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         restart:
 132                 DBG3("[ht-thread] Polling.");
 133                 health_poll_entry();
 134                 ret = lttng_poll_wait(&events, -1);
 135                 DBG3("[ht-thread] Returning from poll on %d fds.",
 136                         LTTNG_POLL_GETNB(&events));
 137                 health_poll_exit();
 138                 if (ret < 0) {
 139                         /*
 140                          * Restart interrupted system call.
 141                          */
 142                         if (errno == EINTR) {
 143                                 continue;
 144                         }
 145                         goto error;
 146                 }
 147
 148                 nb_fd = ret;
 149                 for (i = 0; i < nb_fd; i++) {
 150                         struct lttng_ht *ht;
 151
 152                         health_code_update();
 153
 154                         /* Fetch once the poll data */
 155                         revents = LTTNG_POLL_GETEV(&events, i);
 156                         pollfd = LTTNG_POLL_GETFD(&events, i);
 157
 158                         if (pollfd != ht_cleanup_pipe[0]) {
 159                                 continue;
 160                         }
 161
 162                         if (revents & LPOLLIN) {
 163                                 /* Get socket from dispatch thread. */
 164                                 size_ret = lttng_read(ht_cleanup_pipe[0], &ht,
 165                                                 sizeof(ht));
 166                                 if (size_ret < sizeof(ht)) {
 167                                         PERROR("ht cleanup notify pipe");
 168                                         goto error;
 169                                 }
 170                                 health_code_update();
 171                                 /*
 172                                  * The whole point of this thread is to call
 173                                  * lttng_ht_destroy from a context that is NOT:
 174                                  * 1) a read-side RCU lock,
 175                                  * 2) a call_rcu thread.
 176                                  */
 177                                 lttng_ht_destroy(ht);
 178
 179                                 health_code_update();
 180
 181                                 /*
 182                                  * Ensure that we never process the quit pipe
 183                                  * event while there is still data available
 184                                  * on the ht clean pipe.
 185                                  */
 186                                 goto restart;
 187                         } else if (revents & (LPOLLERR | LPOLLHUP | LPOLLRDHUP)) {
 188                                 ERR("ht cleanup pipe error");
 189                                 goto error;
 190                         } else {
 191                                 ERR("Unexpected poll events %u for sock %d", revents, pollfd);
 192                                 goto error;
 193                         }
 194                 }
 195
 196                 for (i = 0; i < nb_fd; i++) {
 197                         health_code_update();
 198
 199                         /* Fetch once the poll data */
 200                         revents = LTTNG_POLL_GETEV(&events, i);
 201                         pollfd = LTTNG_POLL_GETFD(&events, i);
 202
 203                         if (!revents) {
 204                                 /* No activity for this FD (poll implementation). */
 205                                 continue;
 206                         }
 207
 208                         if (pollfd == ht_cleanup_pipe[0]) {
 209                                 continue;
 210                         }
 211
 212                         /* Thread quit pipe has been closed. Killing thread. */
 213                         ret = check_quit_pipe(pollfd, revents);
 214                         if (ret) {
 215                                 err = 0;
 216                                 DBG("[ht-cleanup] quit.");
 217                                 goto exit;
 218                         }
 219                 }
 220         }
 221
 222 exit:
 223 error:
 224         lttng_poll_clean(&events);
 225 error_poll_create:
 226 error_testpoint:
 227         DBG("[ht-cleanup] Thread terminates.");
 228         if (err) {
 229                 health_error();
 230                 ERR("Health error occurred in %s", __func__);
 231         }
 232         health_unregister(health_sessiond);
 233         rcu_thread_offline();
 234         rcu_unregister_thread();
 235         return NULL;
 236 }
 237
 238 static bool shutdown_ht_cleanup_thread(void *data)
 239 {
 240         int ret;
 241
 242         ret = notify_thread_pipe(ht_cleanup_quit_pipe[1]);
 243         if (ret < 0) {
 244                 ERR("write error on ht_cleanup quit pipe");
 245                 goto end;
 246         }
 247 end:
 248         return ret;
 249 }
 250
 251 struct lttng_thread *launch_ht_cleanup_thread(void)
 252 {
 253         int ret;
 254         struct lttng_thread *thread;
 255
 256         ret = init_pipe(ht_cleanup_pipe);
 257         if (ret) {
 258                 goto error;
 259         }
 260
 261         ret = init_pipe(ht_cleanup_quit_pipe);
 262         if (ret) {
 263                 goto error;
 264         }
 265
 266         thread = lttng_thread_create("HT cleanup",
 267                         thread_ht_cleanup,
 268                         shutdown_ht_cleanup_thread,
 269                         cleanup_ht_cleanup_thread,
 270                         NULL);
 271         if (!thread) {
 272                 goto error;
 273         }
 274         return thread;
 275 error:
 276         cleanup_ht_cleanup_thread(NULL);
 277         return NULL;
 278 }