2 * Unix SMB/CIFS implementation.
3 * thread pool implementation
4 * Copyright (C) Volker Lendecke 2009
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation; either version 3 of the License, or
9 * (at your option) any later version.
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
16 * You should have received a copy of the GNU General Public License
17 * along with this program. If not, see <http://www.gnu.org/licenses/>.
29 #include "system/time.h"
30 #include "system/filesys.h"
32 #include "pthreadpool.h"
33 #include "lib/util/dlinklist.h"
35 struct pthreadpool_job
{
36 struct pthreadpool_job
*next
;
38 void (*fn
)(void *private_data
);
44 * List pthreadpools for fork safety
46 struct pthreadpool
*prev
, *next
;
49 * Control access to this struct
51 pthread_mutex_t mutex
;
54 * Threads waiting for work do so here
56 pthread_cond_t condvar
;
61 struct pthreadpool_job
*jobs
, *last_job
;
69 * indicator to worker threads that they should shut down
74 * maximum number of threads
84 * Number of idle threads
89 * An array of threads that require joining.
92 pthread_t
*exited
; /* We alloc more */
95 static pthread_mutex_t pthreadpools_mutex
= PTHREAD_MUTEX_INITIALIZER
;
96 static struct pthreadpool
*pthreadpools
= NULL
;
97 static pthread_once_t pthreadpool_atfork_initialized
= PTHREAD_ONCE_INIT
;
99 static void pthreadpool_prep_atfork(void);
102 * Initialize a thread pool
105 int pthreadpool_init(unsigned max_threads
, struct pthreadpool
**presult
)
107 struct pthreadpool
*pool
;
110 pool
= (struct pthreadpool
*)malloc(sizeof(struct pthreadpool
));
115 ret
= pipe(pool
->sig_pipe
);
122 ret
= pthread_mutex_init(&pool
->mutex
, NULL
);
124 close(pool
->sig_pipe
[0]);
125 close(pool
->sig_pipe
[1]);
130 ret
= pthread_cond_init(&pool
->condvar
, NULL
);
132 pthread_mutex_destroy(&pool
->mutex
);
133 close(pool
->sig_pipe
[0]);
134 close(pool
->sig_pipe
[1]);
140 pool
->jobs
= pool
->last_job
= NULL
;
141 pool
->num_threads
= 0;
142 pool
->num_exited
= 0;
144 pool
->max_threads
= max_threads
;
147 ret
= pthread_mutex_lock(&pthreadpools_mutex
);
149 pthread_cond_destroy(&pool
->condvar
);
150 pthread_mutex_destroy(&pool
->mutex
);
151 close(pool
->sig_pipe
[0]);
152 close(pool
->sig_pipe
[1]);
156 DLIST_ADD(pthreadpools
, pool
);
158 ret
= pthread_mutex_unlock(&pthreadpools_mutex
);
161 pthread_once(&pthreadpool_atfork_initialized
, pthreadpool_prep_atfork
);
168 static void pthreadpool_prepare(void)
171 struct pthreadpool
*pool
;
173 ret
= pthread_mutex_lock(&pthreadpools_mutex
);
178 while (pool
!= NULL
) {
179 ret
= pthread_mutex_lock(&pool
->mutex
);
185 static void pthreadpool_parent(void)
188 struct pthreadpool
*pool
;
190 pool
= DLIST_TAIL(pthreadpools
);
193 ret
= pthread_mutex_unlock(&pool
->mutex
);
196 if (pool
== pthreadpools
) {
202 ret
= pthread_mutex_unlock(&pthreadpools_mutex
);
206 static void pthreadpool_child(void)
209 struct pthreadpool
*pool
;
211 pool
= DLIST_TAIL(pthreadpools
);
214 close(pool
->sig_pipe
[0]);
215 close(pool
->sig_pipe
[1]);
217 ret
= pipe(pool
->sig_pipe
);
220 pool
->num_threads
= 0;
222 pool
->num_exited
= 0;
228 while (pool
->jobs
!= NULL
) {
229 struct pthreadpool_job
*job
;
231 pool
->jobs
= job
->next
;
234 pool
->last_job
= NULL
;
236 ret
= pthread_mutex_unlock(&pool
->mutex
);
239 if (pool
== pthreadpools
) {
245 ret
= pthread_mutex_unlock(&pthreadpools_mutex
);
249 static void pthreadpool_prep_atfork(void)
251 pthread_atfork(pthreadpool_prepare
, pthreadpool_parent
,
256 * Return the file descriptor which becomes readable when a job has
260 int pthreadpool_signal_fd(struct pthreadpool
*pool
)
262 return pool
->sig_pipe
[0];
266 * Do a pthread_join() on all children that have exited, pool->mutex must be
269 static void pthreadpool_join_children(struct pthreadpool
*pool
)
273 for (i
=0; i
<pool
->num_exited
; i
++) {
274 pthread_join(pool
->exited
[i
], NULL
);
276 pool
->num_exited
= 0;
279 * Deliberately not free and NULL pool->exited. That will be
280 * re-used by realloc later.
285 * Fetch a finished job number from the signal pipe
288 int pthreadpool_finished_job(struct pthreadpool
*pool
)
296 while ((nread
== -1) && (errno
== EINTR
)) {
297 nread
= read(pool
->sig_pipe
[0], &result
, sizeof(int));
302 if (nread
!= sizeof(int)) {
309 * Destroy a thread pool, finishing all threads working for it
312 int pthreadpool_destroy(struct pthreadpool
*pool
)
316 ret
= pthread_mutex_lock(&pool
->mutex
);
321 if ((pool
->jobs
!= NULL
) || pool
->shutdown
) {
322 ret
= pthread_mutex_unlock(&pool
->mutex
);
327 if (pool
->num_threads
> 0) {
329 * We have active threads, tell them to finish, wait for that.
