container/modules/cluster/src/share/org/apache/catalina/cluster/io/SocketObjectReader.java

/*
 * 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.catalina.cluster.io;


import java.net.Socket;

import org.apache.catalina.cluster.tcp.ClusterData;

/**
 * The object reader object is an object used in conjunction with
 * java.nio TCP messages. This object stores the message bytes in a
 * <code>XByteBuffer</code> until a full package has been received.
 * When a full package has been received, the append method will call messageDataReceived
 * on the callback object associated with this object reader.<BR>
 * This object uses an XByteBuffer which is an extendable object buffer that also allows
 * for message encoding and decoding.
 *
 * @author Filip Hanik
 * @author Peter Rossbach
 * @version $Revision$, $Date$
 * @since 5.5.10
 */
public class SocketObjectReader
{
    private Socket socket;
    private ListenCallback callback;
    private XByteBuffer buffer;

    /**
     * use this socket and callback to receive messages
     * @param socket listener socket
     * @param callback ClusterReceiverBase listener
     */
    public SocketObjectReader( Socket socket,
                               ListenCallback callback)  {
        this.socket = socket;
        this.callback = callback;
        this.buffer = new XByteBuffer();
    }

    
    /**
     * Append new bytes to buffer. 
     * Is message complete receiver send message to callback
     * @see org.apache.catalina.cluster.tcp.ClusterReceiverBase#messageDataReceived(ClusterData)
     * @see XByteBuffer#doesPackageExist()
     * @see XByteBuffer#extractPackage(boolean)
     * @param data new transfer buffer
     * @param off offset
     * @param len length in buffer
     * @return number of messages that sended to callback
     * @throws java.io.IOException
     */
    public int append(byte[] data,int off,int len) throws java.io.IOException {
        if(len > 0)
            buffer.append(data,off,len);
        boolean pkgExists = buffer.doesPackageExist();
        int pkgCnt = 0;
        while ( pkgExists ) {
            ClusterData cdata = buffer.extractPackage(true);
            if(callback.isSendAck())
                callback.sendAck() ;
            callback.messageDataReceived(cdata);
            pkgCnt++;
            pkgExists = buffer.doesPackageExist();
        }
        return pkgCnt;
    }

    
    /**
     * send message to callback
     * @see SocketObjectReader#append(byte[], int, int)
     * @return Count of packages written
     * @throws java.io.IOException
     */
    public int execute() throws java.io.IOException {
        return append(null,0,0);
    }

    /**
     * write data to socket (ack)
     * @see org.apache.catalina.cluster.tcp.SocketReplicationListener#sendAck
     * @param data
     * @return Always zero
     * @throws java.io.IOException
     */
    public int write(byte[] data)
       throws java.io.IOException {
       socket.getOutputStream().write(data);
       return 0;

    }
}