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 2.1 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, see <http://www.gnu.org/licenses/>.
27 #include "gthreadpool.h"
29 #include "gasyncqueue.h"
30 #include "gasyncqueueprivate.h"
32 #include "gtestutils.h"
36 * SECTION:thread_pools
37 * @title: Thread Pools
38 * @short_description: pools of threads to execute work concurrently
41 * Sometimes you wish to asynchronously fork out the execution of work
42 * and continue working in your own thread. If that will happen often,
43 * the overhead of starting and destroying a thread each time might be
44 * too high. In such cases reusing already started threads seems like a
45 * good idea. And it indeed is, but implementing this can be tedious
48 * Therefore GLib provides thread pools for your convenience. An added
49 * advantage is, that the threads can be shared between the different
50 * subsystems of your program, when they are using GLib.
52 * To create a new thread pool, you use g_thread_pool_new().
53 * It is destroyed by g_thread_pool_free().
55 * If you want to execute a certain task within a thread pool,
56 * you call g_thread_pool_push().
58 * To get the current number of running threads you call
59 * g_thread_pool_get_num_threads(). To get the number of still
60 * unprocessed tasks you call g_thread_pool_unprocessed(). To control
61 * the maximal number of threads for a thread pool, you use
62 * g_thread_pool_get_max_threads() and g_thread_pool_set_max_threads().
64 * Finally you can control the number of unused threads, that are kept
65 * alive by GLib for future use. The current number can be fetched with
66 * g_thread_pool_get_num_unused_threads(). The maximal number can be
67 * controlled by g_thread_pool_get_max_unused_threads() and
68 * g_thread_pool_set_max_unused_threads(). All currently unused threads
69 * can be stopped by calling g_thread_pool_stop_unused_threads().
73 /* #define DEBUG_MSG(args) g_printerr args ; g_printerr ("\n"); */
75 typedef struct _GRealThreadPool GRealThreadPool
;
79 * @func: the function to execute in the threads of this pool
80 * @user_data: the user data for the threads of this pool
81 * @exclusive: are all threads exclusive to this pool
83 * The #GThreadPool struct represents a thread pool. It has three
84 * public read-only members, but the underlying struct is bigger,
85 * so you must not copy this struct.
87 struct _GRealThreadPool
97 GCompareDataFunc sort_func
;
98 gpointer sort_user_data
;
101 /* The following is just an address to mark the wakeup order for a
102 * thread, it could be any address (as long, as it isn't a valid
103 * GThreadPool address)
105 static const gpointer wakeup_thread_marker
= (gpointer
) &g_thread_pool_new
;
106 static gint wakeup_thread_serial
= 0;
108 /* Here all unused threads are waiting */
109 static GAsyncQueue
*unused_thread_queue
= NULL
;
110 static gint unused_threads
= 0;
111 static gint max_unused_threads
= 2;
112 static gint kill_unused_threads
= 0;
113 static guint max_idle_time
= 15 * 1000;
115 static void g_thread_pool_queue_push_unlocked (GRealThreadPool
*pool
,
117 static void g_thread_pool_free_internal (GRealThreadPool
*pool
);
118 static gpointer
g_thread_pool_thread_proxy (gpointer data
);
119 static gboolean
g_thread_pool_start_thread (GRealThreadPool
*pool
,
121 static void g_thread_pool_wakeup_and_stop_all (GRealThreadPool
*pool
);
122 static GRealThreadPool
* g_thread_pool_wait_for_new_pool (void);
123 static gpointer
g_thread_pool_wait_for_new_task (GRealThreadPool
*pool
);
126 g_thread_pool_queue_push_unlocked (GRealThreadPool
*pool
,
130 g_async_queue_push_sorted_unlocked (pool
->queue
,
133 pool
->sort_user_data
);
135 g_async_queue_push_unlocked (pool
->queue
, data
);
138 static GRealThreadPool
*
139 g_thread_pool_wait_for_new_pool (void)
141 GRealThreadPool
*pool
;
142 gint local_wakeup_thread_serial
;
143 guint local_max_unused_threads
;
144 gint local_max_idle_time
;
145 gint last_wakeup_thread_serial
