1 /* GLIB - Library of useful routines for C programming
2 * Copyright (C) 1995-1997 Peter Mattis, Spencer Kimball and Josh MacDonald
4 * GThreadPool: thread pool implementation.
5 * Copyright (C) 2000 Sebastian Wilhelmi; University of Karlsruhe
7 * This library is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Lesser General Public
9 * License as published by the Free Software Foundation; either
10 * version 2 of the License, or (at your option) any later version.
12 * This library is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * Lesser General Public License for more details.
17 * You should have received a copy of the GNU Lesser General Public
18 * License along with this library; if not, write to the
19 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
20 * Boston, MA 02111-1307, USA.
29 #include "gthreadpool.h"
31 #include "gasyncqueue.h"
32 #include "gasyncqueueprivate.h"
34 #include "gtestutils.h"
38 * SECTION:thread_pools
39 * @title: Thread Pools
40 * @short_description: pools of threads to execute work concurrently
43 * Sometimes you wish to asynchronously fork out the execution of work
44 * and continue working in your own thread. If that will happen often,
45 * the overhead of starting and destroying a thread each time might be
46 * too high. In such cases reusing already started threads seems like a
47 * good idea. And it indeed is, but implementing this can be tedious
50 * Therefore GLib provides thread pools for your convenience. An added
51 * advantage is, that the threads can be shared between the different
52 * subsystems of your program, when they are using GLib.
54 * To create a new thread pool, you use g_thread_pool_new().
55 * It is destroyed by g_thread_pool_free().
57 * If you want to execute a certain task within a thread pool,
58 * you call g_thread_pool_push().
60 * To get the current number of running threads you call
61 * g_thread_pool_get_num_threads(). To get the number of still
62 * unprocessed tasks you call g_thread_pool_unprocessed(). To control
63 * the maximal number of threads for a thread pool, you use
64 * g_thread_pool_get_max_threads() and g_thread_pool_set_max_threads().
66 * Finally you can control the number of unused threads, that are kept
67 * alive by GLib for future use. The current number can be fetched with
68 * g_thread_pool_get_num_unused_threads(). The maximal number can be
69 * controlled by g_thread_pool_get_max_unused_threads() and
70 * g_thread_pool_set_max_unused_threads(). All currently unused threads
71 * can be stopped by calling g_thread_pool_stop_unused_threads().
75 /* #define DEBUG_MSG(args) g_printerr args ; g_printerr ("\n"); */
77 typedef struct _GRealThreadPool GRealThreadPool
;
81 * @func: the function to execute in the threads of this pool
82 * @user_data: the user data for the threads of this pool
83 * @exclusive: are all threads exclusive to this pool
85 * The #GThreadPool struct represents a thread pool. It has three
86 * public read-only members, but the underlying struct is bigger,
87 * so you must not copy this struct.
89 struct _GRealThreadPool
99 GCompareDataFunc sort_func
;
100 gpointer sort_user_data
;
103 /* The following is just an address to mark the wakeup order for a
104 * thread, it could be any address (as long, as it isn't a valid
105 * GThreadPool address)
107 static const gpointer wakeup_thread_marker
= (gpointer
) &g_thread_pool_new
;
108 static gint wakeup_thread_serial
= 0;
110 /* Here all unused threads are waiting */
111 static GAsyncQueue
*unused_thread_queue
= NULL
;
112 static gint unused_threads
= 0;
113 static gint max_unused_threads
= 0;
114 static gint kill_unused_threads
= 0;
115 static guint max_idle_time
= 0;
117 static void g_thread_pool_queue_push_unlocked (GRealThreadPool
*pool
,
119 static void g_thread_pool_free_internal (GRealThreadPool
*pool
