/* GStreamer

 * Copyright (C) 1999,2000 Erik Walthinsen <omega@cse.ogi.edu>

 *                    2005 Wim Taymans <wim@fluendo.com>

 *

 * gsttask.c: Streaming tasks

 *

 * This library is free software; you can redistribute it and/or

 * modify it under the terms of the GNU Library General Public

 * License as published by the Free Software Foundation; either

 * version 2 of the License, or (at your option) any later version.

 *

 * This library is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

 * Library General Public License for more details.

 *

 * You should have received a copy of the GNU Library General Public

 * License along with this library; if not, write to the

 * Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,

 * Boston, MA 02110-1301, USA.

 */

/**

 * SECTION:gsttask

 * @title: GstTask

 * @short_description: Abstraction of GStreamer streaming threads.

 * @see_also: #GstElement, #GstPad

 *

 * #GstTask is used by #GstElement and #GstPad to provide the data passing

 * threads in a #GstPipeline.

 *

 * A #GstPad will typically start a #GstTask to push or pull data to/from the

 * peer pads. Most source elements start a #GstTask to push data. In some cases

 * a demuxer element can start a #GstTask to pull data from a peer element. This

 * is typically done when the demuxer can perform random access on the upstream

 * peer element for improved performance.

 *

 * Although convenience functions exist on #GstPad to start/pause/stop tasks, it

 * might sometimes be needed to create a #GstTask manually if it is not related to

 * a #GstPad.

 *

 * Before the #GstTask can be run, it needs a #GRecMutex that can be set with

 * gst_task_set_lock().

 *

 * The task can be started, paused and stopped with gst_task_start(), gst_task_pause()

 * and gst_task_stop() respectively or with the gst_task_set_state() function.

 *

 * A #GstTask will repeatedly call the #GstTaskFunction with the user data

 * that was provided when creating the task with gst_task_new(). While calling

 * the function it will acquire the provided lock. The provided lock is released

 * when the task pauses or stops.

 *

 * Stopping a task with gst_task_stop() will not immediately make sure the task is

 * not running anymore. Use gst_task_join() to make sure the task is completely

 * stopped and the thread is stopped.

 *

 * After creating a #GstTask, use gst_object_unref() to free its resources. This can

 * only be done when the task is not running anymore.

 *

 * Task functions can send a #GstMessage to send out-of-band data to the

 * application. The application can receive messages from the #GstBus in its

 * mainloop.

 *

 * For debugging purposes, the task will configure its object name as the thread

 * name on Linux. Please note that the object name should be configured before the

 * task is started; changing the object name after the task has been started, has

 * no effect on the thread name.

 */

#include "gst_private.h"

#include "gstinfo.h"

#include "gsttask.h"

#include "glib-compat-private.h"

#include <stdio.h>

#ifdef HAVE_SYS_PRCTL_H

#include <sys/prctl.h>

#endif

#ifdef HAVE_PTHREAD_SETNAME_NP_WITHOUT_TID

#include <pthread.h>

#endif

GST_DEBUG_CATEGORY_STATIC (task_debug);

#define GST_CAT_DEFAULT (task_debug)

#define SET_TASK_STATE(t,s) (g_atomic_int_set (&GST_TASK_STATE(t), (s)))

#define GET_TASK_STATE(t)   ((GstTaskState) g_atomic_int_get (&GST_TASK_STATE(t)))

static const char *

task_state_to_string (GstTaskState state)

{

  switch (state) {

    case GST_TASK_STARTED:

      return "started";

    case GST_TASK_PAUSED:

      return "paused";

    case GST_TASK_STOPPED:

      return "stopped";

    default:

      return "(unknown)";

  }

}

struct _GstTaskPrivate

{

  /* callbacks for managing the thread of this task */

  GstTaskThreadFunc enter_func;

  gpointer enter_user_data;

  GDestroyNotify enter_notify;

  GstTaskThreadFunc leave_func;

  gpointer leave_user_data;

  GDestroyNotify leave_notify;

  /* configured pool */

  GstTaskPool *pool;