;
146 gboolean have_relayed_thread_marker
= FALSE
;
148 local_max_unused_threads
= g_atomic_int_get (&max_unused_threads
);
149 local_max_idle_time
= g_atomic_int_get (&max_idle_time
);
150 last_wakeup_thread_serial
= g_atomic_int_get (&wakeup_thread_serial
);
152 g_atomic_int_inc (&unused_threads
);
156 if (g_atomic_int_get (&unused_threads
) >= local_max_unused_threads
)
158 /* If this is a superfluous thread, stop it. */
161 else if (local_max_idle_time
> 0)
163 /* If a maximal idle time is given, wait for the given time. */
164 DEBUG_MSG (("thread %p waiting in global pool for %f seconds.",
165 g_thread_self (), local_max_idle_time
/ 1000.0));
167 pool
= g_async_queue_timeout_pop (unused_thread_queue
,
168 local_max_idle_time
* 1000);
172 /* If no maximal idle time is given, wait indefinitely. */
173 DEBUG_MSG (("thread %p waiting in global pool.", g_thread_self ()));
174 pool
= g_async_queue_pop (unused_thread_queue
);
177 if (pool
== wakeup_thread_marker
)
179 local_wakeup_thread_serial
= g_atomic_int_get (&wakeup_thread_serial
);
180 if (last_wakeup_thread_serial
== local_wakeup_thread_serial
)
182 if (!have_relayed_thread_marker
)
184 /* If this wakeup marker has been received for
185 * the second time, relay it.
187 DEBUG_MSG (("thread %p relaying wakeup message to "
188 "waiting thread with lower serial.",
191 g_async_queue_push (unused_thread_queue
, wakeup_thread_marker
);
192 have_relayed_thread_marker
= TRUE
;
194 /* If a wakeup marker has been relayed, this thread
195 * will get out of the way for 100 microseconds to
196 * avoid receiving this marker again.
203 if (g_atomic_int_add (&kill_unused_threads
, -1) > 0)
209 DEBUG_MSG (("thread %p updating to new limits.",
212 local_max_unused_threads
= g_atomic_int_get (&max_unused_threads
);
213 local_max_idle_time
= g_atomic_int_get (&max_idle_time
);
214 last_wakeup_thread_serial
= local_wakeup_thread_serial
;
216 have_relayed_thread_marker
= FALSE
;
220 while (pool
== wakeup_thread_marker
);
222 g_atomic_int_add (&unused_threads
, -1);
228 g_thread_pool_wait_for_new_task (GRealThreadPool
*pool
)
230 gpointer task
= NULL
;
232 if (pool
->running
|| (!pool
->immediate
&&
233 g_async_queue_length_unlocked (pool
->queue
) > 0))
235 /* This thread pool is still active. */
236 if (pool
->num_threads
> pool
->max_threads
&& pool
->max_threads
!= -1)
238 /* This is a superfluous thread, so it goes to the global pool. */
239 DEBUG_MSG (("superfluous thread %p in pool %p.",
240 g_thread_self (), pool
));
242 else if (pool
->pool
.exclusive
)
244 /* Exclusive threads stay attached to the pool. */
245 task
= g_async_queue_pop_unlocked (pool
->queue
);
247 DEBUG_MSG (("thread %p in exclusive pool %p waits for task "
248 "(%d running, %d unprocessed).",
249 g_thread_self (), pool
, pool
->num_threads
,
250 g_async_queue_length_unlocked (pool
->queue
)));
254 /* A thread will wait for new tasks for at most 1/2
255 * second before going to the global pool.
257 DEBUG_MSG (("thread %p in pool %p waits for up to a 1/2 second for task "
258 "(%d running, %d unprocessed).",
259 g_thread_self (), pool
, pool
->num_threads
,
260 g_async_queue_length_unlocked (pool
->queue
)));
262 task
= g_async_queue_timeout_pop_unlocked (pool
->queue
,
268 /* This thread pool is inactive, it will no longer process tasks. */
269 DEBUG_MSG (("pool %p not active, thread %p will go to global pool "
270 "(running: %s, immediate: %s, len: %d).",
271 pool
, g_thread_self (),
272 pool
->running
? "true" : "false",
273 pool
->immediate
? "true" : "false",
274 g_async_queue_length_unlocked (pool
->queue
)));
282 g_thread_pool_thread_proxy (gpointer data
)
284 GRealThreadPool
*pool
;
288 DEBUG_MSG (("thread %p started for pool %p.", g_thread_self (), pool
));
290 g_async_queue_lock (pool
->queue
);
296 task
= g_thread_pool_wait_for_new_task (pool
);
299 if (pool
->running
|| !pool
->immediate
)
301 /* A task was received and the thread pool is active,
302 * so execute the function.
