lib/tevent/tevent_threads.c

   1 /*
   2    tevent event library.
   3
   4    Copyright (C) Jeremy Allison 2015
   5
   6      ** NOTE! The following LGPL license applies to the tevent
   7      ** library. This does NOT imply that all of Samba is released
   8      ** under the LGPL
   9
  10    This library is free software; you can redistribute it and/or
  11    modify it under the terms of the GNU Lesser General Public
  12    License as published by the Free Software Foundation; either
  13    version 3 of the License, or (at your option) any later version.
  14
  15    This library is distributed in the hope that it will be useful,
  16    but WITHOUT ANY WARRANTY; without even the implied warranty of
  17    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  18    Lesser General Public License for more details.
  19
  20    You should have received a copy of the GNU Lesser General Public
  21    License along with this library; if not, see <http://www.gnu.org/licenses/>.
  22 */
  23
  24 #include "replace.h"
  25 #include "system/filesys.h"
  26 #include "talloc.h"
  27 #include "tevent.h"
  28 #include "tevent_internal.h"
  29 #include "tevent_util.h"
  30
  31 #if defined(HAVE_PTHREAD)
  32 #include <pthread.h>
  33
  34 struct tevent_immediate_list {
  35         struct tevent_immediate_list *next, *prev;
  36         tevent_immediate_handler_t handler;
  37         struct tevent_immediate *im;
  38         void *private_ptr;
  39 };
  40
  41 struct tevent_thread_proxy {
  42         pthread_mutex_t mutex;
  43         struct tevent_context *dest_ev_ctx;
  44         int read_fd;
  45         int write_fd;
  46         struct tevent_fd *pipe_read_fde;
  47         /* Pending events list. */
  48         struct tevent_immediate_list *im_list;
  49         /* Completed events list. */
  50         struct tevent_immediate_list *tofree_im_list;
  51         struct tevent_immediate *free_im;
  52 };
  53
  54 static void free_im_list(struct tevent_immediate_list **pp_list_head)
  55 {
  56         struct tevent_immediate_list *im_entry = NULL;
  57         struct tevent_immediate_list *im_next = NULL;
  58
  59         for (im_entry = *pp_list_head; im_entry; im_entry = im_next) {
  60                 im_next = im_entry->next;
  61                 DLIST_REMOVE(*pp_list_head, im_entry);
  62                 TALLOC_FREE(im_entry);
  63         }
  64 }
  65
  66 static void free_list_handler(struct tevent_context *ev,
  67                                 struct tevent_immediate *im,
  68                                 void *private_ptr)
  69 {
  70         struct tevent_thread_proxy *tp =
  71                 talloc_get_type_abort(private_ptr, struct tevent_thread_proxy);
  72         int ret;
  73
  74         ret = pthread_mutex_lock(&tp->mutex);
  75         if (ret != 0) {
  76                 abort();
  77                 /* Notreached. */
  78                 return;
  79         }
  80
  81         free_im_list(&tp->tofree_im_list);
  82
  83         ret = pthread_mutex_unlock(&tp->mutex);
  84         if (ret != 0) {
  85                 abort();
  86                 /* Notreached. */
  87                 return;
  88         }
  89 }
  90
  91 static void schedule_immediate_functions(struct tevent_thread_proxy *tp)
  92 {
  93         struct tevent_immediate_list *im_entry = NULL;
  94         struct tevent_immediate_list *im_next = NULL;
  95
  96         for (im_entry = tp->im_list; im_entry; im_entry = im_next) {
  97                 im_next = im_entry->next;
  98                 DLIST_REMOVE(tp->im_list, im_entry);
  99
 100                 tevent_schedule_immediate(im_entry->im,
 101                                         tp->dest_ev_ctx,
 102                                         im_entry->handler,
 103                                         im_entry->private_ptr);
 104
 105                 /* Move from pending list to free list. */
 106                 DLIST_ADD(tp->tofree_im_list, im_entry);
 107         }
 108         if (tp->tofree_im_list != NULL) {
 109                 /*
 110                  * Once the current immediate events
 111                  * are processed, we need to reshedule
 112                  * ourselves to free them. This works
 113                  * as tevent_schedule_immediate()
 114                  * always adds events to the *END* of
 115                  * the immediate events list.