);
120 static gpointer
g_thread_pool_thread_proxy (gpointer data
);
121 static gboolean
g_thread_pool_start_thread (GRealThreadPool
*pool
,
123 static void g_thread_pool_wakeup_and_stop_all (GRealThreadPool
*pool
);
124 static GRealThreadPool
* g_thread_pool_wait_for_new_pool (void);
125 static gpointer
g_thread_pool_wait_for_new_task (GRealThreadPool
*pool
);
128 g_thread_pool_queue_push_unlocked (GRealThreadPool
*pool
,
132 g_async_queue_push_sorted_unlocked (pool
->queue
,
135 pool
->sort_user_data
);
137 g_async_queue_push_unlocked (pool
->queue
, data
);
140 static GRealThreadPool
*
141 g_thread_pool_wait_for_new_pool (void)
143 GRealThreadPool
*pool
;
144 gint local_wakeup_thread_serial
;
145 guint local_max_unused_threads
;
146 gint local_max_idle_time
;
147 gint last_wakeup_thread_serial
;
148 gboolean have_relayed_thread_marker
= FALSE
;
150 local_max_unused_threads
= g_atomic_int_get (&max_unused_threads
);
151 local_max_idle_time
= g_atomic_int_get (&max_idle_time
);
152 last_wakeup_thread_serial
= g_atomic_int_get (&wakeup_thread_serial
);
154 g_atomic_int_inc (&unused_threads
);
158 if (g_atomic_int_get (&unused_threads
) >= local_max_unused_threads
)
160 /* If this is a superfluous thread, stop it. */
163 else if (local_max_idle_time
> 0)
165 /* If a maximal idle time is given, wait for the given time. */
168 g_get_current_time (&end_time
);
169 g_time_val_add (&end_time
, local_max_idle_time
* 1000);
171 DEBUG_MSG (("thread %p waiting in global pool for %f seconds.",
172 g_thread_self (), local_max_idle_time
/ 1000.0));
174 pool
= g_async_queue_timed_pop (unused_thread_queue
, &end_time
);
178 /* If no maximal idle time is given, wait indefinitely. */
179 DEBUG_MSG (("thread %p waiting in global pool.", g_thread_self ()));
180 pool
= g_async_queue_pop (unused_thread_queue
);
183 if (pool
== wakeup_thread_marker
)
185 local_wakeup_thread_serial
= g_atomic_int_get (&wakeup_thread_serial
);
186 if (last_wakeup_thread_serial
== local_wakeup_thread_serial
)
188 if (!have_relayed_thread_marker
)
190 /* If this wakeup marker has been received for
191 * the second time, relay it.
193 DEBUG_MSG (("thread %p relaying wakeup message to "
194 "waiting thread with lower serial.",
197 g_async_queue_push (unused_thread_queue
, wakeup_thread_marker
);
198 have_relayed_thread_marker
= TRUE
;
200 /* If a wakeup marker has been relayed, this thread
201 * will get out of the way for 100 microseconds to
202 * avoid receiving this marker again.
209 if (g_atomic_int_add (&kill_unused_threads
, -1) > 0)
215 DEBUG_MSG (("thread %p updating to new limits.",
218 local_max_unused_threads
= g_atomic_int_get (&max_unused_threads
);
219 local_max_idle_time
= g_atomic_int_get (&max_idle_time
);
220 last_wakeup_thread_serial
= local_wakeup_thread_serial
;
222 have_relayed_thread_marker
= FALSE
;
226 while (pool
== wakeup_thread_marker
);
228 g_atomic_int_add (&unused_threads
, -1);
234 g_thread_pool_wait_for_new_task (GRealThreadPool
*pool
)
236 gpointer task
= NULL
;
238 if (pool
->running
|| (!pool
->immediate
&&
239 g_async_queue_length_unlocked (pool
->queue
) > 0))
241 /* This thread pool is still active. */
242 if (pool
->num_threads
> pool
->max_threads
&& pool
->max_threads
!= -1)
244 /* This is a superfluous thread, so it goes to the global pool. */
245 DEBUG_MSG (("superfluous thread %p in pool %p.",
246 g_thread_self (), pool
));
248 else if (pool
->pool
.exclusive
)
250 /* Exclusive threads stay attached to the pool. */
251 task
= g_async_queue_pop_unlocked (pool
->queue
);
253 DEBUG_MSG (("thread %p in exclusive pool %p waits for task "
254 "(%d running, %d unprocessed).",
255 g_thread_self (), pool
, pool
->num_threads
,
256 g_async_queue_length_unlocked (pool
->queue
)));
260 /* A thread will wait for new tasks for at most 1/2
261 * second before going to the global pool.