304 g_async_queue_unlock (pool
->queue
);
305 DEBUG_MSG (("thread %p in pool %p calling func.",
306 g_thread_self (), pool
));
307 pool
->pool
.func (task
, pool
->pool
.user_data
);
308 g_async_queue_lock (pool
->queue
);
313 /* No task was received, so this thread goes to the global pool. */
314 gboolean free_pool
= FALSE
;
316 DEBUG_MSG (("thread %p leaving pool %p for global pool.",
317 g_thread_self (), pool
));
324 if (pool
->num_threads
== 0)
326 /* If the pool is not running and no other
327 * thread is waiting for this thread pool to
328 * finish and this is the last thread of this
329 * pool, free the pool.
335 /* If the pool is not running and no other
336 * thread is waiting for this thread pool to
337 * finish and this is not the last thread of
338 * this pool and there are no tasks left in the
339 * queue, wakeup the remaining threads.
341 if (g_async_queue_length_unlocked (pool
->queue
) ==
343 g_thread_pool_wakeup_and_stop_all (pool
);
346 else if (pool
->immediate
||
347 g_async_queue_length_unlocked (pool
->queue
) <= 0)
349 /* If the pool is not running and another thread is
350 * waiting for this thread pool to finish and there
351 * are either no tasks left or the pool shall stop
352 * immediately, inform the waiting thread of a change
353 * of the thread pool state.
355 g_cond_broadcast (&pool
->cond
);
359 g_async_queue_unlock (pool
->queue
);
362 g_thread_pool_free_internal (pool
);
364 if ((pool
= g_thread_pool_wait_for_new_pool ()) == NULL
)
367 g_async_queue_lock (pool
->queue
);
369 DEBUG_MSG (("thread %p entering pool %p from global pool.",
370 g_thread_self (), pool
));
372 /* pool->num_threads++ is not done here, but in
373 * g_thread_pool_start_thread to make the new started
374 * thread known to the pool before itself can do it.
383 g_thread_pool_start_thread (GRealThreadPool
*pool
,
386 gboolean success
= FALSE
;
388 if (pool
->num_threads
>= pool
->max_threads
&& pool
->max_threads
!= -1)
389 /* Enough threads are already running */
392 g_async_queue_lock (unused_thread_queue
);
394 if (g_async_queue_length_unlocked (unused_thread_queue
) < 0)
396 g_async_queue_push_unlocked (unused_thread_queue
, pool
);
400 g_async_queue_unlock (unused_thread_queue
);
406 /* No thread was found, we have to start a new one */
407 thread
= g_thread_try_new ("pool", g_thread_pool_thread_proxy
, pool
, error
);
412 g_thread_unref (thread
);
415 /* See comment in g_thread_pool_thread_proxy as to why this is done
425 * @func: a function to execute in the threads of the new thread pool
426 * @user_data: user data that is handed over to @func every time it
428 * @max_threads: the maximal number of threads to execute concurrently
429 * in the new thread pool, -1 means no limit
430 * @exclusive: should this thread pool be exclusive?
431 * @error: return location for error, or %NULL
433 * This function creates a new thread pool.
435 * Whenever you call g_thread_pool_push(), either a new thread is
436 * created or an unused one is reused. At most @max_threads threads
437 * are running concurrently for this thread pool. @max_threads = -1
438 * allows unlimited threads to be created for this thread pool. The
439 * newly created or reused thread now executes the function @func
440 * with the two arguments. The first one is the parameter to
441 * g_thread_pool_push() and the second one is @user_data.
443 * The parameter @exclusive determines whether the thread pool owns
444 * all threads exclusive or shares them with other thread pools.
