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.");
  64
  65                 /* Inifinite blocking call, waiting for transmission */
  66 restart:
  67                 health_poll_entry();
  68                 ret = lttng_poll_wait(&events, -1);
  69                 DBG3("[ht-thread] Returning from poll on %d fds.",
  70                         LTTNG_POLL_GETNB(&events));
  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                         if (!revents) {
  94                                 /*
  95                                  * No activity for this FD
  96                                  * (poll implementation).
  97                                  */
  98                                 continue;
  99                         }
 100
 101                         /* Thread quit pipe has been closed. Killing thread. */
 102                         ret = sessiond_check_thread_quit_pipe(pollfd, revents);
 103                         if (ret) {
 104                                 err = 0;
 105                                 goto exit;
 106                         }
 107                         assert(pollfd == ht_cleanup_pipe[0]);
 108
 109                         if (revents & (LPOLLERR | LPOLLHUP | LPOLLRDHUP)) {
 110                                 ERR("ht cleanup pipe error");
 111                                 goto error;
 112                         } else if (!(revents & LPOLLIN)) {
 113                                 /* No POLLIN and not a catched error, stop the thread. */
 114                                 ERR("ht cleanup failed. revent: %u", revents);
 115                                 goto error;
 116                         }
 117
 118                         /* Get socket from dispatch thread. */
 119                         size_ret = lttng_read(ht_cleanup_pipe[0], &ht,
 120                                         sizeof(ht));
 121                         if (size_ret < sizeof(ht)) {
 122                                 PERROR("ht cleanup notify pipe");
 123                                 goto error;
 124                         }
 125                         health_code_update();
 126                         /*
 127                          * The whole point of this thread is to call
 128                          * lttng_ht_destroy from a context that is NOT:
 129                          * 1) a read-side RCU lock,
 130                          * 2) a call_rcu thread.
 131                          */
 132                         lttng_ht_destroy(ht);
 133
 134                         health_code_update();
 135                 }
 136         }
 137
 138 exit:
 139 error:
 140         lttng_poll_clean(&events);
 141 error_poll_create:
 142 error_testpoint:
 143         utils_close_pipe(ht_cleanup_pipe);
 144         ht_cleanup_pipe[0] = ht_cleanup_pipe[1] = -1;
 145         DBG("[ust-thread] cleanup complete.");
 146         if (err) {
 147                 health_error();
 148                 ERR("Health error occurred in %s", __func__);
 149         }
 150         health_unregister(health_sessiond);
 151         rcu_thread_offline();
 152         rcu_unregister_thread();
 153         return NULL;
 154 }