265 g_get_current_time (&end_time
);
266 g_time_val_add (&end_time
, G_USEC_PER_SEC
/ 2); /* 1/2 second */
268 DEBUG_MSG (("thread %p in pool %p waits for up to a 1/2 second for task "
269 "(%d running, %d unprocessed).",
270 g_thread_self (), pool
, pool
->num_threads
,
271 g_async_queue_length_unlocked (pool
->queue
)));
273 task
= g_async_queue_timed_pop_unlocked (pool
->queue
, &end_time
);
278 /* This thread pool is inactive, it will no longer process tasks. */
279 DEBUG_MSG (("pool %p not active, thread %p will go to global pool "
280 "(running: %s, immediate: %s, len: %d).",
281 pool
, g_thread_self (),
282 pool
->running
? "true" : "false",
283 pool
->immediate
? "true" : "false",
284 g_async_queue_length_unlocked (pool
->queue
)));
292 g_thread_pool_thread_proxy (gpointer data
)
294 GRealThreadPool
*pool
;
298 DEBUG_MSG (("thread %p started for pool %p.", g_thread_self (), pool
));
300 g_async_queue_lock (pool
->queue
);
306 task
= g_thread_pool_wait_for_new_task (pool
);
309 if (pool
->running
|| !pool
->immediate
)
311 /* A task was received and the thread pool is active,
312 * so execute the function.
314 g_async_queue_unlock (pool
->queue
);
315 DEBUG_MSG (("thread %p in pool %p calling func.",
316 g_thread_self (), pool
));
317 pool
->pool
.func (task
, pool
->pool
.user_data
);
318 g_async_queue_lock (pool
->queue
);
323 /* No task was received, so this thread goes to the global pool. */
324 gboolean free_pool
= FALSE
;
326 DEBUG_MSG (("thread %p leaving pool %p for global pool.",
327 g_thread_self (), pool
));
334 if (pool
->num_threads
== 0)
336 /* If the pool is not running and no other
337 * thread is waiting for this thread pool to
338 * finish and this is the last thread of this
339 * pool, free the pool.
345 /* If the pool is not running and no other
346 * thread is waiting for this thread pool to
347 * finish and this is not the last thread of
348 * this pool and there are no tasks left in the
349 * queue, wakeup the remaining threads.
351 if (g_async_queue_length_unlocked (pool
->queue
) ==
353 g_thread_pool_wakeup_and_stop_all (pool
);
356 else if (pool
->immediate
||
357 g_async_queue_length_unlocked (pool
->queue
) <= 0)
359 /* If the pool is not running and another thread is
360 * waiting for this thread pool to finish and there
361 * are either no tasks left or the pool shall stop
362 * immediately, inform the waiting thread of a change
363 * of the thread pool state.
365 g_cond_broadcast (&pool
->cond
);
369 g_async_queue_unlock (pool
->queue
);
372 g_thread_pool_free_internal (pool
);
374 if ((pool
= g_thread_pool_wait_for_new_pool ()) == NULL
)
377 g_async_queue_lock (pool
->queue
);
379 DEBUG_MSG (("thread %p entering pool %p from global pool.",
380 g_thread_self (), pool
));
382 /* pool->num_threads++ is not done here, but in
383 * g_thread_pool_start_thread to make the new started
384 * thread known to the pool before itself can do it.
393 g_thread_pool_start_thread (GRealThreadPool
*pool
,
396 gboolean success
= FALSE
;
398 if (pool
->num_threads
>= pool
->max_threads
&& pool
->max_threads
!= -1)
399 /* Enough threads are already running */
402 g_async_queue_lock (unused_thread_queue
);
404 if (g_async_queue_length_unlocked (unused_thread_queue
) < 0)
406 g_async_queue_push_unlocked (unused_thread_queue
, pool
);
410 g_async_queue_unlock (unused_thread_queue
);
416 /* No thread was found, we have to start a new one */
417 thread
= g_thread_try_new ("pool", g_thread_pool_thread_proxy
, pool
, error
);
422 g_thread_unref (thread
);
425 /* See comment in g_thread_pool_thread_proxy as to why this is done
435 * @func: a function to execute in the threads of the new thread pool
436 * @user_data: user data that is handed over to @func every time it
438 * @max_threads: the maximal number of threads to execute concurrently
439 * in the new thread pool, -1 means no limit
440 * @exclusive: should this thread pool be exclusive?
