data */
  83                         revents = LTTNG_POLL_GETEV(&events, i);
  84                         pollfd = LTTNG_POLL_GETFD(&events, i);
  85
  86                         /* Thread quit pipe has been closed. Killing thread. */
  87                         ret = sessiond_check_thread_quit_pipe(pollfd, revents);
  88                         if (ret) {
  89                                 err = 0;
  90                                 goto exit;
  91                         }
  92                         assert(pollfd == ht_cleanup_pipe[0]);
  93
  94                         if (revents & (LPOLLERR | LPOLLHUP | LPOLLRDHUP)) {
  95                                 ERR("ht cleanup pipe error");
  96                                 goto error;
  97                         } else if (!(revents & LPOLLIN)) {
  98                                 /* No POLLIN and not a catched error, stop the thread. */
  99                                 ERR("ht cleanup failed. revent: %u", revents);
 100                                 goto error;
 101                         }
 102
 103                         do {
 104                                 /* Get socket from dispatch thread. */
 105                                 ret = read(ht_cleanup_pipe[0], &ht, sizeof(ht));
 106                         } while (ret < 0 && errno == EINTR);
 107                         if (ret < 0 || ret < sizeof(ht)) {
 108                                 PERROR("ht cleanup notify pipe");
 109                                 goto error;
 110                         }
 111                         health_code_update();
 112                         /*
 113                          * The whole point of this thread is to call
 114                          * lttng_ht_destroy from a context that is NOT:
 115                          * 1) a read-side RCU lock,
 116                          * 2) a call_rcu thread.
 117                          */
 118                         lttng_ht_destroy(ht);
 119
 120                         health_code_update();
 121                 }
 122         }
 123
 124 exit:
 125 error:
 126         lttng_poll_clean(&events);
 127 error_poll_create:
 128         utils_close_pipe(ht_cleanup_pipe);
 129         ht_cleanup_pipe[0] = ht_cleanup_pipe[1] = -1;
 130         DBG("[ust-thread] cleanup complete.");
 131         if (err) {
 132                 health_error();
 133                 ERR("Health error occurred in %s", __func__);
 134         }
 135         health_unregister();
 136         rcu_thread_offline();
 137         rcu_unregister_thread();
 138         return NULL;
 139 }