| /* GLIB - Library of useful routines for C programming |
| * Copyright (C) 1995-1997 Peter Mattis, Spencer Kimball and Josh MacDonald |
| * |
| * GAsyncQueue: thread pool implementation. |
| * Copyright (C) 2000 Sebastian Wilhelmi; University of Karlsruhe |
| * |
| * This library is free software; you can redistribute it and/or |
| * modify it under the terms of the GNU Lesser General Public |
| * License as published by the Free Software Foundation; either |
| * version 2 of the License, or (at your option) any later version. |
| * |
| * This library is distributed in the hope that it will be useful, |
| * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| * Lesser General Public License for more details. |
| * |
| * You should have received a copy of the GNU Lesser General Public |
| * License along with this library; if not, write to the |
| * Free Software Foundation, Inc., 59 Temple Place - Suite 330, |
| * Boston, MA 02111-1307, USA. |
| */ |
| |
| /* |
| * MT safe |
| */ |
| |
| #include "config.h" |
| |
| #include "galias.h" |
| #include "glib.h" |
| |
| |
| typedef struct _GRealThreadPool GRealThreadPool; |
| |
| struct _GRealThreadPool |
| { |
| GThreadPool pool; |
| GAsyncQueue* queue; |
| gint max_threads; |
| gint num_threads; |
| gboolean running; |
| gboolean immediate; |
| gboolean waiting; |
| }; |
| |
| /* The following is just an address to mark the stop order for a |
| * thread, it could be any address (as long, as it isn't a valid |
| * GThreadPool address) */ |
| static const gpointer stop_this_thread_marker = (gpointer) &g_thread_pool_new; |
| |
| /* Here all unused threads are waiting */ |
| static GAsyncQueue *unused_thread_queue; |
| static gint unused_threads = 0; |
| static gint max_unused_threads = 0; |
| G_LOCK_DEFINE_STATIC (unused_threads); |
| |
| static GMutex *inform_mutex = NULL; |
| static GCond *inform_cond = NULL; |
| |
| static void g_thread_pool_free_internal (GRealThreadPool* pool); |
| static gpointer g_thread_pool_thread_proxy (gpointer data); |
| static void g_thread_pool_start_thread (GRealThreadPool* pool, |
| GError **error); |
| static void g_thread_pool_wakeup_and_stop_all (GRealThreadPool* pool); |
| |
| #define g_thread_should_run(pool, len) \ |
| ((pool)->running || (!(pool)->immediate && (len) > 0)) |
| |
| static gpointer |
| g_thread_pool_thread_proxy (gpointer data) |
| { |
| GRealThreadPool *pool = data; |
| gboolean watcher = FALSE; |
| |
| g_async_queue_lock (pool->queue); |
| while (TRUE) |
| { |
| gpointer task; |
| gboolean goto_global_pool = !pool->pool.exclusive; |
| gint len = g_async_queue_length_unlocked (pool->queue); |
| |
| if (g_thread_should_run (pool, len)) |
| { |
| if (watcher) |
| { |
| /* This thread is actually not needed here, but it waits |
| * for some time anyway. If during that time a new |
| * request arrives, this saves process |
| * swicthes. Otherwise the thread will go to the global |
| * pool afterwards */ |
| GTimeVal end_time; |
| g_get_current_time (&end_time); |
| g_time_val_add (&end_time, G_USEC_PER_SEC / 2); /* 1/2 second */ |
| task = g_async_queue_timed_pop_unlocked (pool->queue, &end_time); |
| } |
| else |
| task = g_async_queue_pop_unlocked (pool->queue); |
| |
| if (task) |
| { |
| watcher = FALSE; |
| if (pool->num_threads > pool->max_threads && |
| pool->max_threads != -1) |
| /* We are in fact a superfluous threads, so we go to |
| * the global pool and just hand the data further to |
| * the next one waiting in the queue */ |
| { |
| g_async_queue_push_unlocked (pool->queue, task); |
| goto_global_pool = TRUE; |
| } |
| else if (pool->running || !pool->immediate) |
| { |
| g_async_queue_unlock (pool->queue); |
| pool->pool.func (task, pool->pool.user_data); |
| g_async_queue_lock (pool->queue); |
| } |
| } |
| len = g_async_queue_length_unlocked (pool->queue); |
| } |
| |
| if (!g_thread_should_run (pool, len)) |
| { |
| g_cond_broadcast (inform_cond); |
