//
// ========================================================================
// 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.client.util;
import java.io.IOException;
import java.io.InputStream;
import java.io.InterruptedIOException;
import java.nio.ByteBuffer;
import java.nio.channels.AsynchronousCloseException;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;
import java.util.concurrent.atomic.AtomicLong;
import java.util.concurrent.atomic.AtomicReference;
import org.eclipse.jetty.client.api.Response;
import org.eclipse.jetty.client.api.Response.Listener;
import org.eclipse.jetty.client.api.Result;
import org.eclipse.jetty.util.IO;
import org.eclipse.jetty.util.log.Log;
import org.eclipse.jetty.util.log.Logger;
/**
* Implementation of {@link Listener} that produces an {@link InputStream}
* that allows applications to read the response content.
* <p />
* Typical usage is:
* <pre>
* InputStreamResponseListener listener = new InputStreamResponseListener();
* client.newRequest(...).send(listener);
*
* // Wait for the response headers to arrive
* Response response = listener.get(5, TimeUnit.SECONDS);
* if (response.getStatus() == 200)
* {
* // Obtain the input stream on the response content
* try (InputStream input = listener.getInputStream())
* {
* // Read the response content
* }
* }
* </pre>
* <p />
* The {@link HttpClient} implementation (the producer) will feed the input stream
* asynchronously while the application (the consumer) is reading from it.
* Chunks of content are maintained in a queue, and it is possible to specify a
* maximum buffer size for the bytes held in the queue, by default 16384 bytes.
* <p />
* If the consumer is faster than the producer, then the consumer will block
* with the typical {@link InputStream#read()} semantic.
* If the consumer is slower than the producer, then the producer will block
* until the client consumes.
*/
public class InputStreamResponseListener extends Listener.Adapter
{
private static final Logger LOG = Log.getLogger(InputStreamResponseListener.class);
private static final byte[] EOF = new byte[0];
private static final byte[] CLOSED = new byte[0];
private static final byte[] FAILURE = new byte[0];
private final BlockingQueue<byte[]> queue = new LinkedBlockingQueue<>();
private final AtomicLong length = new AtomicLong();
private final CountDownLatch responseLatch = new CountDownLatch(1);
private final CountDownLatch resultLatch = new CountDownLatch(1);
private final AtomicReference<InputStream> stream = new AtomicReference<>();
private final long maxBufferSize;
private Response response;
private Result result;
private volatile Throwable failure;
private volatile boolean closed;
public InputStreamResponseListener()
{
this(16 * 1024L);
}
public InputStreamResponseListener(long maxBufferSize)
{
this.maxBufferSize = maxBufferSize;
}
@Override
public void onHeaders(Response response)
{
this.response = response;
responseLatch.countDown();
}
@Override
public void onContent(Response response, ByteBuffer content)
{
if (!closed)
{
int remaining = content.remaining();
if (remaining > 0)
{
byte[] bytes = new byte[remaining];
content.get(bytes);
if (LOG.isDebugEnabled())
LOG.debug("Queuing {}/{} bytes", bytes, remaining);
queue.offer(bytes);
long newLength = length.addAndGet(remaining);
while (newLength >= maxBufferSize)
{
if (LOG.isDebugEnabled())
LOG.debug("Queued bytes limit {}/{} exceeded, waiting", newLength, maxBufferSize);
// Block to avoid infinite buffering
if (!await())
break;
newLength = length.get();
if (LOG.isDebugEnabled())
LOG.debug("Queued bytes limit {}/{} exceeded, woken up", newLength, maxBufferSize);
}
}
else
{
if (LOG.isDebugEnabled())
LOG.debug("Queuing skipped, empty content {}", content);
}
}
else
{
LOG.debug("Queuing skipped, stream already closed");
}
}
@Override
public void onSuccess(Response response)
{
if (LOG.isDebugEnabled())
LOG.debug("Queuing end of content {}{}", EOF, "");
queue.offer(EOF);
signal();
}
@Override
public void onFailure(Response response, Throwable failure)
{
fail(failure);
signal();
}
@Override
public void onComplete(Result result)
{
if (result.isFailed() && failure == null)
fail(result.getFailure());
this.result = result;
resultLatch.countDown();
signal();
}
private void fail(Throwable failure)
{
if (LOG.isDebugEnabled())
LOG.debug("Queuing failure {} {}", FAILURE, failure);
queue.offer(FAILURE);
this.failure = failure;
responseLatch.countDown();
}
protected boolean await()
{
try
{
synchronized (this)
{
while (length.get() >= maxBufferSize && failure == null && !closed)
wait();
// Re-read the values as they may have changed while waiting.
