A class representing GStreamer streaming threads. More...

#include <gstreamermm/task.h>

Inheritance diagram for Gst::Task:

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

typedef sigc::slot< void, const Glib::RefPtr< Gst::Task >&, Glib::Threads::Thread* >	TaskThreadSlot
	Bidirectional slot. More...

typedef TaskThreadSlot	SlotEnter
	For example, void on_enter(const Glib::RefPtr<Gst::Task>& task, Glib::Threads::Thread& thread);. More...

typedef TaskThreadSlot	SlotLeave
	For example, void on_leave(const Glib::RefPtr<Gst::Task>& task, Glib::Threads::Thread& thread);. More...

Public Member Functions
	Task (Task&& src) noexcept

Task&	operator= (Task&& src) noexcept

	~Task () noexcept override

GstTask*	gobj ()
	Provides access to the underlying C GObject. More...

const GstTask*	gobj () const
	Provides access to the underlying C GObject. More...

GstTask*	gobj_copy ()
	Provides access to the underlying C instance. The caller is responsible for unrefing it. Use when directly setting fields in structs. More...

void	set_lock (Glib::Threads::RecMutex& mutex)
	Set the mutex used by the task. More...

void	set_pool (const Glib::RefPtr< Gst::TaskPool >& pool)
	Set pool as the new GstTaskPool for task. More...

Glib::RefPtr< Gst::TaskPool >	get_pool ()
	Get the Gst::TaskPool that this task will use for its streaming threads. More...

Glib::RefPtr< const Gst::TaskPool >	get_pool () const
	Get the Gst::TaskPool that this task will use for its streaming threads. More...

void	set_enter_slot (const SlotEnter& enter_slot)
	Call enter_slot when the task function of task is entered. More...

void	set_leave_slot (const SlotLeave& leave_slot)
	Call leave_func when the task function of task is left. More...

TaskState	get_state () const
	Get the current state of the task. More...

void	set_state (Gst::TaskState state)
	Sets the state of task to state. More...

bool	pause ()
	Pauses task. More...

bool	start ()
	Starts task. More...

bool	stop ()
	Stops task. More...

bool	join ()
	Joins task. More...

Public Member Functions inherited from Gst::Object
	Object (Object&& src) noexcept

Object&	operator= (Object&& src) noexcept

	~Object () noexcept override

GstObject*	gobj ()
	Provides access to the underlying C GObject. More...

const GstObject*	gobj () const
	Provides access to the underlying C GObject. More...

GstObject*	gobj_copy ()
	Provides access to the underlying C instance. The caller is responsible for unrefing it. Use when directly setting fields in structs. More...

bool	is_element () const

bool	is_element_factory () const

bool	is_pad () const

bool	is_pad_template () const

bool	is_bin () const

guint32	get_flags () const
	Returns the entire set of flags for the object. More...

bool	set_name (const Glib::ustring& name)
	Sets the name of object, or gives object a guaranteed unique name (if name is `nullptr`). More...

Glib::ustring	get_name () const
	Returns a copy of the name of object. More...

bool	set_parent (const Glib::RefPtr< Gst::Object >& parent)
	Sets the parent of object to parent. More...

Glib::RefPtr< Gst::Object >	get_parent ()
	Returns the parent of object. More...

Glib::RefPtr< const Gst::Object >	get_parent () const
	Returns the parent of object. More...

void	unparent ()
	Clear the parent of object, removing the associated reference. More...

void	set_control_rate (Gst::ClockTime control_rate)
	Change the control-rate for this object. More...

Gst::ClockTime	get_control_rate () const
	Obtain the control-rate for this object. More...

Gst::ClockTime	suggest_next_sync () const
	Returns a suggestion for timestamps where buffers should be split to get best controller results. More...

bool	sync_values (Gst::ClockTime timestamp)
	Sets the properties of the object, according to the Gst::ControlSources that (maybe) handle them and for the given timestamp. More...

void	set_control_bindings_disabled (bool disabled)
	This function is used to disable all controlled properties of the object for some time, i.e. sync_values() will do nothing. More...

bool	has_asctive_control_bindings () const
	Check if the object has an active controlled properties. More...

bool	has_ancestor (const Glib::RefPtr< const Gst::Object >& ancestor) const
	Check if object has an ancestor ancestor somewhere up in the hierarchy. More...

bool	has_as_ancestor (const Glib::RefPtr< Gst::Object >& ancestor) const
	Check if object has an ancestor ancestor somewhere up in the hierarchy. More...

bool	has_as_parent (const Glib::RefPtr< Gst::Object >& parent) const
	Check if parent is the parent of object. More...

Glib::ustring	get_path_string ()
	Generates a string describing the path of object in the object hierarchy. More...

Glib::PropertyProxy< Glib::ustring >	property_name ()
	The name of the object. More...

Glib::PropertyProxy_ReadOnly< Glib::ustring >	property_name () const
	The name of the object. More...

Glib::PropertyProxy< Glib::RefPtr< Gst::Object > >	property_parent ()
	The parent of the object. More...

Glib::PropertyProxy_ReadOnly< Glib::RefPtr< Gst::Object > >	property_parent () const
	The parent of the object. More...

Glib::SignalProxy< void, const Glib::RefPtr< Gst::Object >&, GParamSpec*>	signal_deep_notify ()

int	get_refcount () const

Static Public Member Functions
static GType	get_type ()
	Get the GType for this class, for use with the underlying GObject type system. More...

static Glib::RefPtr< Task >	create (const SlotTask& task_slot)
	Create a new Gst::Task that will repeatedly call the provided slot as a parameter. More...

static void	cleanup_all ()
	Wait for all tasks to be stopped. More...

