/* GLIB - Library of useful routines for C programming
* Copyright (C) 1995-1997 Peter Mattis, Spencer Kimball and Josh MacDonald
*
- * GAsyncQueue: thread pool implementation.
+ * GThreadPool: thread pool implementation.
* Copyright (C) 2000 Sebastian Wilhelmi; University of Karlsruhe
*
* This library is free software; you can redistribute it and/or
* 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.
+ * License along with this library; if not, see <http://www.gnu.org/licenses/>.
*/
/*
* MT safe
*/
-#include "glib.h"
+#include "config.h"
+
+#include "gthreadpool.h"
+
+#include "gasyncqueue.h"
+#include "gasyncqueueprivate.h"
+#include "gmain.h"
+#include "gtestutils.h"
+#include "gtimer.h"
+
+/**
+ * SECTION:thread_pools
+ * @title: Thread Pools
+ * @short_description: pools of threads to execute work concurrently
+ * @see_also: #GThread
+ *
+ * Sometimes you wish to asynchronously fork out the execution of work
+ * and continue working in your own thread. If that will happen often,
+ * the overhead of starting and destroying a thread each time might be
+ * too high. In such cases reusing already started threads seems like a
+ * good idea. And it indeed is, but implementing this can be tedious
+ * and error-prone.
+ *
+ * Therefore GLib provides thread pools for your convenience. An added
+ * advantage is, that the threads can be shared between the different
+ * subsystems of your program, when they are using GLib.
+ *
+ * To create a new thread pool, you use g_thread_pool_new().
+ * It is destroyed by g_thread_pool_free().
+ *
+ * If you want to execute a certain task within a thread pool,
+ * you call g_thread_pool_push().
+ *
+ * To get the current number of running threads you call
+ * g_thread_pool_get_num_threads(). To get the number of still
+ * unprocessed tasks you call g_thread_pool_unprocessed(). To control
+ * the maximal number of threads for a thread pool, you use
+ * g_thread_pool_get_max_threads() and g_thread_pool_set_max_threads().
+ *
+ * Finally you can control the number of unused threads, that are kept
+ * alive by GLib for future use. The current number can be fetched with
+ * g_thread_pool_get_num_unused_threads(). The maximal number can be
+ * controlled by g_thread_pool_get_max_unused_threads() and
+ * g_thread_pool_set_max_unused_threads(). All currently unused threads
+ * can be stopped by calling g_thread_pool_stop_unused_threads().
+ */
+
+#define DEBUG_MSG(x)
+/* #define DEBUG_MSG(args) g_printerr args ; g_printerr ("\n"); */
typedef struct _GRealThreadPool GRealThreadPool;
+/**
+ * GThreadPool:
+ * @func: the function to execute in the threads of this pool
+ * @user_data: the user data for the threads of this pool
+ * @exclusive: are all threads exclusive to this pool
+ *
+ * The #GThreadPool struct represents a thread pool. It has three
+ * public read-only members, but the underlying struct is bigger,
+ * so you must not copy this struct.
