1 /* GLIB - Library of useful routines for C programming
2 * Copyright (C) 1995-1997 Peter Mattis, Spencer Kimball and Josh MacDonald
4 * GAsyncQueue: 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 typedef struct _GRealThreadPool GRealThreadPool
;
31 struct _GRealThreadPool
42 /* The following is just an address to mark the stop order for a
43 * thread, it could be any address (as long, as it isn;t a valid
44 * GThreadPool address) */
45 static const gpointer stop_this_thread_marker
= (gpointer
) &g_thread_pool_new
;
47 /* Here all unused threads are waiting, depending on their priority */
48 static GAsyncQueue
*unused_thread_queue
[G_THREAD_PRIORITY_URGENT
+ 1];
49 static gint unused_threads
= 0;
50 static gint max_unused_threads
= 0;
51 G_LOCK_DEFINE_STATIC (unused_threads
);
53 static GMutex
*inform_mutex
= NULL
;
54 static GCond
*inform_cond
= NULL
;
56 static void g_thread_pool_free_internal (GRealThreadPool
* pool
);
57 static void g_thread_pool_thread_proxy (gpointer data
);
58 static void g_thread_pool_start_thread (GRealThreadPool
* pool
, GError
**error
);
59 static void g_thread_pool_wakeup_and_stop_all (GRealThreadPool
* pool
);
61 #define g_thread_should_run(pool, len) \
62 ((pool)->running || (!(pool)->immediate && (len) > 0))
65 g_thread_pool_thread_proxy (gpointer data
)
67 GRealThreadPool
*pool
= data
;
69 g_async_queue_lock (pool
->queue
);
73 gboolean goto_global_pool
= !pool
->pool
.exclusive
;
74 gint len
= g_async_queue_length_unlocked (pool
->queue
);
76 if (g_thread_should_run (pool
, len
))
78 task
= g_async_queue_pop_unlocked (pool
->queue
);
80 if (pool
->num_threads
> pool
->max_threads
&& pool
->max_threads
!= -1)
81 /* We are in fact a superfluous threads, so we go to the
82 * global pool and just hand the data further to the next one
83 * waiting in the queue */
85 g_async_queue_push_unlocked (pool
->queue
, task
);
86 goto_global_pool
= TRUE
;
88 else if (pool
->running
|| !pool
->immediate
)
90 g_async_queue_unlock (pool
->queue
);
91 pool
->pool
.thread_func (task
, pool
->pool
.user_data
);
92 g_async_queue_lock (pool
->queue
);
95 len
= g_async_queue_length_unlocked (pool
->queue
);
98 if (!g_thread_should_run (pool
, len
))
99 g_cond_broadcast (inform_cond
);
101 if (!pool
->running
&& (pool
->immediate
|| len
<= 0))
102 goto_global_pool
= TRUE
;
104 /* At this pool there is no thread waiting */
105 goto_global_pool
= FALSE
;
107 if (goto_global_pool
)
109 GThreadPriority priority
= pool
->pool
.priority
;
112 if (!pool
->running
&& !pool
->waiting
)
114 if (pool
->num_threads
== 0)
116 g_async_queue_unlock (pool
->queue
);
117 g_thread_pool_free_internal (pool
);
119 else if (len
== - pool
->num_threads
)
120 g_thread_pool_wakeup_and_stop_all (pool
);
123 g_async_queue_unlock (pool
->queue
);
125 g_async_queue_lock (unused_thread_queue
[priority
]);
127 G_LOCK (unused_threads
);
128 if (unused_threads
>= max_unused_threads
)
130 G_UNLOCK (unused_threads
);
131 g_async_queue_unlock (unused_thread_queue
[priority
]);
132 /* Stop this thread */
136 G_UNLOCK (unused_threads
);
139 g_async_queue_pop_unlocked (unused_thread_queue
[priority
]);
141 G_LOCK (unused_threads
);
143 G_UNLOCK (unused_threads
);
145 g_async_queue_unlock (unused_thread_queue
[priority
]);
147 if (pool
== stop_this_thread_marker
)
148 /* Stop this thread */
151 g_async_queue_lock (pool
->queue
);
153 /* pool->num_threads++ is not done here, but in
154 * g_thread_pool_start_thread to make the new started thread
155 * known to the pool, before itself can do it. */
161 g_thread_pool_start_thread (GRealThreadPool
*pool
,
164 gboolean success
= FALSE
;
165 GThreadPriority priority
= pool
->pool
.priority
;
166 GAsyncQueue
*queue
= unused_thread_queue
[priority
];
168 if (pool
->num_threads
>= pool
->max_threads
&& pool
->max_threads
