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 #include <pthread.h>
  25
  26 #include "lttng-sessiond.h"
  27 #include "health-sessiond.h"
  28 #include "testpoint.h"
  29 #include "utils.h"
  30
  31 int ht_cleanup_quit_pipe[2] = { -1, -1 };
  32
  33 /*
  34  * Check if the ht_cleanup thread quit pipe was triggered.
  35  *
  36  * Return true if it was triggered else false;
  37  */
  38 static bool check_quit_pipe(int fd, uint32_t events)
  39 {
  40         return (fd == ht_cleanup_quit_pipe[0] && (events & LPOLLIN));
  41 }
  42
  43 static int init_pipe(int *pipe_fds)
  44 {
  45         int ret, i;
  46
  47         ret = pipe(pipe_fds);
  48         if (ret < 0) {
  49                 PERROR("ht_cleanup thread quit pipe");
  50                 goto error;
  51         }
  52
  53         for (i = 0; i < 2; i++) {
  54                 ret = fcntl(pipe_fds[i], F_SETFD, FD_CLOEXEC);
  55                 if (ret < 0) {
  56                         PERROR("fcntl ht_cleanup_quit_pipe");
  57                         goto error;
  58                 }
  59         }
  60 error:
  61         return ret;
  62 }
  63
  64 /*
  65  * Create a poll set with O_CLOEXEC and add the thread quit pipe to the set.
  66  */
  67 static int set_pollset(struct lttng_poll_event *events, size_t size)
  68 {
  69         int ret;
  70
  71         ret = lttng_poll_create(events, size, LTTNG_CLOEXEC);
  72         if (ret < 0) {
  73                 goto error;
  74         }
  75
  76         ret = lttng_poll_add(events, ht_cleanup_quit_pipe[0],
  77                         LPOLLIN | LPOLLERR);
  78         if (ret < 0) {
  79                 goto error;
  80         }
  81
  82         ret = lttng_poll_add(events, ht_cleanup_pipe[0], LPOLLIN | LPOLLERR);
  83         if (ret < 0) {
  84                 DBG("[ht-thread] lttng_poll_add error %d.", ret);
  85                 goto error;
  86         }
  87
  88         return 0;
  89
  90 error:
  91         return ret;
  92 }
  93
  94 static void *thread_ht_cleanup(void *data)
  95 {
  96         int ret, i, pollfd, err = -1;
  97         ssize_t size_ret;
  98         uint32_t revents, nb_fd;
  99         struct lttng_poll_event events;
 100
 101         DBG("[ht-thread] startup.");
 102
 103         rcu_register_thread();
 104         rcu_thread_online();
 105
 106         health_register(health_sessiond, HEALTH_SESSIOND_TYPE_HT_CLEANUP);
 107
 108         if (testpoint(sessiond_thread_ht_cleanup)) {
 109                 DBG("[ht-thread] testpoint.");
 110                 goto error_testpoint;
 111         }
 112
 113         health_code_update();
 114
 115         ret = set_pollset(&events, 2);
 116         if (ret < 0) {
 117                 DBG("[ht-thread] sessiond_set_ht_cleanup_thread_pollset error %d.", ret);
 118                 goto error_poll_create;
 119         }
 120
 121         health_code_update();
 122
 123         while (1) {
 124                 DBG3("[ht-thread] Polling.");
 125                 health_poll_entry();
 126                 ret = lttng_poll_wait(&events, -1);
 127                 DBG3("[ht-thread] Returning from poll on %d fds.",
 128                         LTTNG_POLL_GETNB(&events));
 129                 health_poll_exit();
 130                 if (ret < 0) {
 131                         /*
 132                          * Restart interrupted system call.