441 * @error: return location for error, or %NULL
443 * This function creates a new thread pool.
445 * Whenever you call g_thread_pool_push(), either a new thread is
446 * created or an unused one is reused. At most @max_threads threads
447 * are running concurrently for this thread pool. @max_threads = -1
448 * allows unlimited threads to be created for this thread pool. The
449 * newly created or reused thread now executes the function @func
450 * with the two arguments. The first one is the parameter to
451 * g_thread_pool_push() and the second one is @user_data.
453 * The parameter @exclusive determines whether the thread pool owns
454 * all threads exclusive or shares them with other thread pools.
455 * If @exclusive is %TRUE, @max_threads threads are started
456 * immediately and they will run exclusively for this thread pool
457 * until it is destroyed by g_thread_pool_free(). If @exclusive is
458 * %FALSE, threads are created when needed and shared between all
459 * non-exclusive thread pools. This implies that @max_threads may
460 * not be -1 for exclusive thread pools.
462 * @error can be %NULL to ignore errors, or non-%NULL to report
463 * errors. An error can only occur when @exclusive is set to %TRUE
464 * and not all @max_threads threads could be created.
466 * Return value: the new #GThreadPool
469 g_thread_pool_new (GFunc func
,
475 GRealThreadPool
*retval
;
476 G_LOCK_DEFINE_STATIC (init
);
478 g_return_val_if_fail (func
, NULL
);
479 g_return_val_if_fail (!exclusive
|| max_threads
!= -1, NULL
);
480 g_return_val_if_fail (max_threads
>= -1, NULL
);
482 retval
= g_new (GRealThreadPool
, 1);
484 retval
->pool
.func
= func
;
485 retval
->pool
.user_data
= user_data
;
486 retval
->pool
.exclusive
= exclusive
;
487 retval
->queue
= g_async_queue_new ();
488 g_cond_init (&retval
->cond
);
489 retval
->max_threads
= max_threads
;
490 retval
->num_threads
= 0;
491 retval
->running
= TRUE
;
492 retval
->immediate
= FALSE
;
493 retval
->waiting
= FALSE
;
494 retval
->sort_func
= NULL
;
495 retval
->sort_user_data
= NULL
;
498 if (!unused_thread_queue
)
499 unused_thread_queue
= g_async_queue_new ();
502 if (retval
->pool
.exclusive
)
504 g_async_queue_lock (retval
->queue
);
506 while (retval
->num_threads
< retval
->max_threads
)
508 GError
*local_error
= NULL
;
510 if (!g_thread_pool_start_thread (retval
, &local_error
))
512 g_propagate_error (error
, local_error
);
517 g_async_queue_unlock (retval
->queue
);
520 return (GThreadPool
*) retval
;
524 * g_thread_pool_push:
525 * @pool: a #GThreadPool
526 * @data: a new task for @pool
527 * @error: return location for error, or %NULL
529 * Inserts @data into the list of tasks to be executed by @pool.
531 * When the number of currently running threads is lower than the
532 * maximal allowed number of threads, a new thread is started (or
533 * reused) with the properties given to g_thread_pool_new().
534 * Otherwise, @data stays in the queue until a thread in this pool
535 * finishes its previous task and processes @data.
537 * @error can be %NULL to ignore errors, or non-%NULL to report
538 * errors. An error can only occur when a new thread couldn't be
539 * created. In that case @data is simply appended to the queue of
542 * Before version 2.32, this function did not return a success status.