| goto_global_pool = TRUE; |
| } |
| else if (len > 0) |
| { |
| /* At this pool there are no threads waiting, but tasks are. */ |
| goto_global_pool = FALSE; |
| } |
| else if (len == 0 && !watcher && !pool->pool.exclusive) |
| { |
| /* Here neither threads nor tasks are queued and we didn't |
| * just return from a timed wait. We now wait for a limited |
| * time at this pool for new tasks to avoid costly context |
| * switches. */ |
| goto_global_pool = FALSE; |
| watcher = TRUE; |
| } |
| |
| if (goto_global_pool) |
| { |
| pool->num_threads--; |
| |
| if (!pool->running && !pool->waiting) |
| { |
| if (pool->num_threads == 0) |
| { |
| g_async_queue_unlock (pool->queue); |
| g_thread_pool_free_internal (pool); |
| } |
| else |
| { |
| if (len == - pool->num_threads) |
| g_thread_pool_wakeup_and_stop_all (pool); |
| |
| g_async_queue_unlock (pool->queue); |
| } |
| } |
| else |
| g_async_queue_unlock (pool->queue); |
| |
| g_async_queue_lock (unused_thread_queue); |
| |
| G_LOCK (unused_threads); |
| if ((unused_threads >= max_unused_threads && |
| max_unused_threads != -1)) |
| { |
| G_UNLOCK (unused_threads); |
| g_async_queue_unlock (unused_thread_queue); |
| /* Stop this thread */ |
| return NULL; |
| } |
| unused_threads++; |
| G_UNLOCK (unused_threads); |
| |
| pool = g_async_queue_pop_unlocked (unused_thread_queue); |
| |
| G_LOCK (unused_threads); |
| unused_threads--; |
| G_UNLOCK (unused_threads); |
| |
| g_async_queue_unlock (unused_thread_queue); |
| |
| if (pool == stop_this_thread_marker) |
| /* Stop this thread */ |
| return NULL; |
| |
| g_async_queue_lock (pool->queue); |
| |
| /* pool->num_threads++ is not done here, but in |
| * g_thread_pool_start_thread to make the new started thread |
| * known to the pool, before itself can do it. */ |
| } |
| } |
| return NULL; |
| } |
| |
| static void |
| g_thread_pool_start_thread (GRealThreadPool *pool, |
| GError **error) |
| { |
| gboolean success = FALSE; |
| |
| if (pool->num_threads >= pool->max_threads && pool->max_threads != -1) |
| /* Enough threads are already running */ |
| return; |
| |
| g_async_queue_lock (unused_thread_queue); |
| |
| if (g_async_queue_length_unlocked (unused_thread_queue) < 0) |
| { |
| g_async_queue_push_unlocked (unused_thread_queue, pool); |
| success = TRUE; |
| } |
| |
| g_async_queue_unlock (unused_thread_queue); |
| |
| if (!success) |
| { |
| GError *local_error = NULL; |
| /* No thread was found, we have to start a new one */ |
| g_thread_create (g_thread_pool_thread_proxy, pool, FALSE, &local_error); |
| |
| if (local_error) |
| { |
| g_propagate_error (error, local_error); |
| return; |
| } |
| } |
| |
| /* See comment in g_thread_pool_thread_proxy as to why this is done |
| * here and not there */ |
| pool->num_threads++; |
| } |
| |
| /** |
| * g_thread_pool_new: |
| * @func: a function to execute in the threads of the new thread pool |
| * @user_data: user data that is handed over to @func every time it |
| * is called |
| * @max_threads: the maximal number of threads to execute concurrently in |
| * the new thread pool, -1 means no limit |
| * @exclusive: should this thread pool be exclusive? |
| * @error: return location for error |
| * |
| * This function creates a new thread pool. |
| * |
| * Whenever you call g_thread_pool_push(), either a new thread is |
| * created or an unused one is reused. At most @max_threads threads |
| * are running concurrently for this thread pool. @max_threads = -1 |
| * allows unlimited threads to be created for this thread pool. The |
| * newly created or reused thread now executes the function @func with |
| * the two arguments. The first one is the parameter to |
| * g_thread_pool_push() and the second one is @user_data. |
| * |
| * The parameter @exclusive determines, whether the thread pool owns |
| * all threads exclusive or whether the threads are shared |
| * globally. If @exclusive is %TRUE, @max_threads threads are started |