 133                          */
 134                         if (errno == EINTR) {
 135                                 continue;
 136                         }
 137                         goto error;
 138                 }
 139
 140                 nb_fd = ret;
 141                 for (i = 0; i < nb_fd; i++) {
 142                         struct lttng_ht *ht;
 143
 144                         health_code_update();
 145
 146                         /* Fetch once the poll data */
 147                         revents = LTTNG_POLL_GETEV(&events, i);
 148                         pollfd = LTTNG_POLL_GETFD(&events, i);
 149
 150                         if (!revents) {
 151                                 /* No activity for this FD (poll implementation). */
 152                                 continue;
 153                         }
 154
 155                         if (pollfd != ht_cleanup_pipe[0]) {
 156                                 continue;
 157                         }
 158
 159                         if (revents & LPOLLIN) {
 160                                 /* Get socket from dispatch thread. */
 161                                 size_ret = lttng_read(ht_cleanup_pipe[0], &ht,
 162                                                 sizeof(ht));
 163                                 if (size_ret < sizeof(ht)) {
 164                                         PERROR("ht cleanup notify pipe");
 165                                         goto error;
 166                                 }
 167                                 health_code_update();
 168                                 /*
 169                                  * The whole point of this thread is to call
 170                                  * lttng_ht_destroy from a context that is NOT:
 171                                  * 1) a read-side RCU lock,
 172                                  * 2) a call_rcu thread.
 173                                  */
 174                                 lttng_ht_destroy(ht);
 175
 176                                 health_code_update();
 177                         } else if (revents & (LPOLLERR | LPOLLHUP | LPOLLRDHUP)) {
 178                                 ERR("ht cleanup pipe error");
 179                                 goto error;
 180                         } else {
 181                                 ERR("Unexpected poll events %u for sock %d", revents, pollfd);
 182                                 goto error;
 183                         }
 184                 }
 185
 186                 for (i = 0; i < nb_fd; i++) {
 187                         health_code_update();
 188
 189                         /* Fetch once the poll data */
 190                         revents = LTTNG_POLL_GETEV(&events, i);
 191                         pollfd = LTTNG_POLL_GETFD(&events, i);
 192
 193                         if (!revents) {
 194                                 /* No activity for this FD (poll implementation). */
 195                                 continue;
 196                         }
 197
 198                         if (pollfd == ht_cleanup_pipe[0]) {
 199                                 continue;
 200                         }
 201
 202                         /* Thread quit pipe has been closed. Killing thread. */
 203                         ret = check_quit_pipe(pollfd, revents);
 204                         if (ret) {
 205                                 err = 0;
 206                                 DBG("[ht-cleanup] quit.");
 207                                 goto exit;
 208                         }
 209                 }
 210         }
 211
 212 exit:
 213 error:
 214         lttng_poll_clean(&events);
 215 error_poll_create:
 216 error_testpoint:
 217         DBG("[ht-cleanup] Thread terminates.");
 218         if (err) {
 219                 health_error();
 220                 ERR("Health error occurred in %s", __func__);
 221         }
 222         health_unregister(health_sessiond);
 223         rcu_thread_offline();
 224         rcu_unregister_thread();
 225         return NULL;
 226 }
 227
 228 int init_ht_cleanup_thread(pthread_t *thread)
 229 {
 230         int ret;
 231
 232         ret = init_pipe(ht_cleanup_pipe);
 233         if (ret) {
 234                 goto error;
 235         }
 236
 237         ret = init_pipe(ht_cleanup_quit_pipe);
 238         if (ret) {
 239                 goto error_quit_pipe;
 240         }
 241
 242         ret = pthread_create(thread, default_pthread_attr(), thread_ht_cleanup,
 243                         NULL);
 244         if (ret) {
 245                 errno = ret;
 246                 PERROR("pthread_create ht_cleanup");
 247                 goto error_thread;
 248         }
 249
 250 error:
 251         return ret;
 252
 253 error_thread:
 254         utils_close_pipe(ht_cleanup_quit_pipe);
 255 error_quit_pipe:
 256         utils_close_pipe(ht_cleanup_pipe);
 257         return ret;
 258 }
 259
 260 int fini_ht_cleanup_thread(pthread_t *thread)
 261 {
 262         int ret;
 263
 264         ret = notify_thread_pipe(ht_cleanup_quit_pipe[1]);
 265         if (ret < 0) {
 266                 ERR("write error on ht_cleanup quit pipe");
 267                 goto end;
 268         }
 269
 270         ret = pthread_join(*thread, NULL);
 271         if (ret) {
 272                 errno = ret;
 273                 PERROR("pthread_join ht cleanup thread");
 274         }
 275         utils_close_pipe(ht_cleanup_pipe);
 276         utils_close_pipe(ht_cleanup_quit_pipe);
 277 end:
 278         return ret;
 279 }