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Tomcat example source code file (NioSender.java)

This example Tomcat source code file (NioSender.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Tomcat tags/keywords

bytebuffer, bytebuffer, data, exception, inetsocketaddress, io, ioexception, ioexception, key, net, network, nio, niosender, niosender, selector, unable, unable, util, xbytebuffer

The Tomcat NioSender.java source code

/*
 * 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.tribes.transport.nio;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.nio.channels.SocketChannel;
import java.util.Arrays;

import org.apache.catalina.tribes.io.XByteBuffer;
import org.apache.catalina.tribes.transport.AbstractSender;
import org.apache.catalina.tribes.transport.DataSender;
import org.apache.catalina.tribes.RemoteProcessException;
import java.io.EOFException;
import java.net.*;

/**
 * This class is NOT thread safe and should never be used with more than one thread at a time
 * 
 * This is a state machine, handled by the process method
 * States are:
 * - NOT_CONNECTED -> connect() -> CONNECTED
 * - CONNECTED -> setMessage() -> READY TO WRITE
 * - READY_TO_WRITE -> write() -> READY TO WRITE | READY TO READ
 * - READY_TO_READ -> read() -> READY_TO_READ | TRANSFER_COMPLETE
 * - TRANSFER_COMPLETE -> CONNECTED
 * 
 * @author Filip Hanik
 * @version 1.0
 */
public class NioSender extends AbstractSender implements DataSender{

    protected static org.apache.juli.logging.Log log = org.apache.juli.logging.LogFactory.getLog(NioSender.class);

    
    
    protected Selector selector;    
    protected SocketChannel socketChannel;

    /*
     * STATE VARIABLES *
     */
    protected ByteBuffer readbuf = null;
    protected ByteBuffer writebuf = null;
    protected byte[] current = null;
    protected XByteBuffer ackbuf = new XByteBuffer(128,true);
    protected int remaining = 0;
    protected boolean complete;
    
    protected boolean connecting = false;
    
    public NioSender() {
        super();
        
    }
    
    /**
     * State machine to send data
     * @param key SelectionKey
     * @return boolean
     * @throws IOException
     */
    public boolean process(SelectionKey key, boolean waitForAck) throws IOException {
        int ops = key.readyOps();
        key.interestOps(key.interestOps() & ~ops);
        //in case disconnect has been called
        if ((!isConnected()) && (!connecting)) throw new IOException("Sender has been disconnected, can't selection key.");
        if ( !key.isValid() ) throw new IOException("Key is not valid, it must have been cancelled.");
        if ( key.isConnectable() ) {
            if ( socketChannel.finishConnect() ) {
                completeConnect();
                if ( current != null ) key.interestOps(key.interestOps() | SelectionKey.OP_WRITE);
                return false;
            } else  { 
                //wait for the connection to finish
                key.interestOps(key.interestOps() | SelectionKey.OP_CONNECT);
                return false;
            }//end if
        } else if ( key.isWritable() ) {
            boolean writecomplete = write(key);
            if ( writecomplete ) {
                //we are completed, should we read an ack?
                if ( waitForAck ) {
                    //register to read the ack
                    key.interestOps(key.interestOps() | SelectionKey.OP_READ);
                } else {
                    //if not, we are ready, setMessage will reregister us for another write interest
                    //do a health check, we have no way of verify a disconnected
                    //socket since we don't register for OP_READ on waitForAck=false
                    read(key);//this causes overhead
                    setRequestCount(getRequestCount()+1);
                    return true;
                }
            } else {
                //we are not complete, lets write some more
                key.interestOps(key.interestOps()|SelectionKey.OP_WRITE);
            }//end if
        } else if ( key.isReadable() ) {
            boolean readcomplete = read(key);
            if ( readcomplete ) {
                setRequestCount(getRequestCount()+1);
                return true;
            } else {
                key.interestOps(key.interestOps() | SelectionKey.OP_READ);
            }//end if
        } else {
            //unknown state, should never happen
            log.warn("Data is in unknown state. readyOps="+ops);
            throw new IOException("Data is in unknown state. readyOps="+ops);
        }//end if
        return false;
    }

    private void completeConnect() throws SocketException {
        //we connected, register ourselves for writing
        setConnected(true);
        connecting = false;
        setRequestCount(0);
        setConnectTime(System.currentTimeMillis());
        socketChannel.socket().setSendBufferSize(getTxBufSize());
        socketChannel.socket().setReceiveBufferSize(getRxBufSize());
        socketChannel.socket().setSoTimeout((int)getTimeout());
        socketChannel.socket().setSoLinger(getSoLingerOn(),getSoLingerOn()?getSoLingerTime():0);
        socketChannel.socket().setTcpNoDelay(getTcpNoDelay());
        socketChannel.socket().setKeepAlive(getSoKeepAlive());
        socketChannel.socket().setReuseAddress(getSoReuseAddress());
        socketChannel.socket().setOOBInline(getOoBInline());
        socketChannel.socket().setSoLinger(getSoLingerOn(),getSoLingerTime());
        socketChannel.socket().setTrafficClass(getSoTrafficClass());
    }
    
