summaryrefslogtreecommitdiffstats
path: root/lib/tevent/tevent_threads.c
blob: 2dc1f17bc9e895b527f4ecdbba1c88e8241b483a (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
/*
   tevent event library.

   Copyright (C) Jeremy Allison 2015

     ** NOTE! The following LGPL license applies to the tevent
     ** library. This does NOT imply that all of Samba is released
     ** under the LGPL

   This library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 3 of the License, or (at your option) any later version.

   This library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with this library; if not, see <http://www.gnu.org/licenses/>.
*/

#include "replace.h"
#include "system/filesys.h"
#include "talloc.h"
#include "tevent.h"
#include "tevent_internal.h"
#include "tevent_util.h"

#ifdef HAVE_PTHREAD
#include "system/threads.h"

struct tevent_immediate_list {
	struct tevent_immediate_list *next, *prev;
	tevent_immediate_handler_t handler;
	struct tevent_immediate *im;
	void *private_ptr;
};

struct tevent_thread_proxy {
	pthread_mutex_t mutex;
	struct tevent_context *dest_ev_ctx;
	int read_fd;
	int write_fd;
	struct tevent_fd *pipe_read_fde;
	/* Pending events list. */
	struct tevent_immediate_list *im_list;
	/* Completed events list. */
	struct tevent_immediate_list *tofree_im_list;
	struct tevent_immediate *free_im;
};

static void free_im_list(struct tevent_immediate_list **pp_list_head)
{
	struct tevent_immediate_list *im_entry = NULL;
	struct tevent_immediate_list *im_next = NULL;

	for (im_entry = *pp_list_head; im_entry; im_entry = im_next) {
		im_next = im_entry->next;
		DLIST_REMOVE(*pp_list_head, im_entry);
		TALLOC_FREE(im_entry);
	}
}

static void free_list_handler(struct tevent_context *ev,
				struct tevent_immediate *im,
				void *private_ptr)
{
	struct tevent_thread_proxy *tp =
		talloc_get_type_abort(private_ptr, struct tevent_thread_proxy);
	int ret;

	ret = pthread_mutex_lock(&tp->mutex);
	if (ret != 0) {
		abort();
		/* Notreached. */
		return;
	}

	free_im_list(&tp->tofree_im_list);

	ret = pthread_mutex_unlock(&tp->mutex);
	if (ret != 0) {
		abort();
		/* Notreached. */
		return;
	}
}

static void schedule_immediate_functions(struct tevent_thread_proxy *tp)
{
	struct tevent_immediate_list *im_entry = NULL;
	struct tevent_immediate_list *im_next = NULL;

	for (im_entry = tp->im_list; im_entry; im_entry = im_next) {
		im_next = im_entry->next;
		DLIST_REMOVE(tp->im_list, im_entry);

		tevent_schedule_immediate(im_entry->im,
					tp->dest_ev_ctx,
					im_entry->handler,
					im_entry->private_ptr);

		/* Move from pending list to free list. */
		DLIST_ADD(tp->tofree_im_list, im_entry);
	}
	if (tp->tofree_im_list != NULL) {
		/*
		 * Once the current immediate events
		 * are processed, we need to reschedule
		 * ourselves to free them. This works
		 * as tevent_schedule_immediate()
		 * always adds events to the *END* of
		 * the immediate events list.
		 */
		tevent_schedule_immediate(tp->free_im,
					tp->dest_ev_ctx,
					free_list_handler,
					tp);
	}
}

static void pipe_read_handler(struct tevent_context *ev,
				struct tevent_fd *fde,
				uint16_t flags,
				void *private_ptr)
{
	struct tevent_thread_proxy *tp =
		talloc_get_type_abort(private_ptr, struct tevent_thread_proxy);
	ssize_t len = 64;
	int ret;

	ret = pthread_mutex_lock(&tp->mutex);
	if (ret != 0) {
		abort();
		/* Notreached. */
		return;
	}