  /* remember the pool and id that is currently running. */

  gpointer id;

  GstTaskPool *pool_id;

  /* we're currently inside gst_task_join() */

  gboolean joining;

};

#ifdef _MSC_VER

#define WIN32_LEAN_AND_MEAN

#include <windows.h>

typedef HRESULT (WINAPI * pSetThreadDescription) (HANDLE hThread,

    PCWSTR lpThreadDescription);

static pSetThreadDescription SetThreadDescriptionFunc = NULL;

HMODULE kernel32_module = NULL;

struct _THREADNAME_INFO

{

  DWORD dwType;                 // must be 0x1000

  LPCSTR szName;                // pointer to name (in user addr space)

  DWORD dwThreadID;             // thread ID (-1=caller thread)

  DWORD dwFlags;                // reserved for future use, must be zero

};

typedef struct _THREADNAME_INFO THREADNAME_INFO;

static void

SetThreadName (DWORD dwThreadID, LPCSTR szThreadName)

{

  THREADNAME_INFO info;

  info.dwType = 0x1000;

  info.szName = szThreadName;

  info.dwThreadID = dwThreadID;

  info.dwFlags = 0;

  __try {

    RaiseException (0x406D1388, 0, sizeof (info) / sizeof (DWORD),

        (const ULONG_PTR *) &info);

  }

  __except (EXCEPTION_CONTINUE_EXECUTION) {

  }

}

static gboolean

gst_task_win32_load_library (void)

{

  /* FIXME: Add support for UWP app */

#if WINAPI_FAMILY_PARTITION(WINAPI_PARTITION_DESKTOP)

  static gsize _init_once = 0;

  if (g_once_init_enter (&_init_once)) {

    kernel32_module = LoadLibraryW (L"kernel32.dll");

    if (kernel32_module) {

      SetThreadDescriptionFunc =

          (pSetThreadDescription) GetProcAddress (kernel32_module,

          "SetThreadDescription");

      if (!SetThreadDescriptionFunc)

        FreeLibrary (kernel32_module);

    }

    g_once_init_leave (&_init_once, 1);

  }

#endif

  return !!SetThreadDescriptionFunc;

}

static gboolean

gst_task_win32_set_thread_desc (const gchar * name)

{

  HRESULT hr;

  wchar_t *namew;

  if (!gst_task_win32_load_library () || !name)

    return FALSE;

  namew = g_utf8_to_utf16 (name, -1, NULL, NULL, NULL);

  if (!namew)

    return FALSE;

  hr = SetThreadDescriptionFunc (GetCurrentThread (), namew);

  g_free (namew);

  return SUCCEEDED (hr);

}

static void

gst_task_win32_set_thread_name (const gchar * name)

{

  /* Prefer SetThreadDescription over exception based way if available,

   * since thread description set by SetThreadDescription will be preserved

   * in dump file */

  if (!gst_task_win32_set_thread_desc (name))

    SetThreadName ((DWORD) - 1, name);

}

#endif

static void gst_task_finalize (GObject * object);

static void gst_task_func (GstTask * task);

static GMutex pool_lock;

static GstTaskPool *_global_task_pool = NULL;

#define _do_init \

{ \

  GST_DEBUG_CATEGORY_INIT (task_debug, "task", 0, "Processing tasks"); \

}

G_DEFINE_TYPE_WITH_CODE (GstTask, gst_task, GST_TYPE_OBJECT,

    G_ADD_PRIVATE (GstTask) _do_init);

/* Called with pool_lock */

static void

ensure_klass_pool (GstTaskClass * klass)

{

  if (G_UNLIKELY (_global_task_pool == NULL)) {

    _global_task_pool = gst_task_pool_new ();

    gst_task_pool_prepare (_global_task_pool, NULL);

    /* Classes are never destroyed so this ref will never be dropped */

    GST_OBJECT_FLAG_SET (_global_task_pool, GST_OBJECT_FLAG_MAY_BE_LEAKED);

  }

  klass->pool = _global_task_pool;