+ */
struct _GRealThreadPool
{
GThreadPool pool;
- GAsyncQueue* queue;
+ GAsyncQueue *queue;
+ GCond cond;
gint max_threads;
gint num_threads;
gboolean running;
gboolean immediate;
gboolean waiting;
+ GCompareDataFunc sort_func;
+ gpointer sort_user_data;
};
-/* 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;
+/* The following is just an address to mark the wakeup order for a
+ * thread, it could be any address (as long, as it isn't a valid
+ * GThreadPool address)
+ */
+static const gpointer wakeup_thread_marker = (gpointer) &g_thread_pool_new;
+static gint wakeup_thread_serial = 0;
-/* Here all unused threads are waiting, depending on their priority */
-static GAsyncQueue *unused_thread_queue[G_THREAD_PRIORITY_URGENT + 1];
+/* Here all unused threads are waiting */
+static GAsyncQueue *unused_thread_queue = NULL;
static gint unused_threads = 0;
-static gint max_unused_threads = 0;
-G_LOCK_DEFINE_STATIC (unused_threads);
+static gint max_unused_threads = 2;
+static gint kill_unused_threads = 0;
+static guint max_idle_time = 15 * 1000;
+
+static void g_thread_pool_queue_push_unlocked (GRealThreadPool *pool,
+ gpointer data);
+static void g_thread_pool_free_internal (GRealThreadPool *pool);
+static gpointer g_thread_pool_thread_proxy (gpointer data);
+static gboolean g_thread_pool_start_thread (GRealThreadPool *pool,
+ GError **error);
+static void g_thread_pool_wakeup_and_stop_all (GRealThreadPool *pool);
+static GRealThreadPool* g_thread_pool_wait_for_new_pool (void);
+static gpointer g_thread_pool_wait_for_new_task (GRealThreadPool *pool);
-static GMutex *inform_mutex = NULL;
-static GCond *inform_cond = NULL;
+static void
+g_thread_pool_queue_push_unlocked (GRealThreadPool *pool,
+ gpointer data)
+{
+ if (pool->sort_func)
+ g_async_queue_push_sorted_unlocked (pool->queue,
+ data,
+ pool->sort_func,
+ pool->sort_user_data);
+ else
+ g_async_queue_push_unlocked (pool->queue, data);
+}
-static void g_thread_pool_free_internal (GRealThreadPool* pool);
-static void 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);
+static GRealThreadPool*
+g_thread_pool_wait_for_new_pool (void)
+{
+ GRealThreadPool *pool;
+ gint local_wakeup_thread_serial;
+ guint local_max_unused_threads;
+ gint local_max_idle_time;
+ gint last_wakeup_thread_serial;
+ gboolean have_relayed_thread_marker = FALSE;
+
+ local_max_unused_threads = g_atomic_int_get (&max_unused_threads);
+ local_max_idle_time = g_atomic_int_get (&max_idle_time);
+ last_wakeup_thread_serial = g_atomic_int_get (&wakeup_thread_serial);
+
+ g_atomic_int_inc (&unused_threads);
-#define g_thread_should_run(pool, len) \
- ((pool)->running || (!(pool)->immediate && (len) > 0))
+ do
+ {
+ if (g_atomic_int_get (&unused_threads) >= local_max_unused_threads)
+ {
+ /* If this is a superfluous thread, stop it. */
+ pool = NULL;
+ }
+ else if (local_max_idle_time > 0)
+ {
+ /* If a maximal idle time is given, wait for the given time. */
+ DEBUG_MSG (("thread %p waiting in global pool for %f seconds.",
+ g_thread_self (), local_max_idle_time / 1000.0));
+
+ pool = g_async_queue_timeout_pop (unused_thread_queue,
+ local_max_idle_time * 1000);
+ }
+ else
+ {
+ /* If no maximal idle time is given, wait indefinitely. */
+ DEBUG_MSG (("thread %p waiting in global pool.", g_thread_self ()));
+ pool = g_async_queue_pop (unused_thread_queue);
+ }
+
+ if (pool == wakeup_thread_marker)
+ {
+ local_wakeup_thread_serial = g_atomic_int_get (&wakeup_thread_serial);
+ if (last_wakeup_thread_serial == local_wakeup_thread_serial)
+ {
+ if (!have_relayed_thread_marker)
+ {
+ /* If this wakeup marker has been received for
+ * the second time, relay it.
+ */
+ DEBUG_MSG (("thread %p relaying wakeup message to "
+ "waiting thread with lower serial.",
+ g_thread_self ()));
+
+ g_async_queue_push (unused_thread_queue, wakeup_thread_marker);
+ have_relayed_thread_marker = TRUE;
+
+ /* If a wakeup marker has been relayed, this thread
+ * will get out of the way for 100 microseconds to
+ * avoid receiving this marker again.