334 if (pool
->num_idle
> 0) {
336 * Wake the idle threads. They will find pool->quit to
337 * be set and exit themselves
339 ret
= pthread_cond_broadcast(&pool
->condvar
);
341 pthread_mutex_unlock(&pool
->mutex
);
346 while ((pool
->num_threads
> 0) || (pool
->num_exited
> 0)) {
348 if (pool
->num_exited
> 0) {
349 pthreadpool_join_children(pool
);
353 * A thread that shuts down will also signal
356 ret
= pthread_cond_wait(&pool
->condvar
, &pool
->mutex
);
358 pthread_mutex_unlock(&pool
->mutex
);
364 ret
= pthread_mutex_unlock(&pool
->mutex
);
368 ret
= pthread_mutex_destroy(&pool
->mutex
);
369 ret1
= pthread_cond_destroy(&pool
->condvar
);
378 ret
= pthread_mutex_lock(&pthreadpools_mutex
);
382 DLIST_REMOVE(pthreadpools
, pool
);
383 ret
= pthread_mutex_unlock(&pthreadpools_mutex
);
386 close(pool
->sig_pipe
[0]);
387 pool
->sig_pipe
[0] = -1;
389 close(pool
->sig_pipe
[1]);
390 pool
->sig_pipe
[1] = -1;
399 * Prepare for pthread_exit(), pool->mutex must be locked
401 static void pthreadpool_server_exit(struct pthreadpool
*pool
)
405 pool
->num_threads
-= 1;
407 exited
= (pthread_t
*)realloc(
408 pool
->exited
, sizeof(pthread_t
*) * (pool
->num_exited
+ 1));
410 if (exited
== NULL
) {
411 /* lost a thread status */
414 pool
->exited
= exited
;
416 pool
->exited
[pool
->num_exited
] = pthread_self();
417 pool
->num_exited
+= 1;
420 static void *pthreadpool_server(void *arg
)
422 struct pthreadpool
*pool
= (struct pthreadpool
*)arg
;
425 res
= pthread_mutex_lock(&pool
->mutex
);
432 struct pthreadpool_job
*job
;
435 * idle-wait at most 1 second. If nothing happens in that
436 * time, exit this thread.
439 clock_gettime(CLOCK_REALTIME
, &ts
);
442 while ((pool
->jobs
== NULL
) && (pool
->shutdown
== 0)) {
445 res
= pthread_cond_timedwait(
446 &pool
->condvar
, &pool
->mutex
, &ts
);
449 if (res
== ETIMEDOUT
) {
451 if (pool
->jobs
== NULL
) {
453 * we timed out and still no work for
456 pthreadpool_server_exit(pool
);
457 pthread_mutex_unlock(&pool
->mutex
);
472 * Ok, there's work for us to do, remove the job from
473 * the pthreadpool list
475 pool
->jobs
= job
->next
;
476 if (pool
->last_job
== job
) {
477 pool
->last_job
= NULL
;
481 * Do the work with the mutex unlocked
484 res
= pthread_mutex_unlock(&pool
->mutex
);
487 job
->fn(job
->private_data
);
489 written
= write(pool
->sig_pipe
[1], &job
->id
,
494 res
= pthread_mutex_lock(&pool
->mutex
);
497 if (written
!= sizeof(int)) {
498 pthreadpool_server_exit(pool
);
499 pthread_mutex_unlock(&pool
->mutex
);
504 if ((pool
->jobs
== NULL
) && (pool
->shutdown
!= 0)) {
506 * No more work to do and we're asked to shut down, so
509 pthreadpool_server_exit(pool
);
511 if (pool
->num_threads
== 0) {
513 * Ping the main thread waiting for all of us
514 * workers to have quit.
516 pthread_cond_broadcast(&pool
->condvar
);
519 pthread_mutex_unlock(&pool
->mutex
);
525 int pthreadpool_add_job(struct pthreadpool
*pool
, int job_id
,
526 void (*fn
)(void *private_data
), void *private_data
)
528 struct pthreadpool_job
*job
;
531 sigset_t mask
, omask
;
533 job
= (struct pthreadpool_job
*)malloc(sizeof(struct pthreadpool_job
));
539 job
->private_data
= private_data
;
543 res
= pthread_mutex_lock(&pool
->mutex
);
549 if (pool
->shutdown
) {
551 * Protect against the pool being shut down while
552 * trying to add a job
554 res
= pthread_mutex_unlock(&pool
->mutex
);
561 * Just some cleanup under the mutex
563 pthreadpool_join_children(pool
);
566 * Add job to the end of the queue
568 if (pool
->jobs
== NULL
) {
572 pool
->last_job
->next
= job
;
574 pool
->last_job
= job
;
576 if (pool
->num_idle
> 0) {
578 * We have idle threads, wake one.
580 res
= pthread_cond_signal(&pool
->condvar
);
581 pthread_mutex_unlock(&pool
->mutex
);
585 if ((pool
->max_threads
!= 0) &&
586 (pool
->num_threads
>= pool
->max_threads
)) {
588 * No more new threads, we just queue the request
590 pthread_mutex_unlock(&pool
->mutex
);
595 * Create a new worker thread. It should not receive any signals.
600 res
= pthread_sigmask(SIG_BLOCK
, &mask
, &omask
);
602 pthread_mutex_unlock(&pool
->mutex
);
606 res
= pthread_create(&thread_id
, NULL
, pthreadpool_server
,
609 pool
->num_threads
+= 1;
612 assert(pthread_sigmask(SIG_SETMASK
, &omask
, NULL
) == 0);
614 pthread_mutex_unlock(&pool
->mutex
);