 116                  */
 117                 tevent_schedule_immediate(tp->free_im,
 118                                         tp->dest_ev_ctx,
 119                                         free_list_handler,
 120                                         tp);
 121         }
 122 }
 123
 124 static void pipe_read_handler(struct tevent_context *ev,
 125                                 struct tevent_fd *fde,
 126                                 uint16_t flags,
 127                                 void *private_ptr)
 128 {
 129         struct tevent_thread_proxy *tp =
 130                 talloc_get_type_abort(private_ptr, struct tevent_thread_proxy);
 131         ssize_t len = 64;
 132         int ret;
 133
 134         ret = pthread_mutex_lock(&tp->mutex);
 135         if (ret != 0) {
 136                 abort();
 137                 /* Notreached. */
 138                 return;
 139         }
 140
 141         /*
 142          * Clear out all data in the pipe. We
 143          * don't really care if this returns -1.
 144          */
 145         while (len == 64) {
 146                 char buf[64];
 147                 len = read(tp->read_fd, buf, 64);
 148         };
 149
 150         schedule_immediate_functions(tp);
 151
 152         ret = pthread_mutex_unlock(&tp->mutex);
 153         if (ret != 0) {
 154                 abort();
 155                 /* Notreached. */
 156                 return;
 157         }
 158 }
 159
 160 static int tevent_thread_proxy_destructor(struct tevent_thread_proxy *tp)
 161 {
 162         int ret;
 163
 164         ret = pthread_mutex_lock(&tp->mutex);
 165         if (ret != 0) {
 166                 abort();
 167                 /* Notreached. */
 168                 return 0;
 169         }
 170
 171         TALLOC_FREE(tp->pipe_read_fde);
 172
 173         if (tp->read_fd != -1) {
 174                 (void)close(tp->read_fd);
 175                 tp->read_fd = -1;
 176         }
 177         if (tp->write_fd != -1) {
 178                 (void)close(tp->write_fd);
 179                 tp->write_fd = -1;
 180         }
 181
 182         /* Hmmm. It's probably an error if we get here with
 183            any non-NULL immediate entries.. */
 184
 185         free_im_list(&tp->im_list);
 186         free_im_list(&tp->tofree_im_list);
 187
 188         TALLOC_FREE(tp->free_im);
 189
 190         ret = pthread_mutex_unlock(&tp->mutex);
 191         if (ret != 0) {
 192                 abort();
 193                 /* Notreached. */
 194                 return 0;
 195         }
 196
 197         ret = pthread_mutex_destroy(&tp->mutex);
 198         if (ret != 0) {
 199                 abort();
 200                 /* Notreached. */
 201                 return 0;
 202         }
 203
 204         return 0;
 205 }
 206
 207 /*
 208  * Create a struct that can be passed to other threads
 209  * to allow them to signal the struct tevent_context *
 210  * passed in.
 211  */
 212
 213 struct tevent_thread_proxy *tevent_thread_proxy_create(
 214                 struct tevent_context *dest_ev_ctx)
 215 {
 216         int ret;
 217         int pipefds[2];
 218         struct tevent_thread_proxy *tp;
 219
 220         tp = talloc_zero(dest_ev_ctx, struct tevent_thread_proxy);
 221         if (tp == NULL) {
 222                 return NULL;
 223         }
 224
 225         ret = pthread_mutex_init(&tp->mutex, NULL);
 226         if (ret != 0) {
 227                 goto fail;
 228         }
 229
 230         tp->dest_ev_ctx = dest_ev_ctx;
 231         tp->read_fd = -1;
 232         tp->write_fd = -1;
 233
 234         talloc_set_destructor(tp, tevent_thread_proxy_destructor);
 235
 236         ret = pipe(pipefds);
 237         if (ret == -1) {
 238                 goto fail;
 239         }
 240
 241         tp->read_fd = pipefds[0];
 242         tp->write_fd = pipefds[1];
 243
 244         ret = ev_set_blocking(pipefds[0], false);
 245         if (ret != 0) {
 246                 goto fail;
 247         }
 248         ret = ev_set_blocking(pipefds[1], false);
 249         if (ret != 0) {
 250                 goto fail;
 251         }
 252         if (!ev_set_close_on_exec(pipefds[0])) {
 253                 goto fail;
 254         }
 255         if (!ev_set_close_on_exec(pipefds[1])) {
 256                 goto fail;
 257         }
 258
 259         tp->pipe_read_fde = tevent_add_fd(dest_ev_ctx,
 260                                 tp,
 261                                 tp->read_fd,
 262                                 TEVENT_FD_READ,
 263                                 pipe_read_handler,
 264                                 tp);
 265         if (tp->pipe_read_fde == NULL) {
 266                 goto fail;
 267         }
 268
 269         /*
 270          * Create an immediate event to free
 271          * completed lists.
