Package 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:
Serializable,Callable<ExecutionResult<T>>
public abstract class StepTask<T>
extends Object
implements Callable<ExecutionResult<T>>, 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()).
1. By using the Future
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()).
- Author:
- Mark Hall (mhall{[at]}pentaho{[dot]}com)
- See Also:
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Constructor Summary
ConstructorsConstructorDescriptionConstructor.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 TypeMethodDescriptioncall()Executor service calls this method to do the workbooleanGet whether thisStepTaskmust run single threaded - i.e.booleanGet whether thisStepTaskis resource intensive (cpu/memory) or not.abstract voidprocess()The actual work gets done here.voidsetMustRunSingleThreaded(boolean singleThreaded) Set whether thisStepTaskmust run single threaded - i.e.voidsetResourceIntensive(boolean resourceIntensive) Set whether thisStepTaskis resource intensive (cpu/memory) or not.
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Constructor Details
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StepTask
Constructor. Use this constructor if you are going to access the Future returned by ExecutionEnvironment.submitTask().- Parameters:
source- the source step producing this task
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StepTask
Constructor. Use this constructor if you are going to access the Future returned by ExecutionEnvironment.submitTask()- Parameters:
source- the source step producing this taskresourceIntensive- true if this task is cpu/memory intensive
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StepTask
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 taskcallback- the callback to use
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StepTask
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 taskcallback- the callback to useresourceIntensive- true if this task is cpu/memory intensive
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Method Details
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setResourceIntensive
public void setResourceIntensive(boolean resourceIntensive) Set whether thisStepTaskis resource intensive (cpu/memory) or not. By default, aStepTaskis resource intensive- Parameters:
resourceIntensive- false if thisStepTaskis not resource intensive
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isResourceIntensive
public boolean isResourceIntensive()Get whether thisStepTaskis resource intensive (cpu/memory) or not. By default, aStepTaskis resource intensive- Returns:
- false if this
StepTaskis not resource intensive
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setMustRunSingleThreaded
public void setMustRunSingleThreaded(boolean singleThreaded) Set whether thisStepTaskmust 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
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getMustRunSingleThreaded
public boolean getMustRunSingleThreaded()Get whether thisStepTaskmust 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
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call
Executor service calls this method to do the work -
process
The actual work gets done here. Subclasses to override. Subclasses can use getExecutionResult() to obtain an ExecutionResult object to store their results in- Throws:
Exception
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