| * immediately and they will run exclusively for this thread pool until |
| * it is destroyed by g_thread_pool_free(). If @exclusive is %FALSE, |
| * threads are created, when needed and shared between all |
| * non-exclusive thread pools. This implies that @max_threads may not |
| * be -1 for exclusive thread pools. |
| * |
| * @error can be %NULL to ignore errors, or non-%NULL to report |
| * errors. An error can only occur when @exclusive is set to %TRUE and |
| * not all @max_threads threads could be created. |
| * |
| * Return value: the new #GThreadPool |
| **/ |
| GThreadPool* |
| g_thread_pool_new (GFunc func, |
| gpointer user_data, |
| gint max_threads, |
| gboolean exclusive, |
| GError **error) |
| { |
| GRealThreadPool *retval; |
| G_LOCK_DEFINE_STATIC (init); |
| |
| g_return_val_if_fail (func, NULL); |
| g_return_val_if_fail (!exclusive || max_threads != -1, NULL); |
| g_return_val_if_fail (max_threads >= -1, NULL); |
| g_return_val_if_fail (g_thread_supported (), NULL); |
| |
| retval = g_new (GRealThreadPool, 1); |
| |
| retval->pool.func = func; |
| retval->pool.user_data = user_data; |
| retval->pool.exclusive = exclusive; |
| retval->queue = g_async_queue_new (); |
| retval->max_threads = max_threads; |
| retval->num_threads = 0; |
| retval->running = TRUE; |
| |
| G_LOCK (init); |
| |
| if (!inform_mutex) |
| { |
| inform_mutex = g_mutex_new (); |
| inform_cond = g_cond_new (); |
| unused_thread_queue = g_async_queue_new (); |
| } |
| |
| G_UNLOCK (init); |
| |
| if (retval->pool.exclusive) |
| { |
| g_async_queue_lock (retval->queue); |
| |
| while (retval->num_threads < retval->max_threads) |
| { |
| GError *local_error = NULL; |
| g_thread_pool_start_thread (retval, &local_error); |
| if (local_error) |
| { |
| g_propagate_error (error, local_error); |
| break; |
| } |
| } |
| |
| g_async_queue_unlock (retval->queue); |
| } |
| |
| return (GThreadPool*) retval; |
| } |
| |
| /** |
| * g_thread_pool_push: |
| * @pool: a #GThreadPool |
| * @data: a new task for @pool |
| * @error: return location for error |
| * |
| * Inserts @data into the list of tasks to be executed by @pool. When |
| * the number of currently running threads is lower than the maximal |
| * allowed number of threads, a new thread is started (or reused) with |
| * the properties given to g_thread_pool_new (). Otherwise @data stays |
| * in the queue until a thread in this pool finishes its previous task |
| * and processes @data. |
| * |
| * @error can be %NULL to ignore errors, or non-%NULL to report |
| * errors. An error can only occur when a new thread couldn't be |
| * created. In that case @data is simply appended to the queue of work |
| * to do. |
| **/ |
| void |
| g_thread_pool_push (GThreadPool *pool, |
| gpointer data, |
| GError **error) |
| { |
| GRealThreadPool *real = (GRealThreadPool*) pool; |
| |
| g_return_if_fail (real); |
| |
| g_async_queue_lock (real->queue); |
| |
| if (!real->running) |
| { |
| g_async_queue_unlock (real->queue); |
| g_return_if_fail (real->running); |
| } |
| |
| if (g_async_queue_length_unlocked (real->queue) >= 0) |
| /* No thread is waiting in the queue */ |
| g_thread_pool_start_thread (real, error); |
| |
| g_async_queue_push_unlocked (real->queue, data); |
| g_async_queue_unlock (real->queue); |
| } |
| |
| /** |
| * g_thread_pool_set_max_threads: |
| * @pool: a #GThreadPool |
| * @max_threads: a new maximal number of threads for @pool |
| * @error: return location for error |
| * |
| * Sets the maximal allowed number of threads for @pool. A value of -1 |
| * means, that the maximal number of threads is unlimited. |
| * |
| * Setting @max_threads to 0 means stopping all work for @pool. It is |
| * effectively frozen until @max_threads is set to a non-zero value |
| * again. |
| * |
| * A thread is never terminated while calling @func, as supplied by |
| * g_thread_pool_new (). Instead the maximal number of threads only |
