net.grinder.communication.StreamReceiver Maven / Gradle / Ivy
// Copyright (C) 2003 - 2011 Philip Aston
// All rights reserved.
//
// This file is part of The Grinder software distribution. Refer to
// the file LICENSE which is part of The Grinder distribution for
// licensing details. The Grinder distribution is available on the
// Internet at http://grinder.sourceforge.net/
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
// FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
// COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
// INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
// (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
// SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
// HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
// STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
// OF THE POSSIBILITY OF SUCH DAMAGE.
package net.grinder.communication;
import java.io.InputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import net.grinder.common.Closer;
import net.grinder.common.UncheckedInterruptedException;
/**
* Manages receipt of messages from a server over a stream.
*
* @author Philip Aston
*/
public class StreamReceiver implements Receiver {
private final InputStream m_inputStream;
private final Object m_streamLock;
// Guarded by m_streamLock.
private boolean m_shutdown = false;
/**
* Constructor.
*
* @param inputStream The input stream to read from.
*/
public StreamReceiver(InputStream inputStream) {
this(inputStream, inputStream);
}
/**
* Constructor.
*
* @param inputStream The input stream to read from.
* @param streamLock Lock on this object around all stream operations.
*/
private StreamReceiver(InputStream inputStream, Object streamLock) {
m_inputStream = inputStream;
m_streamLock = streamLock;
}
/**
* Block until a message is available. Typically called from a
* message dispatch loop.
*
* @return The message or null if shut down.
* @throws CommunicationException If an error occurred receiving a message.
*/
public final Message waitForMessage() throws CommunicationException {
try {
final Message message;
// This blocks holding the lock, by design.
synchronized (m_streamLock) {
if (m_shutdown) {
return null;
}
final ObjectInputStream objectStream =
new ObjectInputStream(m_inputStream);
message = (Message)objectStream.readObject();
if (message instanceof CloseCommunicationMessage) {
shutdown();
return null;
}
}
return message;
}
catch (IOException e) {
UncheckedInterruptedException.ioException(e);
throw new CommunicationException("Failed to read message", e);
}
catch (ClassNotFoundException e) {
throw new CommunicationException("Failed to read message", e);
}
}
/**
* Cleanly shut down the Receiver. Ignore errors,
* connection has probably been reset by peer.
*/
public void shutdown() {
synchronized (m_streamLock) {
m_shutdown = true;
}
Closer.close(m_inputStream);
}
}