Module swim.concurrent

Package swim.concurrent

Class AbstractTask

java.lang.Object

swim.concurrent.AbstractTask

All Implemented Interfaces:

Task, TaskFunction

public abstract class AbstractTask
extends Object
implements Task

Skeletal implementation of a stateful Task.

Field Summary

Fields

Modifier and Type	Field	Description
protected TaskContext	taskContext	Context used to manage this Task; null if this Task is not bound to an execution Stage.

Constructor Summary

Constructors

Constructor	Description
AbstractTask()

Method Summary

Modifier and Type	Method	Description
boolean	cancel()	Cancels this task to prevent it from executing.
boolean	cue()	Schedules this task to execute as a sequential process.
boolean	isCued()	Returns true if the task is currently scheduled for execution.
abstract void	runTask()	Executes this sequential process.
void	setTaskContext(TaskContext taskContext)	Sets the context used to managed this Task.
Stage	stage()	Returns the execution Stage to which this task is bound.
TaskContext	taskContext()	Returns the context used to managed this Task.
void	taskDidCancel()	Lifecycle callback invoked after this Task is explicitly cancelled.
boolean	taskWillBlock()	Returns true if this Task might block its thread of execution when running; returns false if this Task will never block.
void	taskWillCue()	Lifecycle callback invoked before this Task is scheduled for execution.

Methods inherited from class java.lang.Object

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

Field Detail

taskContext

protected TaskContext taskContext

Context used to manage this Task; null if this Task is not bound to an execution Stage.

Constructor Detail

AbstractTask

public AbstractTask()

Method Detail

taskContext

public final TaskContext taskContext()

Description copied from interface: Task

Returns the context used to managed this Task. Returns null if this Task is not bound to a Stage.

Specified by:

taskContext in interface Task

setTaskContext

public void setTaskContext(TaskContext taskContext)

Description copied from interface: Task

Sets the context used to managed this Task. A TaskContext is assigned when binding this Task to a Stage.

Specified by:

setTaskContext in interface Task

runTask

public abstract void runTask()

Description copied from interface: Task

Executes this sequential process. Only one thread at a time will execute runTask for this Task.

Specified by:

runTask in interface Task

Specified by:

runTask in interface TaskFunction

taskWillBlock

public boolean taskWillBlock()

Description copied from interface: Task

Returns true if this Task might block its thread of execution when running; returns false if this Task will never block. Used by the execution Stage to prevent thread starvation when concurrently running many blocking tasks.

Specified by:

taskWillBlock in interface Task

taskWillCue

public void taskWillCue()

Description copied from interface: Task

Lifecycle callback invoked before this Task is scheduled for execution.

Specified by:

taskWillCue in interface Task

taskDidCancel

public void taskDidCancel()

Description copied from interface: Task

Lifecycle callback invoked after this Task is explicitly cancelled.

Specified by:

taskDidCancel in interface Task

stage

public Stage stage()

Returns the execution Stage to which this task is bound. Delegates to the assigned taskContext.

Throws:

TaskException - if taskContext is null.

isCued

public boolean isCued()

Returns true if the task is currently scheduled for execution. Delegates to the assigned taskContext, if set; otherwise returns false.

cue

public boolean cue()

Schedules this task to execute as a sequential process. Returns true if this operation caused the scheduling of this task; returns false if this task was already scheduled to execute. This task becomes uncued prior to the the invocation of runTask(), enabling this task to re-cue itself while running. Delegates to the assigned taskContext.

Throws:

TaskException - if taskContext is null.

cancel

public boolean cancel()

Cancels this task to prevent it from executing. Returns true if this operation caused the cancellation of this task; returns false if this task was not scheduled to execute. Delegates to the assigned taskContext.