+ */
+ g_usleep (100);
+ }
+ }
+ else
+ {
+ if (g_atomic_int_add (&kill_unused_threads, -1) > 0)
+ {
+ pool = NULL;
+ break;
+ }
+
+ DEBUG_MSG (("thread %p updating to new limits.",
+ g_thread_self ()));
+
+ local_max_unused_threads = g_atomic_int_get (&max_unused_threads);
+ local_max_idle_time = g_atomic_int_get (&max_idle_time);
+ last_wakeup_thread_serial = local_wakeup_thread_serial;
+
+ have_relayed_thread_marker = FALSE;
+ }
+ }
+ }
+ while (pool == wakeup_thread_marker);
-static void
+ g_atomic_int_add (&unused_threads, -1);
+
+ return pool;
+}
+
+static gpointer
+g_thread_pool_wait_for_new_task (GRealThreadPool *pool)
+{
+ gpointer task = NULL;
+
+ if (pool->running || (!pool->immediate &&
+ g_async_queue_length_unlocked (pool->queue) > 0))
+ {
+ /* This thread pool is still active. */
+ if (pool->num_threads > pool->max_threads && pool->max_threads != -1)
+ {
+ /* This is a superfluous thread, so it goes to the global pool. */
+ DEBUG_MSG (("superfluous thread %p in pool %p.",
+ g_thread_self (), pool));
+ }
+ else if (pool->pool.exclusive)
+ {
+ /* Exclusive threads stay attached to the pool. */
+ task = g_async_queue_pop_unlocked (pool->queue);
+
+ DEBUG_MSG (("thread %p in exclusive pool %p waits for task "
+ "(%d running, %d unprocessed).",
+ g_thread_self (), pool, pool->num_threads,
+ g_async_queue_length_unlocked (pool->queue)));
+ }
+ else
+ {
+ /* A thread will wait for new tasks for at most 1/2
+ * second before going to the global pool.
+ */
+ DEBUG_MSG (("thread %p in pool %p waits for up to a 1/2 second for task "
+ "(%d running, %d unprocessed).",
+ g_thread_self (), pool, pool->num_threads,
+ g_async_queue_length_unlocked (pool->queue)));
+
+ task = g_async_queue_timeout_pop_unlocked (pool->queue,
+ G_USEC_PER_SEC / 2);
+ }
+ }
+ else
+ {
+ /* This thread pool is inactive, it will no longer process tasks. */
+ DEBUG_MSG (("pool %p not active, thread %p will go to global pool "
+ "(running: %s, immediate: %s, len: %d).",
+ pool, g_thread_self (),
+ pool->running ? "true" : "false",
+ pool->immediate ? "true" : "false",
+ g_async_queue_length_unlocked (pool->queue)));
+ }
+
+ return task;
+}
+
+
+static gpointer
g_thread_pool_thread_proxy (gpointer data)
{
- GRealThreadPool *pool = data;
+ GRealThreadPool *pool;
+
+ pool = data;
+
+ DEBUG_MSG (("thread %p started for pool %p.", g_thread_self (), pool));
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))
- {
- task = g_async_queue_pop_unlocked (pool->queue);
-
- 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.thread_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);
-
- if (!pool->running && (pool->immediate || len <= 0))
- goto_global_pool = TRUE;
- else if (len >= 0)
- /* At this pool there is no thread waiting */
- goto_global_pool = FALSE;
-
- if (goto_global_pool)
- {
- GThreadPriority priority = pool->pool.priority;
- 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);
- }
- else
- g_async_queue_unlock (pool->queue);
-
- g_async_queue_lock (unused_thread_queue[priority]);
-
- G_LOCK (unused_threads);
- if (unused_threads >= max_unused_threads)
- {
- G_UNLOCK (unused_threads);
- g_async_queue_unlock (unused_thread_queue[priority]);
- /* Stop this thread */
- return;
- }
- unused_threads++;
- G_UNLOCK (unused_threads);
-
- pool =
- g_async_queue_pop_unlocked (unused_thread_queue[priority]);
-
- G_LOCK (unused_threads);
- unused_threads--;
- G_UNLOCK (unused_threads);
-
- g_async_queue_unlock (unused_thread_queue[priority]);
-
- if (pool == stop_this_thread_marker)
- /* Stop this thread */
- return;
-
- 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. */
- }
+ gpointer task;
+
+ task = g_thread_pool_wait_for_new_task (pool);
+ if (task)
+ {
+ if (pool->running || !pool->immediate)
+ {
+ /* A task was received and the thread pool is active,
+ * so execute the function.
