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New File implementing an asynchronous queue to be used for asynchronous
2000-04-28 Sebastian Wilhelmi <wilhelmi@ira.uka.de> * gasyncqueue.c: New File implementing an asynchronous queue to be used for asynchronous inter-thread communication. * gthreadpool.c: New File implementing a thread pool to be used for distributing work among several threads. * glib.h: Added the type and function declarations for these two types. * tests/threadpool-test.c: New File implementing a test for the thread pool. This also checks the asynchronous queue underlying the thread pool. * tests/Makefile.am: Changed accordingly.
This commit is contained in:
Sebastian Wilhelmi
committed by
Sebastian Wilhelmi
Sebastian Wilhelmi
parent
f0e9f522c2
commit
1418fe3a6d
520
gthreadpool.c
Normal file
520
gthreadpool.c
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@@ -0,0 +1,520 @@
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/* GLIB - Library of useful routines for C programming
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* Copyright (C) 1995-1997 Peter Mattis, Spencer Kimball and Josh MacDonald
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*
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* GAsyncQueue: thread pool implementation.
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* Copyright (C) 2000 Sebastian Wilhelmi; University of Karlsruhe
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Library General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Library General Public License for more details.
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*
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* You should have received a copy of the GNU Library General Public
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* License along with this library; if not, write to the
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* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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* Boston, MA 02111-1307, USA.
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*/
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/*
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* MT safe
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*/
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#include "glib.h"
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typedef struct _GRealThreadPool GRealThreadPool;
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struct _GRealThreadPool
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{
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GThreadPool pool;
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GAsyncQueue* queue;
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gint max_threads;
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gint num_threads;
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gboolean running;
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gboolean immediate;
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gboolean waiting;
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};
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/* The following is just an address to mark the stop order for a
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* thread, it could be any address (as long, as it isn;t a valid
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* GThreadPool address) */
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static const gpointer stop_this_thread_marker = &g_thread_pool_new;
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/* Here all unused threads are waiting, depending on their priority */
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static GAsyncQueue *unused_thread_queue[G_THREAD_PRIORITY_URGENT + 1];
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static gint unused_threads = 0;
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static gint max_unused_threads = 0;
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G_LOCK_DEFINE_STATIC (unused_threads);
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static GMutex *inform_mutex = NULL;
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static GCond *inform_cond = NULL;
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static void g_thread_pool_free_internal (GRealThreadPool* pool);
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static void g_thread_pool_thread_proxy (gpointer data);
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static void g_thread_pool_start_thread (GRealThreadPool* pool);
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static void g_thread_pool_wakeup_and_stop_all (GRealThreadPool* pool);
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#define g_thread_should_run(pool, len) \
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((pool)->running || (!(pool)->immediate && (len) > 0))
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static void
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g_thread_pool_thread_proxy (gpointer data)
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{
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GRealThreadPool *pool = data;
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GThread* self = g_thread_self ();
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g_async_queue_lock (pool->queue);
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while (TRUE)
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{
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gpointer task;
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gboolean goto_global_pool = !pool->pool.exclusive;
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gint len = g_async_queue_length_unlocked (pool->queue);
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if (g_thread_should_run (pool, len))
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{
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task = g_async_queue_pop_unlocked (pool->queue);
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if (pool->num_threads > pool->max_threads && pool->max_threads != -1)
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/* We are in fact a superfluous threads, so we go to the
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* global pool and just hand the data further to the next one
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* waiting in the queue */
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{
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g_async_queue_push_unlocked (pool->queue, task);
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goto_global_pool = TRUE;
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}
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else if (pool->running || !pool->immediate)
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{
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g_async_queue_unlock (pool->queue);
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pool->pool.thread_func (task, pool->pool.user_data);
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g_async_queue_lock (pool->queue);
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}
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len = g_async_queue_length_unlocked (pool->queue);
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}
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if (!g_thread_should_run (pool, len))
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g_cond_broadcast (inform_cond);
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if (!pool->running && (pool->immediate || len <= 0))
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goto_global_pool = TRUE;
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else if (len >= 0)
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/* At this pool there is no thread waiting */
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goto_global_pool = FALSE;
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if (goto_global_pool)
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{
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GThreadPriority priority = pool->pool.priority;
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pool->num_threads--;
