/* GLIB - Library of useful routines for C programming
* Copyright (C) 1995-1997 Peter Mattis, Spencer Kimball and Josh MacDonald
*
- * GAsyncQueue: asynchronous queue implementation, based on Gqueue.
+ * GAsyncQueue: asynchronous queue implementation, based on GQueue.
* Copyright (C) 2000 Sebastian Wilhelmi; University of Karlsruhe
*
* This library is free software; you can redistribute it and/or
* SECTION:async_queues
* @title: Asynchronous Queues
* @short_description: asynchronous communication between threads
+ * @see_also: #GThreadPool
*
* Often you need to communicate between different threads. In general
* it's safer not to do this by shared memory, but by explicit message
* it will always be used by at least 2 concurrent threads.
*
* For using an asynchronous queue you first have to create one with
- * g_async_queue_new(). A newly-created queue will get the reference
- * count 1. Whenever another thread is creating a new reference of (that
- * is, pointer to) the queue, it has to increase the reference count
- * (using g_async_queue_ref()). Also, before removing this reference,
- * the reference count has to be decreased (using g_async_queue_unref()).
- * After that the queue might no longer exist so you must not access
- * it after that point.
- *
- * A thread, which wants to send a message to that queue simply calls
+ * g_async_queue_new(). #GAsyncQueue structs are reference counted,
+ * use g_async_queue_ref() and g_async_queue_unref() to manage your
+ * references.
+ *
+ * A thread which wants to send a message to that queue simply calls
* g_async_queue_push() to push the message to the queue.
*
- * A thread, which is expecting messages from an asynchronous queue
+ * A thread which is expecting messages from an asynchronous queue
* simply calls g_async_queue_pop() for that queue. If no message is
* available in the queue at that point, the thread is now put to sleep
* until a message arrives. The message will be removed from the queue
* This can be necessary to ensure the integrity of the queue, but should
* only be used when really necessary, as it can make your life harder
* if used unwisely. Normally you should only use the locking function
- * variants (those without the suffix _unlocked)
+ * variants (those without the _unlocked suffix).
+ *
+ * In many cases, it may be more convenient to use #GThreadPool when
+ * you need to distribute work to a set of worker threads instead of
+ * using #GAsyncQueue manually. #GThreadPool uses a GAsyncQueue
+ * internally.
*/
/**
* GAsyncQueue:
*
- * The GAsyncQueue struct is an opaque data structure, which represents
+ * The GAsyncQueue struct is an opaque data structure which represents
* an asynchronous queue. It should only be accessed through the
* <function>g_async_queue_*</function> functions.
*/
gint ref_count;
};
-typedef struct {
+typedef struct
+{
GCompareDataFunc func;
gpointer user_data;
} SortData;
/**
* g_async_queue_new:
- *
- * Creates a new asynchronous queue with the initial reference count of 1.
- *
- * Return value: the new #GAsyncQueue.
- **/
-GAsyncQueue*
+ *
+ * Creates a new asynchronous queue.
+ *
+ * Return value: a new #GAsyncQueue. Free with g_async_queue_unref()
+ */
+GAsyncQueue *
g_async_queue_new (void)
{
- GAsyncQueue* retval = g_new (GAsyncQueue, 1);
- g_mutex_init (&retval->mutex);
- retval->cond = NULL;
- g_queue_init (&retval->queue);
- retval->waiting_threads = 0;
- retval->ref_count = 1;
- retval->item_free_func = NULL;
- return retval;
+ return g_async_queue_new_full (NULL);
}
/**
* g_async_queue_new_full:
* @item_free_func: function to free queue elements
- *
- * Creates a new asynchronous queue with an initial reference count of 1 and
- * sets up a destroy notify function that is used to free any remaining
- * queue items when the queue is destroyed after the final unref.
*
- * Return value: the new #GAsyncQueue.
+ * Creates a new asynchronous queue and sets up a destroy notify
+ * function that is used to free any remaining queue items when
+ * the queue is destroyed after the final unref.
