/**
*
* Copyright 2004 Hiram Chirino
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.activeio.adapter;
import java.io.IOException;
import java.io.InterruptedIOException;
import org.activeio.AsynchChannel;
import org.activeio.ChannelFactory;
import org.activeio.FilterAsynchChannel;
import org.activeio.Packet;
import org.activeio.PacketData;
import org.activeio.RequestChannel;
import org.activeio.RequestListener;
import org.activeio.packet.AppendedPacket;
import org.activeio.packet.ByteArrayPacket;
import EDU.oswego.cs.dl.util.concurrent.ConcurrentHashMap;
import EDU.oswego.cs.dl.util.concurrent.Executor;
import EDU.oswego.cs.dl.util.concurrent.Slot;
/**
* Creates a {@see org.activeio.RequestChannel} out of a {@see org.activeio.AsynchChannel}. This
* {@see org.activeio.RequestChannel} is thread safe and mutiplexes concurrent requests and responses over
* the underlying {@see org.activeio.AsynchChannel}.
*
* @version $Revision$
*/
final public class AsynchChannelToConcurrentRequestChannel extends FilterAsynchChannel implements RequestChannel {
private static final byte PASSTHROUGH = 0x00;
private static final byte REQUEST = 0x01;
private static final byte RESPONSE = 0x02;
private static final ByteArrayPacket PASSTHROUGH_PACKET = new ByteArrayPacket(new byte[]{PASSTHROUGH});
private final ConcurrentHashMap requestMap = new ConcurrentHashMap();
private final Executor requestExecutor;
private short nextRequestId = 0;
private final Object writeMutex = new Object();
private RequestListener requestListener;
public AsynchChannelToConcurrentRequestChannel(AsynchChannel next) {
this(next, ChannelFactory.DEFAULT_EXECUTOR);
}
public AsynchChannelToConcurrentRequestChannel(AsynchChannel next, Executor requestExecutor) {
super(next);
this.requestExecutor=requestExecutor;
}
synchronized short getNextRequestId() {
return nextRequestId++;
}
/**
* @see org.activeio.FilterAsynchChannel#write(org.activeio.channel.Packet)
*/
public void write(Packet packet) throws IOException {
Packet passThrough = AppendedPacket.join(PASSTHROUGH_PACKET.duplicate(), packet);
synchronized(writeMutex) {
super.write(passThrough);
}
}
/**
* @see org.activeio.FilterAsynchChannel#onPacket(org.activeio.channel.Packet)
*/
public void onPacket(final Packet packet) {
switch( packet.read() ) {
case PASSTHROUGH:
super.onPacket(packet);
break;
case REQUEST:
try {
requestExecutor.execute(new Runnable(){
public void run() {
serviceRequest(packet);
}
});
} catch (InterruptedException e) {
Thread.currentThread().interrupt();
}
break;
case RESPONSE:
serviceReponse(packet);
break;
}
}
private void serviceRequest(Packet packet) {
try {
if( requestListener ==null )
throw new IOException("The RequestListener has not been set.");
PacketData data = new PacketData(packet);
short requestId = data.readShort();
Packet reponse = requestListener.onRequest(packet);
// Send the response...
Packet header = createHeaderPacket(RESPONSE, requestId);
Packet rc = AppendedPacket.join(header, packet);
synchronized(writeMutex) {
super.write(rc);
}
} catch (IOException e) {
super.onPacketError(e);
}
}
private void serviceReponse(Packet packet) {
try {
PacketData data = new PacketData(packet);
short requestId = data.readShort();
Slot responseSlot = (Slot) requestMap.get(new Short(requestId));
responseSlot.put(packet);
} catch (IOException e) {
super.onPacketError(e);
} catch (InterruptedException e) {
Thread.currentThread().interrupt();
}
}
public Packet request(Packet request, long timeout) throws IOException {
Short requestId = new Short(getNextRequestId());
Slot responseSlot = new Slot();
requestMap.put(requestId, responseSlot);
Packet header = createHeaderPacket(REQUEST, requestId.shortValue());
Packet packet = AppendedPacket.join(header, request);
synchronized(writeMutex) {
super.write(packet);
}
try {
if( timeout == WAIT_FOREVER_TIMEOUT ) {
return (Packet) responseSlot.take();
} else if (timeout == NO_WAIT_TIMEOUT ) {
return (Packet) responseSlot.poll(1);
} else {
return (Packet) responseSlot.poll(timeout);
}
} catch (InterruptedException e) {
throw new InterruptedIOException(e.getMessage());
} finally {
requestMap.remove(requestId);
}
}
private Packet createHeaderPacket(byte type, short requestId) throws IOException {
ByteArrayPacket header = new ByteArrayPacket(new byte[]{3});
PacketData data = new PacketData(header);
data.writeByte(type);
data.writeShort(requestId);
header.flip();
return header;
}
public void setRequestListener(RequestListener requestListener) throws IOException {
this.requestListener = requestListener;
}
public RequestListener getRequestListener() {
return requestListener;
}
}