!= -1)
169 /* Enough threads are already running */
172 g_async_queue_lock (queue
);
174 if (g_async_queue_length_unlocked (queue
) < 0)
176 /* First we try a thread with the right priority */
177 g_async_queue_push_unlocked (queue
, pool
);
181 g_async_queue_unlock (queue
);
183 /* We will not search for threads with other priorities, because changing
184 * priority is quite unportable */
188 GError
*local_error
= NULL
;
189 /* No thread was found, we have to start one new */
190 g_thread_create (g_thread_pool_thread_proxy
, pool
,
191 pool
->pool
.stack_size
, FALSE
,
192 pool
->pool
.bound
, priority
, &local_error
);
196 g_propagate_error (error
, local_error
);
201 /* See comment in g_thread_pool_thread_proxy as to why this is done
202 * here and not there */
207 g_thread_pool_new (GFunc thread_func
,
211 GThreadPriority priority
,
216 GRealThreadPool
*retval
;
218 g_return_val_if_fail (thread_func
, NULL
);
219 g_return_val_if_fail (!exclusive
|| max_threads
!= -1, NULL
);
220 g_return_val_if_fail (max_threads
>= -1, NULL
);
221 g_return_val_if_fail (g_thread_supported (), NULL
);
223 retval
= g_new (GRealThreadPool
, 1);
225 retval
->pool
.thread_func
= thread_func
;
226 retval
->pool
.stack_size
= stack_size
;
227 retval
->pool
.bound
= bound
;
228 retval
->pool
.priority
= priority
;
229 retval
->pool
.exclusive
= exclusive
;
230 retval
->pool
.user_data
= user_data
;
231 retval
->queue
= g_async_queue_new ();
232 retval
->max_threads
= max_threads
;
233 retval
->num_threads
= 0;
234 retval
->running
= TRUE
;
238 inform_mutex
= g_mutex_new ();
239 inform_cond
= g_cond_new ();
240 for (priority
= G_THREAD_PRIORITY_LOW
;
241 priority
< G_THREAD_PRIORITY_URGENT
+ 1; priority
++)
242 unused_thread_queue
[priority
] = g_async_queue_new ();
245 if (retval
->pool
.exclusive
)
247 g_async_queue_lock (retval
->queue
);
249 while (retval
->num_threads
< retval
->max_threads
)
251 GError
*local_error
= NULL
;
252 g_thread_pool_start_thread (retval
, &local_error
);
255 g_propagate_error (error
, local_error
);
260 g_async_queue_unlock (retval
->queue
);
263 return (GThreadPool
*) retval
;
267 g_thread_pool_push (GThreadPool
*pool
,
271 GRealThreadPool
*real
= (GRealThreadPool
*) pool
;
273 g_return_if_fail (real
);
275 g_async_queue_lock (real
->queue
);
279 g_async_queue_unlock (real
->queue
);
280 g_return_if_fail (real
->running
);
283 if (!pool
->exclusive
&& g_async_queue_length_unlocked (real
->queue
) >= 0)
284 /* No thread is waiting in the queue */
285 g_thread_pool_start_thread (real
, error
);
287 g_async_queue_push_unlocked (real
->queue
, data
);
288 g_async_queue_unlock (real
->queue
);
292 g_thread_pool_set_max_threads (GThreadPool
*pool
,
296 GRealThreadPool
*real
= (GRealThreadPool
*) pool
;
299 g_return_if_fail (real
);
300 g_return_if_fail (real
->running
);
301 g_return_if_fail (!real
->pool
.exclusive
|| max_threads
!= -1);
302 g_return_if_fail (max_threads
>= -1);
304 g_async_queue_lock (real
->queue
);
306 real
->max_threads
= max_threads
;
309 to_start
= real
->max_threads
- real
->num_threads
;
311 to_start
= g_async_queue_length_unlocked (real
->queue
);
313 for ( ; to_start
> 0; to_start
--)
315 GError
*local_error
= NULL
;
316 g_thread_pool_start_thread (real
, &local_error
);
319 g_propagate_error (error
, local_error
);
324 g_async_queue_unlock (real
->queue
);
328 g_thread_pool_get_max_threads (GThreadPool
*pool
)
330 GRealThreadPool
*real
= (GRealThreadPool
*) pool
;
333 g_return_val_if_fail (real
, 0);
334 g_return_val_if_fail (real
->running
, 0);
336 g_async_queue_lock (real
->queue
);
338 retval
= real
->max_threads
;
340 g_async_queue_unlock (real
->queue
);
346 g_thread_pool_get_num_threads (GThreadPool
*pool
)
348 GRealThreadPool
*real
= (GRealThreadPool
*) pool
;
351 g_return_val_if_fail (real
, 0);
