/*
* Copyright (C) 2008 Trustin Heuiseung Lee
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, 5th Floor, Boston, MA 02110-1301 USA
*/
package net.gleamynode.netty.handler.codec.frame;
import static net.gleamynode.netty.channel.Channels.*;
import net.gleamynode.netty.buffer.ChannelBuffer;
import net.gleamynode.netty.buffer.ChannelBuffers;
import net.gleamynode.netty.channel.Channel;
import net.gleamynode.netty.channel.ChannelHandlerContext;
import net.gleamynode.netty.channel.ChannelPipelineCoverage;
import net.gleamynode.netty.channel.ChannelStateEvent;
import net.gleamynode.netty.channel.ExceptionEvent;
import net.gleamynode.netty.channel.MessageEvent;
import net.gleamynode.netty.channel.SimpleChannelHandler;
/**
* @author The Netty Project (netty@googlegroups.com)
* @author Trustin Lee (trustin@gmail.com)
*
* @version $Rev:231 $, $Date:2008-06-12 16:44:50 +0900 (목, 12 6월 2008) $
*
*/
@ChannelPipelineCoverage("one")
public abstract class FrameDecoder extends SimpleChannelHandler {
private final ChannelBuffer cumulation = ChannelBuffers.dynamicBuffer();
@Override
public void messageReceived(
ChannelHandlerContext ctx, MessageEvent e) throws Exception {
Object m = e.getMessage();
if (!(m instanceof ChannelBuffer)) {
ctx.sendUpstream(e);
return;
}
ChannelBuffer input = (ChannelBuffer) m;
if (!input.isReadable()) {
return;
}
ChannelBuffer cumulation = this.cumulation;
cumulation.discardReadBytes();
cumulation.writeBytes(input);
callDecode(ctx, e.getChannel());
}
@Override
public void channelDisconnected(
ChannelHandlerContext ctx, ChannelStateEvent e) throws Exception {
cleanup(ctx, e);
}
@Override
public void exceptionCaught(
ChannelHandlerContext ctx, ExceptionEvent e) throws Exception {
ctx.sendUpstream(e);
}
protected abstract Object decode(
ChannelHandlerContext ctx, Channel channel, ChannelBuffer buffer) throws Exception;
private void callDecode(ChannelHandlerContext context, Channel channel) throws Exception {
while (cumulation.isReadable()) {
int oldReaderIndex = cumulation.readerIndex();
Object frame = decode(context, channel, cumulation);
if (frame == null) {
if (oldReaderIndex == cumulation.readerIndex()) {
// Seems like more data is required.
// Let's wait for the next notification.
break;
} else {
// Previous data has been discarded.
// Probably it's reading on.
continue;
}
} else if (oldReaderIndex == cumulation.readerIndex()) {
throw new IllegalStateException(
"decode() method must read at least one byte " +
"if it returned a frame.");
}
fireMessageReceived(context, channel, frame);
}
}
private void cleanup(ChannelHandlerContext ctx, ChannelStateEvent e)
throws Exception {
if (cumulation.isReadable()) {
// Make sure all frames were read before notifying a closed channel.
callDecode(ctx, e.getChannel());
if (cumulation.isReadable()) {
// and send the remainders too if necessary.
fireMessageReceived(
ctx, e.getChannel(), cumulation.readBytes(cumulation.readableBytes()));
}
}
ctx.sendUpstream(e);
}
}