org.eclipse.jetty.util

Class CompletableCallback

java.lang.Object

org.eclipse.jetty.util.CompletableCallback

All Implemented Interfaces:

Callback

public abstract class CompletableCallback
extends Object
implements Callback

A callback to be used by driver code that needs to know whether the callback has been succeeded or failed (that is, completed) just after the asynchronous operation or not, typically because further processing depends on the callback being completed. The driver code competes with the asynchronous operation to complete the callback.

If the callback is already completed, the driver code continues the processing, otherwise it suspends it. If it is suspended, the callback will be completed some time later, and resume() or abort(Throwable) will be called to allow the application to resume the processing.

Typical usage:

 CompletableCallback callback = new CompletableCallback()
 {
     @Override
     public void resume()
     {
         // continue processing
     }

     @Override
     public void abort(Throwable failure)
     {
         // abort processing
     }
 }
 asyncOperation(callback);
 boolean completed = callback.tryComplete();
 if (completed)
     // suspend processing, async operation not done yet
 else
     // continue processing, async operation already done
 

Nested Class Summary

Nested classes/interfaces inherited from interface org.eclipse.jetty.util.Callback

Callback.Adapter

Constructor Summary

Constructors

Constructor and Description
CompletableCallback()

Method Summary

Methods

Modifier and Type	Method and Description
abstract void	abort(Throwable failure) Callback method invoked when this callback is failed after a first call to tryComplete().
void	failed(Throwable x) Callback invoked when the operation fails.
abstract void	resume() Callback method invoked when this callback is succeeded after a first call to tryComplete().
void	succeeded() Callback invoked when the operation completes.
boolean	tryComplete() Tries to complete this callback; driver code should call this method once after the asynchronous operation to detect whether the asynchronous operation has already completed or not.

Methods inherited from class java.lang.Object

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

Constructor Detail

CompletableCallback

public CompletableCallback()

Method Detail

succeeded

public void succeeded()

Description copied from interface: Callback

Callback invoked when the operation completes.

Specified by:

succeeded in interface Callback

See Also:

Callback.failed(Throwable)

failed

public void failed(Throwable x)

Description copied from interface: Callback

Callback invoked when the operation fails.

Specified by:

failed in interface Callback

Parameters:

x - the reason for the operation failure

resume

public abstract void resume()

Callback method invoked when this callback is succeeded after a first call to tryComplete().

abort

public abstract void abort(Throwable failure)

Callback method invoked when this callback is failed after a first call to tryComplete().

tryComplete

public boolean tryComplete()

Tries to complete this callback; driver code should call this method once after the asynchronous operation to detect whether the asynchronous operation has already completed or not.

Returns:

whether the attempt to complete was successful.