}

static void

gst_task_class_init (GstTaskClass * klass)

{

  GObjectClass *gobject_class;

  gobject_class = (GObjectClass *) klass;

  gobject_class->finalize = gst_task_finalize;

}

static void

gst_task_init (GstTask * task)

{

  GstTaskClass *klass;

  klass = GST_TASK_GET_CLASS (task);

  task->priv = gst_task_get_instance_private (task);

  task->priv->joining = FALSE;

  task->running = FALSE;

  task->thread = NULL;

  task->lock = NULL;

  g_cond_init (&task->cond);

  SET_TASK_STATE (task, GST_TASK_STOPPED);

  /* use the default klass pool for this task, users can

   * override this later */

  g_mutex_lock (&pool_lock);

  ensure_klass_pool (klass);

  task->priv->pool = gst_object_ref (klass->pool);

  g_mutex_unlock (&pool_lock);

}

static void

gst_task_finalize (GObject * object)

{

  GstTask *task = GST_TASK (object);

  GstTaskPrivate *priv = task->priv;

  GST_DEBUG ("task %p finalize", task);

  if (priv->enter_notify)

    priv->enter_notify (priv->enter_user_data);

  if (priv->leave_notify)

    priv->leave_notify (priv->leave_user_data);

  if (task->notify)

    task->notify (task->user_data);

  gst_object_unref (priv->pool);

  /* task thread cannot be running here since it holds a ref

   * to the task so that the finalize could not have happened */

  g_cond_clear (&task->cond);

  G_OBJECT_CLASS (gst_task_parent_class)->finalize (object);

}

/* should be called with the object LOCK */

static void

gst_task_configure_name (GstTask * task)

{

#if defined(HAVE_SYS_PRCTL_H) && defined(PR_SET_NAME)

  const gchar *name;

  gchar thread_name[17] = { 0, };

  GST_OBJECT_LOCK (task);

  name = GST_OBJECT_NAME (task);

  /* set the thread name to something easily identifiable */

  if (!snprintf (thread_name, 17, "%s", GST_STR_NULL (name))) {

    GST_DEBUG_OBJECT (task, "Could not create thread name for '%s'", name);

  } else {

    GST_DEBUG_OBJECT (task, "Setting thread name to '%s'", thread_name);

    if (prctl (PR_SET_NAME, (unsigned long int) thread_name, 0, 0, 0))

      GST_DEBUG_OBJECT (task, "Failed to set thread name");

  }

  GST_OBJECT_UNLOCK (task);

#elif defined(HAVE_PTHREAD_SETNAME_NP_WITHOUT_TID)

  const gchar *name;

  GST_OBJECT_LOCK (task);

  name = GST_OBJECT_NAME (task);

  /* set the thread name to something easily identifiable */

  GST_DEBUG_OBJECT (task, "Setting thread name to '%s'", name);

  if (pthread_setname_np (name))

    GST_DEBUG_OBJECT (task, "Failed to set thread name");

  GST_OBJECT_UNLOCK (task);

#elif defined (_MSC_VER)

  const gchar *name;

  name = GST_OBJECT_NAME (task);

  /* set the thread name to something easily identifiable */

  GST_DEBUG_OBJECT (task, "Setting thread name to '%s'", name);

  gst_task_win32_set_thread_name (name);

#endif

}

static void

gst_task_func (GstTask * task)

{

  GRecMutex *lock;

  GThread *tself;

  GstTaskPrivate *priv;

  gboolean joining;

  priv = task->priv;

  tself = g_thread_self ();

  GST_DEBUG ("Entering task %p, thread %p", task, tself);

  /* we have to grab the lock to get the mutex. We also

   * mark our state running so that nobody can mess with

   * the mutex. */

  GST_OBJECT_LOCK (task);

  if (GET_TASK_STATE (task) == GST_TASK_STOPPED)

    goto exit;

  lock = GST_TASK_GET_LOCK (task);

  if (G_UNLIKELY (lock == NULL))

    goto no_lock;

  task->thread = tself;

  GST_OBJECT_UNLOCK (task);

