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776 lines
20 KiB
C
776 lines
20 KiB
C
/* GStreamer
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* Copyright (C) 1999,2000 Erik Walthinsen <omega@cse.ogi.edu>
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* 2005 Wim Taymans <wim@fluendo.com>
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*
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* gsttask.c: Streaming tasks
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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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* SECTION:gsttask
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* @short_description: Abstraction of GStreamer streaming threads.
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* @see_also: #GstElement, #GstPad
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*
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* #GstTask is used by #GstElement and #GstPad to provide the data passing
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* threads in a #GstPipeline.
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*
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* A #GstPad will typically start a #GstTask to push or pull data to/from the
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* peer pads. Most source elements start a #GstTask to push data. In some cases
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* a demuxer element can start a #GstTask to pull data from a peer element. This
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* is typically done when the demuxer can perform random access on the upstream
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* peer element for improved performance.
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*
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* Although convenience functions exist on #GstPad to start/pause/stop tasks, it
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* might sometimes be needed to create a #GstTask manually if it is not related to
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* a #GstPad.
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*
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* Before the #GstTask can be run, it needs a #GStaticRecMutex that can be set with
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* gst_task_set_lock().
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*
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* The task can be started, paused and stopped with gst_task_start(), gst_task_pause()
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* and gst_task_stop() respectively or with the gst_task_set_state() function.
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*
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* A #GstTask will repeatedly call the #GstTaskFunction with the user data
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* that was provided when creating the task with gst_task_create(). While calling
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* the function it will acquire the provided lock. The provided lock is released
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* when the task pauses or stops.
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*
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* Stopping a task with gst_task_stop() will not immediately make sure the task is
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* not running anymore. Use gst_task_join() to make sure the task is completely
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* stopped and the thread is stopped.
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*
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* After creating a #GstTask, use gst_object_unref() to free its resources. This can
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* only be done it the task is not running anymore.
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*
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* Last reviewed on 2006-02-13 (0.10.4)
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*/
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#include "gst_private.h"
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#include "gstinfo.h"
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#include "gsttask.h"
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GST_DEBUG_CATEGORY_STATIC (task_debug);
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#define GST_CAT_DEFAULT (task_debug)
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#define GST_TASK_GET_PRIVATE(obj) \
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(G_TYPE_INSTANCE_GET_PRIVATE ((obj), GST_TYPE_TASK, GstTaskPrivate))
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struct _GstTaskPrivate
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{
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/* callbacks for managing the thread of this task */
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GstTaskThreadCallbacks thr_callbacks;
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gpointer thr_user_data;
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GDestroyNotify thr_notify;
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gboolean prio_set;
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GThreadPriority priority;
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/* configured pool */
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GstTaskPool *pool;
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/* remember the pool and id that is currently running. */
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gpointer id;
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GstTaskPool *pool_id;
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};
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static void gst_task_class_init (GstTaskClass * klass);
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static void gst_task_init (GstTask * task);
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static void gst_task_finalize (GObject * object);
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static void gst_task_func (GstTask * task);
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static GStaticMutex pool_lock = G_STATIC_MUTEX_INIT;
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#define _do_init \
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{ \
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GST_DEBUG_CATEGORY_INIT (task_debug, "task", 0, "Processing tasks"); \
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}
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G_DEFINE_TYPE_WITH_CODE (GstTask, gst_task, GST_TYPE_OBJECT, _do_init);
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static void
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init_klass_pool (GstTaskClass * klass)
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{
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g_static_mutex_lock (&pool_lock);
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if (klass->pool) {
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gst_task_pool_cleanup (klass->pool);
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gst_object_unref (klass->pool);
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}
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klass->pool = gst_task_pool_new ();
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gst_task_pool_prepare (klass->pool, NULL);
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g_static_mutex_unlock (&pool_lock);
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}
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static void
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gst_task_class_init (GstTaskClass * klass)
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{
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GObjectClass *gobject_class;
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gobject_class = (GObjectClass *) klass;
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g_type_class_add_private (klass, sizeof (GstTaskPrivate));
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gobject_class->finalize = GST_DEBUG_FUNCPTR (gst_task_finalize);
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init_klass_pool (klass);
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}
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static void
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gst_task_init (GstTask * task)
