org.apache.flink.runtime.io.async

Class AbstractAsyncCallableWithResources<V>

java.lang.Object

org.apache.flink.runtime.io.async.AbstractAsyncCallableWithResources<V>

Type Parameters:

V - return type of the asynchronous call.

All Implemented Interfaces:

Callable<V>, AsyncDoneCallback, AsyncStoppable, StoppableCallbackCallable<V>

public abstract class AbstractAsyncCallableWithResources<V>
extends Object
implements StoppableCallbackCallable<V>

This abstract class encapsulates the lifecycle and execution strategy for asynchronous operations that use resources.

Constructor Summary

Constructors

Constructor and Description
AbstractAsyncCallableWithResources()

Method Summary

Modifier and Type	Method and Description
protected abstract void	acquireResources() Open the IO Handle (e.g.
V	call() This method implements the strategy for the actual IO operation:
void	done(boolean canceled) Optional callback that subclasses can implement.
Exception	getStopException() Returns a potential exception that might have been observed while stopping the operation.
boolean	isCalled() True once the async method was called.
boolean	isStopped() Check if the IO operation is stopped
protected abstract V	performOperation() Implements the actual operation.
protected abstract void	releaseResources() Releases resources acquired by this object.
void	stop() Stops the I/O operation by closing the I/O handle.
protected abstract void	stopOperation() This method implements how the operation is stopped.

Methods inherited from class java.lang.Object

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

Constructor Detail

AbstractAsyncCallableWithResources

public AbstractAsyncCallableWithResources()

Method Detail

call

public final V call()
             throws Exception

This method implements the strategy for the actual IO operation:

1) Acquire resources asynchronously and atomically w.r.t stopping. 2) Performs the operation 3) Releases resources.

Specified by:

call in interface Callable<V>

Returns:

Result of the IO operation, e.g. a deserialized object.

Throws:

Exception - exception that happened during the call.

acquireResources

protected abstract void acquireResources()
                                  throws Exception

Open the IO Handle (e.g. a stream) on which the operation will be performed.

Throws:

Exception - if there was a problem in acquiring.

performOperation

protected abstract V performOperation()
                               throws Exception

Implements the actual operation.

Returns:

Result of the operation

Throws:

Exception - if there was a problem in executing the operation.

releaseResources

protected abstract void releaseResources()
                                  throws Exception

Releases resources acquired by this object.

Throws:

Exception - if there was a problem in releasing resources.

stopOperation

protected abstract void stopOperation()
                               throws Exception

This method implements how the operation is stopped. Usually this involves interrupting or closing some resources like streams to return from blocking calls.

Throws:

Exception - on problems during the stopping.

stop

public final void stop()

Stops the I/O operation by closing the I/O handle. If an exception is thrown on close, it can be accessed via #getStopException().

Specified by:

stop in interface AsyncStoppable

done

public void done(boolean canceled)

Optional callback that subclasses can implement. This is called when the callable method completed, e.g. because it finished or was stopped.

Specified by:

done in interface AsyncDoneCallback

Parameters:

canceled - true if the callback is done, but was canceled

isCalled

public boolean isCalled()

True once the async method was called.

isStopped

public boolean isStopped()

Check if the IO operation is stopped

Specified by:

isStopped in interface AsyncStoppable

Returns:

true if stop() was called

getStopException

public Exception getStopException()

Returns a potential exception that might have been observed while stopping the operation.

Specified by:

getStopException in interface AsyncStoppable

Returns:

Exception that can happen during stop