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Diffstat (limited to 'qpid/java/common/src/main/java/org/apache/qpid/codec/AMQDecoder.java')
| -rw-r--r-- | qpid/java/common/src/main/java/org/apache/qpid/codec/AMQDecoder.java | 340 |
1 files changed, 340 insertions, 0 deletions
diff --git a/qpid/java/common/src/main/java/org/apache/qpid/codec/AMQDecoder.java b/qpid/java/common/src/main/java/org/apache/qpid/codec/AMQDecoder.java new file mode 100644 index 0000000000..281c0761d9 --- /dev/null +++ b/qpid/java/common/src/main/java/org/apache/qpid/codec/AMQDecoder.java @@ -0,0 +1,340 @@ +/* + * + * 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.IoSession; +import org.apache.mina.common.SimpleByteBufferAllocator; +import org.apache.mina.filter.codec.CumulativeProtocolDecoder; +import org.apache.mina.filter.codec.ProtocolDecoderOutput; + +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 extends CumulativeProtocolDecoder +{ + + private static final String BUFFER = AMQDecoder.class.getName() + ".Buffer"; + + /** 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); + } + + /** + * Delegates decoding AMQP from the data buffer that Mina has retrieved from the wire, to the data or protocol + * intiation decoders. + * + * @param session The Mina session. + * @param in The raw byte buffer. + * @param out The Mina object output gatherer to write decoded objects to. + * + * @return <tt>true</tt> if the data was decoded, <tt>false<tt> if more is needed and the data should accumulate. + * + * @throws Exception If the data cannot be decoded for any reason. + */ + protected boolean doDecode(IoSession session, ByteBuffer in, ProtocolDecoderOutput out) throws Exception + { + + boolean decoded; + if (_expectProtocolInitiation + || (firstDecode + && (in.remaining() > 0) + && (in.get(in.position()) == (byte)'A'))) + { + decoded = doDecodePI(session, in, out); + } + else + { + decoded = doDecodeDataBlock(session, in, out); + } + if(firstDecode && decoded) + { + firstDecode = false; + } + return decoded; + } + + /** + * Decodes AMQP data, delegating the decoding to an {@link AMQDataBlockDecoder}. + * + * @param session The Mina session. + * @param in The raw byte buffer. + * @param out The Mina object output gatherer to write decoded objects to. + * + * @return <tt>true</tt> if the data was decoded, <tt>false<tt> if more is needed and the data should accumulate. + * + * @throws Exception If the data cannot be decoded for any reason. + */ + protected boolean doDecodeDataBlock(IoSession session, ByteBuffer in, ProtocolDecoderOutput out) throws Exception + { + int pos = in.position(); + boolean enoughData = _dataBlockDecoder.decodable(in.buf()); + in.position(pos); + if (!enoughData) + { + // returning false means it will leave the contents in the buffer and + // call us again when more data has been read + return false; + } + else + { + _dataBlockDecoder.decode(session, in, out); + + return true; + } + } + + /** + * Decodes an AMQP initiation, delegating the decoding to a {@link ProtocolInitiation.Decoder}. + * + * @param session The Mina session. + * @param in The raw byte buffer. + * @param out The Mina object output gatherer to write decoded objects to. + * + * @return <tt>true</tt> if the data was decoded, <tt>false<tt> if more is needed and the data should accumulate. + * + * @throws Exception If the data cannot be decoded for any reason. + */ + private boolean doDecodePI(IoSession session, ByteBuffer in, ProtocolDecoderOutput out) throws Exception + { + boolean enoughData = _piDecoder.decodable(in.buf()); + if (!enoughData) + { + // returning false means it will leave the contents in the buffer and + // call us again when more data has been read + return false; + } + else + { + ProtocolInitiation pi = new ProtocolInitiation(in.buf()); + out.write(pi); + + return true; + } + } + + /** + * 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; + } + + + /** + * Cumulates content of <tt>in</tt> into internal buffer and forwards + * decoding request to {@link #doDecode(IoSession, ByteBuffer, ProtocolDecoderOutput)}. + * <tt>doDecode()</tt> is invoked repeatedly until it returns <tt>false</tt> + * and the cumulative buffer is compacted after decoding ends. + * + * @throws IllegalStateException if your <tt>doDecode()</tt> returned + * <tt>true</tt> not consuming the cumulative buffer. + */ + public void decode( IoSession session, ByteBuffer in, + ProtocolDecoderOutput out ) throws Exception + { + ByteBuffer buf = ( ByteBuffer ) session.getAttribute( BUFFER ); + // if we have a session buffer, append data to that otherwise + // use the buffer read from the network directly + if( buf != null ) + { + buf.put( in ); + buf.flip(); + } + else + { + buf = in; + } + + for( ;; ) + { + int oldPos = buf.position(); + boolean decoded = doDecode( session, buf, out ); + if( decoded ) + { + if( buf.position() == oldPos ) + { + throw new IllegalStateException( + "doDecode() can't return true when buffer is not consumed." ); + } + + if( !buf.hasRemaining() ) + { + break; + } + } + else + { + break; + } + } + + // if there is any data left that cannot be decoded, we store + // it in a buffer in the session and next time this decoder is + // invoked the session buffer gets appended to + if ( buf.hasRemaining() ) + { + storeRemainingInSession( buf, session ); + } + else + { + removeSessionBuffer( session ); + } + } + + /** + * Releases the cumulative buffer used by the specified <tt>session</tt>. + * Please don't forget to call <tt>super.dispose( session )</tt> when + * you override this method. + */ + public void dispose( IoSession session ) throws Exception + { + removeSessionBuffer( session ); + } + + private void removeSessionBuffer(IoSession session) + { + ByteBuffer buf = ( ByteBuffer ) session.getAttribute( BUFFER ); + if( buf != null ) + { + buf.release(); + session.removeAttribute( BUFFER ); + } + } + + private static final SimpleByteBufferAllocator SIMPLE_BYTE_BUFFER_ALLOCATOR = new SimpleByteBufferAllocator(); + + private void storeRemainingInSession(ByteBuffer buf, IoSession session) + { + ByteBuffer remainingBuf = SIMPLE_BYTE_BUFFER_ALLOCATOR.allocate( buf.remaining(), false ); + remainingBuf.setAutoExpand( true ); + remainingBuf.put( buf ); + session.setAttribute( BUFFER, remainingBuf ); + } + + 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; + } +} |