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 _LGPL_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                 DBG("[ht-thread] testpoint.");
  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                 DBG("[ht-thread] sessiond_set_ht_cleanup_thread_pollset error %d.", ret);
  53                 goto error_poll_create;
  54         }
  55
  56         /* Add pipe to the pollset. */
  57         ret = lttng_poll_add(&events, ht_cleanup_pipe[0], LPOLLIN | LPOLLERR);
  58         if (ret < 0) {
  59                 DBG("[ht-thread] lttng_poll_add error %d.", ret);
  60                 goto error;
  61         }
  62
  63         health_code_update();
  64
  65         while (1) {
  66                 DBG3("[ht-thread] Polling.");
  67
  68                 /* Inifinite blocking call, waiting for transmission */
  69 restart:
  70                 health_poll_entry();
  71                 ret = lttng_poll_wait(&events, -1);
  72                 DBG3("[ht-thread] Returning from poll on %d fds.",
  73                         LTTNG_POLL_GETNB(&events));
  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 (!revents) {
  97                                 /* No activity for this FD (poll implementation). */
  98                                 continue;
  99                         }
 100
 101                         if (pollfd != ht_cleanup_pipe[0]) {
 102                                 continue;
 103                         }
 104
 105                         if (revents & LPOLLIN) {
 106                                 /* Get socket from dispatch thread. */
 107                                 size_ret = lttng_read(ht_cleanup_pipe[0], &ht,
 108                                                 sizeof(ht));
 109                                 if (size_ret < sizeof(ht)) {
 110                                         PERROR("ht cleanup notify pipe");
 111                                         goto error;
 112                                 }
 113                                 health_code_update();
 114                                 /*
 115                                  * The whole point of this thread is to call
 116                                  * lttng_ht_destroy from a context that is NOT:
 117                                  * 1) a read-side RCU lock,
 118                                  * 2) a call_rcu thread.
 119                                  */
 120                                 lttng_ht_destroy(ht);
 121
 122                                 health_code_update();
 123                         } else if (revents & (LPOLLERR | LPOLLHUP | LPOLLRDHUP)) {
 124                                 ERR("ht cleanup pipe error");
 125                                 goto error;
 126                         } else {
 127                                 ERR("Unexpected poll events %u for sock %d", revents, pollfd);
 128                                 goto error;
 129                         }
 130                 }
 131
 132                 for (i = 0; i < nb_fd; i++) {
 133                         health_code_update();
 134
 135                         /* Fetch once the poll data */
 136                         revents = LTTNG_POLL_GETEV(&events, i);
 137                         pollfd = LTTNG_POLL_GETFD(&events, i);
 138
 139                         if (!revents) {
 140                                 /* No activity for this FD (poll implementation). */
 141                                 continue;
 142                         }
 143
 144                         if (pollfd == ht_cleanup_pipe[0]) {
 145                                 continue;
 146                         }
 147
 148                         /* Thread quit pipe has been closed. Killing thread. */
 149                         ret = sessiond_check_ht_cleanup_quit(pollfd, revents);
 150                         if (ret) {
 151                                 err = 0;
 152                                 DBG("[ht-cleanup] quit.");
 153                                 goto exit;
 154                         }
 155                 }
 156         }
 157
 158 exit:
 159 error:
 160         lttng_poll_clean(&events);
 161 error_poll_create:
 162 error_testpoint:
 163         DBG("[ht-cleanup] Thread terminates.");
 164         if (err) {
 165                 health_error();
 166                 ERR("Health error occurred in %s", __func__);
 167         }
 168         health_unregister(health_sessiond);
 169         rcu_thread_offline();
 170         rcu_unregister_thread();
 171         return NULL;
 172 }