544 * Return value: %TRUE on success, %FALSE if an error occurred
547 g_thread_pool_push (GThreadPool
*pool
,
551 GRealThreadPool
*real
;
554 real
= (GRealThreadPool
*) pool
;
556 g_return_val_if_fail (real
, FALSE
);
557 g_return_val_if_fail (real
->running
, FALSE
);
561 g_async_queue_lock (real
->queue
);
563 if (g_async_queue_length_unlocked (real
->queue
) >= 0)
565 /* No thread is waiting in the queue */
566 GError
*local_error
= NULL
;
568 if (!g_thread_pool_start_thread (real
, &local_error
))
570 g_propagate_error (error
, local_error
);
575 g_thread_pool_queue_push_unlocked (real
, data
);
576 g_async_queue_unlock (real
->queue
);
582 * g_thread_pool_set_max_threads:
583 * @pool: a #GThreadPool
584 * @max_threads: a new maximal number of threads for @pool,
585 * or -1 for unlimited
586 * @error: return location for error, or %NULL
588 * Sets the maximal allowed number of threads for @pool.
589 * A value of -1 means that the maximal number of threads
590 * is unlimited. If @pool is an exclusive thread pool, setting
591 * the maximal number of threads to -1 is not allowed.
593 * Setting @max_threads to 0 means stopping all work for @pool.
594 * It is effectively frozen until @max_threads is set to a non-zero
597 * A thread is never terminated while calling @func, as supplied by
598 * g_thread_pool_new(). Instead the maximal number of threads only
599 * has effect for the allocation of new threads in g_thread_pool_push().
600 * A new thread is allocated, whenever the number of currently
601 * running threads in @pool is smaller than the maximal number.
603 * @error can be %NULL to ignore errors, or non-%NULL to report
604 * errors. An error can only occur when a new thread couldn't be
607 * Before version 2.32, this function did not return a success status.
609 * Return value: %TRUE on success, %FALSE if an error occurred
612 g_thread_pool_set_max_threads (GThreadPool
*pool
,
616 GRealThreadPool
*real
;
620 real
= (GRealThreadPool
*) pool
;
622 g_return_val_if_fail (real
, FALSE
);
623 g_return_val_if_fail (real
->running
, FALSE
);
624 g_return_val_if_fail (!real
->pool
.exclusive
|| max_threads
!= -1, FALSE
);
625 g_return_val_if_fail (max_threads
>= -1, FALSE
);
629 g_async_queue_lock (real
->queue
);
631 real
->max_threads
= max_threads
;
634 to_start
= real
->max_threads
- real
->num_threads
;
636 to_start
= g_async_queue_length_unlocked (real
->queue
);
638 for ( ; to_start
> 0; to_start
--)
640 GError
*local_error
= NULL
;
642 if (!g_thread_pool_start_thread (real
, &local_error
))
644 g_propagate_error (error
, local_error
);
650 g_async_queue_unlock (real
->queue
);
656 * g_thread_pool_get_max_threads:
657 * @pool: a #GThreadPool
659 * Returns the maximal number of threads for @pool.
661 * Return value: the maximal number of threads
664 g_thread_pool_get_max_threads (GThreadPool
*pool
)
666 GRealThreadPool
*real
;
669 real
= (GRealThreadPool
*) pool
;
671 g_return_val_if_fail (real
, 0);
672 g_return_val_if_fail (real
->running
, 0);
674 g_async_queue_lock (real
->queue
);
675 retval
= real
->max_threads
;
676 g_async_queue_unlock (real
->queue
);
682 * g_thread_pool_get_num_threads:
683 * @pool: a #GThreadPool
685 * Returns the number of threads currently running in @pool.
687 * Return value: the number of threads currently running
690 g_thread_pool_get_num_threads (GThreadPool
*pool
)
692 GRealThreadPool
*real
;
695 real
= (GRealThreadPool
*) pool
;
697 g_return_val_if_fail (real
, 0);
698 g_return_val_if_fail (real
->running
, 0);
700 g_async_queue_lock (real
->queue
);
701 retval
= real
->num_threads
;
702 g_async_queue_unlock (real
->queue
);
708 * g_thread_pool_unprocessed:
709 * @pool: a #GThreadPool
711 * Returns the number of tasks still unprocessed in @pool.