	/*
	 * Clear out all data in the pipe. We
	 * don't really care if this returns -1.
	 */
	while (len == 64) {
		char buf[64];
		len = read(tp->read_fd, buf, 64);
	};

	schedule_immediate_functions(tp);

	ret = pthread_mutex_unlock(&tp->mutex);
	if (ret != 0) {
		abort();
		/* Notreached. */
		return;
	}
}

static int tevent_thread_proxy_destructor(struct tevent_thread_proxy *tp)
{
	int ret;

	ret = pthread_mutex_lock(&tp->mutex);
	if (ret != 0) {
		abort();
		/* Notreached. */
		return 0;
	}

	TALLOC_FREE(tp->pipe_read_fde);

	if (tp->read_fd != -1) {
		(void)close(tp->read_fd);
		tp->read_fd = -1;
	}
	if (tp->write_fd != -1) {
		(void)close(tp->write_fd);
		tp->write_fd = -1;
	}

	/* Hmmm. It's probably an error if we get here with
	   any non-NULL immediate entries.. */

	free_im_list(&tp->im_list);
	free_im_list(&tp->tofree_im_list);

	TALLOC_FREE(tp->free_im);

	ret = pthread_mutex_unlock(&tp->mutex);
	if (ret != 0) {
		abort();
		/* Notreached. */
		return 0;
	}

	ret = pthread_mutex_destroy(&tp->mutex);
	if (ret != 0) {
		abort();
		/* Notreached. */
		return 0;
	}

	return 0;
}

/*
 * Create a struct that can be passed to other threads
 * to allow them to signal the struct tevent_context *
 * passed in.
 */

struct tevent_thread_proxy *tevent_thread_proxy_create(
		struct tevent_context *dest_ev_ctx)
{
	int ret;
	int pipefds[2];
	struct tevent_thread_proxy *tp;

	if (dest_ev_ctx->wrapper.glue != NULL) {
		/*
		 * stacking of wrappers is not supported
		 */
		tevent_debug(dest_ev_ctx->wrapper.glue->main_ev,
			     TEVENT_DEBUG_FATAL,
			     "%s() not allowed on a wrapper context\n",
			     __func__);
		errno = EINVAL;
		return NULL;
	}

	tp = talloc_zero(dest_ev_ctx, struct tevent_thread_proxy);
	if (tp == NULL) {
		return NULL;
	}

	ret = pthread_mutex_init(&tp->mutex, NULL);
	if (ret != 0) {
		goto fail;
	}

	tp->dest_ev_ctx = dest_ev_ctx;
	tp->read_fd = -1;
	tp->write_fd = -1;

	talloc_set_destructor(tp, tevent_thread_proxy_destructor);

	ret = pipe(pipefds);
	if (ret == -1) {
		goto fail;
	}

	tp->read_fd = pipefds[0];
	tp->write_fd = pipefds[1];

	ret = ev_set_blocking(pipefds[0], false);
	if (ret != 0) {
		goto fail;
	}
	ret = ev_set_blocking(pipefds[1], false);
	if (ret != 0) {
		goto fail;
	}
	if (!ev_set_close_on_exec(pipefds[0])) {
		goto fail;
	}
	if (!ev_set_close_on_exec(pipefds[1])) {
		goto fail;
	}

	tp->pipe_read_fde = tevent_add_fd(dest_ev_ctx,
				tp,
				tp->read_fd,
				TEVENT_FD_READ,
				pipe_read_handler,
				tp);
	if (tp->pipe_read_fde == NULL) {
		goto fail;
	}

	/*
	 * Create an immediate event to free
	 * completed lists.
	 */
	tp->free_im = tevent_create_immediate(tp);
	if (tp->free_im == NULL) {
		goto fail;
	}

	return tp;

  fail:

	TALLOC_FREE(tp);
	return NULL;
}

/*
 * This function schedules an immediate event to be called with argument
 * *pp_private in the thread context of dest_ev_ctx. Caller doesn't
 * wait for activation to take place, this is simply fire-and-forget.
 *
 * pp_im must be a pointer to an immediate event talloced on
 * a context owned by the calling thread, or the NULL context.
 * Ownership of *pp_im will be transferred to the tevent library.
 *
 * pp_private can be null, or contents of *pp_private must be
 * talloc'ed memory on a context owned by the calling thread
 * or the NULL context. If non-null, ownership of *pp_private will
 * be transferred to the tevent library.
 *
 * If you want to return a message, have the destination use the
 * same function call to send back to the caller.
 */


