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-sessiond.h"
  27 #include "testpoint.h"
  28
  29 void *thread_ht_cleanup(void *data)
  30 {
  31         int ret, i, pollfd, err = -1;
  32         ssize_t size_ret;
  33         uint32_t revents, nb_fd;
  34         struct lttng_poll_event events;
  35
  36         DBG("[ht-thread] startup.");
  37
  38         rcu_register_thread();
  39         rcu_thread_online();
  40
  41         health_register(health_sessiond, HEALTH_SESSIOND_TYPE_HT_CLEANUP);
  42
  43         if (testpoint(sessiond_thread_ht_cleanup)) {
  44                 goto error_testpoint;
  45         }
  46
  47         health_code_update();
  48
  49         ret = sessiond_set_thread_pollset(&events, 2);
  50         if (ret < 0) {
  51                 goto error_poll_create;
  52         }
  53
  54         /* Add pipe to the pollset. */
  55         ret = lttng_poll_add(&events, ht_cleanup_pipe[0], LPOLLIN | LPOLLERR);
  56         if (ret < 0) {
  57                 goto error;
  58         }
  59
  60         health_code_update();
  61
  62         while (1) {
  63                 DBG3("[ht-thread] Polling on %d fds.",
  64                         LTTNG_POLL_GETNB(&events));
  65
  66                 /* Inifinite blocking call, waiting for transmission */
  67 restart:
  68                 health_poll_entry();
  69                 ret = lttng_poll_wait(&events, -1);
  70                 health_poll_exit();
  71                 if (ret < 0) {
  72                         /*
  73                          * Restart interrupted system call.
  74                          */
  75                         if (errno == EINTR) {
  76                                 goto restart;
  77                         }
  78                         goto error;
  79                 }
  80
  81                 nb_fd = ret;
  82
  83                 for (i = 0; i < nb_fd; i++) {
  84                         struct lttng_ht *ht;
  85
  86                         health_code_update();
  87
  88                         /* Fetch once the poll data */
  89                         revents = LTTNG_POLL_GETEV(&events, i);
  90                         pollfd = LTTNG_POLL_GETFD(&events, i);
  91
  92                         /* Thread quit pipe has been closed. Killing thread. */
  93                         ret = sessiond_check_thread_quit_pipe(pollfd, revents);
  94                         if (ret) {
  95                                 err = 0;
  96                                 goto exit;
  97                         }
  98                         assert(pollfd == ht_cleanup_pipe[0]);
  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
 129 exit:
 130 error:
 131         lttng_poll_clean(&events);
 132 error_poll_create:
 133 error_testpoint:
 134         utils_close_pipe(ht_cleanup_pipe);
 135         ht_cleanup_pipe[0] = ht_cleanup_pipe[1] = -1;
 136         DBG("[ust-thread] cleanup complete.");
 137         if (err) {
 138                 health_error();
 139                 ERR("Health error occurred in %s", __func__);
 140         }
 141         health_unregister(health_sessiond);
 142         rcu_thread_offline();
 143         rcu_unregister_thread();
 144         return NULL;
 145 }