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{
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GstTaskClass *klass;
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klass = GST_TASK_GET_CLASS (task);
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task->priv = GST_TASK_GET_PRIVATE (task);
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task->running = FALSE;
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task->abidata.ABI.thread = NULL;
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task->lock = NULL;
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task->cond = g_cond_new ();
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task->state = GST_TASK_STOPPED;
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task->priv->prio_set = FALSE;
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/* use the default klass pool for this task, users can
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* override this later */
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g_static_mutex_lock (&pool_lock);
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task->priv->pool = gst_object_ref (klass->pool);
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g_static_mutex_unlock (&pool_lock);
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}
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static void
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gst_task_finalize (GObject * object)
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{
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GstTask *task = GST_TASK (object);
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GstTaskPrivate *priv = task->priv;
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GST_DEBUG ("task %p finalize", task);
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if (priv->thr_notify)
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priv->thr_notify (priv->thr_user_data);
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priv->thr_notify = NULL;
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priv->thr_user_data = NULL;
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gst_object_unref (priv->pool);
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/* task thread cannot be running here since it holds a ref
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* to the task so that the finalize could not have happened */
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g_cond_free (task->cond);
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task->cond = NULL;
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G_OBJECT_CLASS (gst_task_parent_class)->finalize (object);
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}
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static void
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gst_task_func (GstTask * task)
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{
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GStaticRecMutex *lock;
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GThread *tself;
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GstTaskPrivate *priv;
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priv = task->priv;
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tself = g_thread_self ();
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GST_DEBUG ("Entering task %p, thread %p", task, tself);
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/* we have to grab the lock to get the mutex. We also
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* mark our state running so that nobody can mess with
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* the mutex. */
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GST_OBJECT_LOCK (task);
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if (task->state == GST_TASK_STOPPED)
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goto exit;
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lock = GST_TASK_GET_LOCK (task);
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if (G_UNLIKELY (lock == NULL))
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goto no_lock;
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task->abidata.ABI.thread = tself;
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/* only update the priority when it was changed */
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if (priv->prio_set)
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g_thread_set_priority (tself, priv->priority);
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GST_OBJECT_UNLOCK (task);
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/* fire the enter_thread callback when we need to */
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if (priv->thr_callbacks.enter_thread)
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priv->thr_callbacks.enter_thread (task, tself, priv->thr_user_data);
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/* locking order is TASK_LOCK, LOCK */
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g_static_rec_mutex_lock (lock);
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GST_OBJECT_LOCK (task);
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while (G_LIKELY (task->state != GST_TASK_STOPPED)) {
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while (G_UNLIKELY (task->state == GST_TASK_PAUSED)) {
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gint t;
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t = g_static_rec_mutex_unlock_full (lock);
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if (t <= 0) {
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g_warning ("wrong STREAM_LOCK count %d", t);
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}
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GST_TASK_SIGNAL (task);
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GST_TASK_WAIT (task);
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GST_OBJECT_UNLOCK (task);
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/* locking order.. */
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if (t > 0)
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g_static_rec_mutex_lock_full (lock, t);
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GST_OBJECT_LOCK (task);
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if (G_UNLIKELY (task->state == GST_TASK_STOPPED))
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goto done;
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}
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GST_OBJECT_UNLOCK (task);
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task->func (task->data);
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GST_OBJECT_LOCK (task);
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}
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done:
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GST_OBJECT_UNLOCK (task);
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g_static_rec_mutex_unlock (lock);
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GST_OBJECT_LOCK (task);
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task->abidata.ABI.thread = NULL;
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exit:
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if (priv->thr_callbacks.leave_thread) {
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/* fire the leave_thread callback when we need to. We need to do this before
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* we signal the task and with the task lock released. */
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GST_OBJECT_UNLOCK (task);
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priv->thr_callbacks.leave_thread (task, tself, priv->thr_user_data);
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GST_OBJECT_LOCK (task);
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} else {
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/* restore normal priority when releasing back into the pool, we will not
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* touch the priority when a custom callback has been installed. */
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g_thread_set_priority (tself, G_THREAD_PRIORITY_NORMAL);
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}
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/* now we allow messing with the lock again by setting the running flag to
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* FALSE. Together with the SIGNAL this is the sign for the _join() to
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* complete.
