weka.knowledgeflow

Class StepTask<T>

java.lang.Object

weka.knowledgeflow.StepTask<T>

Type Parameters:

T - the type of the result stored in the returned ExecutionResult object

All Implemented Interfaces:

java.io.Serializable, java.util.concurrent.Callable<ExecutionResult<T>>

Direct Known Subclasses:

BoundaryPlotter.SchemeRowTask, ClassifierPerformanceEvaluator.EvaluationTask

public abstract class StepTask<T>
extends java.lang.Object
implements java.util.concurrent.Callable<ExecutionResult<T>>, java.io.Serializable

A task that can be executed by the ExecutionEnvironment's submitTask() service. Step's wanting to use this to execute units of work in parallel must extends it and can work with it in one of two ways:

1. By using the Future returned by submitTask(), or
2. By registering an implementation of StepCallback when creating a subclass of StepTask.
Subclasses of StepTask should store their results (and potentially errors) in the provided ExecutionResult member variable (obtainable by calling getExecutionResult()).

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
protected StepTaskCallback<T>	m_callback Optional callback to invoke after the processing is complete
protected CallbackNotifierDelegate	m_callbackNotifier The callback notifier delegate.
protected LogManager	m_log The log to use
protected boolean	m_mustRunSingleThreaded True if only one of these tasks can be executing at any one time in the Knowledge Flow/JVM.
protected boolean	m_resourceIntensive True if this is a high resource (cpu/memory) task
protected ExecutionResult<T>	m_result The result of executing the task - ready to be populated by subclass's call() implementation

Constructor Summary

Constructors

Constructor and Description
StepTask(Step source) Constructor.
StepTask(Step source, boolean resourceIntensive) Constructor.
StepTask(Step source, StepTaskCallback<T> callback) Constructor with supplied callback.
StepTask(Step source, StepTaskCallback<T> callback, boolean resourceIntensive) Constructor with supplied callback.

Method Summary

Modifier and Type	Method and Description
ExecutionResult<T>	call() Executor service calls this method to do the work
protected CallbackNotifierDelegate	getCallbackNotifierDelegate() Get the callback notifier delegate to use.
protected ExecutionResult<T>	getExecutionResult() Get the result of execution
protected LogManager	getLogHandler() Get the LogHandler to use for logging
boolean	getMustRunSingleThreaded() Get whether this StepTask must run single threaded - i.e. only one of these tasks is executing at any one time in the JVM.
boolean	isResourceIntensive() Get whether this StepTask is resource intensive (cpu/memory) or not.
protected void	notifyCallback() Notifies the registered callback (if any)
abstract void	process() The actual work gets done here.
protected void	setCallbackNotifierDelegate(CallbackNotifierDelegate delegate) Set the callback notifier delegate to use.
protected void	setExecutionResult(ExecutionResult<T> execResult) Set the result of execution
protected void	setLogHandler(LogManager log) Set the logger to use.
void	setMustRunSingleThreaded(boolean singleThreaded) Set whether this StepTask must run single threaded - i.e. only one of these tasks is executing at any one time in the JVM.
void	setResourceIntensive(boolean resourceIntensive) Set whether this StepTask is resource intensive (cpu/memory) or not.

Methods inherited from class java.lang.Object

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

Field Detail

m_result

protected ExecutionResult<T> m_result

The result of executing the task - ready to be populated by subclass's call() implementation

m_callback

protected transient StepTaskCallback<T> m_callback

Optional callback to invoke after the processing is complete

m_log

protected LogManager m_log

The log to use

m_resourceIntensive

protected boolean m_resourceIntensive

True if this is a high resource (cpu/memory) task

m_mustRunSingleThreaded

protected boolean m_mustRunSingleThreaded

True if only one of these tasks can be executing at any one time in the Knowledge Flow/JVM. This has priority over isResourceIntensive() and causes the task to run on an executor service with one worker thread.

m_callbackNotifier

protected CallbackNotifierDelegate m_callbackNotifier

The callback notifier delegate. Performs the actual notification back to the step

Constructor Detail

StepTask

public StepTask(Step source)

Constructor. Use this constructor if you are going to access the Future returned by ExecutionEnvironment.submitTask().