445 * If @exclusive is %TRUE, @max_threads threads are started
446 * immediately and they will run exclusively for this thread pool
447 * until it is destroyed by g_thread_pool_free(). If @exclusive is
448 * %FALSE, threads are created when needed and shared between all
449 * non-exclusive thread pools. This implies that @max_threads may
450 * not be -1 for exclusive thread pools. Besides, exclusive thread
451 * pools are not affected by g_thread_pool_set_max_idle_time()
452 * since their threads are never considered idle and returned to the
455 * @error can be %NULL to ignore errors, or non-%NULL to report
456 * errors. An error can only occur when @exclusive is set to %TRUE
457 * and not all @max_threads threads could be created.
458 * See #GThreadError for possible errors that may occur.
459 * Note, even in case of error a valid #GThreadPool is returned.
461 * Returns: the new #GThreadPool
464 g_thread_pool_new (GFunc func
,
470 GRealThreadPool
*retval
;
471 G_LOCK_DEFINE_STATIC (init
);
473 g_return_val_if_fail (func
, NULL
);
474 g_return_val_if_fail (!exclusive
|| max_threads
!= -1, NULL
);
475 g_return_val_if_fail (max_threads
>= -1, NULL
);
477 retval
= g_new (GRealThreadPool
, 1);
479 retval
->pool
.func
= func
;
480 retval
->pool
.user_data
= user_data
;
481 retval
->pool
.exclusive
= exclusive
;
482 retval
->queue
= g_async_queue_new ();
483 g_cond_init (&retval
->cond
);
484 retval
->max_threads
= max_threads
;
485 retval
->num_threads
= 0;
486 retval
->running
= TRUE
;
487 retval
->immediate
= FALSE
;
488 retval
->waiting
= FALSE
;
489 retval
->sort_func
= NULL
;
490 retval
->sort_user_data
= NULL
;
493 if (!unused_thread_queue
)
494 unused_thread_queue
= g_async_queue_new ();
497 if (retval
->pool
.exclusive
)
499 g_async_queue_lock (retval
->queue
);
501 while (retval
->num_threads
< retval
->max_threads
)
503 GError
*local_error
= NULL
;
505 if (!g_thread_pool_start_thread (retval
, &local_error
))
507 g_propagate_error (error
, local_error
);
512 g_async_queue_unlock (retval
->queue
);
515 return (GThreadPool
*) retval
;
519 * g_thread_pool_push:
520 * @pool: a #GThreadPool
521 * @data: a new task for @pool
522 * @error: return location for error, or %NULL
524 * Inserts @data into the list of tasks to be executed by @pool.
526 * When the number of currently running threads is lower than the
527 * maximal allowed number of threads, a new thread is started (or
528 * reused) with the properties given to g_thread_pool_new().
529 * Otherwise, @data stays in the queue until a thread in this pool
530 * finishes its previous task and processes @data.
532 * @error can be %NULL to ignore errors, or non-%NULL to report
533 * errors. An error can only occur when a new thread couldn't be
534 * created. In that case @data is simply appended to the queue of
537 * Before version 2.32, this function did not return a success status.
539 * Returns: %TRUE on success, %FALSE if an error occurred
542 g_thread_pool_push (GThreadPool
*pool
,
546 GRealThreadPool
*real
;
549 real
= (GRealThreadPool
*) pool
;
551 g_return_val_if_fail (real
, FALSE
);
552 g_return_val_if_fail (real
->running
, FALSE
);
556 g_async_queue_lock (real
->queue
);
558 if (g_async_queue_length_unlocked (real
->queue
) >= 0)
560 /* No thread is waiting in the queue */
561 GError
*local_error
= NULL
;
563 if (!g_thread_pool_start_thread (real
, &local_error
))
565 g_propagate_error (error
, local_error
);
570 g_thread_pool_queue_push_unlocked (real
, data
);
571 g_async_queue_unlock (real
->queue
);
577 * g_thread_pool_set_max_threads:
578 * @pool: a #GThreadPool
579 * @max_threads: a new maximal number of threads for @pool,
580 * or -1 for unlimited
581 * @error: return location for error, or %NULL
583 * Sets the maximal allowed number of threads for @pool.