+ */
+ g_async_queue_unlock (pool->queue);
+ DEBUG_MSG (("thread %p in pool %p calling func.",
+ g_thread_self (), pool));
+ pool->pool.func (task, pool->pool.user_data);
+ g_async_queue_lock (pool->queue);
+ }
+ }
+ else
+ {
+ /* No task was received, so this thread goes to the global pool. */
+ gboolean free_pool = FALSE;
+
+ DEBUG_MSG (("thread %p leaving pool %p for global pool.",
+ g_thread_self (), pool));
+ pool->num_threads--;
+
+ if (!pool->running)
+ {
+ if (!pool->waiting)
+ {
+ if (pool->num_threads == 0)
+ {
+ /* If the pool is not running and no other
+ * thread is waiting for this thread pool to
+ * finish and this is the last thread of this
+ * pool, free the pool.
+ */
+ free_pool = TRUE;
+ }
+ else
+ {
+ /* If the pool is not running and no other
+ * thread is waiting for this thread pool to
+ * finish and this is not the last thread of
+ * this pool and there are no tasks left in the
+ * queue, wakeup the remaining threads.
+ */
+ if (g_async_queue_length_unlocked (pool->queue) ==
+ - pool->num_threads)
+ g_thread_pool_wakeup_and_stop_all (pool);
+ }
+ }
+ else if (pool->immediate ||
+ g_async_queue_length_unlocked (pool->queue) <= 0)
+ {
+ /* If the pool is not running and another thread is
+ * waiting for this thread pool to finish and there
+ * are either no tasks left or the pool shall stop
+ * immediately, inform the waiting thread of a change
+ * of the thread pool state.
+ */
+ g_cond_broadcast (&pool->cond);
+ }
+ }
+
+ g_async_queue_unlock (pool->queue);
+
+ if (free_pool)
+ g_thread_pool_free_internal (pool);
+
+ if ((pool = g_thread_pool_wait_for_new_pool ()) == NULL)
+ break;
+
+ g_async_queue_lock (pool->queue);
+
+ DEBUG_MSG (("thread %p entering pool %p from global pool.",
+ g_thread_self (), pool));
+
+ /* 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)
+static gboolean
+g_thread_pool_start_thread (GRealThreadPool *pool,
+ GError **error)
{
gboolean success = FALSE;
- GThreadPriority priority = pool->pool.priority;
- GAsyncQueue *queue = unused_thread_queue[priority];
-
+
if (pool->num_threads >= pool->max_threads && pool->max_threads != -1)
/* Enough threads are already running */
- return;
+ return TRUE;
- g_async_queue_lock (queue);
+ g_async_queue_lock (unused_thread_queue);
- if (g_async_queue_length_unlocked (queue) < 0)
+ if (g_async_queue_length_unlocked (unused_thread_queue) < 0)
{
- /* First we try a thread with the right priority */
- g_async_queue_push_unlocked (queue, pool);
+ g_async_queue_push_unlocked (unused_thread_queue, pool);
success = TRUE;
}
- g_async_queue_unlock (queue);
+ g_async_queue_unlock (unused_thread_queue);
- /* We will not search for threads with other priorities, because changing
- * priority is quite unportable */
-
if (!success)
{
- GError *local_error = NULL;
- /* No thread was found, we have to start one new */
- g_thread_create (g_thread_pool_thread_proxy, pool,
- pool->pool.stack_size, FALSE,
