Package com.inductiveautomation.ignition.gateway.tasks

Class AbstractTask

java.lang.Object

com.inductiveautomation.ignition.gateway.tasks.AbstractTask

All Implemented Interfaces:

Task

public abstract class AbstractTask
extends java.lang.Object
implements Task

This abstract implementation of Task handles some of the complexity of dealing with pausing, cancelling, and resuming. Implementations only have to implement doTaskWork(), though they may also implement the state related functions to allow for pausing.

Nested Class Summary

Nested classes/interfaces inherited from interface com.inductiveautomation.ignition.gateway.tasks.Task

Task.TaskStateModel

Constructor Summary

Constructors

Constructor	Description
AbstractTask(java.util.UUID id)

Method Summary

Modifier and Type	Method	Description
protected void	applyTaskStateModel(Task.TaskStateModel model)	Can be overridden by sub classes to receive the state model before the task is resumed.
void	cancel(long timeoutMS)	When called, the task should stop as quickly as possible.
protected abstract void	doTaskWork(TaskContext context)	Should execute the work of the task.
protected TaskContext	getCurrentContext()
java.util.UUID	getId()
protected LoggerEx	getLogger()
protected abstract java.lang.String	getLoggerName()
protected java.util.Optional<Task.TaskStateModel>	getTaskStateModel()	Can be overridded by sub tasks to provide a state model when the task is suspended.
protected boolean	isStopped()
void	resume(Task.TaskStateModel state)
void	run(TaskContext context)	Executes the task.
java.util.Optional<Task.TaskStateModel>	suspend(long timeoutMS)	When called, the task should stop as quickly as possible.

Methods inherited from class java.lang.Object

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

Methods inherited from interface com.inductiveautomation.ignition.gateway.tasks.Task

getErrors

Constructor Detail

AbstractTask

public AbstractTask(java.util.UUID id)

Method Detail

getId

public java.util.UUID getId()

Specified by:

getId in interface Task

getLoggerName

protected abstract java.lang.String getLoggerName()

getLogger

protected LoggerEx getLogger()

getCurrentContext

protected TaskContext getCurrentContext()

isStopped

protected boolean isStopped()

run

public final void run(TaskContext context)
               throws java.lang.Exception

Description copied from interface: Task

Executes the task. This function should block until completion. If there is a problem executing the task, an exception should be thrown. It is important to note that while this function should block, the task must expect that at some point, suspend or cancel may be called.

Specified by:

run in interface Task

Throws:

java.lang.Exception

suspend

public java.util.Optional<Task.TaskStateModel> suspend(long timeoutMS)
                                                throws java.util.concurrent.TimeoutException,
                                                       java.lang.InterruptedException

Description copied from interface: Task

When called, the task should stop as quickly as possible. If the task is able to resume, it should return a state that will be provided to it when restarted. If this function returns an empty value, it will not be resumed. If appropriate, the call should try to implement the timeout restriction passed in. A timeout of 0 means "no timeout".

Specified by:

suspend in interface Task

Throws:

java.util.concurrent.TimeoutException

java.lang.InterruptedException

resume

public void resume(Task.TaskStateModel state)

Specified by:

resume in interface Task

cancel

public void cancel(long timeoutMS)
            throws java.util.concurrent.TimeoutException,
                   java.lang.InterruptedException

Description copied from interface: Task

When called, the task should stop as quickly as possible. If appropriate, the call should try to implement the timeout restriction passed in. A timeout of 0 means "no timeout".

Specified by:

cancel in interface Task

Throws:

java.util.concurrent.TimeoutException

java.lang.InterruptedException

getTaskStateModel

protected java.util.Optional<Task.TaskStateModel> getTaskStateModel()

Can be overridded by sub tasks to provide a state model when the task is suspended. This will be called after doTaskWork() has exited when the task is "stopped"

applyTaskStateModel

protected void applyTaskStateModel(Task.TaskStateModel model)

Can be overridden by sub classes to receive the state model before the task is resumed. At some point soon after this is called, the doTaskWork() function will be called.

doTaskWork

protected abstract void doTaskWork(TaskContext context)
                            throws java.lang.Exception

Should execute the work of the task. It is possible that this function will be called multiple times in the lifecycle of the task. The task may be paused, or the task may choose to yield execution. To yield, it should set its state to "WAITING", and return out of this function. At some point later, it can be resumed by calling resumeTask() on the context, or by the task manager.

Inside of this function, the task should periodically check isStopped to see if the task has been paused or canceled.

Throws:

java.lang.Exception