Package org.freedesktop.gstreamer.gst

Class Task

java.lang.Object

org.javagi.base.ProxyInstance

org.gnome.gobject.TypeInstance

org.gnome.gobject.GObject

org.gnome.gobject.InitiallyUnowned

org.freedesktop.gstreamer.gst.GstObject

org.freedesktop.gstreamer.gst.Task

All Implemented Interfaces:

Proxy

@Generated("io.github.jwharm.JavaGI")
public class Task
extends GstObject

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.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	Task.Builder<B extends Task.Builder<B>>	Inner class implementing a builder pattern to construct a GObject with properties.
static class	Task.TaskClass

Nested classes/interfaces inherited from class org.freedesktop.gstreamer.gst.GstObject

GstObject.DeepNotifyCallback, GstObject.Object$Impl, GstObject.ObjectClass

Nested classes/interfaces inherited from class org.gnome.gobject.InitiallyUnowned

InitiallyUnowned.InitiallyUnownedClass

Nested classes/interfaces inherited from class org.gnome.gobject.GObject

GObject.NotifyCallback

Constructor Summary

Constructors

Constructor	Description
Task()	Creates a new Task.
Task(MemorySegment address)	Create a Task proxy instance for the provided memory address.
Task(@Nullable TaskFunction func)	Create a new Task that will repeatedly call the provided func with userData as a parameter.

Method Summary

Modifier and Type	Method	Description
protected Task	asParent()	Returns this instance as if it were its parent type.
static Task.Builder<? extends Task.Builder>	builder()	A Task.Builder object constructs a Task with the specified properties.
static void	cleanupAll()	Wait for all tasks to be stopped.
static MemoryLayout	getMemoryLayout()	The memory layout of the native struct.
TaskPool	getPool()	Get the GstTaskPool that this task will use for its streaming threads.
TaskState	getState()	Get the current state of the task.
static @Nullable Type	getType()	Get the GType of the Task class
boolean	join()	Joins task. After this call, it is safe to unref the task and clean up the lock set with gst_task_set_lock().
boolean	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.
boolean	resume()	Resume this Task in case it was paused.
void	setEnterCallback(@Nullable TaskThreadFunc enterFunc)	Call enterFunc when the task function of this Task is entered.
void	setLeaveCallback(@Nullable TaskThreadFunc leaveFunc)	Call leaveFunc when the task function of this Task is left.
void	setLock(RecMutex mutex)	Set the mutex used by the task.
void	setPool(TaskPool pool)	Set pool as the new GstTaskPool for task. Any new streaming threads that will be created by this Task will now use pool.
boolean	setState(TaskState state)	Sets the state of this Task to state.
boolean	start()	Starts task. The this Task must have a lock associated with it using gst_task_set_lock() or this function will return false.
boolean	stop()	Stops task. This method merely schedules the task to stop and will not wait for the task to have completely stopped.

Methods inherited from class org.freedesktop.gstreamer.gst.GstObject

addControlBinding, checkUniqueness, deepNotify, defaultDeepNotify, defaultError, emitDeepNotify, getControlBinding, getControlRate, getGValueArray, getName, getParent, getPathString, getValue, getValueArray, hasActiveControlBindings, hasAncestor, hasAsAncestor, hasAsParent, onDeepNotify, ref, refSink, removeControlBinding, replace, setControlBindingDisabled, setControlBindingsDisabled, setControlRate, setName, setParent, suggestNextSync, syncValues, unparent, unref

Methods inherited from class org.gnome.gobject.GObject

addToggleRef, addWeakPointer, bindProperty, bindProperty, bindProperty, bindPropertyFull, bindPropertyFull, bindPropertyWithClosures, bindPropertyWithClosures, compatControl, connect, connect, connect, constructed, disconnect, dispatchPropertiesChanged, dispose, dupData, dupQdata, emit, emitNotify, finalize_, forceFloating, freezeNotify, get, getData, getProperty, getProperty, getProperty, getQdata, getv, interfaceFindProperty, interfaceInstallProperty, interfaceListProperties, isFloating, newInstance, newInstance, newv, notify, notify, notifyByPspec, onNotify, refSink, removeToggleRef, removeWeakPointer, replaceData, replaceQdata, runDispose, set, setData, setDataFull, setProperty, setProperty, setProperty, setQdata, setQdataFull, setv, stealData, stealQdata, takeRef, thawNotify, watchClosure, weakRef, weakUnref, withProperties

Methods inherited from class org.gnome.gobject.TypeInstance

callParent, callParent, cast, getPrivate, readGClass, writeGClass

Methods inherited from class org.javagi.base.ProxyInstance

equals, handle, hashCode

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, toString, wait, wait, wait

Constructor Details

Task

public Task(MemorySegment address)

Create a Task proxy instance for the provided memory address.

Parameters:

address - the memory address of the native object

Task

public Task(@Nullable TaskFunction func)

Create a new Task that will repeatedly call the provided func with userData 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.

Parameters:

func - The GstTaskFunction to use

Task

public Task()

Creates a new Task.

Method Details

getType

public static @Nullable Type getType()

Get the GType of the Task class

Returns:

the GType

getMemoryLayout

public static MemoryLayout getMemoryLayout()

The memory layout of the native struct.

Returns:

the memory layout

asParent

protected Task asParent()

Returns this instance as if it were its parent type. This is mostly synonymous to the Java super keyword, but will set the native typeclass function pointers to the parent type. When overriding a native virtual method in Java, "chaining up" with super.methodName() doesn't work, because it invokes the overridden function pointer again. To chain up, call asParent().methodName(). This will call the native function pointer of this virtual method in the typeclass of the parent type.

Overrides:

asParent in class GstObject

cleanupAll

public static void cleanupAll()

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.

getPool

public TaskPool getPool()

Get the GstTaskPool that this task will use for its streaming threads.

MT safe.

Returns:

the GstTaskPool used by task. gst_object_unref() after usage.

getState

public TaskState getState()

Get the current state of the task.

Returns:

The GstTaskState of the task

MT safe.

join

public boolean 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.

pause

public boolean 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.

resume

public boolean resume()

Resume this 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

setEnterCallback

public void setEnterCallback(@Nullable TaskThreadFunc enterFunc)

Call enterFunc when the task function of this Task is entered. userData will be passed to enterFunc and notify will be called when userData is no longer referenced.

Parameters:

enterFunc - a GstTaskThreadFunc

setLeaveCallback

public void setLeaveCallback(@Nullable TaskThreadFunc leaveFunc)

Call leaveFunc when the task function of this Task is left. userData will be passed to leaveFunc and notify will be called when userData is no longer referenced.

Parameters:

leaveFunc - a GstTaskThreadFunc

setLock

public void setLock(RecMutex mutex)

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.

Parameters:

mutex - The GRecMutex to use

setPool

public void setPool(TaskPool pool)

Set pool as the new GstTaskPool for task. Any new streaming threads that will be created by this Task will now use pool.

MT safe.

Parameters:

pool - a GstTaskPool

setState

public boolean setState(TaskState state)

Sets the state of this Task to state.

The this 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.

Parameters:

state - the new task state

Returns:

true if the state could be changed.

start

public boolean start()

Starts task. The this 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.

stop

public boolean 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.

builder

public static Task.Builder<? extends Task.Builder> builder()

A Task.Builder object constructs a Task with the specified properties. Use the various set...() methods to set properties, and finish construction with Task.Builder.build().

Returns:

the builder object