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* Note that we still have not dropped the final ref on the task. We could
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* check here if there is a pending join() going on and drop the last ref
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* before releasing the lock as we can be sure that a ref is held by the
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* caller of the join(). */
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task->running = FALSE;
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GST_TASK_SIGNAL (task);
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GST_OBJECT_UNLOCK (task);
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GST_DEBUG ("Exit task %p, thread %p", task, g_thread_self ());
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gst_object_unref (task);
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return;
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no_lock:
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{
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g_warning ("starting task without a lock");
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goto exit;
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}
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}
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/**
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* gst_task_cleanup_all:
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*
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* Wait for all tasks to be stopped. This is mainly used internally
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* to ensure proper cleanup of internal data structures in test suites.
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*
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* MT safe.
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*/
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void
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gst_task_cleanup_all (void)
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{
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GstTaskClass *klass;
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if ((klass = g_type_class_peek (GST_TYPE_TASK))) {
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init_klass_pool (klass);
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}
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}
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/**
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* gst_task_create:
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* @func: The #GstTaskFunction to use
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* @data: User data to pass to @func
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*
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* Create a new Task that will repeatedly call the provided @func
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* with @data as a parameter. Typically the task will run in
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* a new thread.
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*
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* The function cannot be changed after the task has been created. You
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* must create a new #GstTask to change the function.
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*
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* This function will not yet create and start a thread. Use gst_task_start() or
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* gst_task_pause() to create and start the GThread.
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*
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* Before the task can be used, a #GStaticRecMutex must be configured using the
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* gst_task_set_lock() function. This lock will always be acquired while
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* @func is called.
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*
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* Returns: A new #GstTask.
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*
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* MT safe.
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*/
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GstTask *
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gst_task_create (GstTaskFunction func, gpointer data)
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{
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GstTask *task;
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task = g_object_new (GST_TYPE_TASK, NULL);
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task->func = func;
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task->data = data;
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GST_DEBUG ("Created task %p", task);
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return task;
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}
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/**
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* gst_task_set_lock:
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* @task: The #GstTask to use
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* @mutex: The #GMutex to use
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*
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* Set the mutex used by the task. The mutex will be acquired before
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* calling the #GstTaskFunction.
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*
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* This function has to be called before calling gst_task_pause() or
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* gst_task_start().
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*
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* MT safe.
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*/
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void
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gst_task_set_lock (GstTask * task, GStaticRecMutex * mutex)
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{
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GST_OBJECT_LOCK (task);
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if (G_UNLIKELY (task->running))
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goto is_running;
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GST_TASK_GET_LOCK (task) = mutex;
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GST_OBJECT_UNLOCK (task);
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return;
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/* ERRORS */
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is_running:
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{
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GST_OBJECT_UNLOCK (task);
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g_warning ("cannot call set_lock on a running task");
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}
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}
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/**
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* gst_task_set_priority:
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* @task: a #GstTask
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* @priority: a new priority for @task
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*
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* Changes the priority of @task to @priority.
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*
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* Note: try not to depend on task priorities.
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*
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* MT safe.
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*
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* Since: 0.10.24
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*/
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void
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gst_task_set_priority (GstTask * task, GThreadPriority priority)
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{
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GstTaskPrivate *priv;
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GThread *thread;
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g_return_if_fail (GST_IS_TASK (task));
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priv = task->priv;
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GST_OBJECT_LOCK (task);
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priv->prio_set = TRUE;
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priv->priority = priority;
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thread = task->abidata.ABI.thread;
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if (thread != NULL) {
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/* if this task already has a thread, we can configure the priority right
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* away, else we do that when we assign a thread to the task. */
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g_thread_set_priority (thread, priority);
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}
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GST_OBJECT_UNLOCK (task);
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}
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/**
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* gst_task_get_pool:
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* @task: a #GstTask
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*
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* Get the #GstTaskPool that this task will use for its streaming
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* threads.