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if (!pool->running && !pool->waiting)
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{
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if (pool->num_threads == 0)
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{
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g_async_queue_unlock (pool->queue);
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g_thread_pool_free_internal (pool);
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}
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else if (len == - pool->num_threads)
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g_thread_pool_wakeup_and_stop_all (pool);
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}
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else
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g_async_queue_unlock (pool->queue);
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g_async_queue_lock (unused_thread_queue[priority]);
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G_LOCK (unused_threads);
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if (unused_threads >= max_unused_threads)
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{
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G_UNLOCK (unused_threads);
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g_async_queue_unlock (unused_thread_queue[priority]);
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/* Stop this thread */
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return;
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}
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unused_threads++;
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G_UNLOCK (unused_threads);
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pool =
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g_async_queue_pop_unlocked (unused_thread_queue[priority]);
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G_LOCK (unused_threads);
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unused_threads--;
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G_UNLOCK (unused_threads);
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g_async_queue_unlock (unused_thread_queue[priority]);
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if (pool == stop_this_thread_marker)
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/* Stop this thread */
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return;
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g_async_queue_lock (pool->queue);
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if (pool->pool.priority != self->priority)
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g_thread_set_priority (self, pool->pool.priority);
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/* pool->num_threads++ is not done here, but in
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* g_thread_pool_start_thread to make the new started thread
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* known to the pool, before itself can do it. */
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}
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}
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}
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static void
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g_thread_pool_start_thread (GRealThreadPool* pool)
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{
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gboolean success = FALSE;
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GThreadPriority priority = pool->pool.priority;
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GAsyncQueue *queue = unused_thread_queue[priority];
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if (pool->num_threads >= pool->max_threads && pool->max_threads != -1)
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/* Enough threads are already running */
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return;
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g_async_queue_lock (queue);
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if (g_async_queue_length_unlocked (queue) < 0)
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{
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/* First we try a thread with the right priority */
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g_async_queue_push_unlocked (queue, pool);
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success = TRUE;
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}
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g_async_queue_unlock (queue);
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if (!success)
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{
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/* Now we search for threads with other priorities too, but
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* only, when there is more than one unused thread with that
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* priority. */
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GThreadPriority priority;
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for (priority = G_THREAD_PRIORITY_LOW;
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priority < G_THREAD_PRIORITY_URGENT + 1; priority++)
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{
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queue = unused_thread_queue[priority];
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g_async_queue_lock (queue);
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if (g_async_queue_length_unlocked (queue) < -1)
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{
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g_async_queue_push_unlocked (queue, pool);
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success = TRUE;
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}
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g_async_queue_unlock (queue);
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}
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}
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if (!success)
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/* No thread was found, we have to start one new */
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g_thread_create (g_thread_pool_thread_proxy, pool, pool->pool.stack_size,
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FALSE, pool->pool.bound, priority);
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/* See comment in g_thread_pool_thread_proxy as to why this is done
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* here and not there */
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pool->num_threads++;
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}
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GThreadPool*
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g_thread_pool_new (GFunc thread_func,
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gint max_threads,
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gulong stack_size,
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gboolean bound,
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GThreadPriority priority,
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gboolean exclusive,
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gpointer user_data)
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{
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GRealThreadPool *retval;
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g_return_val_if_fail (thread_func, NULL);
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g_return_val_if_fail (!exclusive || max_threads != -1, NULL);
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g_return_val_if_fail (max_threads >= -1, NULL);
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g_return_val_if_fail (g_thread_supported (), NULL);
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retval = g_new (GRealThreadPool, 1);
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retval->pool.thread_func = thread_func;
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retval->pool.stack_size = stack_size;
