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                 DBG("[ht-thread] testpoint.");
  46                 goto error_testpoint;
  47         }
  48
  49         health_code_update();
  50
  51         ret = sessiond_set_ht_cleanup_thread_pollset(&events, 2);
  52         if (ret < 0) {
  53                 DBG("[ht-thread] sessiond_set_ht_cleanup_thread_pollset error %d.", ret);
  54                 goto error_poll_create;
  55         }
  56
  57         /* Add pipe to the pollset. */
  58         ret = lttng_poll_add(&events, ht_cleanup_pipe[0], LPOLLIN | LPOLLERR);
  59         if (ret < 0) {
  60                 DBG("[ht-thread] lttng_poll_add error %d.", ret);
  61                 goto error;
  62         }
  63
  64         health_code_update();
  65
  66         while (1) {
  67                 int handled_event;
  68
  69                 DBG3("[ht-thread] Polling.");
  70
  71                 /* Inifinite blocking call, waiting for transmission */
  72 restart:
  73                 handled_event = 0;
  74                 health_poll_entry();
  75                 ret = lttng_poll_wait(&events, -1);
  76                 DBG3("[ht-thread] Returning from poll on %d fds.",
  77                         LTTNG_POLL_GETNB(&events));
  78                 health_poll_exit();
  79                 if (ret < 0) {
  80                         /*
  81                          * Restart interrupted system call.
  82                          */
  83                         if (errno == EINTR) {
  84                                 goto restart;
  85                         }
  86                         goto error;
  87                 }
  88
  89                 nb_fd = ret;
  90
  91                 for (i = 0; i < nb_fd; i++) {
  92                         struct lttng_ht *ht;
  93
  94                         health_code_update();
  95
  96                         /* Fetch once the poll data */
  97                         revents = LTTNG_POLL_GETEV(&events, i);
  98                         pollfd = LTTNG_POLL_GETFD(&events, i);
  99
 100                         if (!revents) {
 101                                 /* No activity for this FD (poll implementation). */
 102                                 continue;
 103                         }
 104
 105                         if (pollfd != ht_cleanup_pipe[0]) {
 106                                 continue;
 107                         }
 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                 /* Only check cleanup quit when no more work to do. */
 138                 if (handled_event) {
 139                         continue;
 140                 }
 141
 142                 for (i = 0; i < nb_fd; i++) {
 143                         health_code_update();
 144
 145                         /* Fetch once the poll data */
 146                         revents = LTTNG_POLL_GETEV(&events, i);
 147                         pollfd = LTTNG_POLL_GETFD(&events, i);
 148
 149                         if (!revents) {
 150                                 /* No activity for this FD (poll implementation). */
 151                                 continue;
 152                         }
 153
 154                         if (pollfd == ht_cleanup_pipe[0]) {
 155                                 continue;
 156                         }
 157
 158                         /* Thread quit pipe has been closed. Killing thread. */
 159                         ret = sessiond_check_ht_cleanup_quit(pollfd, revents);
 160                         if (ret) {
 161                                 err = 0;
 162                                 DBG("[ht-cleanup] quit.");
 163                                 goto exit;
 164                         }
 165                 }
 166         }
 167
 168 exit:
 169 error:
 170         lttng_poll_clean(&events);
 171 error_poll_create:
 172 error_testpoint:
 173         DBG("[ht-cleanup] Thread terminates.");
 174         if (err) {
 175                 health_error();
 176                 ERR("Health error occurred in %s", __func__);
 177         }
 178         health_unregister(health_sessiond);
 179         rcu_thread_offline();
 180         rcu_unregister_thread();
 181         return NULL;
 182 }