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/*
*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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.apache.qpid.codec;
import java.util.ArrayList;
import org.apache.mina.common.ByteBuffer;
import org.apache.mina.common.SimpleByteBufferAllocator;
import org.apache.qpid.framing.AMQDataBlock;
import org.apache.qpid.framing.AMQDataBlockDecoder;
import org.apache.qpid.framing.AMQFrameDecodingException;
import org.apache.qpid.framing.AMQMethodBodyFactory;
import org.apache.qpid.framing.AMQProtocolVersionException;
import org.apache.qpid.framing.ProtocolInitiation;
import org.apache.qpid.protocol.AMQVersionAwareProtocolSession;
/**
* AMQDecoder delegates the decoding of AMQP either to a data block decoder, or in the case of new connections, to a
* protocol initiation decoder. It is a cumulative decoder, which means that it can accumulate data to decode in the
* buffer until there is enough data to decode.
*
* <p/>One instance of this class is created per session, so any changes or configuration done at run time to the
* decoder will only affect decoding of the protocol session data to which is it bound.
*
* <p/><table id="crc"><caption>CRC Card</caption>
* <tr><th> Responsibilities <th> Collaborations
* <tr><td> Delegate protocol initiation to its decoder. <td> {@link ProtocolInitiation.Decoder}
* <tr><td> Delegate AMQP data to its decoder. <td> {@link AMQDataBlockDecoder}
* <tr><td> Accept notification that protocol initiation has completed.
* </table>
*
* @todo If protocol initiation decoder not needed, then don't create it. Probably not a big deal, but it adds to the
* per-session overhead.
*/
public class AMQDecoder
{
/** Holds the 'normal' AMQP data decoder. */
private AMQDataBlockDecoder _dataBlockDecoder = new AMQDataBlockDecoder();
/** Holds the protocol initiation decoder. */
private ProtocolInitiation.Decoder _piDecoder = new ProtocolInitiation.Decoder();
/** Flag to indicate whether this decoder needs to handle protocol initiation. */
private boolean _expectProtocolInitiation;
private boolean firstDecode = true;
private AMQMethodBodyFactory _bodyFactory;
private ByteBuffer _remainingBuf;
/**
* Creates a new AMQP decoder.
*
* @param expectProtocolInitiation <tt>true</tt> if this decoder needs to handle protocol initiation.
*/
public AMQDecoder(boolean expectProtocolInitiation, AMQVersionAwareProtocolSession session)
{
_expectProtocolInitiation = expectProtocolInitiation;
_bodyFactory = new AMQMethodBodyFactory(session);
}
/**
* Sets the protocol initation flag, that determines whether decoding is handled by the data decoder of the protocol
* initation decoder. This method is expected to be called with <tt>false</tt> once protocol initation completes.
*
* @param expectProtocolInitiation <tt>true</tt> to use the protocol initiation decoder, <tt>false</tt> to use the
* data decoder.
*/
public void setExpectProtocolInitiation(boolean expectProtocolInitiation)
{
_expectProtocolInitiation = expectProtocolInitiation;
}
private static final SimpleByteBufferAllocator SIMPLE_BYTE_BUFFER_ALLOCATOR = new SimpleByteBufferAllocator();
public ArrayList<AMQDataBlock> decodeBuffer(java.nio.ByteBuffer buf) throws AMQFrameDecodingException, AMQProtocolVersionException
{
// get prior remaining data from accumulator
ArrayList<AMQDataBlock> dataBlocks = new ArrayList<AMQDataBlock>();
ByteBuffer msg;
// if we have a session buffer, append data to that otherwise
// use the buffer read from the network directly
if( _remainingBuf != null )
{
_remainingBuf.put(buf);
_remainingBuf.flip();
msg = _remainingBuf;
}
else
{
msg = ByteBuffer.wrap(buf);
}
if (_expectProtocolInitiation
|| (firstDecode
&& (msg.remaining() > 0)
&& (msg.get(msg.position()) == (byte)'A')))
{
if (_piDecoder.decodable(msg.buf()))
{
dataBlocks.add(new ProtocolInitiation(msg.buf()));
}
}
else
{
boolean enoughData = true;
while (enoughData)
{
int pos = msg.position();
enoughData = _dataBlockDecoder.decodable(msg);
msg.position(pos);
if (enoughData)
{
dataBlocks.add(_dataBlockDecoder.createAndPopulateFrame(_bodyFactory, msg));
}
else
{
_remainingBuf = SIMPLE_BYTE_BUFFER_ALLOCATOR.allocate(msg.remaining(), false);
_remainingBuf.setAutoExpand(true);
_remainingBuf.put(msg);
}
}
}
if(firstDecode && dataBlocks.size() > 0)
{
firstDecode = false;
}
return dataBlocks;
}
}
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