- pool->pool.bound, priority, &local_error);
-
- if (local_error)
- {
- g_propagate_error (error, local_error);
- return;
- }
+ GThread *thread;
+
+ /* No thread was found, we have to start a new one */
+ thread = g_thread_try_new ("pool", g_thread_pool_thread_proxy, pool, error);
+
+ if (thread == NULL)
+ return FALSE;
+
+ g_thread_unref (thread);
}
/* See comment in g_thread_pool_thread_proxy as to why this is done
- * here and not there */
+ * here and not there
+ */
pool->num_threads++;
+
+ return TRUE;
}
-GThreadPool*
-g_thread_pool_new (GFunc thread_func,
- gint max_threads,
- gulong stack_size,
- gboolean bound,
- GThreadPriority priority,
- gboolean exclusive,
- gpointer user_data,
- GError **error)
+/**
+ * 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, or %NULL
+ *
+ * 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 shares them with other thread pools.
+ * 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. Besides, exclusive thread
+ * pools are not affected by g_thread_pool_set_max_idle_time()
+ * since their threads are never considered idle and returned to the
+ * global pool.
+ *
+ * @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.
+ * See #GThreadError for possible errors that may occur.
+ * Note, even in case of error a valid #GThreadPool is returned.
+ *
+ * Returns: 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 (thread_func, NULL);
+ 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.thread_func = thread_func;
- retval->pool.stack_size = stack_size;
- retval->pool.bound = bound;
- retval->pool.priority = priority;
- retval->pool.exclusive = exclusive;
+ retval->pool.func = func;
retval->pool.user_data = user_data;
+ retval->pool.exclusive = exclusive;
retval->queue = g_async_queue_new ();
+ g_cond_init (&retval->cond);
retval->max_threads = max_threads;
retval->num_threads = 0;
retval->running = TRUE;
+ retval->immediate = FALSE;
+ retval->waiting = FALSE;
+ retval->sort_func = NULL;
+ retval->sort_user_data = NULL;
- if (!inform_mutex)
- {
- inform_mutex = g_mutex_new ();
- inform_cond = g_cond_new ();
- for (priority = G_THREAD_PRIORITY_LOW;
- priority < G_THREAD_PRIORITY_URGENT + 1; priority++)
- unused_thread_queue[priority] = g_async_queue_new ();
- }
+ G_LOCK (init);
+ if (!unused_thread_queue)
+ 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;
- }
- }
+ {
+ GError *local_error = NULL;
+
+ if (!g_thread_pool_start_thread (retval, &local_error))
+ {
+ g_propagate_error (error, local_error);
+ break;
+ }
+ }
g_async_queue_unlock (retval->queue);
}
return (GThreadPool*) retval;
}
-void
-g_thread_pool_push (GThreadPool *pool,
- gpointer data,
- GError **error)
+/**
+ * g_thread_pool_push:
+ * @pool: a #GThreadPool
+ * @data: a new task for @pool
+ * @error: return location for error, or %NULL
+ *
+ * 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.
+ *
+ * Before version 2.32, this function did not return a success status.