+ *
+ * Return value: a new #GAsyncQueue. Free with g_async_queue_unref()
*
* Since: 2.16
- **/
-GAsyncQueue*
+ */
+GAsyncQueue *
g_async_queue_new_full (GDestroyNotify item_free_func)
{
- GAsyncQueue *async_queue = g_async_queue_new ();
- async_queue->item_free_func = item_free_func;
- return async_queue;
+ GAsyncQueue *queue;
+
+ queue = g_new (GAsyncQueue, 1);
+ g_mutex_init (&queue->mutex);
+ queue->cond = NULL;
+ g_queue_init (&queue->queue);
+ queue->waiting_threads = 0;
+ queue->ref_count = 1;
+ queue->item_free_func = NULL;
+
+ return queue;
}
/**
* g_async_queue_ref:
- * @queue: a #GAsyncQueue.
+ * @queue: a #GAsyncQueue
*
- * Increases the reference count of the asynchronous @queue by 1. You
- * do not need to hold the lock to call this function.
+ * Increases the reference count of the asynchronous @queue by 1.
+ * You do not need to hold the lock to call this function.
*
* Returns: the @queue that was passed in (since 2.6)
- **/
+ */
GAsyncQueue *
g_async_queue_ref (GAsyncQueue *queue)
{
g_return_val_if_fail (queue, NULL);
-
+
g_atomic_int_inc (&queue->ref_count);
return queue;
/**
* g_async_queue_ref_unlocked:
- * @queue: a #GAsyncQueue.
- *
+ * @queue: a #GAsyncQueue
+ *
* Increases the reference count of the asynchronous @queue by 1.
*
* @Deprecated: Since 2.8, reference counting is done atomically
* so g_async_queue_ref() can be used regardless of the @queue's
* lock.
- **/
-void
+ */
+void
g_async_queue_ref_unlocked (GAsyncQueue *queue)
{
g_return_if_fail (queue);
-
+
g_atomic_int_inc (&queue->ref_count);
}
/**
* g_async_queue_unref_and_unlock:
- * @queue: a #GAsyncQueue.
- *
- * Decreases the reference count of the asynchronous @queue by 1 and
- * releases the lock. This function must be called while holding the
- * @queue's lock. If the reference count went to 0, the @queue will be
- * destroyed and the memory allocated will be freed.
+ * @queue: a #GAsyncQueue
+ *
+ * Decreases the reference count of the asynchronous @queue by 1
+ * and releases the lock. This function must be called while holding
+ * the @queue's lock. If the reference count went to 0, the @queue
+ * will be destroyed and the memory allocated will be freed.
*
* @Deprecated: Since 2.8, reference counting is done atomically
* so g_async_queue_unref() can be used regardless of the @queue's
* lock.
- **/
-void
+ */
+void
g_async_queue_unref_and_unlock (GAsyncQueue *queue)
{
g_return_if_fail (queue);
/**
* g_async_queue_unref:
* @queue: a #GAsyncQueue.
- *
- * Decreases the reference count of the asynchronous @queue by 1. If
- * the reference count went to 0, the @queue will be destroyed and the
- * memory allocated will be freed. So you are not allowed to use the
- * @queue afterwards, as it might have disappeared. You do not need to
- * hold the lock to call this function.
- **/
-void
+ *
+ * Decreases the reference count of the asynchronous @queue by 1.
+ *
+ * If the reference count went to 0, the @queue will be destroyed
+ * and the memory allocated will be freed. So you are not allowed
+ * to use the @queue afterwards, as it might have disappeared.
+ * You do not need to hold the lock to call this function.
+ */
+void
g_async_queue_unref (GAsyncQueue *queue)
{
g_return_if_fail (queue);
-
+
if (g_atomic_int_dec_and_test (&queue->ref_count))
{
g_return_if_fail (queue->waiting_threads == 0);
g_mutex_clear (&queue->mutex);
if (queue->cond)
- g_cond_free (queue->cond);
+ g_cond_free (queue->cond);
if (queue->item_free_func)
g_queue_foreach (&queue->queue, (GFunc) queue->item_free_func, NULL);
g_queue_clear (&queue->queue);
/**
* g_async_queue_lock:
- * @queue: a #GAsyncQueue.
- *
- * Acquires the @queue's lock. After that you can only call the
- * <function>g_async_queue_*_unlocked()</function> function variants on that
- * @queue. Otherwise it will deadlock.
- **/
+ * @queue: a #GAsyncQueue
+ *
+ * Acquires the @queue's lock. If another thread is already
+ * holding the lock, this call will block until the lock
+ * becomes available.