584 * A value of -1 means that the maximal number of threads
585 * is unlimited. If @pool is an exclusive thread pool, setting
586 * the maximal number of threads to -1 is not allowed.
588 * Setting @max_threads to 0 means stopping all work for @pool.
589 * It is effectively frozen until @max_threads is set to a non-zero
592 * A thread is never terminated while calling @func, as supplied by
593 * g_thread_pool_new(). Instead the maximal number of threads only
594 * has effect for the allocation of new threads in g_thread_pool_push().
595 * A new thread is allocated, whenever the number of currently
596 * running threads in @pool is smaller than the maximal number.
598 * @error can be %NULL to ignore errors, or non-%NULL to report
599 * errors. An error can only occur when a new thread couldn't be
602 * Before version 2.32, this function did not return a success status.
604 * Returns: %TRUE on success, %FALSE if an error occurred
607 g_thread_pool_set_max_threads (GThreadPool
*pool
,
611 GRealThreadPool
*real
;
615 real
= (GRealThreadPool
*) pool
;
617 g_return_val_if_fail (real
, FALSE
);
618 g_return_val_if_fail (real
->running
, FALSE
);
619 g_return_val_if_fail (!real
->pool
.exclusive
|| max_threads
!= -1, FALSE
);
620 g_return_val_if_fail (max_threads
>= -1, FALSE
);
624 g_async_queue_lock (real
->queue
);
626 real
->max_threads
= max_threads
;
629 to_start
= real
->max_threads
- real
->num_threads
;
631 to_start
= g_async_queue_length_unlocked (real
->queue
);
633 for ( ; to_start
> 0; to_start
--)
635 GError
*local_error
= NULL
;
637 if (!g_thread_pool_start_thread (real
, &local_error
))
639 g_propagate_error (error
, local_error
);
645 g_async_queue_unlock (real
->queue
);
651 * g_thread_pool_get_max_threads:
652 * @pool: a #GThreadPool
654 * Returns the maximal number of threads for @pool.
656 * Returns: the maximal number of threads
659 g_thread_pool_get_max_threads (GThreadPool
*pool
)
661 GRealThreadPool
*real
;
664 real
= (GRealThreadPool
*) pool
;
666 g_return_val_if_fail (real
, 0);
667 g_return_val_if_fail (real
->running
, 0);
669 g_async_queue_lock (real
->queue
);
670 retval
= real
->max_threads
;
671 g_async_queue_unlock (real
->queue
);
677 * g_thread_pool_get_num_threads:
678 * @pool: a #GThreadPool
680 * Returns the number of threads currently running in @pool.
682 * Returns: the number of threads currently running
685 g_thread_pool_get_num_threads (GThreadPool
*pool
)
687 GRealThreadPool
*real
;
690 real
= (GRealThreadPool
*) pool
;
692 g_return_val_if_fail (real
, 0);
693 g_return_val_if_fail (real
->running
, 0);
695 g_async_queue_lock (real
->queue
);
696 retval
= real
->num_threads
;
697 g_async_queue_unlock (real
->queue
);
703 * g_thread_pool_unprocessed:
704 * @pool: a #GThreadPool
706 * Returns the number of tasks still unprocessed in @pool.
708 * Returns: the number of unprocessed tasks
711 g_thread_pool_unprocessed (GThreadPool
*pool
)
713 GRealThreadPool
*real
;
716 real
= (GRealThreadPool
*) pool
;
718 g_return_val_if_fail (real
, 0);
719 g_return_val_if_fail (real
->running
, 0);
721 unprocessed
= g_async_queue_length (real
->queue
);
723 return MAX (unprocessed
, 0);
727 * g_thread_pool_free:
728 * @pool: a #GThreadPool
729 * @immediate: should @pool shut down immediately?
730 * @wait_: should the function wait for all tasks to be finished?
732 * Frees all resources allocated for @pool.
734 * If @immediate is %TRUE, no new task is processed for @pool.
735 * Otherwise @pool is not freed before the last task is processed.
736 * Note however, that no thread of this pool is interrupted while
737 * processing a task. Instead at least all still running threads
738 * can finish their tasks before the @pool is freed.