+ *
+ * Returns: %TRUE on success, %FALSE if an error occurred
+ */
+gboolean
+g_thread_pool_push (GThreadPool *pool,
+ gpointer data,
+ GError **error)
{
- GRealThreadPool *real = (GRealThreadPool*) pool;
+ GRealThreadPool *real;
+ gboolean result;
- g_return_if_fail (real);
+ real = (GRealThreadPool*) pool;
+
+ g_return_val_if_fail (real, FALSE);
+ g_return_val_if_fail (real->running, FALSE);
+
+ result = TRUE;
g_async_queue_lock (real->queue);
-
- if (!real->running)
+
+ if (g_async_queue_length_unlocked (real->queue) >= 0)
{
- g_async_queue_unlock (real->queue);
- g_return_if_fail (real->running);
- }
+ /* No thread is waiting in the queue */
+ GError *local_error = NULL;
- if (!pool->exclusive && g_async_queue_length_unlocked (real->queue) >= 0)
- /* No thread is waiting in the queue */
- g_thread_pool_start_thread (real, error);
+ if (!g_thread_pool_start_thread (real, &local_error))
+ {
+ g_propagate_error (error, local_error);
+ result = FALSE;
+ }
+ }
- g_async_queue_push_unlocked (real->queue, data);
+ g_thread_pool_queue_push_unlocked (real, data);
g_async_queue_unlock (real->queue);
+
+ return result;
}
-void
-g_thread_pool_set_max_threads (GThreadPool *pool,
- gint max_threads,
- GError **error)
+/**
+ * g_thread_pool_set_max_threads:
+ * @pool: a #GThreadPool
+ * @max_threads: a new maximal number of threads for @pool,
+ * or -1 for unlimited
+ * @error: return location for error, or %NULL
+ *
+ * Sets the maximal allowed number of threads for @pool.
+ * A value of -1 means that the maximal number of threads
+ * is unlimited. If @pool is an exclusive thread pool, setting
+ * the maximal number of threads to -1 is not allowed.
+ *
+ * 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.
+ *
+ * Before version 2.32, this function did not return a success status.
+ *
+ * Returns: %TRUE on success, %FALSE if an error occurred
+ */
+gboolean
+g_thread_pool_set_max_threads (GThreadPool *pool,
+ gint max_threads,
+ GError **error)
{
- GRealThreadPool *real = (GRealThreadPool*) pool;
+ GRealThreadPool *real;
gint to_start;
+ gboolean result;
- 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);
+ real = (GRealThreadPool*) pool;
+
+ g_return_val_if_fail (real, FALSE);
+ g_return_val_if_fail (real->running, FALSE);
+ g_return_val_if_fail (!real->pool.exclusive || max_threads != -1, FALSE);
+ g_return_val_if_fail (max_threads >= -1, FALSE);
+
+ result = TRUE;
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;
- }
+
+ if (!g_thread_pool_start_thread (real, &local_error))
+ {
+ g_propagate_error (error, local_error);
+ result = FALSE;
+ break;
+ }
}
-
+
g_async_queue_unlock (real->queue);
+
+ return result;
}
+/**
+ * g_thread_pool_get_max_threads:
+ * @pool: a #GThreadPool
+ *
+ * Returns the maximal number of threads for @pool.
+ *
+ * Returns: the maximal number of threads
+ */
gint
-g_thread_pool_get_max_threads (GThreadPool *pool)
+g_thread_pool_get_max_threads (GThreadPool *pool)
{
- GRealThreadPool *real = (GRealThreadPool*) pool;
+ GRealThreadPool *real;
gint retval;
+ real = (GRealThreadPool*) pool;
+
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.
+ *
+ * Returns: the number of threads currently running
+ */
guint
-g_thread_pool_get_num_threads (GThreadPool *pool)
+g_thread_pool_get_num_threads (GThreadPool *pool)
{
- GRealThreadPool *real = (GRealThreadPool*) pool;
+ GRealThreadPool *real;
guint retval;
+ real = (GRealThreadPool*) pool;
+
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.