+ *
+ * Call g_async_queue_unlock() to drop the lock again.
+ *
+ * While holding the lock, you can only call the
+ * <function>g_async_queue_*_unlocked()</function> functions
+ * on @queue. Otherwise, deadlock may occur.
+ */
void
g_async_queue_lock (GAsyncQueue *queue)
{
/**
* g_async_queue_unlock:
- * @queue: a #GAsyncQueue.
- *
+ * @queue: a #GAsyncQueue
+ *
* Releases the queue's lock.
- **/
-void
+ *
+ * Calling this function when you have not acquired
+ * the with g_async_queue_lock() leads to undefined
+ * behaviour.
+ */
+void
g_async_queue_unlock (GAsyncQueue *queue)
{
g_return_if_fail (queue);
/**
* g_async_queue_push:
- * @queue: a #GAsyncQueue.
- * @data: @data to push into the @queue.
+ * @queue: a #GAsyncQueue
+ * @data: @data to push into the @queue
*
* Pushes the @data into the @queue. @data must not be %NULL.
- **/
+ */
void
-g_async_queue_push (GAsyncQueue* queue, gpointer data)
+g_async_queue_push (GAsyncQueue *queue,
+ gpointer data)
{
g_return_if_fail (queue);
g_return_if_fail (data);
/**
* g_async_queue_push_unlocked:
- * @queue: a #GAsyncQueue.
- * @data: @data to push into the @queue.
- *
- * Pushes the @data into the @queue. @data must not be %NULL. This
- * function must be called while holding the @queue's lock.
- **/
+ * @queue: a #GAsyncQueue
+ * @data: @data to push into the @queue
+ *
+ * Pushes the @data into the @queue. @data must not be %NULL.
+ *
+ * This function must be called while holding the @queue's lock.
+ */
void
-g_async_queue_push_unlocked (GAsyncQueue* queue, gpointer data)
+g_async_queue_push_unlocked (GAsyncQueue *queue,
+ gpointer data)
{
g_return_if_fail (queue);
g_return_if_fail (data);
* g_async_queue_push_sorted:
* @queue: a #GAsyncQueue
* @data: the @data to push into the @queue
- * @func: the #GCompareDataFunc is used to sort @queue. This function
- * is passed two elements of the @queue. The function should return
- * 0 if they are equal, a negative value if the first element
- * should be higher in the @queue or a positive value if the first
- * element should be lower in the @queue than the second element.
+ * @func: the #GCompareDataFunc is used to sort @queue
* @user_data: user data passed to @func.
- *
+ *
* Inserts @data into @queue using @func to determine the new
- * position.
- *
+ * position.
+ *
* This function requires that the @queue is sorted before pushing on
- * new elements.
- *
+ * new elements, see g_async_queue_sort().
+ *
* This function will lock @queue before it sorts the queue and unlock
* it when it is finished.
- *
- * For an example of @func see g_async_queue_sort().
+ *
+ * For an example of @func see g_async_queue_sort().
*
* Since: 2.10
- **/
+ */
void
g_async_queue_push_sorted (GAsyncQueue *queue,
- gpointer data,
- GCompareDataFunc func,
- gpointer user_data)
+ gpointer data,
+ GCompareDataFunc func,
+ gpointer user_data)
{
g_return_if_fail (queue != NULL);
g_mutex_unlock (&queue->mutex);
}
-static gint
-g_async_queue_invert_compare (gpointer v1,
- gpointer v2,
- SortData *sd)
+static gint
+g_async_queue_invert_compare (gpointer v1,
+ gpointer v2,
+ SortData *sd)
{
return -sd->func (v1, v2, sd->user_data);
}
* g_async_queue_push_sorted_unlocked:
* @queue: a #GAsyncQueue
* @data: the @data to push into the @queue
- * @func: the #GCompareDataFunc is used to sort @queue. This function
- * is passed two elements of the @queue. The function should return
- * 0 if they are equal, a negative value if the first element
- * should be higher in the @queue or a positive value if the first
- * element should be lower in the @queue than the second element.
+ * @func: the #GCompareDataFunc is used to sort @queue
* @user_data: user data passed to @func.
- *
+ *
* Inserts @data into @queue using @func to determine the new
* position.