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retval->pool.bound = bound;
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retval->pool.priority = priority;
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retval->pool.exclusive = exclusive;
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retval->pool.user_data = user_data;
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retval->queue = g_async_queue_new ();
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retval->max_threads = max_threads;
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retval->num_threads = 0;
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retval->running = TRUE;
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if (!inform_mutex)
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{
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inform_mutex = g_mutex_new ();
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inform_cond = g_cond_new ();
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for (priority = G_THREAD_PRIORITY_LOW;
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priority < G_THREAD_PRIORITY_URGENT + 1; priority++)
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unused_thread_queue[priority] = g_async_queue_new ();
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}
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if (retval->pool.exclusive)
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{
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g_async_queue_lock (retval->queue);
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while (retval->num_threads < retval->max_threads)
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g_thread_pool_start_thread (retval);
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g_async_queue_unlock (retval->queue);
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}
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return (GThreadPool*) retval;
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}
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void
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g_thread_pool_push (GThreadPool *pool,
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gpointer data)
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{
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GRealThreadPool *real = (GRealThreadPool*) pool;
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g_return_if_fail (real);
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g_async_queue_lock (real->queue);
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if (!real->running)
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{
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g_async_queue_unlock (real->queue);
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g_return_if_fail (real->running);
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}
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if (!pool->exclusive && g_async_queue_length_unlocked (real->queue) >= 0)
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{
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/* No thread is waiting in the queue */
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g_thread_pool_start_thread (real);
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}
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g_async_queue_push_unlocked (real->queue, data);
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g_async_queue_unlock (real->queue);
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}
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void
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g_thread_pool_set_max_threads (GThreadPool *pool,
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gint max_threads)
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{
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GRealThreadPool *real = (GRealThreadPool*) pool;
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gint to_start;
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g_return_if_fail (real);
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g_return_if_fail (real->running);
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g_return_if_fail (!real->pool.exclusive || max_threads != -1);
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g_return_if_fail (max_threads >= -1);
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g_async_queue_lock (real->queue);
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real->max_threads = max_threads;
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if (pool->exclusive)
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to_start = real->max_threads - real->num_threads;
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else
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to_start = g_async_queue_length_unlocked (real->queue);
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for ( ; to_start > 0; to_start--)
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g_thread_pool_start_thread (real);
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g_async_queue_unlock (real->queue);
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}
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gint
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g_thread_pool_get_max_threads (GThreadPool *pool)
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{
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GRealThreadPool *real = (GRealThreadPool*) pool;
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gint retval;
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g_return_val_if_fail (real, 0);
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g_return_val_if_fail (real->running, 0);
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g_async_queue_lock (real->queue);
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retval = real->max_threads;
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g_async_queue_unlock (real->queue);
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return retval;
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}
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guint
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g_thread_pool_get_num_threads (GThreadPool *pool)
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{
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GRealThreadPool *real = (GRealThreadPool*) pool;
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guint retval;
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g_return_val_if_fail (real, 0);
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g_return_val_if_fail (real->running, 0);
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g_async_queue_lock (real->queue);
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retval = real->num_threads;
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g_async_queue_unlock (real->queue);
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return retval;
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}
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guint
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g_thread_pool_unprocessed (GThreadPool *pool)
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{
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GRealThreadPool *real = (GRealThreadPool*) pool;
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gint unprocessed;
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g_return_val_if_fail (real, 0);
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g_return_val_if_fail (real->running, 0);
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unprocessed = g_async_queue_length (real->queue);
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return MAX (unprocessed, 0);
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}
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void
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g_thread_pool_free (GThreadPool *pool,
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gboolean immediate,
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gboolean wait)
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{