 272          */
 273         tp->free_im = tevent_create_immediate(tp);
 274         if (tp->free_im == NULL) {
 275                 goto fail;
 276         }
 277
 278         return tp;
 279
 280   fail:
 281
 282         TALLOC_FREE(tp);
 283         return NULL;
 284 }
 285
 286 /*
 287  * This function schedules an immediate event to be called with argument
 288  * *pp_private in the thread context of dest_ev_ctx. Caller doesn't
 289  * wait for activation to take place, this is simply fire-and-forget.
 290  *
 291  * pp_im must be a pointer to an immediate event talloced on
 292  * a context owned by the calling thread, or the NULL context.
 293  * Ownership of *pp_im will be transfered to the tevent library.
 294  *
 295  * pp_private can be null, or contents of *pp_private must be
 296  * talloc'ed memory on a context owned by the calling thread
 297  * or the NULL context. If non-null, ownership of *pp_private will
 298  * be transfered to the tevent library.
 299  *
 300  * If you want to return a message, have the destination use the
 301  * same function call to send back to the caller.
 302  */
 303
 304
 305 void tevent_thread_proxy_schedule(struct tevent_thread_proxy *tp,
 306                                   struct tevent_immediate **pp_im,
 307                                   tevent_immediate_handler_t handler,
 308                                   void *pp_private_data)
 309 {
 310         struct tevent_immediate_list *im_entry;
 311         int ret;
 312         char c;
 313         ssize_t written;
 314
 315         ret = pthread_mutex_lock(&tp->mutex);
 316         if (ret != 0) {
 317                 abort();
 318                 /* Notreached. */
 319                 return;
 320         }
 321
 322         if (tp->write_fd == -1) {
 323                 /* In the process of being destroyed. Ignore. */
 324                 goto end;
 325         }
 326
 327         /* Create a new immediate_list entry. MUST BE ON THE NULL CONTEXT */
 328         im_entry = talloc_zero(NULL, struct tevent_immediate_list);
 329         if (im_entry == NULL) {
 330                 goto end;
 331         }
 332
 333         im_entry->handler = handler;
 334         im_entry->im = talloc_move(im_entry, pp_im);
 335
 336         if (pp_private_data != NULL) {
 337                 void **pptr = (void **)pp_private_data;
 338                 im_entry->private_ptr = talloc_move(im_entry, pptr);
 339         }
 340
 341         DLIST_ADD(tp->im_list, im_entry);
 342
 343         /* And notify the dest_ev_ctx to wake up. */
 344         c = '\0';
 345         do {
 346                 written = write(tp->write_fd, &c, 1);
 347         } while (written == -1 && errno == EINTR);
 348
 349   end:
 350
 351         ret = pthread_mutex_unlock(&tp->mutex);
 352         if (ret != 0) {
 353                 abort();
 354                 /* Notreached. */
 355         }
 356 }
 357 #else
 358 /* !HAVE_PTHREAD */
 359 struct tevent_thread_proxy *tevent_thread_proxy_create(
 360                 struct tevent_context *dest_ev_ctx)
 361 {
 362         errno = ENOSYS;
 363         return NULL;
 364 }
 365
 366 void tevent_thread_proxy_schedule(struct tevent_thread_proxy *tp,
 367                                   struct tevent_immediate **pp_im,
 368                                   tevent_immediate_handler_t handler,
 369                                   void *pp_private_data)
 370 {
 371         ;
 372 }
 373 #endif