    

    protected boolean read(SelectionKey key) throws IOException {
        //if there is no message here, we are done
        if ( current == null ) return true;
        int read = socketChannel.read(readbuf);
        //end of stream
        if ( read == -1 ) throw new IOException("Unable to receive an ack message. EOF on socket channel has been reached.");
        //no data read
        else if ( read == 0 ) return false;
        readbuf.flip();
        ackbuf.append(readbuf,read);
        readbuf.clear();
        if (ackbuf.doesPackageExist() ) {
            byte[] ackcmd = ackbuf.extractDataPackage(true).getBytes();
            boolean ack = Arrays.equals(ackcmd,org.apache.catalina.tribes.transport.Constants.ACK_DATA);
            boolean fack = Arrays.equals(ackcmd,org.apache.catalina.tribes.transport.Constants.FAIL_ACK_DATA);
            if ( fack && getThrowOnFailedAck() ) throw new RemoteProcessException("Received a failed ack:org.apache.catalina.tribes.transport.Constants.FAIL_ACK_DATA");
            return ack || fack;
        } else {
            return false;
        }
    }

    
    protected boolean write(SelectionKey key) throws IOException {
        if ( (!isConnected()) || (this.socketChannel==null)) {
            throw new IOException("NioSender is not connected, this should not occur.");
        }
        if ( current != null ) {
            if ( remaining > 0 ) {
                //weve written everything, or we are starting a new package
                //protect against buffer overwrite
                int byteswritten = socketChannel.write(writebuf);
                if (byteswritten == -1 ) throw new EOFException();
                remaining -= byteswritten;
                //if the entire message was written from the buffer
                //reset the position counter
                if ( remaining < 0 ) {
                    remaining = 0;
                }
            }
            return (remaining==0);
        }
        //no message to send, we can consider that complete
        return true;
    }

    /**
     * connect - blocking in this operation
     *
     * @throws IOException
     * @todo Implement this org.apache.catalina.tribes.transport.IDataSender method
     */
    public synchronized void connect() throws IOException {
        if ( connecting ) return;
        connecting = true;
        if ( isConnected() ) throw new IOException("NioSender is already in connected state.");
        if ( readbuf == null ) {
            readbuf = getReadBuffer();
        } else {
            readbuf.clear();
        }
        if ( writebuf == null ) {
            writebuf = getWriteBuffer();
        } else {
            writebuf.clear();
        }
        
        InetSocketAddress addr = new InetSocketAddress(getAddress(),getPort());
        if ( socketChannel != null ) throw new IOException("Socket channel has already been established. Connection might be in progress.");
        socketChannel = SocketChannel.open();
        socketChannel.configureBlocking(false);
        if ( socketChannel.connect(addr) ) {
            completeConnect();
            socketChannel.register(getSelector(), SelectionKey.OP_WRITE, this);
        } else {
            socketChannel.register(getSelector(), SelectionKey.OP_CONNECT, this);
        }
    }
    

    /**
     * disconnect
     *
     * @todo Implement this org.apache.catalina.tribes.transport.IDataSender method
     */
    public void disconnect() {
        try {
            connecting = false;
            setConnected(false);
            if ( socketChannel != null ) {
                try {
                    try {socketChannel.socket().close();}catch ( Exception x){}
                    //error free close, all the way
                    //try {socket.shutdownOutput();}catch ( Exception x){}
                    //try {socket.shutdownInput();}catch ( Exception x){}
                    //try {socket.close();}catch ( Exception x){}
                    try {socketChannel.close();}catch ( Exception x){}
                }finally {
                    socketChannel = null;
                }
            }
        } catch ( Exception x ) {
            log.error("Unable to disconnect NioSender. msg="+x.getMessage());
            if ( log.isDebugEnabled() ) log.debug("Unable to disconnect NioSender. msg="+x.getMessage(),x);
        } finally {
        }

    }
    
    public void reset() {
        if ( isConnected() && readbuf == null) {
            readbuf = getReadBuffer();
        }
        if ( readbuf != null ) readbuf.clear();
        if ( writebuf != null ) writebuf.clear();
        current = null;
        ackbuf.clear();
        remaining = 0;
        complete = false;
        setAttempt(0);
        setRequestCount(0);
        setConnectTime(-1);
    }

    private ByteBuffer getReadBuffer() { 
        return getBuffer(getRxBufSize());
    }
    
    private ByteBuffer getWriteBuffer() {
        return getBuffer(getTxBufSize());
    }

    private ByteBuffer getBuffer(int size) {
        return (getDirectBuffer()?ByteBuffer.allocateDirect(size):ByteBuffer.allocate(size));
    }
    
    /**
    * sendMessage
    *
    * @param data ChannelMessage
    * @throws IOException
    * @todo Implement this org.apache.catalina.tribes.transport.IDataSender method
    */
   public synchronized void setMessage(byte[] data) throws IOException {
       setMessage(data,0,data.length);
   }

   public synchronized void setMessage(byte[] data,int offset, int length) throws IOException {
       if ( data != null ) {
           current = data;
           remaining = length;
           ackbuf.clear();
           if ( writebuf != null ) writebuf.clear();
           else writebuf = getBuffer(length);
           if ( writebuf.capacity() < length ) writebuf = getBuffer(length);
           writebuf.put(data,offset,length);
           //writebuf.rewind();
           //set the limit so that we don't write non wanted data
           //writebuf.limit(length);
           writebuf.flip();
           if (isConnected()) {
               socketChannel.register(getSelector(), SelectionKey.OP_WRITE, this);
           }
       } 
   }
   
   public byte[] getMessage() {
       return current;
   }



    public boolean isComplete() {
        return complete;
    }

    public Selector getSelector() {
        return selector;
    }

    public void setSelector(Selector selector) {
        this.selector = selector;
    }


    public void setComplete(boolean complete) {
        this.complete = complete;
    }
}

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