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//
// ========================================================================
// Copyright (c) 1995-2014 Mort Bay Consulting Pty. Ltd.
// ------------------------------------------------------------------------
// All rights reserved. This program and the accompanying materials
// 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
// http://www.opensource.org/licenses/apache2.0.php
//
// You may elect to redistribute this code under either of these licenses.
// ========================================================================
//
package org.eclipse.jetty.util;
import java.io.IOException;
import java.util.concurrent.CancellationException;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.Future;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;
import java.util.concurrent.atomic.AtomicBoolean;
public class FuturePromise<C> implements Future<C>,Promise<C>
{
private static Throwable COMPLETED=new Throwable();
private final AtomicBoolean _done=new AtomicBoolean(false);
private final CountDownLatch _latch=new CountDownLatch(1);
private Throwable _cause;
private C _result;
public FuturePromise()
{}
public FuturePromise(C result)
{
_cause=COMPLETED;
_result=result;
_done.set(true);
_latch.countDown();
}
public FuturePromise(C ctx, Throwable failed)
{
_result=ctx;
_cause=failed;
_done.set(true);
_latch.countDown();
}
@Override
public void succeeded(C result)
{
if (_done.compareAndSet(false,true))
{
_result=result;
_cause=COMPLETED;
_latch.countDown();
}
}
@Override
public void failed(Throwable cause)
{
if (_done.compareAndSet(false,true))
{
_cause=cause;
_latch.countDown();
}
}
@Override
public boolean cancel(boolean mayInterruptIfRunning)
{
if (_done.compareAndSet(false,true))
{
_result=null;
_cause=new CancellationException();
_latch.countDown();
return true;
}
return false;
}
@Override
public boolean isCancelled()
{
if (_done.get())
{
try
{
_latch.await();
}
catch (InterruptedException e)
{
throw new RuntimeException(e);
}
return _cause instanceof CancellationException;
}
return false;
}
@Override
public boolean isDone()
{
return _done.get() && _latch.getCount()==0;
}
@Override
public C get() throws InterruptedException, ExecutionException
{
_latch.await();
if (_cause==COMPLETED)
return _result;
if (_cause instanceof CancellationException)
throw (CancellationException) new CancellationException().initCause(_cause);
throw new ExecutionException(_cause);
}
@Override
public C get(long timeout, TimeUnit unit) throws InterruptedException, ExecutionException, TimeoutException
{
if (!_latch.await(timeout,unit))
throw new TimeoutException();
if (_cause==COMPLETED)
return _result;
if (_cause instanceof TimeoutException)
throw (TimeoutException)_cause;
if (_cause instanceof CancellationException)
throw (CancellationException) new CancellationException().initCause(_cause);
throw new ExecutionException(_cause);
}
public static void rethrow(ExecutionException e) throws IOException
{
Throwable cause=e.getCause();
if (cause instanceof IOException)
throw (IOException)cause;
if (cause instanceof Error)
throw (Error)cause;
if (cause instanceof RuntimeException)
throw (RuntimeException)cause;
throw new RuntimeException(cause);
}
@Override
public String toString()
{
return String.format("FutureCallback@%x{%b,%b,%s}",hashCode(),_done.get(),_cause==COMPLETED,_result);
}
}
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