Gst::Task Class Reference

Gst::Task — Abstraction of GStreamer streaming threads. More...

#include <task.h>

Inheritance diagram for Gst::Task:

Gst::Object

List of all members.

Public Types

typedef sigc::slot<void> SlotTask
 For example, void on_do_task();.

Public Member Functions

virtual ~Task ()
GstTask* gobj ()
 Provides access to the underlying C GObject.
const GstTask* gobj () const
 Provides access to the underlying C GObject.
GstTask* gobj_copy ()
 Provides access to the underlying C instance. The caller is responsible for unrefing it. Use when directly setting fields in structs.
TaskState get_state ()
 Get the current state of the task.
bool join ()
 Joins task.
bool pause ()
 Pauses task.
void set_lock (Glib::StaticRecMutex& mutex)
 Set the mutex used by the task.
bool start ()
 Starts task.
bool stop ()
 Stops task.

Static Public Member Functions

static Glib::RefPtr<Taskcreate (const SlotTask& task_slot)
 Create a new Gst::Task that will repeadedly call the provided slot as a parameter.
static void cleanup_all ()
 Wait for all tasks to be stopped.

Protected Member Functions

 Task (const SlotTask& task_slot)

Related Functions

(Note that these are not member functions.)

Glib::RefPtr<Gst::Taskwrap (GstTask* object, bool take_copy=false)
 A Glib::wrap() method for this object.


Detailed Description

Gst::Task — Abstraction of GStreamer streaming threads.

Gst::Task is used by Gst::Element and Gst::Pad to provide the data passing threads in a Gst::Pipeline.

A Gst::Pad will typically start a Gst::Task to push or pull data to/from the peer pads. Most source elements start a Gst::Task to push data. In some cases a demuxer element can start a Gst::Task 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 Gst::Pad to start/pause/stop tasks, it might sometimes be needed to create a Gst::Task manually if it is not related to a Gst::Pad.

Before the Gst::Task can be run, it needs a Glib::StaticRecMutex that can be set with set_lock().

The task can be started, paused and stopped with start(), pause() and stop() respectively.

A Gst::Task will repeadedly call the Gst::Task::SlotTask that was provided when creating the task with create(). Before calling the function it will acquire the provided lock.

Stopping a task with stop() will not immediatly make sure the task is not running anymore. Use join() to make sure the task is completely stopped and the thread is stopped.

Last reviewed on 2006-02-13 (0.10.4)


Member Typedef Documentation

typedef sigc::slot<void> Gst::Task::SlotTask

For example, void on_do_task();.


Constructor & Destructor Documentation

virtual Gst::Task::~Task (  )  [virtual]

Gst::Task::Task ( const SlotTask task_slot  )  [protected]


Member Function Documentation

static void Gst::Task::cleanup_all (  )  [static]

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.

static Glib::RefPtr<Task> Gst::Task::create ( const SlotTask task_slot  )  [static]

Create a new Gst::Task that will repeadedly call the provided slot as a parameter.

Typically the task will run in a new thread.

The slot cannot be changed after the task has been created. You must create a new Gst::Task to change the slot.

Parameters:
task_slot The Gst::Task::SlotTask to use.
Returns:
A new Gst::Task. MT safe.

TaskState Gst::Task::get_state (  ) 

Get the current state of the task.

Returns:
The Gst::TaskState of the task
MT safe.

const GstTask* Gst::Task::gobj (  )  const [inline]

Provides access to the underlying C GObject.

Reimplemented from Gst::Object.

GstTask* Gst::Task::gobj (  )  [inline]

Provides access to the underlying C GObject.

Reimplemented from Gst::Object.

GstTask* Gst::Task::gobj_copy (  ) 

Provides access to the underlying C instance. The caller is responsible for unrefing it. Use when directly setting fields in structs.

Reimplemented from Gst::Object.

bool Gst::Task::join (  ) 

Joins task.

After this call, it is safe to unref the task and clean up the lock set with 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.

bool Gst::Task::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.

void Gst::Task::set_lock ( Glib::StaticRecMutex &  mutex  ) 

Set the mutex used by the task.

The mutex will be acquired before calling the Gst::TaskFunction.

This function has to be called before calling pause() or start().

MT safe.

Parameters:
mutex The Mutex to use.

bool Gst::Task::start (  ) 

Starts task.

The task must have a lock associated with it using set_lock() or this function will return false.

Returns:
true if the task could be started.
MT safe.

bool Gst::Task::stop (  ) 

Stops task.

This method merely schedules the task to stop and will not wait for the task to have completely stopped. Use join() to stop and wait for completion.

Returns:
true if the task could be stopped.
MT safe.


Friends And Related Function Documentation

Glib::RefPtr<Gst::Task> wrap ( GstTask *  object,
bool  take_copy = false 
) [related]

A Glib::wrap() method for this object.

Parameters:
object The C instance.
take_copy False if the result should take ownership of the C instance. True if it should take a new copy or ref.
Returns:
A C++ instance that wraps this C instance.


The documentation for this class was generated from the following file:

Generated on Thu Jan 15 09:33:13 2009 for gstreamermm by  doxygen 1.5.7.1