+ *
+ * Returns: the number of unprocessed tasks
+ */
guint
-g_thread_pool_unprocessed (GThreadPool *pool)
+g_thread_pool_unprocessed (GThreadPool *pool)
{
- GRealThreadPool *real = (GRealThreadPool*) pool;
+ GRealThreadPool *real;
gint unprocessed;
+ real = (GRealThreadPool*) pool;
+
g_return_val_if_fail (real, 0);
g_return_val_if_fail (real->running, 0);
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)
+g_thread_pool_free (GThreadPool *pool,
+ gboolean immediate,
+ gboolean wait_)
{
- GRealThreadPool *real = (GRealThreadPool*) pool;
+ GRealThreadPool *real;
+
+ 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 immediatly, when it's not empty */
- g_return_if_fail (immediate || real->max_threads != 0 ||
- g_async_queue_length (real->queue) == 0);
+
+ /* If 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;
+ real->waiting = wait_;
- if (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);
+ while (g_async_queue_length_unlocked (real->queue) != -real->num_threads &&
+ !(immediate && real->num_threads == 0))
+ g_cond_wait (&real->cond, _g_async_queue_get_mutex (real->queue));
}
- if (g_async_queue_length_unlocked (real->queue) == -real->num_threads)
+ if (immediate || 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;
- }
+ * 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 */
+
+ /* The last thread should cleanup the pool */
+ real->waiting = FALSE;
g_async_queue_unlock (real->queue);
}
g_thread_pool_free_internal (GRealThreadPool* pool)
{
g_return_if_fail (pool);
- g_return_if_fail (!pool->running);
+ g_return_if_fail (pool->running == FALSE);
g_return_if_fail (pool->num_threads == 0);
g_async_queue_unref (pool->queue);
+ g_cond_clear (&pool->cond);
g_free (pool);
}
static void
-g_thread_pool_wakeup_and_stop_all (GRealThreadPool* pool)
+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->running == FALSE);
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;
+ pool->immediate = TRUE;
+
+ /*
+ * So here we're sending bogus data to the pool threads, which
+ * should cause them each to wake up, and check the above
+ * pool->immediate condition. However we don't want that
+ * data to be sorted (since it'll crash the sorter).
+ */
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.
+ *
+ * The default value is 2.
+ */
void
g_thread_pool_set_max_unused_threads (gint max_threads)
{
- g_return_if_fail (max_threads >= -1);
+ g_return_if_fail (max_threads >= -1);
- G_LOCK (unused_threads);
-
- max_unused_threads = max_threads;
+ g_atomic_int_set (&max_unused_threads, max_threads);
- if (max_unused_threads < unused_threads && max_unused_threads != -1)
+ if (max_threads != -1)
{
- guint close_down_num = unused_threads - max_unused_threads;
- GThreadPriority priority;
-
- while (close_down_num > 0)
- {
- guint old_close_down_num = close_down_num;
- for (priority = G_THREAD_PRIORITY_LOW;
- priority < G_THREAD_PRIORITY_URGENT + 1 && close_down_num > 0;
- priority++)
- {
- GAsyncQueue *queue = unused_thread_queue[priority];
- g_async_queue_lock (queue);
-
- if (g_async_queue_length_unlocked (queue) < 0)
- {
- g_async_queue_push_unlocked (queue,
- stop_this_thread_marker);
- close_down_num--;
- }
-
- g_async_queue_unlock (queue);
- }
-
- /* Just to make sure, there are no counting problems */
- g_assert (old_close_down_num != close_down_num);
- }
+ max_threads -= g_atomic_int_get (&unused_threads);
+ if (max_threads < 0)
+ {
+ g_atomic_int_set (&kill_unused_threads, -max_threads);
+ g_atomic_int_inc (&wakeup_thread_serial);
+
+ g_async_queue_lock (unused_thread_queue);
+
+ do
+ {
+ g_async_queue_push_unlocked (unused_thread_queue,
+ wakeup_thread_marker);
+ }
+ while (++max_threads);
+
+ 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.
+ *
+ * Returns: 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 g_atomic_int_get (&max_unused_threads);
+}
- return retval;
+/**
+ * g_thread_pool_get_num_unused_threads:
+ *
+ * Returns the number of currently unused threads.