713 * Return value: the number of unprocessed tasks
716 g_thread_pool_unprocessed (GThreadPool
*pool
)
718 GRealThreadPool
*real
;
721 real
= (GRealThreadPool
*) pool
;
723 g_return_val_if_fail (real
, 0);
724 g_return_val_if_fail (real
->running
, 0);
726 unprocessed
= g_async_queue_length (real
->queue
);
728 return MAX (unprocessed
, 0);
732 * g_thread_pool_free:
733 * @pool: a #GThreadPool
734 * @immediate: should @pool shut down immediately?
735 * @wait_: should the function wait for all tasks to be finished?
737 * Frees all resources allocated for @pool.
739 * If @immediate is %TRUE, no new task is processed for @pool.
740 * Otherwise @pool is not freed before the last task is processed.
741 * Note however, that no thread of this pool is interrupted while
742 * processing a task. Instead at least all still running threads
743 * can finish their tasks before the @pool is freed.
745 * If @wait_ is %TRUE, the functions does not return before all
746 * tasks to be processed (dependent on @immediate, whether all
747 * or only the currently running) are ready.
748 * Otherwise the function returns immediately.
750 * After calling this function @pool must not be used anymore.
753 g_thread_pool_free (GThreadPool
*pool
,
757 GRealThreadPool
*real
;
759 real
= (GRealThreadPool
*) pool
;
761 g_return_if_fail (real
);
762 g_return_if_fail (real
->running
);
764 /* If there's no thread allowed here, there is not much sense in
765 * not stopping this pool immediately, when it's not empty
767 g_return_if_fail (immediate
||
768 real
->max_threads
!= 0 ||
769 g_async_queue_length (real
->queue
) == 0);
771 g_async_queue_lock (real
->queue
);
773 real
->running
= FALSE
;
774 real
->immediate
= immediate
;
775 real
->waiting
= wait_
;
779 while (g_async_queue_length_unlocked (real
->queue
) != -real
->num_threads
&&
780 !(immediate
&& real
->num_threads
== 0))
781 g_cond_wait (&real
->cond
, _g_async_queue_get_mutex (real
->queue
));
784 if (immediate
|| g_async_queue_length_unlocked (real
->queue
) == -real
->num_threads
)
786 /* No thread is currently doing something (and nothing is left
787 * to process in the queue)
789 if (real
->num_threads
== 0)
791 /* No threads left, we clean up */
792 g_async_queue_unlock (real
->queue
);
793 g_thread_pool_free_internal (real
);
797 g_thread_pool_wakeup_and_stop_all (real
);
800 /* The last thread should cleanup the pool */
801 real
->waiting
= FALSE
;
802 g_async_queue_unlock (real
->queue
);
806 g_thread_pool_free_internal (GRealThreadPool
* pool
)
808 g_return_if_fail (pool
);
809 g_return_if_fail (pool
->running
== FALSE
);
810 g_return_if_fail (pool
->num_threads
== 0);
812 g_async_queue_unref (pool
->queue
);
813 g_cond_clear (&pool
->cond
);
819 g_thread_pool_wakeup_and_stop_all (GRealThreadPool
*pool
)
823 g_return_if_fail (pool
);
824 g_return_if_fail (pool
->running
== FALSE
);
825 g_return_if_fail (pool
->num_threads
!= 0);
827 pool
->immediate
= TRUE
;
829 for (i
= 0; i
< pool
->num_threads
; i
++)
830 g_thread_pool_queue_push_unlocked (pool
, GUINT_TO_POINTER (1));
834 * g_thread_pool_set_max_unused_threads:
835 * @max_threads: maximal number of unused threads
837 * Sets the maximal number of unused threads to @max_threads.
838 * If @max_threads is -1, no limit is imposed on the number
842 g_thread_pool_set_max_unused_threads (gint max_threads
)
844 g_return_if_fail (max_threads
>= -1);
846 g_atomic_int_set (&max_unused_threads
, max_threads
);
848 if (max_threads
!= -1)
850 max_threads
-= g_atomic_int_get (&unused_threads
);
853 g_atomic_int_set (&kill_unused_threads
, -max_threads
);
854 g_atomic_int_inc (&wakeup_thread_serial
);
856 g_async_queue_lock (unused_thread_queue
);
860 g_async_queue_push_unlocked (unused_thread_queue
,
861 wakeup_thread_marker
);
863 while (++max_threads
);
865 g_async_queue_unlock (unused_thread_queue
);
871 * g_thread_pool_get_max_unused_threads:
873 * Returns the maximal allowed number of unused threads.
