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