//
// ========================================================================
// 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.
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//
package com.facebook.presto.jdbc.internal.jetty.client.util;
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 com.facebook.presto.jdbc.internal.jetty.client.HttpContentResponse;
import com.facebook.presto.jdbc.internal.jetty.client.api.ContentResponse;
import com.facebook.presto.jdbc.internal.jetty.client.api.Request;
import com.facebook.presto.jdbc.internal.jetty.client.api.Result;
/**
* A {@link BufferingResponseListener} that is also a {@link Future}, to allow applications
* to block (indefinitely or for a timeout) until {@link #onComplete(Result)} is called,
* or to {@link #cancel(boolean) abort} the request/response conversation.
* <p />
* Typical usage is:
* <pre>
* Request request = httpClient.newRequest(...)...;
* FutureResponseListener listener = new FutureResponseListener(request);
* request.send(listener); // Asynchronous send
* ContentResponse response = listener.get(5, TimeUnit.SECONDS); // Timed block
* </pre>
*/
public class FutureResponseListener extends BufferingResponseListener implements Future<ContentResponse>
{
private final CountDownLatch latch = new CountDownLatch(1);
private final Request request;
private ContentResponse response;
private Throwable failure;
private volatile boolean cancelled;
public FutureResponseListener(Request request)
{
this(request, 2 * 1024 * 1024);
}
public FutureResponseListener(Request request, int maxLength)
{
super(maxLength);
this.request = request;
}
public Request getRequest()
{
return request;
}
@Override
public void onComplete(Result result)
{
response = new HttpContentResponse(result.getResponse(), getContent(), getEncoding());
failure = result.getFailure();
latch.countDown();
}
@Override
public boolean cancel(boolean mayInterruptIfRunning)
{
cancelled = true;
return request.abort(new CancellationException());
}
@Override
public boolean isCancelled()
{
return cancelled;
}
@Override
public boolean isDone()
{
return latch.getCount() == 0 || isCancelled();
}
@Override
public ContentResponse get() throws InterruptedException, ExecutionException
{
latch.await();
return getResult();
}
@Override
public ContentResponse get(long timeout, TimeUnit unit) throws InterruptedException, ExecutionException, TimeoutException
{
boolean expired = !latch.await(timeout, unit);
if (expired)
throw new TimeoutException();
return getResult();
}
private ContentResponse getResult() throws ExecutionException
{
if (isCancelled())
throw (CancellationException)new CancellationException().initCause(failure);
if (failure != null)
throw new ExecutionException(failure);
return response;
}
}