- *
+ *
+ * The sort function @func is passed two elements of the @queue.
+ * It should return 0 if they are equal, a negative value if the
+ * first element should be higher in the @queue or a positive value
+ * if the first element should be lower in the @queue than the second
+ * element.
+ *
* This function requires that the @queue is sorted before pushing on
- * new elements.
- *
- * This function is called while holding the @queue's lock.
- *
- * For an example of @func see g_async_queue_sort().
+ * new elements, see g_async_queue_sort().
+ *
+ * This function must be called while holding the @queue's lock.
+ *
+ * For an example of @func see g_async_queue_sort().
*
* Since: 2.10
- **/
+ */
void
g_async_queue_push_sorted_unlocked (GAsyncQueue *queue,
- gpointer data,
- GCompareDataFunc func,
- gpointer user_data)
+ gpointer data,
+ GCompareDataFunc func,
+ gpointer user_data)
{
SortData sd;
-
+
g_return_if_fail (queue != NULL);
sd.func = func;
sd.user_data = user_data;
g_queue_insert_sorted (&queue->queue,
- data,
- (GCompareDataFunc)g_async_queue_invert_compare,
- &sd);
+ data,
+ (GCompareDataFunc)g_async_queue_invert_compare,
+ &sd);
if (queue->waiting_threads > 0)
g_cond_signal (queue->cond);
}
static gpointer
-g_async_queue_pop_intern_unlocked (GAsyncQueue *queue,
- gboolean try,
- GTimeVal *end_time)
+g_async_queue_pop_intern_unlocked (GAsyncQueue *queue,
+ gboolean try,
+ GTimeVal *end_time)
{
gpointer retval;
if (!g_queue_peek_tail_link (&queue->queue))
{
if (try)
- return NULL;
-
+ return NULL;
+
if (!queue->cond)
- queue->cond = g_cond_new ();
+ queue->cond = g_cond_new ();
if (!end_time)
{
queue->waiting_threads++;
- while (!g_queue_peek_tail_link (&queue->queue))
+ while (!g_queue_peek_tail_link (&queue->queue))
g_cond_wait (queue->cond, &queue->mutex);
queue->waiting_threads--;
}
break;
queue->waiting_threads--;
if (!g_queue_peek_tail_link (&queue->queue))
- return NULL;
+ return NULL;
}
}
/**
* g_async_queue_pop:
- * @queue: a #GAsyncQueue.
- *
- * Pops data from the @queue. This function blocks until data become
- * available.
+ * @queue: a #GAsyncQueue
*
- * Return value: data from the queue.
- **/
+ * Pops data from the @queue. If @queue is empty, this function
+ * blocks until data becomes available.
+ *
+ * Return value: data from the queue
+ */
gpointer
-g_async_queue_pop (GAsyncQueue* queue)
+g_async_queue_pop (GAsyncQueue *queue)
{
gpointer retval;
/**
* g_async_queue_pop_unlocked:
- * @queue: a #GAsyncQueue.
- *
- * Pops data from the @queue. This function blocks until data become
- * available. This function must be called while holding the @queue's
- * lock.
+ * @queue: a #GAsyncQueue
+ *
+ * Pops data from the @queue. If @queue is empty, this function
+ * blocks until data becomes available.
+ *
+ * This function must be called while holding the @queue's lock.
*
* Return value: data from the queue.
- **/
+ */
gpointer
-g_async_queue_pop_unlocked (GAsyncQueue* queue)
+g_async_queue_pop_unlocked (GAsyncQueue *queue)
{
g_return_val_if_fail (queue, NULL);
/**
* g_async_queue_try_pop:
- * @queue: a #GAsyncQueue.
- *
- * Tries to pop data from the @queue. If no data is available, %NULL is
- * returned.
+ * @queue: a #GAsyncQueue
+ *
+ * Tries to pop data from the @queue. If no data is available,
+ * %NULL is returned.
*
* Return value: data from the queue or %NULL, when no data is
- * available immediately.
- **/
+ * available immediately.
+ */
gpointer
-g_async_queue_try_pop (GAsyncQueue* queue)
+g_async_queue_try_pop (GAsyncQueue *queue)
{
gpointer retval;
/**
* g_async_queue_try_pop_unlocked:
- * @queue: a #GAsyncQueue.