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GRealThreadPool *real = (GRealThreadPool*) pool;
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g_return_if_fail (real);
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g_return_if_fail (real->running);
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/* It there's no thread allowed here, there is not much sense in
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* not stopping this pool immediatly, when it's not empty */
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g_return_if_fail (immediate || real->max_threads != 0 ||
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g_async_queue_length (real->queue) == 0);
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g_async_queue_lock (real->queue);
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real->running = FALSE;
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real->immediate = immediate;
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real->waiting = wait;
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if (wait)
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{
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g_mutex_lock (inform_mutex);
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while (g_async_queue_length_unlocked (real->queue) != -real->num_threads)
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{
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g_async_queue_unlock (real->queue);
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g_cond_wait (inform_cond, inform_mutex);
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g_async_queue_lock (real->queue);
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}
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g_mutex_unlock (inform_mutex);
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}
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if (g_async_queue_length_unlocked (real->queue) == -real->num_threads)
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{
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/* No thread is currently doing something (and nothing is left
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* to process in the queue) */
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if (real->num_threads == 0) /* No threads left, we clean up */
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{
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g_async_queue_unlock (real->queue);
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g_thread_pool_free_internal (real);
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return;
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}
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g_thread_pool_wakeup_and_stop_all (real);
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}
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real->waiting = FALSE; /* The last thread should cleanup the pool */
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g_async_queue_unlock (real->queue);
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}
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static void
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g_thread_pool_free_internal (GRealThreadPool* pool)
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{
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g_return_if_fail (pool);
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g_return_if_fail (!pool->running);
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g_return_if_fail (pool->num_threads == 0);
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g_async_queue_unref (pool->queue);
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g_free (pool);
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}
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static void
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g_thread_pool_wakeup_and_stop_all (GRealThreadPool* pool)
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{
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guint i;
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g_return_if_fail (pool);
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g_return_if_fail (!pool->running);
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g_return_if_fail (pool->num_threads != 0);
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g_return_if_fail (g_async_queue_length_unlocked (pool->queue) ==
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-pool->num_threads);
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pool->immediate = TRUE;
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for (i = 0; i < pool->num_threads; i++)
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g_async_queue_push_unlocked (pool->queue, GUINT_TO_POINTER (1));
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}
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void
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g_thread_pool_set_max_unused_threads (gint max_threads)
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{
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g_return_if_fail (max_threads >= -1);
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G_LOCK (unused_threads);
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max_unused_threads = max_threads;
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if (max_unused_threads < unused_threads && max_unused_threads != -1)
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{
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guint close_down_num = unused_threads - max_unused_threads;
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GThreadPriority priority;
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while (close_down_num > 0)
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{
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guint old_close_down_num = close_down_num;
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for (priority = G_THREAD_PRIORITY_LOW;
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priority < G_THREAD_PRIORITY_URGENT + 1 && close_down_num > 0;
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priority++)
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{
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GAsyncQueue *queue = unused_thread_queue[priority];
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g_async_queue_lock (queue);
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if (g_async_queue_length_unlocked (queue) < 0)
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{
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g_async_queue_push_unlocked (queue,
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stop_this_thread_marker);
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close_down_num--;
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}
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g_async_queue_unlock (queue);
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}
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/* Just to make sure, there are no counting problems */
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g_assert (old_close_down_num != close_down_num);
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}
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}
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G_UNLOCK (unused_threads);
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}
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gint
|
||||
g_thread_pool_get_max_unused_threads (void)
|
||||
{
|
||||
gint retval;
|
||||
|
||||
G_LOCK (unused_threads);
|
||||
retval = max_unused_threads;
|
||||
G_UNLOCK (unused_threads);
|
||||
|
||||
return retval;
|
||||
}
|
||||
|
||||
guint g_thread_pool_get_num_unused_threads (void)
|
||||
{
|
||||
guint retval;
|
||||
|
||||
G_LOCK (unused_threads);
|
||||
retval = unused_threads;
|
||||
G_UNLOCK (unused_threads);
|
||||
|
||||
return retval;
|
||||
}
|
||||
|
||||
void g_thread_pool_stop_unused_threads (void)
|
||||
{
|
||||
guint oldval = g_thread_pool_get_max_unused_threads ();
|
||||
g_thread_pool_set_max_unused_threads (0);
|
||||
g_thread_pool_set_max_unused_threads (oldval);
|
||||
}
|
||||
Reference in New Issue
Block a user