+ *
+ * Returns: the number of currently unused threads
+ */
+guint
+g_thread_pool_get_num_unused_threads (void)
+{
+ return g_atomic_int_get (&unused_threads);
}
-guint g_thread_pool_get_num_unused_threads (void)
+/**
+ * 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 retval;
-
- G_LOCK (unused_threads);
- retval = unused_threads;
- G_UNLOCK (unused_threads);
+ guint oldval;
- return retval;
-}
+ oldval = g_thread_pool_get_max_unused_threads ();
-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);
}
+
+/**
+ * g_thread_pool_set_sort_function:
+ * @pool: a #GThreadPool
+ * @func: the #GCompareDataFunc used to sort the list of tasks.
+ * This function is passed two tasks. It should return
+ * 0 if the order in which they are handled does not matter,
+ * a negative value if the first task should be processed before
+ * the second or a positive value if the second task should be
+ * processed first.
+ * @user_data: user data passed to @func
+ *
+ * Sets the function used to sort the list of tasks. This allows the
+ * tasks to be processed by a priority determined by @func, and not
+ * just in the order in which they were added to the pool.
+ *
+ * Note, if the maximum number of threads is more than 1, the order
+ * that threads are executed cannot be guaranteed 100%. Threads are
+ * scheduled by the operating system and are executed at random. It
+ * cannot be assumed that threads are executed in the order they are
+ * created.
+ *
+ * Since: 2.10
+ */
+void
+g_thread_pool_set_sort_function (GThreadPool *pool,
+ GCompareDataFunc func,
+ gpointer user_data)
+{
+ GRealThreadPool *real;
+
+ real = (GRealThreadPool*) pool;
+
+ g_return_if_fail (real);
+ g_return_if_fail (real->running);
+
+ g_async_queue_lock (real->queue);
+
+ real->sort_func = func;
+ real->sort_user_data = user_data;
+
+ if (func)
+ g_async_queue_sort_unlocked (real->queue,
+ real->sort_func,
+ real->sort_user_data);
+
+ g_async_queue_unlock (real->queue);
+}
+
+/**
+ * g_thread_pool_set_max_idle_time:
+ * @interval: the maximum @interval (in milliseconds)
+ * a thread can be idle
+ *
+ * This function will set the maximum @interval that a thread
+ * waiting in the pool for new tasks can be idle for before
+ * being stopped. This function is similar to calling
+ * g_thread_pool_stop_unused_threads() on a regular timeout,
+ * except this is done on a per thread basis.
+ *
+ * By setting @interval to 0, idle threads will not be stopped.
+ *
+ * The default value is 15000 (15 seconds).
+ *
+ * Since: 2.10
+ */
+void
+g_thread_pool_set_max_idle_time (guint interval)
+{
+ guint i;
+
+ g_atomic_int_set (&max_idle_time, interval);
+
+ i = g_atomic_int_get (&unused_threads);
+ if (i > 0)
+ {
+ g_atomic_int_inc (&wakeup_thread_serial);
+ g_async_queue_lock (unused_thread_queue);
+
+ do
+ {
+ g_async_queue_push_unlocked (unused_thread_queue,
+ wakeup_thread_marker);
+ }
+ while (--i);
+
+ g_async_queue_unlock (unused_thread_queue);
+ }
+}
+
+/**
+ * g_thread_pool_get_max_idle_time:
+ *
+ * This function will return the maximum @interval that a
+ * thread will wait in the thread pool for new tasks before
+ * being stopped.
+ *
+ * If this function returns 0, threads waiting in the thread
+ * pool for new work are not stopped.
+ *
+ * Returns: the maximum @interval (milliseconds) to wait
+ * for new tasks in the thread pool before stopping the
+ * thread
+ *
+ * Since: 2.10
+ */
+guint
+g_thread_pool_get_max_idle_time (void)
+{
+ return g_atomic_int_get (&max_idle_time);
+}
projects / platform / upstream / glib.git / blobdiff