Package org.teiid.transport

Source Code of org.teiid.transport.ObjectEncoder

/*
* JBoss, Home of Professional Open Source
*
* Copyright 2008, Red Hat Middleware LLC, and individual contributors
* by the @author tags. See the COPYRIGHT.txt in the distribution for a
* full listing of individual contributors.
*
* This 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 software 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 software; if not, write to the Free
* Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
* 02110-1301 USA, or see the FSF site: http://www.fsf.org.
*/
package org.teiid.transport;

import static org.jboss.netty.buffer.ChannelBuffers.*;
import static org.jboss.netty.channel.Channels.*;

import java.io.BufferedInputStream;
import java.io.InputStream;
import java.io.ObjectInputStream;

import org.jboss.netty.buffer.ChannelBuffer;
import org.jboss.netty.buffer.ChannelBufferOutputStream;
import org.jboss.netty.channel.ChannelDownstreamHandler;
import org.jboss.netty.channel.ChannelEvent;
import org.jboss.netty.channel.ChannelHandlerContext;
import org.jboss.netty.channel.ChannelPipelineCoverage;
import org.jboss.netty.channel.Channels;
import org.jboss.netty.channel.MessageEvent;
import org.jboss.netty.handler.stream.ChunkedInput;
import org.jboss.netty.handler.stream.ChunkedStream;
import org.teiid.core.util.ExternalizeUtil;
import org.teiid.netty.handler.codec.serialization.CompactObjectOutputStream;
import org.teiid.netty.handler.codec.serialization.ObjectDecoderInputStream;


/**
* An encoder which serializes a Java object into a {@link ChannelBuffer}.
* <p>
* Please note that the serialized form this encoder produces is not
* compatible with the standard {@link ObjectInputStream}.  Please use
* {@link ObjectDecoder} or {@link ObjectDecoderInputStream} to ensure the
* interoperability with this encoder.
*
* @author The Netty Project (netty-dev@lists.jboss.org)
* @author Trustin Lee (tlee@redhat.com)
*
* @version $Rev:231 $, $Date:2008-06-12 16:44:50 +0900 (목, 12 6월 2008) $
*
* @apiviz.landmark
* @apiviz.has org.jboss.netty.handler.codec.serialization.ObjectEncoderOutputStream - - - compatible with
*/
@ChannelPipelineCoverage("all")
public class ObjectEncoder implements ChannelDownstreamHandler {
    private static final byte[] LENGTH_PLACEHOLDER = new byte[4];
  private static final int CHUNK_SIZE = (1 << 16) - 1;

    private final int estimatedLength;

    /**
     * Creates a new encoder with the estimated length of 512 bytes.
     */
    public ObjectEncoder() {
        this(512);
    }

    /**
     * Creates a new encoder.
     *
     * @param estimatedLength
     *        the estimated byte length of the serialized form of an object.
     *        If the length of the serialized form exceeds this value, the
     *        internal buffer will be expanded automatically at the cost of
     *        memory bandwidth.  If this value is too big, it will also waste
     *        memory bandwidth.  To avoid unnecessary memory copy or allocation
     *        cost, please specify the properly estimated value.
     */
    public ObjectEncoder(int estimatedLength) {
        if (estimatedLength < 0) {
            throw new IllegalArgumentException(
                    "estimatedLength: " + estimatedLength);
        }
        this.estimatedLength = estimatedLength;
    }
   
    public void handleDownstream(
            final ChannelHandlerContext ctx, ChannelEvent evt) throws Exception {
        if (!(evt instanceof MessageEvent)) {
            ctx.sendDownstream(evt);
            return;
        }

        MessageEvent e = (MessageEvent) evt;
       
        if (e.getMessage() instanceof ChunkedInput) {
            ctx.sendDownstream(evt);
            return;
        }
       
        ChannelBufferOutputStream bout =
            new ChannelBufferOutputStream(dynamicBuffer(
                    estimatedLength, ctx.getChannel().getConfig().getBufferFactory()));
        bout.write(LENGTH_PLACEHOLDER);
        final CompactObjectOutputStream oout = new CompactObjectOutputStream(bout);
        oout.writeObject(e.getMessage());
        ExternalizeUtil.writeCollection(oout, oout.getReferences());
        oout.flush();
        oout.close();

        ChannelBuffer encoded = bout.buffer();
        encoded.setInt(0, encoded.writerIndex() - 4);
        write(ctx, e.getFuture(), encoded, e.getRemoteAddress());
    for (InputStream is : oout.getStreams()) {
      Channels.write(ctx.getChannel(), new AnonymousChunkedStream(new BufferedInputStream(is, CHUNK_SIZE)));
    }
    }
   
    static class AnonymousChunkedStream extends ChunkedStream {

    public AnonymousChunkedStream(InputStream in) {
      super(in, CHUNK_SIZE);
    }
     
    @Override
    public Object nextChunk() throws Exception {
      ChannelBuffer cb = (ChannelBuffer)super.nextChunk();
      int length = cb.capacity();
      ChannelBuffer prefix = wrappedBuffer(new byte[2]);
      prefix.setShort(0, (short)length);
      if (!hasNextChunk()) {
        //append a 0 short
        return wrappedBuffer(prefix, cb, wrappedBuffer(new byte[2]));
      }
     
      return wrappedBuffer(prefix, cb);
    }
   
    }

}
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