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*
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* MT safe.
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*
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* Returns: the #GstTaskPool used by @task. gst_object_unref()
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* after usage.
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*
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* Since: 0.10.24
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*/
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GstTaskPool *
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gst_task_get_pool (GstTask * task)
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{
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GstTaskPool *result;
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GstTaskPrivate *priv;
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g_return_val_if_fail (GST_IS_TASK (task), NULL);
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priv = task->priv;
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GST_OBJECT_LOCK (task);
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result = gst_object_ref (priv->pool);
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GST_OBJECT_UNLOCK (task);
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return result;
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}
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/**
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* gst_task_set_pool:
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* @task: a #GstTask
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* @pool: a #GstTaskPool
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*
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* Set @pool as the new GstTaskPool for @task. Any new streaming threads that
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* will be created by @task will now use @pool.
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*
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* MT safe.
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*
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* Since: 0.10.24
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*/
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void
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gst_task_set_pool (GstTask * task, GstTaskPool * pool)
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{
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GstTaskPool *old;
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GstTaskPrivate *priv;
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g_return_if_fail (GST_IS_TASK (task));
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g_return_if_fail (GST_IS_TASK_POOL (pool));
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priv = task->priv;
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GST_OBJECT_LOCK (task);
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if (priv->pool != pool) {
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old = priv->pool;
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priv->pool = gst_object_ref (pool);
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} else
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old = NULL;
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GST_OBJECT_UNLOCK (task);
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if (old)
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gst_object_unref (old);
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}
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/**
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* gst_task_set_thread_callbacks:
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* @task: The #GstTask to use
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* @callbacks: a #GstTaskThreadCallbacks pointer
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* @user_data: user data passed to the callbacks
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* @notify: called when @user_data is no longer referenced
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*
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* Set callbacks which will be executed when a new thread is needed, the thread
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* function is entered and left and when the thread is joined.
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*
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* By default a thread for @task will be created from a default thread pool.
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*
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* Objects can use custom GThreads or can perform additional configuration of
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* the threads (such as changing the thread priority) by installing callbacks.
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*
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* MT safe.
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*
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* Since: 0.10.24
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*/
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void
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gst_task_set_thread_callbacks (GstTask * task,
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GstTaskThreadCallbacks * callbacks, gpointer user_data,
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GDestroyNotify notify)
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{
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GDestroyNotify old_notify;
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g_return_if_fail (task != NULL);
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g_return_if_fail (GST_IS_TASK (task));
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g_return_if_fail (callbacks != NULL);
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GST_OBJECT_LOCK (task);
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old_notify = task->priv->thr_notify;
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if (old_notify) {
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gpointer old_data;
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old_data = task->priv->thr_user_data;
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task->priv->thr_user_data = NULL;
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task->priv->thr_notify = NULL;
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GST_OBJECT_UNLOCK (task);
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old_notify (old_data);
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GST_OBJECT_LOCK (task);
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}
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task->priv->thr_callbacks = *callbacks;
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task->priv->thr_user_data = user_data;
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task->priv->thr_notify = notify;
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GST_OBJECT_UNLOCK (task);
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}
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/**
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* gst_task_get_state:
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* @task: The #GstTask to query
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*
|
|
* Get the current state of the task.
|
|
*
|
|
* Returns: The #GstTaskState of the task
|
|
*
|
|
* MT safe.
|
|
*/
|
|
GstTaskState
|
|
gst_task_get_state (GstTask * task)
|
|
{
|
|
GstTaskState result;
|
|
|
|
g_return_val_if_fail (GST_IS_TASK (task), GST_TASK_STOPPED);
|
|
|
|
GST_OBJECT_LOCK (task);
|
|
result = task->state;
|
|
GST_OBJECT_UNLOCK (task);
|
|
|
|
return result;
|
|
}
|
|
|
|
/* make sure the task is running and start a thread if it's not.