void tevent_thread_proxy_schedule(struct tevent_thread_proxy *tp,
				  struct tevent_immediate **pp_im,
				  tevent_immediate_handler_t handler,
				  void *pp_private_data)
{
	struct tevent_immediate_list *im_entry;
	int ret;
	char c;
	ssize_t written;

	ret = pthread_mutex_lock(&tp->mutex);
	if (ret != 0) {
		abort();
		/* Notreached. */
		return;
	}

	if (tp->write_fd == -1) {
		/* In the process of being destroyed. Ignore. */
		goto end;
	}

	/* Create a new immediate_list entry. MUST BE ON THE NULL CONTEXT */
	im_entry = talloc_zero(NULL, struct tevent_immediate_list);
	if (im_entry == NULL) {
		goto end;
	}

	im_entry->handler = handler;
	im_entry->im = talloc_move(im_entry, pp_im);

	if (pp_private_data != NULL) {
		void **pptr = (void **)pp_private_data;
		im_entry->private_ptr = talloc_move(im_entry, pptr);
	}

	DLIST_ADD(tp->im_list, im_entry);

	/* And notify the dest_ev_ctx to wake up. */
	c = '\0';
	do {
		written = write(tp->write_fd, &c, 1);
	} while (written == -1 && errno == EINTR);

  end:

	ret = pthread_mutex_unlock(&tp->mutex);
	if (ret != 0) {
		abort();
		/* Notreached. */
	}
}
#else
/* !HAVE_PTHREAD */
struct tevent_thread_proxy *tevent_thread_proxy_create(
		struct tevent_context *dest_ev_ctx)
{
	errno = ENOSYS;
	return NULL;
}

void tevent_thread_proxy_schedule(struct tevent_thread_proxy *tp,
				  struct tevent_immediate **pp_im,
				  tevent_immediate_handler_t handler,
				  void *pp_private_data)
{
	;
}
#endif

static int tevent_threaded_context_destructor(
	struct tevent_threaded_context *tctx)
{
	struct tevent_context *main_ev = tevent_wrapper_main_ev(tctx->event_ctx);
	int ret;

	if (main_ev != NULL) {
		DLIST_REMOVE(main_ev->threaded_contexts, tctx);
	}

	/*
	 * We have to coordinate with _tevent_threaded_schedule_immediate's
	 * unlock of the event_ctx_mutex. We're in the main thread here,
	 * and we can be scheduled before the helper thread finalizes its
	 * call _tevent_threaded_schedule_immediate. This means we would
	 * pthreadpool_destroy a locked mutex, which is illegal.
	 */
	ret = pthread_mutex_lock(&tctx->event_ctx_mutex);
	if (ret != 0) {
		abort();
	}

	ret = pthread_mutex_unlock(&tctx->event_ctx_mutex);
	if (ret != 0) {
		abort();
	}

	ret = pthread_mutex_destroy(&tctx->event_ctx_mutex);
	if (ret != 0) {
		abort();
	}

	return 0;
}

struct tevent_threaded_context *tevent_threaded_context_create(
	TALLOC_CTX *mem_ctx, struct tevent_context *ev)
{
#ifdef HAVE_PTHREAD
	struct tevent_context *main_ev = tevent_wrapper_main_ev(ev);
	struct tevent_threaded_context *tctx;
	int ret;

	ret = tevent_common_wakeup_init(main_ev);
	if (ret != 0) {
		errno = ret;
		return NULL;
	}

	tctx = talloc(mem_ctx, struct tevent_threaded_context);
	if (tctx == NULL) {
		return NULL;
	}
	tctx->event_ctx = ev;

	ret = pthread_mutex_init(&tctx->event_ctx_mutex, NULL);
	if (ret != 0) {
		TALLOC_FREE(tctx);
		return NULL;
	}