  /* fire the enter_func callback when we need to */

  if (priv->enter_func)

    priv->enter_func (task, tself, priv->enter_user_data);

  /* locking order is TASK_LOCK, LOCK */

  g_rec_mutex_lock (lock);

  /* configure the thread name now */

  gst_task_configure_name (task);

  while (G_LIKELY (GET_TASK_STATE (task) != GST_TASK_STOPPED)) {

    GST_OBJECT_LOCK (task);

    while (G_UNLIKELY (GST_TASK_STATE (task) == GST_TASK_PAUSED)) {

      g_rec_mutex_unlock (lock);

      GST_TASK_SIGNAL (task);

      GST_INFO_OBJECT (task, "Task going to paused");

      GST_TASK_WAIT (task);

      GST_INFO_OBJECT (task, "Task resume from paused");

      GST_OBJECT_UNLOCK (task);

      /* locking order.. */

      g_rec_mutex_lock (lock);

      GST_OBJECT_LOCK (task);

    }

    if (G_UNLIKELY (GET_TASK_STATE (task) == GST_TASK_STOPPED)) {

      GST_OBJECT_UNLOCK (task);

      break;

    } else {

      GST_OBJECT_UNLOCK (task);

    }

    task->func (task->user_data);

  }

  g_rec_mutex_unlock (lock);

  GST_OBJECT_LOCK (task);

  task->thread = NULL;

exit:

  if (priv->leave_func) {

    /* fire the leave_func callback when we need to. We need to do this before

     * we signal the task and with the task lock released. */

    GST_OBJECT_UNLOCK (task);

    priv->leave_func (task, tself, priv->leave_user_data);

    GST_OBJECT_LOCK (task);

  }

  /* now we allow messing with the lock again by setting the running flag to

   * %FALSE. Together with the SIGNAL this is the sign for the _join() to

   * complete. */

  task->running = FALSE;

  GST_TASK_SIGNAL (task);

  /* Someone called join() while we're exiting, so they are holding

   * a reference and we can drop ours already. This ensures that finalize() is

   * called when the joiner's reference is dropped. */

  joining = task->priv->joining;

  if (joining)

    gst_object_unref (task);

  GST_DEBUG ("Exit task %p, thread %p", task, g_thread_self ());

  GST_OBJECT_UNLOCK (task);

  if (!joining)

    gst_object_unref (task);

  return;

no_lock:

  {

    g_warning ("starting task without a lock");

    goto exit;

  }

}

/**

 * gst_task_cleanup_all:

 *

 * Wait for all tasks to be stopped. This is mainly used internally

 * to ensure proper cleanup of internal data structures in test suites.

 *

 * MT safe.

 */

void

gst_task_cleanup_all (void)

{

  GstTaskClass *klass;

  if ((klass = g_type_class_peek (GST_TYPE_TASK))) {

    if (klass->pool) {

      g_mutex_lock (&pool_lock);

      gst_task_pool_cleanup (klass->pool);

      gst_object_unref (klass->pool);

      klass->pool = NULL;

      _global_task_pool = NULL;

      g_mutex_unlock (&pool_lock);

    }

  }

  /* Clean up a GThreadPool associated with gst_*_async_call() if any */

  _priv_gst_thread_pool_cleanup ();

}

/**

 * gst_task_new:

 * @func: The #GstTaskFunction to use

 * @user_data: User data to pass to @func

 * @notify: the function to call when @user_data is no longer needed.

 *

 * Create a new Task that will repeatedly call the provided @func

 * with @user_data as a parameter. Typically the task will run in

 * a new thread.

 *

 * The function cannot be changed after the task has been created. You

 * must create a new #GstTask to change the function.

 *

 * This function will not yet create and start a thread. Use gst_task_start() or

 * gst_task_pause() to create and start the GThread.

 *

 * Before the task can be used, a #GRecMutex must be configured using the

 * gst_task_set_lock() function. This lock will always be acquired while

 * @func is called.

 *

 * Returns: (transfer full): A new #GstTask.