| * has effect for the allocation of new threads in g_thread_pool_push(). |
| * A new thread is allocated, whenever the number of currently |
| * running threads in @pool is smaller than the maximal number. |
| * |
| * @error can be %NULL to ignore errors, or non-%NULL to report |
| * errors. An error can only occur when a new thread couldn't be |
| * created. |
| **/ |
| void |
| g_thread_pool_set_max_threads (GThreadPool *pool, |
| gint max_threads, |
| GError **error) |
| { |
| GRealThreadPool *real = (GRealThreadPool*) pool; |
| gint to_start; |
| |
| g_return_if_fail (real); |
| g_return_if_fail (real->running); |
| g_return_if_fail (!real->pool.exclusive || max_threads != -1); |
| g_return_if_fail (max_threads >= -1); |
| |
| g_async_queue_lock (real->queue); |
| |
| real->max_threads = max_threads; |
| |
| if (pool->exclusive) |
| to_start = real->max_threads - real->num_threads; |
| else |
| to_start = g_async_queue_length_unlocked (real->queue); |
| |
| for ( ; to_start > 0; to_start--) |
| { |
| GError *local_error = NULL; |
| g_thread_pool_start_thread (real, &local_error); |
| if (local_error) |
| { |
| g_propagate_error (error, local_error); |
| break; |
| } |
| } |
| |
| g_async_queue_unlock (real->queue); |
| } |
| |
| /** |
| * g_thread_pool_get_max_threads: |
| * @pool: a #GThreadPool |
| * |
| * Returns the maximal number of threads for @pool. |
| * |
| * Return value: the maximal number of threads |
| **/ |
| gint |
| g_thread_pool_get_max_threads (GThreadPool *pool) |
| { |
| GRealThreadPool *real = (GRealThreadPool*) pool; |
| gint retval; |
| |
| g_return_val_if_fail (real, 0); |
| g_return_val_if_fail (real->running, 0); |
| |
| g_async_queue_lock (real->queue); |
| |
| retval = real->max_threads; |
| |
| g_async_queue_unlock (real->queue); |
| |
| return retval; |
| } |
| |
| /** |
| * g_thread_pool_get_num_threads: |
| * @pool: a #GThreadPool |
| * |
| * Returns the number of threads currently running in @pool. |
| * |
| * Return value: the number of threads currently running |
| **/ |
| guint |
| g_thread_pool_get_num_threads (GThreadPool *pool) |
| { |
| GRealThreadPool *real = (GRealThreadPool*) pool; |
| guint retval; |
| |
| g_return_val_if_fail (real, 0); |
| g_return_val_if_fail (real->running, 0); |
| |
| g_async_queue_lock (real->queue); |
| |
| retval = real->num_threads; |
| |
| g_async_queue_unlock (real->queue); |
| |
| return retval; |
| } |
| |
| /** |
| * g_thread_pool_unprocessed: |
| * @pool: a #GThreadPool |
| * |
| * Returns the number of tasks still unprocessed in @pool. |
| * |
| * Return value: the number of unprocessed tasks |
| **/ |
| guint |
| g_thread_pool_unprocessed (GThreadPool *pool) |
| { |
| GRealThreadPool *real = (GRealThreadPool*) pool; |
| gint unprocessed; |
| |
| g_return_val_if_fail (real, 0); |
| g_return_val_if_fail (real->running, 0); |
| |
| unprocessed = g_async_queue_length (real->queue); |
| |
| return MAX (unprocessed, 0); |
| } |
| |
| /** |
| * g_thread_pool_free: |
| * @pool: a #GThreadPool |
| * @immediate: should @pool shut down immediately? |
| * @wait: should the function wait for all tasks to be finished? |
| * |
| * Frees all resources allocated for @pool. |
| * |
| * If @immediate is %TRUE, no new task is processed for |
| * @pool. Otherwise @pool is not freed before the last task is |
| * processed. Note however, that no thread of this pool is |
| * interrupted, while processing a task. Instead at least all still |
| * running threads can finish their tasks before the @pool is freed. |
| * |
| * If @wait is %TRUE, the functions does not return before all tasks |
| * to be processed (dependent on @immediate, whether all or only the |
| * currently running) are ready. Otherwise the function returns immediately. |
| * |
| * After calling this function @pool must not be used anymore. |
| **/ |
| void |
| g_thread_pool_free (GThreadPool *pool, |
| gboolean immediate, |