	DLIST_ADD(main_ev->threaded_contexts, tctx);
	talloc_set_destructor(tctx, tevent_threaded_context_destructor);

	return tctx;
#else
	errno = ENOSYS;
	return NULL;
#endif
}

static int tevent_threaded_schedule_immediate_destructor(struct tevent_immediate *im)
{
	if (im->event_ctx != NULL) {
		abort();
	}
	return 0;
}

void _tevent_threaded_schedule_immediate(struct tevent_threaded_context *tctx,
					 struct tevent_immediate *im,
					 tevent_immediate_handler_t handler,
					 void *private_data,
					 const char *handler_name,
					 const char *location)
{
#ifdef HAVE_PTHREAD
	const char *create_location = im->create_location;
	struct tevent_context *main_ev = NULL;
	struct tevent_wrapper_glue *glue = NULL;
	int ret, wakeup_fd;

	ret = pthread_mutex_lock(&tctx->event_ctx_mutex);
	if (ret != 0) {
		abort();
	}

	if (tctx->event_ctx == NULL) {
		/*
		 * Our event context is already gone.
		 */
		ret = pthread_mutex_unlock(&tctx->event_ctx_mutex);
		if (ret != 0) {
			abort();
		}
		return;
	}

	glue = tctx->event_ctx->wrapper.glue;

	if ((im->event_ctx != NULL) || (handler == NULL)) {
		abort();
	}
	if (im->destroyed) {
		abort();
	}
	if (im->busy) {
		abort();
	}

	main_ev = tevent_wrapper_main_ev(tctx->event_ctx);

	*im = (struct tevent_immediate) {
		.event_ctx		= tctx->event_ctx,
		.wrapper		= glue,
		.handler		= handler,
		.private_data		= private_data,
		.handler_name		= handler_name,
		.create_location	= create_location,
		.schedule_location	= location,
	};

	/*
	 * Make sure the event won't be destroyed while
	 * it's part of the ev->scheduled_immediates list.
	 * _tevent_schedule_immediate() will reset the destructor
	 * in tevent_common_threaded_activate_immediate().
	 */
	talloc_set_destructor(im, tevent_threaded_schedule_immediate_destructor);

	ret = pthread_mutex_lock(&main_ev->scheduled_mutex);
	if (ret != 0) {
		abort();
	}

	DLIST_ADD_END(main_ev->scheduled_immediates, im);
	wakeup_fd = main_ev->wakeup_fd;

	ret = pthread_mutex_unlock(&main_ev->scheduled_mutex);
	if (ret != 0) {
		abort();
	}

	ret = pthread_mutex_unlock(&tctx->event_ctx_mutex);
	if (ret != 0) {
		abort();
	}

	/*
	 * We might want to wake up the main thread under the lock. We
	 * had a slightly similar situation in pthreadpool, changed
	 * with 1c4284c7395f23. This is not exactly the same, as the
	 * wakeup is only a last-resort thing in case the main thread
	 * is sleeping. Doing the wakeup under the lock can easily
	 * lead to a contended mutex, which is much more expensive
	 * than a noncontended one. So I'd opt for the lower footprint
	 * initially. Maybe we have to change that later.
	 */
	tevent_common_wakeup_fd(wakeup_fd);
#else
	/*
	 * tevent_threaded_context_create() returned NULL with ENOSYS...
	 */
	abort();
#endif
}

void tevent_common_threaded_activate_immediate(struct tevent_context *ev)
{
#ifdef HAVE_PTHREAD
	int ret;
	ret = pthread_mutex_lock(&ev->scheduled_mutex);
	if (ret != 0) {
		abort();
	}

	while (ev->scheduled_immediates != NULL) {
		struct tevent_immediate *im = ev->scheduled_immediates;
		struct tevent_immediate copy = *im;

		DLIST_REMOVE(ev->scheduled_immediates, im);

		TEVENT_DEBUG(ev, TEVENT_DEBUG_TRACE,
			     "Schedule immediate event \"%s\": %p from thread into main\n",
			     im->handler_name, im);
		im->handler_name = NULL;
		_tevent_schedule_immediate(im,
					   ev,
					   copy.handler,
					   copy.private_data,
					   copy.handler_name,
					   copy.schedule_location);
	}

	ret = pthread_mutex_unlock(&ev->scheduled_mutex);
	if (ret != 0) {
		abort();
	}
#else
	/*
	 * tevent_threaded_context_create() returned NULL with ENOSYS...
	 */
	abort();
#endif
}