|
|
* This function must be called with the task LOCK. */
|
|
static gboolean
|
|
start_task (GstTask * task)
|
|
{
|
|
gboolean res = TRUE;
|
|
GError *error = NULL;
|
|
GstTaskPrivate *priv;
|
|
|
|
priv = task->priv;
|
|
|
|
/* new task, We ref before so that it remains alive while
|
|
* the thread is running. */
|
|
gst_object_ref (task);
|
|
/* mark task as running so that a join will wait until we schedule
|
|
* and exit the task function. */
|
|
task->running = TRUE;
|
|
|
|
/* push on the thread pool, we remember the original pool because the user
|
|
* could change it later on and then we join to the wrong pool. */
|
|
priv->pool_id = gst_object_ref (priv->pool);
|
|
priv->id =
|
|
gst_task_pool_push (priv->pool_id, (GstTaskPoolFunction) gst_task_func,
|
|
task, &error);
|
|
|
|
if (error != NULL) {
|
|
g_warning ("failed to create thread: %s", error->message);
|
|
g_error_free (error);
|
|
res = FALSE;
|
|
}
|
|
return res;
|
|
}
|
|
|
|
|
|
/**
|
|
* gst_task_set_state:
|
|
* @task: a #GstTask
|
|
* @state: the new task state
|
|
*
|
|
* Sets the state of @task to @state.
|
|
*
|
|
* The @task must have a lock associated with it using
|
|
* gst_task_set_lock() when going to GST_TASK_STARTED or GST_TASK_PAUSED or
|
|
* this function will return %FALSE.
|
|
*
|
|
* MT safe.
|
|
*
|
|
* Returns: %TRUE if the state could be changed.
|
|
*
|
|
* Since: 0.10.24
|
|
*/
|
|
gboolean
|
|
gst_task_set_state (GstTask * task, GstTaskState state)
|
|
{
|
|
GstTaskState old;
|
|
gboolean res = TRUE;
|
|
|
|
g_return_val_if_fail (GST_IS_TASK (task), FALSE);
|
|
|
|
GST_DEBUG_OBJECT (task, "Changing task %p to state %d", task, state);
|
|
|
|
GST_OBJECT_LOCK (task);
|
|
if (state != GST_TASK_STOPPED)
|
|
if (G_UNLIKELY (GST_TASK_GET_LOCK (task) == NULL))
|
|
goto no_lock;
|
|
|
|
/* if the state changed, do our thing */
|
|
old = task->state;
|
|
if (old != state) {
|
|
task->state = state;
|
|
switch (old) {
|
|
case GST_TASK_STOPPED:
|
|
/* If the task already has a thread scheduled we don't have to do
|
|
* anything. */
|
|
if (G_UNLIKELY (!task->running))
|
|
res = start_task (task);
|
|
break;
|
|
case GST_TASK_PAUSED:
|
|
/* when we are paused, signal to go to the new state */
|
|
GST_TASK_SIGNAL (task);
|
|
break;
|
|
case GST_TASK_STARTED:
|
|
/* if we were started, we'll go to the new state after the next
|
|
* iteration. */
|
|
break;
|
|
}
|
|
}
|
|
GST_OBJECT_UNLOCK (task);
|
|
|
|
return res;
|
|
|
|
/* ERRORS */
|
|
no_lock:
|
|
{
|
|
GST_WARNING_OBJECT (task, "state %d set on task without a lock", state);
|
|
GST_OBJECT_UNLOCK (task);
|
|
g_warning ("task without a lock can't be set to state %d", state);
|
|
return FALSE;
|
|
}
|
|
}
|
|
|
|
/**
|
|
* gst_task_start:
|
|
* @task: The #GstTask to start
|
|
*
|
|
* Starts @task. The @task must have a lock associated with it using
|
|
* gst_task_set_lock() or this function will return %FALSE.
|
|
*
|
|
* Returns: %TRUE if the task could be started.
|
|
*
|
|
* MT safe.
|
|
*/
|
|
gboolean
|
|
gst_task_start (GstTask * task)
|
|
{
|
|
return gst_task_set_state (task, GST_TASK_STARTED);
|
|
}
|
|
|
|
/**
|
|
* gst_task_stop:
|
|
* @task: The #GstTask to stop
|
|
*
|
|
* Stops @task. This method merely schedules the task to stop and
|
|
* will not wait for the task to have completely stopped. Use
|
|
* gst_task_join() to stop and wait for completion.