return failure == null && !closed;
}
}
catch (InterruptedException x)
{
Thread.currentThread().interrupt();
return false;
}
}
protected void signal()
{
synchronized (this)
{
notifyAll();
}
}
/**
* Waits for the given timeout for the response to be available, then returns it.
* <p />
* The wait ends as soon as all the HTTP headers have been received, without waiting for the content.
* To wait for the whole content, see {@link #await(long, TimeUnit)}.
*
* @param timeout the time to wait
* @param unit the timeout unit
* @return the response
* @throws InterruptedException if the thread is interrupted
* @throws TimeoutException if the timeout expires
* @throws ExecutionException if a failure happened
*/
public Response get(long timeout, TimeUnit unit) throws InterruptedException, TimeoutException, ExecutionException
{
boolean expired = !responseLatch.await(timeout, unit);
if (expired)
throw new TimeoutException();
if (failure != null)
throw new ExecutionException(failure);
return response;
}
/**
* Waits for the given timeout for the whole request/response cycle to be finished,
* then returns the corresponding result.
* <p />
*
* @param timeout the time to wait
* @param unit the timeout unit
* @return the result
* @throws InterruptedException if the thread is interrupted
* @throws TimeoutException if the timeout expires
* @see #get(long, TimeUnit)
*/
public Result await(long timeout, TimeUnit unit) throws InterruptedException, TimeoutException
{
boolean expired = !resultLatch.await(timeout, unit);
if (expired)
throw new TimeoutException();
return result;
}
/**
* Returns an {@link InputStream} providing the response content bytes.
* <p />
* The method may be invoked only once; subsequent invocations will return a closed {@link InputStream}.
*
* @return an input stream providing the response content
*/
public InputStream getInputStream()
{
InputStream result = new Input();
if (stream.compareAndSet(null, result))
return result;
return IO.getClosedStream();
}
private class Input extends InputStream
{
private byte[] bytes;
private int index;
@Override
public int read() throws IOException
{
while (true)
{
if (bytes == EOF)
{
// Mark the fact that we saw -1,
// so that in the close case we don't throw
index = -1;
return -1;
}
else if (bytes == FAILURE)
{
throw failure();
}
else if (bytes == CLOSED)
{
if (index < 0)
return -1;
throw new AsynchronousCloseException();
}
else if (bytes != null)
{
int result = bytes[index] & 0xFF;
if (++index == bytes.length)
{
length.addAndGet(-index);
bytes = null;
index = 0;
signal();
}
return result;
}
else
{
bytes = take();
if (LOG.isDebugEnabled())
LOG.debug("Dequeued {}/{} bytes", bytes, bytes.length);
}
}
}
private IOException failure()
{
if (failure instanceof IOException)
return (IOException)failure;
else
return new IOException(failure);
}
private byte[] take() throws IOException
{
try
{
return queue.take();
}
catch (InterruptedException x)
{
throw new InterruptedIOException();
}
}
@Override
public void close() throws IOException
{
if (!closed)
{
super.close();
if (LOG.isDebugEnabled())
LOG.debug("Queuing close {}{}", CLOSED, "");
queue.offer(CLOSED);
closed = true;
signal();
}
}
}
}