740 * If @wait_ is %TRUE, the functions does not return before all
741 * tasks to be processed (dependent on @immediate, whether all
742 * or only the currently running) are ready.
743 * Otherwise the function returns immediately.
745 * After calling this function @pool must not be used anymore.
748 g_thread_pool_free (GThreadPool
*pool
,
752 GRealThreadPool
*real
;
754 real
= (GRealThreadPool
*) pool
;
756 g_return_if_fail (real
);
757 g_return_if_fail (real
->running
);
759 /* If there's no thread allowed here, there is not much sense in
760 * not stopping this pool immediately, when it's not empty
762 g_return_if_fail (immediate
||
763 real
->max_threads
!= 0 ||
764 g_async_queue_length (real
->queue
) == 0);
766 g_async_queue_lock (real
->queue
);
768 real
->running
= FALSE
;
769 real
->immediate
= immediate
;
770 real
->waiting
= wait_
;
774 while (g_async_queue_length_unlocked (real
->queue
) != -real
->num_threads
&&
775 !(immediate
&& real
->num_threads
== 0))
776 g_cond_wait (&real
->cond
, _g_async_queue_get_mutex (real
->queue
));
779 if (immediate
|| g_async_queue_length_unlocked (real
->queue
) == -real
->num_threads
)
781 /* No thread is currently doing something (and nothing is left
782 * to process in the queue)
784 if (real
->num_threads
== 0)
786 /* No threads left, we clean up */
787 g_async_queue_unlock (real
->queue
);
788 g_thread_pool_free_internal (real
);
792 g_thread_pool_wakeup_and_stop_all (real
);
795 /* The last thread should cleanup the pool */
796 real
->waiting
= FALSE
;
797 g_async_queue_unlock (real
->queue
);
801 g_thread_pool_free_internal (GRealThreadPool
* pool
)
803 g_return_if_fail (pool
);
804 g_return_if_fail (pool
->running
== FALSE
);
805 g_return_if_fail (pool
->num_threads
== 0);
807 g_async_queue_unref (pool
->queue
);
808 g_cond_clear (&pool
->cond
);
814 g_thread_pool_wakeup_and_stop_all (GRealThreadPool
*pool
)
818 g_return_if_fail (pool
);
819 g_return_if_fail (pool
->running
== FALSE
);
820 g_return_if_fail (pool
->num_threads
!= 0);
822 pool
->immediate
= TRUE
;
825 * So here we're sending bogus data to the pool threads, which
826 * should cause them each to wake up, and check the above
827 * pool->immediate condition. However we don't want that
828 * data to be sorted (since it'll crash the sorter).
830 for (i
= 0; i
< pool
->num_threads
; i
++)
831 g_async_queue_push_unlocked (pool
->queue
, GUINT_TO_POINTER (1));
835 * g_thread_pool_set_max_unused_threads:
836 * @max_threads: maximal number of unused threads
838 * Sets the maximal number of unused threads to @max_threads.
839 * If @max_threads is -1, no limit is imposed on the number
842 * The default value is 2.
845 g_thread_pool_set_max_unused_threads (gint max_threads
)
847 g_return_if_fail (max_threads
>= -1);
849 g_atomic_int_set (&max_unused_threads
, max_threads
);
851 if (max_threads
!= -1)
853 max_threads
-= g_atomic_int_get (&unused_threads
);
856 g_atomic_int_set (&kill_unused_threads
, -max_threads
);
857 g_atomic_int_inc (&wakeup_thread_serial
);
859 g_async_queue_lock (unused_thread_queue
);
863 g_async_queue_push_unlocked (unused_thread_queue
,
864 wakeup_thread_marker
);
866 while (++max_threads
);
868 g_async_queue_unlock (unused_thread_queue
);
874 * g_thread_pool_get_max_unused_threads:
876 * Returns the maximal allowed number of unused threads.
878 * Returns: the maximal number of unused threads
881 g_thread_pool_get_max_unused_threads (void)
883 return g_atomic_int_get (&max_unused_threads
);
887 * g_thread_pool_get_num_unused_threads:
889 * Returns the number of currently unused threads.