|
|
*
|
|
* Returns: %TRUE if the task could be stopped.
|
|
*
|
|
* MT safe.
|
|
*/
|
|
gboolean
|
|
gst_task_stop (GstTask * task)
|
|
{
|
|
return gst_task_set_state (task, GST_TASK_STOPPED);
|
|
}
|
|
|
|
/**
|
|
* gst_task_pause:
|
|
* @task: The #GstTask to pause
|
|
*
|
|
* Pauses @task. This method can also be called on a task in the
|
|
* stopped state, in which case a thread will be started and will remain
|
|
* in the paused state. This function does not wait for the task to complete
|
|
* the paused state.
|
|
*
|
|
* Returns: %TRUE if the task could be paused.
|
|
*
|
|
* MT safe.
|
|
*/
|
|
gboolean
|
|
gst_task_pause (GstTask * task)
|
|
{
|
|
return gst_task_set_state (task, GST_TASK_PAUSED);
|
|
}
|
|
|
|
/**
|
|
* gst_task_join:
|
|
* @task: The #GstTask to join
|
|
*
|
|
* Joins @task. After this call, it is safe to unref the task
|
|
* and clean up the lock set with gst_task_set_lock().
|
|
*
|
|
* The task will automatically be stopped with this call.
|
|
*
|
|
* This function cannot be called from within a task function as this
|
|
* would cause a deadlock. The function will detect this and print a
|
|
* g_warning.
|
|
*
|
|
* Returns: %TRUE if the task could be joined.
|
|
*
|
|
* MT safe.
|
|
*/
|
|
gboolean
|
|
gst_task_join (GstTask * task)
|
|
{
|
|
GThread *tself;
|
|
GstTaskPrivate *priv;
|
|
gpointer id;
|
|
GstTaskPool *pool = NULL;
|
|
|
|
priv = task->priv;
|
|
|
|
g_return_val_if_fail (GST_IS_TASK (task), FALSE);
|
|
|
|
tself = g_thread_self ();
|
|
|
|
GST_DEBUG_OBJECT (task, "Joining task %p, thread %p", task, tself);
|
|
|
|
/* we don't use a real thread join here because we are using
|
|
* thread pools */
|
|
GST_OBJECT_LOCK (task);
|
|
if (G_UNLIKELY (tself == task->abidata.ABI.thread))
|
|
goto joining_self;
|
|
task->state = GST_TASK_STOPPED;
|
|
/* signal the state change for when it was blocked in PAUSED. */
|
|
GST_TASK_SIGNAL (task);
|
|
/* we set the running flag when pushing the task on the thread pool.
|
|
* This means that the task function might not be called when we try
|
|
* to join it here. */
|
|
while (G_LIKELY (task->running))
|
|
GST_TASK_WAIT (task);
|
|
/* clean the thread */
|
|
task->abidata.ABI.thread = NULL;
|
|
/* get the id and pool to join */
|
|
pool = priv->pool_id;
|
|
id = priv->id;
|
|
priv->pool_id = NULL;
|
|
priv->id = NULL;
|
|
GST_OBJECT_UNLOCK (task);
|
|
|
|
if (pool) {
|
|
if (id)
|
|
gst_task_pool_join (pool, id);
|
|
gst_object_unref (pool);
|
|
}
|
|
|
|
GST_DEBUG_OBJECT (task, "Joined task %p", task);
|
|
|
|
return TRUE;
|
|
|
|
/* ERRORS */
|
|
joining_self:
|
|
{
|
|
GST_WARNING_OBJECT (task, "trying to join task from its thread");
|
|
GST_OBJECT_UNLOCK (task);
|
|
g_warning ("\nTrying to join task %p from its thread would deadlock.\n"
|
|
"You cannot change the state of an element from its streaming\n"
|
|
"thread. Use g_idle_add() or post a GstMessage on the bus to\n"
|
|
"schedule the state change from the main thread.\n", task);
|
|
return FALSE;
|
|
}
|
|
}
|