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 (!revents) {
 159                                 /* No activity for this FD (poll implementation). */
 160                                 continue;
 161                         }
 162
 163                         if (pollfd != ht_cleanup_pipe[0]) {
 164                                 continue;
 165                         }
 166
 167                         if (revents & LPOLLIN) {
 168                                 /* Get socket from dispatch thread. */
 169                                 size_ret = lttng_read(ht_cleanup_pipe[0], &ht,
 170                                                 sizeof(ht));
 171                                 if (size_ret < sizeof(ht)) {
 172                                         PERROR("ht cleanup notify pipe");
 173                                         goto error;
 174                                 }
 175                                 health_code_update();
 176                                 /*
 177                                  * The whole point of this thread is to call
 178                                  * lttng_ht_destroy from a context that is NOT:
 179                                  * 1) a read-side RCU lock,
 180                                  * 2) a call_rcu thread.
 181                                  */
 182                                 lttng_ht_destroy(ht);
 183
 184                                 health_code_update();
 185
 186                                 /*
 187                                  * Ensure that we never process the quit pipe
 188                                  * event while there is still data available
 189                                  * on the ht clean pipe.
 190                                  */
 191                                 goto restart;
 192                         } else if (revents & (LPOLLERR | LPOLLHUP | LPOLLRDHUP)) {
 193                                 ERR("ht cleanup pipe error");
 194                                 goto error;
 195                         } else {
 196                                 ERR("Unexpected poll events %u for sock %d", revents, pollfd);
 197                                 goto error;
 198                         }
 199                 }
 200
 201                 for (i = 0; i < nb_fd; i++) {
 202                         health_code_update();
 203
 204                         /* Fetch once the poll data */
 205                         revents = LTTNG_POLL_GETEV(&events, i);
 206                         pollfd = LTTNG_POLL_GETFD(&events, i);
 207
 208                         if (!revents) {
 209                                 /* No activity for this FD (poll implementation). */
 210                                 continue;
 211                         }
 212
 213                         if (pollfd == ht_cleanup_pipe[0]) {
 214                                 continue;
 215                         }
 216
 217                         /* Thread quit pipe has been closed. Killing thread. */
 218                         ret = check_quit_pipe(pollfd, revents);
 219                         if (ret) {
 220                                 err = 0;
 221                                 DBG("[ht-cleanup] quit.");
 222                                 goto exit;
 223                         }
 224                 }
 225         }
 226
 227 exit:
 228 error:
 229         lttng_poll_clean(&events);
 230 error_poll_create:
 231 error_testpoint:
 232         DBG("[ht-cleanup] Thread terminates.");
 233         if (err) {
 234                 health_error();
 235                 ERR("Health error occurred in %s", __func__);
 236         }
 237         health_unregister(health_sessiond);
 238         rcu_thread_offline();
 239         rcu_unregister_thread();
 240         return NULL;
 241 }
 242
 243 static bool shutdown_ht_cleanup_thread(void *data)
 244 {
 245         int ret;
 246
 247         ret = notify_thread_pipe(ht_cleanup_quit_pipe[1]);
 248         if (ret < 0) {
 249                 ERR("write error on ht_cleanup quit pipe");
 250                 goto end;
 251         }
 252 end:
 253         return ret;
 254 }
 255
 256 struct lttng_thread *launch_ht_cleanup_thread(void)
 257 {
 258         int ret;
 259         struct lttng_thread *thread;
 260
 261         ret = init_pipe(ht_cleanup_pipe);
 262         if (ret) {
 263                 goto error;
 264         }
 265
 266         ret = init_pipe(ht_cleanup_quit_pipe);
 267         if (ret) {
 268                 goto error;
 269         }
 270
 271         thread = lttng_thread_create("HT cleanup",
 272                         thread_ht_cleanup,
 273                         shutdown_ht_cleanup_thread,
 274                         cleanup_ht_cleanup_thread,
 275                         NULL);
 276         if (!thread) {
 277                 ret = -1;
 278                 goto error;
 279         }
 280         return thread;
 281 error:
 282         cleanup_ht_cleanup_thread(NULL);
 283         return NULL;
 284 }