352 g_return_val_if_fail (real
->running
, 0);
354 g_async_queue_lock (real
->queue
);
356 retval
= real
->num_threads
;
358 g_async_queue_unlock (real
->queue
);
364 g_thread_pool_unprocessed (GThreadPool
*pool
)
366 GRealThreadPool
*real
= (GRealThreadPool
*) pool
;
369 g_return_val_if_fail (real
, 0);
370 g_return_val_if_fail (real
->running
, 0);
372 unprocessed
= g_async_queue_length (real
->queue
);
374 return MAX (unprocessed
, 0);
378 g_thread_pool_free (GThreadPool
*pool
,
382 GRealThreadPool
*real
= (GRealThreadPool
*) pool
;
384 g_return_if_fail (real
);
385 g_return_if_fail (real
->running
);
386 /* It there's no thread allowed here, there is not much sense in
387 * not stopping this pool immediatly, when it's not empty */
388 g_return_if_fail (immediate
|| real
->max_threads
!= 0 ||
389 g_async_queue_length (real
->queue
) == 0);
391 g_async_queue_lock (real
->queue
);
393 real
->running
= FALSE
;
394 real
->immediate
= immediate
;
395 real
->waiting
= wait
;
399 g_mutex_lock (inform_mutex
);
400 while (g_async_queue_length_unlocked (real
->queue
) != -real
->num_threads
)
402 g_async_queue_unlock (real
->queue
);
403 g_cond_wait (inform_cond
, inform_mutex
);
404 g_async_queue_lock (real
->queue
);
406 g_mutex_unlock (inform_mutex
);
409 if (g_async_queue_length_unlocked (real
->queue
) == -real
->num_threads
)
411 /* No thread is currently doing something (and nothing is left
412 * to process in the queue) */
413 if (real
->num_threads
== 0) /* No threads left, we clean up */
415 g_async_queue_unlock (real
->queue
);
416 g_thread_pool_free_internal (real
);
420 g_thread_pool_wakeup_and_stop_all (real
);
423 real
->waiting
= FALSE
; /* The last thread should cleanup the pool */
424 g_async_queue_unlock (real
->queue
);
428 g_thread_pool_free_internal (GRealThreadPool
* pool
)
430 g_return_if_fail (pool
);
431 g_return_if_fail (!pool
->running
);
432 g_return_if_fail (pool
->num_threads
== 0);
434 g_async_queue_unref (pool
->queue
);
440 g_thread_pool_wakeup_and_stop_all (GRealThreadPool
* pool
)
444 g_return_if_fail (pool
);
445 g_return_if_fail (!pool
->running
);
446 g_return_if_fail (pool
->num_threads
!= 0);
447 g_return_if_fail (g_async_queue_length_unlocked (pool
->queue
) ==
450 pool
->immediate
= TRUE
;
451 for (i
= 0; i
< pool
->num_threads
; i
++)
452 g_async_queue_push_unlocked (pool
->queue
, GUINT_TO_POINTER (1));
456 g_thread_pool_set_max_unused_threads (gint max_threads
)
458 g_return_if_fail (max_threads
>= -1);
460 G_LOCK (unused_threads
);
462 max_unused_threads
= max_threads
;
464 if (max_unused_threads
< unused_threads
&& max_unused_threads
!= -1)
466 guint close_down_num
= unused_threads
- max_unused_threads
;
467 GThreadPriority priority
;
469 while (close_down_num
> 0)
471 guint old_close_down_num
= close_down_num
;
472 for (priority
= G_THREAD_PRIORITY_LOW
;
473 priority
< G_THREAD_PRIORITY_URGENT
+ 1 && close_down_num
> 0;
476 GAsyncQueue
*queue
= unused_thread_queue
[priority
];
477 g_async_queue_lock (queue
);
479 if (g_async_queue_length_unlocked (queue
) < 0)
481 g_async_queue_push_unlocked (queue
,
482 stop_this_thread_marker
);
486 g_async_queue_unlock (queue
);
489 /* Just to make sure, there are no counting problems */
490 g_assert (old_close_down_num
!= close_down_num
);
494 G_UNLOCK (unused_threads
);
498 g_thread_pool_get_max_unused_threads (void)
502 G_LOCK (unused_threads
);
503 retval
= max_unused_threads
;
504 G_UNLOCK (unused_threads
);
509 guint
g_thread_pool_get_num_unused_threads (void)
513 G_LOCK (unused_threads
);
514 retval
= unused_threads
;
515 G_UNLOCK (unused_threads
);
520 void g_thread_pool_stop_unused_threads (void)
522 guint oldval
= g_thread_pool_get_max_unused_threads ();
523 g_thread_pool_set_max_unused_threads (0);
524 g_thread_pool_set_max_unused_threads (oldval
);