com.facebook.presto.jdbc.internal.jetty.util.Callback Maven / Gradle / Ivy
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// Copyright (c) 1995-2016 Mort Bay Consulting Pty. Ltd.
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// are made available under the terms of the Eclipse Public License v1.0
// and Apache License v2.0 which accompanies this distribution.
//
// The Eclipse Public License is available at
// http://www.eclipse.org/legal/epl-v10.html
//
// The Apache License v2.0 is available at
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package com.facebook.presto.jdbc.internal.jetty.util;
/**
* A callback abstraction that handles completed/failed events of asynchronous operations.
*
* Semantically this is equivalent to an optimise Promise<Void>, but callback is a more meaningful
* name than EmptyPromise
*/
public interface Callback
{
/**
* Instance of Adapter that can be used when the callback methods need an empty
* implementation without incurring in the cost of allocating a new Adapter object.
*/
static Callback NOOP = new Callback(){};
/**
* Callback invoked when the operation completes.
*
* @see #failed(Throwable)
*/
default void succeeded()
{}
/**
* Callback invoked when the operation fails.
* @param x the reason for the operation failure
*/
default void failed(Throwable x)
{}
/**
* @return True if the callback is known to never block the caller
*/
default boolean isNonBlocking()
{
return false;
}
/**
* Callback interface that declares itself as non-blocking
*/
interface NonBlocking extends Callback
{
@Override
public default boolean isNonBlocking()
{
return true;
}
}
/**
* Empty implementation of {@link Callback}
*/
@Deprecated
static class Adapter implements Callback
{}
}