| gboolean wait) |
| { |
| GRealThreadPool *real = (GRealThreadPool*) pool; |
| |
| g_return_if_fail (real); |
| g_return_if_fail (real->running); |
| /* It there's no thread allowed here, there is not much sense in |
| * not stopping this pool immediately, when it's not empty */ |
| g_return_if_fail (immediate || real->max_threads != 0 || |
| g_async_queue_length (real->queue) == 0); |
| |
| g_async_queue_lock (real->queue); |
| |
| real->running = FALSE; |
| real->immediate = immediate; |
| real->waiting = wait; |
| |
| if (wait) |
| { |
| g_mutex_lock (inform_mutex); |
| while (g_async_queue_length_unlocked (real->queue) != -real->num_threads) |
| { |
| g_async_queue_unlock (real->queue); |
| g_cond_wait (inform_cond, inform_mutex); |
| g_async_queue_lock (real->queue); |
| } |
| g_mutex_unlock (inform_mutex); |
| } |
| |
| if (g_async_queue_length_unlocked (real->queue) == -real->num_threads) |
| { |
| /* No thread is currently doing something (and nothing is left |
| * to process in the queue) */ |
| if (real->num_threads == 0) /* No threads left, we clean up */ |
| { |
| g_async_queue_unlock (real->queue); |
| g_thread_pool_free_internal (real); |
| return; |
| } |
| |
| g_thread_pool_wakeup_and_stop_all (real); |
| } |
| |
| real->waiting = FALSE; /* The last thread should cleanup the pool */ |
| g_async_queue_unlock (real->queue); |
| } |
| |
| static void |
| g_thread_pool_free_internal (GRealThreadPool* pool) |
| { |
| g_return_if_fail (pool); |
| g_return_if_fail (!pool->running); |
| g_return_if_fail (pool->num_threads == 0); |
| |
| g_async_queue_unref (pool->queue); |
| |
| g_free (pool); |
| } |
| |
| static void |
| g_thread_pool_wakeup_and_stop_all (GRealThreadPool* pool) |
| { |
| guint i; |
| |
| g_return_if_fail (pool); |
| g_return_if_fail (!pool->running); |
| g_return_if_fail (pool->num_threads != 0); |
| g_return_if_fail (g_async_queue_length_unlocked (pool->queue) == |
| -pool->num_threads); |
| |
| pool->immediate = TRUE; |
| for (i = 0; i < pool->num_threads; i++) |
| g_async_queue_push_unlocked (pool->queue, GUINT_TO_POINTER (1)); |
| } |
| |
| /** |
| * g_thread_pool_set_max_unused_threads: |
| * @max_threads: maximal number of unused threads |
| * |
| * Sets the maximal number of unused threads to @max_threads. If |
| * @max_threads is -1, no limit is imposed on the number of unused |
| * threads. |
| **/ |
| void |
| g_thread_pool_set_max_unused_threads (gint max_threads) |
| { |
| g_return_if_fail (max_threads >= -1); |
| |
| G_LOCK (unused_threads); |
| |
| max_unused_threads = max_threads; |
| |
| if (max_unused_threads < unused_threads && max_unused_threads != -1) |
| { |
| guint i; |
| |
| g_async_queue_lock (unused_thread_queue); |
| for (i = unused_threads - max_unused_threads; i > 0; i--) |
| g_async_queue_push_unlocked (unused_thread_queue, |
| stop_this_thread_marker); |
| g_async_queue_unlock (unused_thread_queue); |
| } |
| |
| G_UNLOCK (unused_threads); |
| } |
| |
| /** |
| * g_thread_pool_get_max_unused_threads: |
| * |
| * Returns the maximal allowed number of unused threads. |
| * |
| * Return value: the maximal number of unused threads |
| **/ |
| 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; |
| } |
| |
| /** |
| * g_thread_pool_get_num_unused_threads: |
| * |
| * Returns the number of currently unused threads. |
| * |
| * Return value: the number of currently unused threads |
| **/ |
| guint g_thread_pool_get_num_unused_threads (void) |
| { |
| guint retval; |
| |
| G_LOCK (unused_threads); |
| retval = unused_threads; |
| G_UNLOCK (unused_threads); |
| |
| return retval; |
| } |
| |
| /** |
| * g_thread_pool_stop_unused_threads: |
| * |
| * Stops all currently unused threads. This does not change the |
| * maximal number of unused threads. This function can be used to |
| * regularly stop all unused threads e.g. from g_timeout_add(). |
| **/ |
| 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); |
| } |