Static Public Member Functions inherited from Gst::Object
static GType	get_type ()
	Get the GType for this class, for use with the underlying GObject type system. More...

static bool	check_uniqueness (const Glib::ListHandle< const Gst::Object >& list, const Glib::ustring& name)
	Checks to see if there is any object named name in list. More...

Protected Member Functions
	Task (const SlotTask& task_slot)

Protected Member Functions inherited from Gst::Object
virtual void	on_deep_notify (const Glib::RefPtr< Gst::Object >& prop_object, GParamSpec* prop)
	This is a default handler for the signal signal_deep_notify(). More...

Related Functions
(Note that these are not member functions.)
Glib::RefPtr< Gst::Task >	wrap (GstTask* object, bool take_copy=false)
	A Glib::wrap() method for this object. More...

Related Functions inherited from Gst::Object
Glib::RefPtr< Gst::Object >	wrap (GstObject* object, bool take_copy=false)
	A Glib::wrap() method for this object. More...

Detailed Description

A class representing 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.

Task functions can send a Gst::Message to send out-of-band data to the application. The application can receive messages from the Gst::Bus 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.

Last reviewed on 2015-10-14 (1.5.2)

Member Typedef Documentation

◆ SlotEnter

typedef TaskThreadSlot Gst::Task::SlotEnter

For example, void on_enter(const Glib::RefPtr<Gst::Task>& task, Glib::Threads::Thread& thread);.

A thread is entered, this slot is called when the new thread enters its function.

◆ SlotLeave

typedef TaskThreadSlot Gst::Task::SlotLeave

For example, void on_leave(const Glib::RefPtr<Gst::Task>& task, Glib::Threads::Thread& thread);.

A thread is exiting, this is called when the thread is about to leave its function.

◆ SlotTask

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

For example, void on_do_task();.

◆ TaskThreadSlot

typedef sigc::slot<void, const Glib::RefPtr<Gst::Task>&, Glib::Threads::Thread*> Gst::Task::TaskThreadSlot

Bidirectional slot.

Constructor & Destructor Documentation

◆ Task() [1/2]

Gst::Task::Task ( Task&& src )

noexcept

◆ ~Task()

Gst::Task::~Task ( )

overridenoexcept

◆ Task() [2/2]

Gst::Task::Task ( const SlotTask& task_slot )

explicitprotected

Member Function Documentation

◆ cleanup_all()

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.

◆ create()

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

static

Create a new Gst::Task that will repeatedly 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.

◆ get_pool() [1/2]

Glib::RefPtr<Gst::TaskPool> Gst::Task::get_pool ( )

Get the Gst::TaskPool that this task will use for its streaming threads.

MT safe.

Returns: The Gst::TaskPool used by task. Gst::Object::unref() after usage.

◆ get_pool() [2/2]

Glib::RefPtr<const Gst::TaskPool> Gst::Task::get_pool ( ) const

Get the Gst::TaskPool that this task will use for its streaming threads.

MT safe.

Returns: The Gst::TaskPool used by task. Gst::Object::unref() after usage.

◆ get_state()

TaskState Gst::Task::get_state ( ) const

Get the current state of the task.

Returns: The Gst::TaskState of the task

MT safe.

◆ get_type()

static GType Gst::Task::get_type ( )

static

Get the GType for this class, for use with the underlying GObject type system.

◆ gobj() [1/2]

GstTask* Gst::Task::gobj ( )

inline

Provides access to the underlying C GObject.

◆ gobj() [2/2]

const GstTask* Gst::Task::gobj ( ) const

inline

Provides access to the underlying C GObject.

◆ gobj_copy()

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.

◆ join()

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.

◆ operator=()

Task& Gst::Task::operator= ( Task&& src )

noexcept

◆ pause()

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.

◆ set_enter_slot()

void Gst::Task::set_enter_slot ( const SlotEnter& enter_slot )

Call enter_slot when the task function of task is entered.

Parameters

enter_slot

◆ set_leave_slot()

void Gst::Task::set_leave_slot ( const SlotLeave& leave_slot )

Call leave_func when the task function of task is left.

Parameters

leave_slot

◆ set_lock()

void Gst::Task::set_lock ( Glib::Threads::RecMutex & 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 RecMutex to use.

◆ set_pool()

void Gst::Task::set_pool ( const Glib::RefPtr< Gst::TaskPool >& pool )

Set pool as the new GstTaskPool for task.

Any new streaming threads that will be created by task will now use pool.

MT safe.

Parameters

pool	A Gst::TaskPool.

◆ set_state()

void Gst::Task::set_state ( Gst::TaskState state )

Sets the state of task to state.

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

MT safe.

Parameters

state The new task state.

Returns: true if the state could be changed.

◆ start()

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.

◆ stop()

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

◆ wrap()

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

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.

Public Types

Public Member Functions

Static Public Member Functions

Protected Member Functions

Related Functions

Detailed Description

Member Typedef Documentation

◆ SlotEnter

◆ SlotLeave

◆ SlotTask

◆ TaskThreadSlot

Constructor & Destructor Documentation

◆ Task() [1/2]

◆ ~Task()

◆ Task() [2/2]

Member Function Documentation

◆ cleanup_all()

◆ create()

◆ get_pool() [1/2]

◆ get_pool() [2/2]

◆ get_state()

◆ get_type()

◆ gobj() [1/2]

◆ gobj() [2/2]

◆ gobj_copy()

◆ join()

◆ operator=()

◆ pause()

◆ set_enter_slot()

◆ set_leave_slot()

◆ set_lock()

◆ set_pool()

◆ set_state()

◆ start()

◆ stop()

Friends And Related Function Documentation

◆ wrap()