 *

 * MT safe.

 */

GstTask *

gst_task_new (GstTaskFunction func, gpointer user_data, GDestroyNotify notify)

{

  GstTask *task;

  g_return_val_if_fail (func != NULL, NULL);

  task = g_object_new (GST_TYPE_TASK, NULL);

  task->func = func;

  task->user_data = user_data;

  task->notify = notify;

  GST_DEBUG ("Created task %p", task);

  /* clear floating flag */

  gst_object_ref_sink (task);

  return task;

}

/**

 * gst_task_set_lock:

 * @task: The #GstTask to use

 * @mutex: The #GRecMutex to use

 *

 * Set the mutex used by the task. The mutex will be acquired before

 * calling the #GstTaskFunction.

 *

 * This function has to be called before calling gst_task_pause() or

 * gst_task_start().

 *

 * MT safe.

 */

void

gst_task_set_lock (GstTask * task, GRecMutex * mutex)

{

  g_return_if_fail (GST_IS_TASK (task));

  GST_OBJECT_LOCK (task);

  if (G_UNLIKELY (task->running))

    goto is_running;

  GST_INFO ("setting stream lock %p on task %p", mutex, task);

  GST_TASK_GET_LOCK (task) = mutex;

  GST_OBJECT_UNLOCK (task);

  return;

  /* ERRORS */

is_running:

  {

    GST_OBJECT_UNLOCK (task);

    g_warning ("cannot call set_lock on a running task");

  }

}

/**

 * gst_task_get_pool:

 * @task: a #GstTask

 *

 * Get the #GstTaskPool that this task will use for its streaming

 * threads.

 *

 * MT safe.

 *

 * Returns: (transfer full): the #GstTaskPool used by @task. gst_object_unref()

 * after usage.

 */

GstTaskPool *

gst_task_get_pool (GstTask * task)

{

  GstTaskPool *result;

  GstTaskPrivate *priv;

  g_return_val_if_fail (GST_IS_TASK (task), NULL);

  priv = task->priv;

  GST_OBJECT_LOCK (task);

  result = gst_object_ref (priv->pool);

  GST_OBJECT_UNLOCK (task);

  return result;

}

/**

 * gst_task_set_pool:

 * @task: a #GstTask

 * @pool: (transfer none): a #GstTaskPool

 *

 * Set @pool as the new GstTaskPool for @task. Any new streaming threads that

 * will be created by @task will now use @pool.

 *

 * MT safe.

 */

void

gst_task_set_pool (GstTask * task, GstTaskPool * pool)

{

  GstTaskPool *old;

  GstTaskPrivate *priv;

  g_return_if_fail (GST_IS_TASK (task));

  g_return_if_fail (GST_IS_TASK_POOL (pool));

  priv = task->priv;

  GST_OBJECT_LOCK (task);

  if (priv->pool != pool) {

    old = priv->pool;

    priv->pool = gst_object_ref (pool);

  } else

    old = NULL;

  GST_OBJECT_UNLOCK (task);

  if (old)

    gst_object_unref (old);

}

/**

 * gst_task_set_enter_callback:

 * @task: The #GstTask to use

 * @enter_func: (in): a #GstTaskThreadFunc

 * @user_data: user data passed to @enter_func

 * @notify: called when @user_data is no longer referenced

 *

 * Call @enter_func when the task function of @task is entered. @user_data will

 * be passed to @enter_func and @notify will be called when @user_data is no

 * longer referenced.

