non-aligned ByteBuffers into messages and messages into ByteBuffers. git-svn-id: https://jmonkeyengine.googlecode.com/svn/trunk@7013 75d07b2b-3a1a-0410-a2c5-0572b91ccdca3.0
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/* |
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* Copyright (c) 2011 jMonkeyEngine |
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* All rights reserved. |
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* |
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* Redistribution and use in source and binary forms, with or without |
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* modification, are permitted provided that the following conditions are |
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* met: |
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* |
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* * Redistributions of source code must retain the above copyright |
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* notice, this list of conditions and the following disclaimer. |
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* |
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* * Redistributions in binary form must reproduce the above copyright |
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* notice, this list of conditions and the following disclaimer in the |
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* documentation and/or other materials provided with the distribution. |
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* |
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* * Neither the name of 'jMonkeyEngine' nor the names of its contributors |
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* may be used to endorse or promote products derived from this software |
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* without specific prior written permission. |
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* |
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED |
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* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR |
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR |
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* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, |
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* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, |
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* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR |
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* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF |
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* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING |
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* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS |
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* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
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*/ |
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|
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package com.jme3.network.base; |
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|
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import java.io.IOException; |
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import java.nio.ByteBuffer; |
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import java.util.*; |
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import com.jme3.network.Message; |
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import com.jme3.network.serializing.Serializer; |
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/** |
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* Consolidates the conversion of messages to/from byte buffers |
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* and provides a rolling message buffer. ByteBuffers can be |
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* pushed in and messages will be extracted, accumulated, and |
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* available for retrieval. This is not thread safe and is meant |
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* to be used within a single message processing thread. |
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* |
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* <p>The protocol is based on a simple length + data format |
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* where two bytes represent the (short) length of the data |
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* and the rest is the raw data for the Serializers class.</p> |
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* |
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* @version $Revision$ |
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* @author Paul Speed |
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*/ |
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public class MessageProtocol |
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{ |
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private LinkedList<Message> messages = new LinkedList<Message>(); |
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private ByteBuffer current; |
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private int size; |
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/** |
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* Converts a message to a ByteBuffer using the Serializer |
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* and the (short length) + data protocol. If target is null |
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* then a 32k byte buffer will be created and filled. |
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*/ |
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public static ByteBuffer messageToBuffer( Message message, ByteBuffer target ) |
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{ |
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// Could let the caller pass their own in
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ByteBuffer buffer = target == null ? ByteBuffer.allocate( 32767 + 2 ) : target; |
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try { |
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buffer.position( 2 ); |
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Serializer.writeClassAndObject( buffer, message ); |
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buffer.flip(); |
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short dataLength = (short)(buffer.remaining() - 2); |
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buffer.putShort( dataLength ); |
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buffer.position( 0 ); |
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return buffer; |
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} catch( IOException e ) { |
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throw new RuntimeException( "Error serializing message", e ); |
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} |
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} |
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|
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/** |
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* Retrieves and removes an extracted message from the accumulated buffer |
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* or returns null if there are no more messages. |
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*/ |
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public Message getMessage() |
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{ |
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if( messages.isEmpty() ) { |
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return null; |
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} |
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return messages.removeFirst(); |
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} |
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|
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/** |
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* Adds the specified buffer, extracting the contained messages |
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* and making them available to getMessage(). The left over |
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* data is buffered to be combined with future data. |
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& |
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* @return The total number of queued messages after this call. |
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*/ |
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public int addBuffer( ByteBuffer buffer ) |
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{ |
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// push the data from the buffer into as
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// many messages as we can
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while( buffer.remaining() > 0 ) { |
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if( current == null ) { |
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// We are not currently reading an object so
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// grab the size.
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// Note: this is somewhat limiting... int would
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// be better.
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size = buffer.getShort(); |
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current = ByteBuffer.allocate(size); |
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} |
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if( current.remaining() <= buffer.remaining() ) { |
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// We have at least one complete object so
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// copy what we can into current, create a message,
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// and then continue pulling from buffer.
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// Artificially set the limit so we don't overflow
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int extra = buffer.remaining() - current.remaining(); |
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buffer.limit( buffer.position() + current.remaining() ); |
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// Now copy the data
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current.put( buffer ); |
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current.flip(); |
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// Now set the limit back to a good value
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buffer.limit( buffer.position() + extra ); |
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createMessage( current ); |
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current = null; |
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} else { |
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// Not yet a complete object so just copy what we have
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current.put( buffer ); |
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} |
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} |
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return messages.size(); |
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} |
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/** |
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* Creates a message from the properly sized byte buffer |
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* and adds it to the messages queue. |
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*/ |
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protected void createMessage( ByteBuffer buffer ) |
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{ |
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try { |
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Object obj = Serializer.readClassAndObject( buffer ); |
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Message m = (Message)obj; |
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messages.add(m); |
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} catch( IOException e ) { |
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throw new RuntimeException( "Error deserializing object", e ); |
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} |
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} |
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} |
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