- *
- * Tries to pop data from the @queue. If no data is available, %NULL is
- * returned. This function must be called while holding the @queue's
- * lock.
+ * @queue: a #GAsyncQueue
+ *
+ * Tries to pop data from the @queue. If no data is available,
+ * %NULL is returned.
+ *
+ * This function must be called while holding the @queue's lock.
*
* Return value: data from the queue or %NULL, when no data is
- * available immediately.
- **/
+ * available immediately.
+ */
gpointer
-g_async_queue_try_pop_unlocked (GAsyncQueue* queue)
+g_async_queue_try_pop_unlocked (GAsyncQueue *queue)
{
g_return_val_if_fail (queue, NULL);
/**
* g_async_queue_timed_pop:
- * @queue: a #GAsyncQueue.
- * @end_time: a #GTimeVal, determining the final time.
+ * @queue: a #GAsyncQueue
+ * @end_time: a #GTimeVal, determining the final time
*
- * Pops data from the @queue. If no data is received before @end_time,
- * %NULL is returned.
+ * Pops data from the @queue. If the queue is empty, blocks until
+ * @end_time or until data becomes available.
*
- * To easily calculate @end_time a combination of g_get_current_time()
+ * If no data is received before @end_time, %NULL is returned.
+ *
+ * To easily calculate @end_time, a combination of g_get_current_time()
* and g_time_val_add() can be used.
*
* Return value: data from the queue or %NULL, when no data is
- * received before @end_time.
- **/
+ * received before @end_time.
+ */
gpointer
-g_async_queue_timed_pop (GAsyncQueue* queue, GTimeVal *end_time)
+g_async_queue_timed_pop (GAsyncQueue *queue,
+ GTimeVal *end_time)
{
gpointer retval;
retval = g_async_queue_pop_intern_unlocked (queue, FALSE, end_time);
g_mutex_unlock (&queue->mutex);
- return retval;
+ return retval;
}
/**
* g_async_queue_timed_pop_unlocked:
- * @queue: a #GAsyncQueue.
- * @end_time: a #GTimeVal, determining the final time.
+ * @queue: a #GAsyncQueue
+ * @end_time: a #GTimeVal, determining the final time
+ *
+ * Pops data from the @queue. If the queue is empty, blocks until
+ * @end_time or until data becomes available.
*
- * Pops data from the @queue. If no data is received before @end_time,
- * %NULL is returned. This function must be called while holding the
- * @queue's lock.
+ * If no data is received before @end_time, %NULL is returned.
*
- * To easily calculate @end_time a combination of g_get_current_time()
+ * To easily calculate @end_time, a combination of g_get_current_time()
* and g_time_val_add() can be used.
*
+ * This function must be called while holding the @queue's lock.
+ *
* Return value: data from the queue or %NULL, when no data is
- * received before @end_time.
- **/
+ * received before @end_time.
+ */
gpointer
-g_async_queue_timed_pop_unlocked (GAsyncQueue* queue, GTimeVal *end_time)
+g_async_queue_timed_pop_unlocked (GAsyncQueue *queue,
+ GTimeVal *end_time)
{
g_return_val_if_fail (queue, NULL);
/**
* g_async_queue_length:
* @queue: a #GAsyncQueue.
- *
- * Returns the length of the queue, negative values mean waiting
- * threads, positive values mean available entries in the
- * @queue. Actually this function returns the number of data items in
- * the queue minus the number of waiting threads. Thus a return value
- * of 0 could mean 'n' entries in the queue and 'n' thread waiting.
- * That can happen due to locking of the queue or due to
- * scheduling.
*
- * Return value: the length of the @queue.
- **/
+ * Returns the length of the queue.
+ *
+ * Actually this function returns the number of data items in
+ * the queue minus the number of waiting threads, so a negative
+ * value means waiting threads, and a positive value means available
+ * entries in the @queue. A return value of 0 could mean n entries
+ * in the queue and n threads waiting. This can happen due to locking
+ * of the queue or due to scheduling.
+ *
+ * Return value: the length of the @queue
+ */
gint
-g_async_queue_length (GAsyncQueue* queue)
+g_async_queue_length (GAsyncQueue *queue)
{
gint retval;
/**
* g_async_queue_length_unlocked:
- * @queue: a #GAsyncQueue.