 */

void

gst_task_set_enter_callback (GstTask * task, GstTaskThreadFunc enter_func,

    gpointer user_data, GDestroyNotify notify)

{

  GDestroyNotify old_notify;

  g_return_if_fail (task != NULL);

  g_return_if_fail (GST_IS_TASK (task));

  GST_OBJECT_LOCK (task);

  if ((old_notify = task->priv->enter_notify)) {

    gpointer old_data = task->priv->enter_user_data;

    task->priv->enter_user_data = NULL;

    task->priv->enter_notify = NULL;

    GST_OBJECT_UNLOCK (task);

    old_notify (old_data);

    GST_OBJECT_LOCK (task);

  }

  task->priv->enter_func = enter_func;

  task->priv->enter_user_data = user_data;

  task->priv->enter_notify = notify;

  GST_OBJECT_UNLOCK (task);

}

/**

 * gst_task_set_leave_callback:

 * @task: The #GstTask to use

 * @leave_func: (in): a #GstTaskThreadFunc

 * @user_data: user data passed to @leave_func

 * @notify: called when @user_data is no longer referenced

 *

 * Call @leave_func when the task function of @task is left. @user_data will

 * be passed to @leave_func and @notify will be called when @user_data is no

 * longer referenced.

 */

void

gst_task_set_leave_callback (GstTask * task, GstTaskThreadFunc leave_func,

    gpointer user_data, GDestroyNotify notify)

{

  GDestroyNotify old_notify;

  g_return_if_fail (task != NULL);

  g_return_if_fail (GST_IS_TASK (task));

  GST_OBJECT_LOCK (task);

  if ((old_notify = task->priv->leave_notify)) {

    gpointer old_data = task->priv->leave_user_data;

    task->priv->leave_user_data = NULL;

    task->priv->leave_notify = NULL;

    GST_OBJECT_UNLOCK (task);

    old_notify (old_data);

    GST_OBJECT_LOCK (task);

  }

  task->priv->leave_func = leave_func;

  task->priv->leave_user_data = user_data;

  task->priv->leave_notify = notify;

  GST_OBJECT_UNLOCK (task);

}

/**

 * gst_task_get_state:

 * @task: The #GstTask to query

 *

 * 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);

  result = GET_TASK_STATE (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;

  task->priv->joining = FALSE;

  /* 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;

}

static inline gboolean

gst_task_set_state_unlocked (GstTask * task, GstTaskState state)

{

  GstTaskState old;

  gboolean res = TRUE;

  GST_DEBUG_OBJECT (task, "Changing task %p to state %s", task,

      task_state_to_string (state));

  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 = GET_TASK_STATE (task);

  if (old != state) {

    SET_TASK_STATE (task, 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;

    }

  }

  return res;

  /* ERRORS */

no_lock:

  {

    GST_WARNING_OBJECT (task, "state %s set on task without a lock",

        task_state_to_string (state));

    g_warning ("task without a lock can't be set to state %s",

        task_state_to_string (state));

    return FALSE;

  }

}

/**

 * 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.

 */

gboolean

gst_task_set_state (GstTask * task, GstTaskState state)

{

  gboolean res = TRUE;

  g_return_val_if_fail (GST_IS_TASK (task), FALSE);

  GST_OBJECT_LOCK (task);

  res = gst_task_set_state_unlocked (task, state);

  GST_OBJECT_UNLOCK (task);

  return res;

}

/**

 * 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_resume:

 * @task: The #GstTask to resume

 *

 * Resume @task in case it was paused. If the task was stopped, it will

 * remain in that state and this function will return %FALSE.

 *

 * Returns: %TRUE if the task could be resumed.

 *

 * MT safe.

 * Since: 1.18

 */

gboolean

gst_task_resume (GstTask * task)

{

  gboolean res = FALSE;

  g_return_val_if_fail (GST_IS_TASK (task), FALSE);

  GST_OBJECT_LOCK (task);

  if (GET_TASK_STATE (task) != GST_TASK_STOPPED)

    res = gst_task_set_state_unlocked (task, GST_TASK_STARTED);

  GST_OBJECT_UNLOCK (task);

  return res;

}

/**

 * 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;

  g_return_val_if_fail (GST_IS_TASK (task), FALSE);

  priv = task->priv;

  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->thread))

    goto joining_self;

  priv->joining = TRUE;

  SET_TASK_STATE (task, 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->thread = NULL;

  /* get the id and pool to join */

  pool = priv->pool_id;

  id = priv->id;

  priv->pool_id = NULL;

  priv->id = NULL;

  priv->joining = FALSE;

  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;

  }

}