875 * Return value: the maximal number of unused threads
878 g_thread_pool_get_max_unused_threads (void)
880 return g_atomic_int_get (&max_unused_threads
);
884 * g_thread_pool_get_num_unused_threads:
886 * Returns the number of currently unused threads.
888 * Return value: the number of currently unused threads
891 g_thread_pool_get_num_unused_threads (void)
893 return g_atomic_int_get (&unused_threads
);
897 * g_thread_pool_stop_unused_threads:
899 * Stops all currently unused threads. This does not change the
900 * maximal number of unused threads. This function can be used to
901 * regularly stop all unused threads e.g. from g_timeout_add().
904 g_thread_pool_stop_unused_threads (void)
908 oldval
= g_thread_pool_get_max_unused_threads ();
910 g_thread_pool_set_max_unused_threads (0);
911 g_thread_pool_set_max_unused_threads (oldval
);
915 * g_thread_pool_set_sort_function:
916 * @pool: a #GThreadPool
917 * @func: the #GCompareDataFunc used to sort the list of tasks.
918 * This function is passed two tasks. It should return
919 * 0 if the order in which they are handled does not matter,
920 * a negative value if the first task should be processed before
921 * the second or a positive value if the second task should be
923 * @user_data: user data passed to @func
925 * Sets the function used to sort the list of tasks. This allows the
926 * tasks to be processed by a priority determined by @func, and not
927 * just in the order in which they were added to the pool.
929 * Note, if the maximum number of threads is more than 1, the order
930 * that threads are executed cannot be guaranteed 100%. Threads are
931 * scheduled by the operating system and are executed at random. It
932 * cannot be assumed that threads are executed in the order they are
938 g_thread_pool_set_sort_function (GThreadPool
*pool
,
939 GCompareDataFunc func
,
942 GRealThreadPool
*real
;
944 real
= (GRealThreadPool
*) pool
;
946 g_return_if_fail (real
);
947 g_return_if_fail (real
->running
);
949 g_async_queue_lock (real
->queue
);
951 real
->sort_func
= func
;
952 real
->sort_user_data
= user_data
;
955 g_async_queue_sort_unlocked (real
->queue
,
957 real
->sort_user_data
);
959 g_async_queue_unlock (real
->queue
);
963 * g_thread_pool_set_max_idle_time:
964 * @interval: the maximum @interval (in milliseconds)
965 * a thread can be idle
967 * This function will set the maximum @interval that a thread
968 * waiting in the pool for new tasks can be idle for before
969 * being stopped. This function is similar to calling
970 * g_thread_pool_stop_unused_threads() on a regular timeout,
971 * except this is done on a per thread basis.
973 * By setting @interval to 0, idle threads will not be stopped.
975 * This function makes use of g_async_queue_timed_pop () using
981 g_thread_pool_set_max_idle_time (guint interval
)
985 g_atomic_int_set (&max_idle_time
, interval
);
987 i
= g_atomic_int_get (&unused_threads
);
990 g_atomic_int_inc (&wakeup_thread_serial
);
991 g_async_queue_lock (unused_thread_queue
);
995 g_async_queue_push_unlocked (unused_thread_queue
,
996 wakeup_thread_marker
);
1000 g_async_queue_unlock (unused_thread_queue
);
1005 * g_thread_pool_get_max_idle_time:
1007 * This function will return the maximum @interval that a
1008 * thread will wait in the thread pool for new tasks before
1011 * If this function returns 0, threads waiting in the thread
1012 * pool for new work are not stopped.
1014 * Return value: the maximum @interval (milliseconds) to wait
1015 * for new tasks in the thread pool before stopping the
1021 g_thread_pool_get_max_idle_time (void)
1023 return g_atomic_int_get (&max_idle_time
);