- *
- * Returns the length of the queue, negative values mean waiting
- * threads, positive values mean available entries in the
- * @queue. Actually this function returns the number of data items in
- * the queue minus the number of waiting threads. Thus a return value
- * of 0 could mean 'n' entries in the queue and 'n' thread waiting.
- * That can happen due to locking of the queue or due to
- * scheduling. This function must be called while holding the @queue's
- * lock.
+ * @queue: a #GAsyncQueue
+ *
+ * Returns the length of the queue.
+ *
+ * Actually this function returns the number of data items in
+ * the queue minus the number of waiting threads, so a negative
+ * value means waiting threads, and a positive value means available
+ * entries in the @queue. A return value of 0 could mean n entries
+ * in the queue and n threads waiting. This can happen due to locking
+ * of the queue or due to scheduling.
+ *
+ * This function must be called while holding the @queue's lock.
*
* Return value: the length of the @queue.
- **/
+ */
gint
-g_async_queue_length_unlocked (GAsyncQueue* queue)
+g_async_queue_length_unlocked (GAsyncQueue *queue)
{
g_return_val_if_fail (queue, 0);
/**
* g_async_queue_sort:
* @queue: a #GAsyncQueue
- * @func: the #GCompareDataFunc is used to sort @queue. This
- * function is passed two elements of the @queue. The function
- * should return 0 if they are equal, a negative value if the
- * first element should be higher in the @queue or a positive
- * value if the first element should be lower in the @queue than
- * the second element.
+ * @func: the #GCompareDataFunc is used to sort @queue
* @user_data: user data passed to @func
*
- * Sorts @queue using @func.
+ * Sorts @queue using @func.
+ *
+ * The sort function @func is passed two elements of the @queue.
+ * It should return 0 if they are equal, a negative value if the
+ * first element should be higher in the @queue or a positive value
+ * if the first element should be lower in the @queue than the second
+ * element.
*
* This function will lock @queue before it sorts the queue and unlock
* it when it is finished.
* |[
* gint32 id1;
* gint32 id2;
- *
+ *
* id1 = GPOINTER_TO_INT (element1);
* id2 = GPOINTER_TO_INT (element2);
- *
+ *
* return (id1 > id2 ? +1 : id1 == id2 ? 0 : -1);
* ]|
*
* Since: 2.10
- **/
+ */
void
g_async_queue_sort (GAsyncQueue *queue,
- GCompareDataFunc func,
- gpointer user_data)
+ GCompareDataFunc func,
+ gpointer user_data)
{
g_return_if_fail (queue != NULL);
g_return_if_fail (func != NULL);
/**
* g_async_queue_sort_unlocked:
* @queue: a #GAsyncQueue
- * @func: the #GCompareDataFunc is used to sort @queue. This
- * function is passed two elements of the @queue. The function
- * should return 0 if they are equal, a negative value if the
- * first element should be higher in the @queue or a positive
- * value if the first element should be lower in the @queue than
- * the second element.
+ * @func: the #GCompareDataFunc is used to sort @queue
* @user_data: user data passed to @func
*
- * Sorts @queue using @func.
+ * Sorts @queue using @func.
+ *
+ * The sort function @func is passed two elements of the @queue.
+ * It should return 0 if they are equal, a negative value if the
+ * first element should be higher in the @queue or a positive value
+ * if the first element should be lower in the @queue than the second
+ * element.
+ *
+ * This function must be called while holding the @queue's lock.
*
- * This function is called while holding the @queue's lock.
- *
* Since: 2.10
- **/
+ */
void
g_async_queue_sort_unlocked (GAsyncQueue *queue,
- GCompareDataFunc func,
- gpointer user_data)
+ GCompareDataFunc func,
+ gpointer user_data)
{
SortData sd;
sd.user_data = user_data;
g_queue_sort (&queue->queue,
- (GCompareDataFunc)g_async_queue_invert_compare,
- &sd);
+ (GCompareDataFunc)g_async_queue_invert_compare,
+ &sd);
}
/*
* Private API
*/
-GMutex*
-_g_async_queue_get_mutex (GAsyncQueue* queue)
+GMutex *
+_g_async_queue_get_mutex (GAsyncQueue *queue)
{
g_return_val_if_fail (queue, NULL);