891 * Returns: the number of currently unused threads
894 g_thread_pool_get_num_unused_threads (void)
896 return g_atomic_int_get (&unused_threads
);
900 * g_thread_pool_stop_unused_threads:
902 * Stops all currently unused threads. This does not change the
903 * maximal number of unused threads. This function can be used to
904 * regularly stop all unused threads e.g. from g_timeout_add().
907 g_thread_pool_stop_unused_threads (void)
911 oldval
= g_thread_pool_get_max_unused_threads ();
913 g_thread_pool_set_max_unused_threads (0);
914 g_thread_pool_set_max_unused_threads (oldval
);
918 * g_thread_pool_set_sort_function:
919 * @pool: a #GThreadPool
920 * @func: the #GCompareDataFunc used to sort the list of tasks.
921 * This function is passed two tasks. It should return
922 * 0 if the order in which they are handled does not matter,
923 * a negative value if the first task should be processed before
924 * the second or a positive value if the second task should be
926 * @user_data: user data passed to @func
928 * Sets the function used to sort the list of tasks. This allows the
929 * tasks to be processed by a priority determined by @func, and not
930 * just in the order in which they were added to the pool.
932 * Note, if the maximum number of threads is more than 1, the order
933 * that threads are executed cannot be guaranteed 100%. Threads are
934 * scheduled by the operating system and are executed at random. It
935 * cannot be assumed that threads are executed in the order they are
941 g_thread_pool_set_sort_function (GThreadPool
*pool
,
942 GCompareDataFunc func
,
945 GRealThreadPool
*real
;
947 real
= (GRealThreadPool
*) pool
;
949 g_return_if_fail (real
);
950 g_return_if_fail (real
->running
);
952 g_async_queue_lock (real
->queue
);
954 real
->sort_func
= func
;
955 real
->sort_user_data
= user_data
;
958 g_async_queue_sort_unlocked (real
->queue
,
960 real
->sort_user_data
);
962 g_async_queue_unlock (real
->queue
);
966 * g_thread_pool_move_to_front:
967 * @pool: a #GThreadPool
968 * @data: an unprocessed item in the pool
970 * Moves the item to the front of the queue of unprocessed
971 * items, so that it will be processed next.
973 * Returns: %TRUE if the item was found and moved
978 g_thread_pool_move_to_front (GThreadPool
*pool
,
981 GRealThreadPool
*real
= (GRealThreadPool
*) pool
;
984 g_async_queue_lock (real
->queue
);
986 found
= g_async_queue_remove_unlocked (real
->queue
, data
);
988 g_async_queue_push_front_unlocked (real
->queue
, data
);
990 g_async_queue_unlock (real
->queue
);
996 * g_thread_pool_set_max_idle_time:
997 * @interval: the maximum @interval (in milliseconds)
998 * a thread can be idle
1000 * This function will set the maximum @interval that a thread
1001 * waiting in the pool for new tasks can be idle for before
1002 * being stopped. This function is similar to calling
1003 * g_thread_pool_stop_unused_threads() on a regular timeout,
1004 * except this is done on a per thread basis.
1006 * By setting @interval to 0, idle threads will not be stopped.
1008 * The default value is 15000 (15 seconds).
1013 g_thread_pool_set_max_idle_time (guint interval
)
1017 g_atomic_int_set (&max_idle_time
, interval
);
1019 i
= g_atomic_int_get (&unused_threads
);
1022 g_atomic_int_inc (&wakeup_thread_serial
);
1023 g_async_queue_lock (unused_thread_queue
);
1027 g_async_queue_push_unlocked (unused_thread_queue
,
1028 wakeup_thread_marker
);
1032 g_async_queue_unlock (unused_thread_queue
);
1037 * g_thread_pool_get_max_idle_time:
1039 * This function will return the maximum @interval that a
1040 * thread will wait in the thread pool for new tasks before
1043 * If this function returns 0, threads waiting in the thread
1044 * pool for new work are not stopped.
1046 * Returns: the maximum @interval (milliseconds) to wait
1047 * for new tasks in the thread pool before stopping the
1053 g_thread_pool_get_max_idle_time (void)
1055 return g_atomic_int_get (&max_idle_time
);