Parameters:

source - the source step producing this task

StepTask

public StepTask(Step source,
                boolean resourceIntensive)

Constructor. Use this constructor if you are going to access the Future returned by ExecutionEnvironment.submitTask()

Parameters:

source - the source step producing this task

resourceIntensive - true if this task is cpu/memory intensive

StepTask

public StepTask(Step source,
                StepTaskCallback<T> callback)

Constructor with supplied callback. Use this constructor to be notified via the supplied callback when a the task has completed processing

Parameters:

source - the source step producing this task

callback - the callback to use

StepTask

public StepTask(Step source,
                StepTaskCallback<T> callback,
                boolean resourceIntensive)

Constructor with supplied callback. Use this constructor to be notified via the supplied callback when a task has completed processing

Parameters:

source - the source step producing this task

callback - the callback to use

resourceIntensive - true if this task is cpu/memory intensive

Method Detail

setResourceIntensive

public void setResourceIntensive(boolean resourceIntensive)

Set whether this StepTask is resource intensive (cpu/memory) or not. By default, a StepTask is resource intensive

Parameters:

resourceIntensive - false if this StepTask is not resource intensive

isResourceIntensive

public boolean isResourceIntensive()

Get whether this StepTask is resource intensive (cpu/memory) or not. By default, a StepTask is resource intensive

Returns:

false if this StepTask is not resource intensive

setMustRunSingleThreaded

public void setMustRunSingleThreaded(boolean singleThreaded)

Set whether this StepTask must run single threaded - i.e. only one of these tasks is executing at any one time in the JVM. The Knowledge Flow uses a special executor service with a single worker thread to execute these tasks. This property, if true, overrides isResourceIntensive().

Parameters:

singleThreaded - true if this task must run single threaded

getMustRunSingleThreaded

public boolean getMustRunSingleThreaded()

Get whether this StepTask must run single threaded - i.e. only one of these tasks is executing at any one time in the JVM. The Knowledge Flow uses a special executor service with a single worker thread to execute these tasks. This property, if true, overrides isResourceIntensive().

Returns:

true if this task must run single threaded

getCallbackNotifierDelegate

protected final CallbackNotifierDelegate getCallbackNotifierDelegate()

Get the callback notifier delegate to use. This method is used by the Execution environment and is not normally of interest to subclasses

Returns:

the callback notifier delegate in use

setCallbackNotifierDelegate

protected final void setCallbackNotifierDelegate(CallbackNotifierDelegate delegate)

Set the callback notifier delegate to use. This method is used by the Execution environment and is not normally of interest to subclasses

Parameters:

delegate - the delegate to use

getLogHandler

protected final LogManager getLogHandler()

Get the LogHandler to use for logging

Returns:

the LogHandler

setLogHandler

protected final void setLogHandler(LogManager log)

Set the logger to use. This is used by the execution environment - subclasses should call getLogHandler() to do logging

Parameters:

log - the log to use

notifyCallback

protected final void notifyCallback()
                             throws java.lang.Exception

Notifies the registered callback (if any)

Throws:

java.lang.Exception - if a problem occurs

getExecutionResult

protected final ExecutionResult<T> getExecutionResult()

Get the result of execution

Returns:

the result of execution

setExecutionResult

protected final void setExecutionResult(ExecutionResult<T> execResult)

Set the result of execution

Parameters:

execResult - the result of execution

call

public ExecutionResult<T> call()
                        throws java.lang.Exception

Executor service calls this method to do the work

Specified by:

call in interface java.util.concurrent.Callable<ExecutionResult<T>>

Returns:

the results of execution in an ExecutionResult

Throws:

java.lang.Exception

process

public abstract void process()
                      throws java.lang.Exception

The actual work gets done here. Subclasses to override. Subclasses can use getExecutionResult() to obtain an ExecutionResult object to store their results in

Throws:

java.lang.Exception