Tomcat example source code file (TcpPingInterceptor.java)

This example Tomcat source code file (TcpPingInterceptor.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

atomicinteger, channeldata, channelexception, channelexception, channelinterceptor, pingthread, pingthread, received, tcp, tcp, tcpfailuredetector, unable, util, weakreference, weakreference

The Tomcat TcpPingInterceptor.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.group.interceptors;

import java.lang.ref.WeakReference;
import java.util.Arrays;
import java.util.concurrent.atomic.AtomicInteger;

import org.apache.catalina.tribes.ChannelException;
import org.apache.catalina.tribes.ChannelInterceptor;
import org.apache.catalina.tribes.ChannelMessage;
import org.apache.catalina.tribes.Member;
import org.apache.catalina.tribes.group.ChannelInterceptorBase;
import org.apache.catalina.tribes.io.ChannelData;

/**
 * 
 * Sends a ping to all members.
 * Configure this interceptor with the TcpFailureDetector below it,
 * and the TcpFailureDetector will act as the membership guide.
 * @author Filip Hanik
 * @version 1.0
 */

public class TcpPingInterceptor extends ChannelInterceptorBase {
    
    protected static org.apache.juli.logging.Log log = 
        org.apache.juli.logging.LogFactory.getLog(TcpPingInterceptor.class);
    
    protected static byte[] TCP_PING_DATA = new byte[] {
        79, -89, 115, 72, 121, -33, 67, -55, -97, 111, -119, -128, -95, 91, 7, 20,
        125, -39, 82, 91, -21, -33, 67, -102, -73, 126, -66, -113, -127, 103, 30, -74,
        55, 21, -66, -121, 69, 33, 76, -88, -65, 10, 77, 19, 83, 56, 21, 50,
        85, -10, -108, -73, 58, -33, 33, 120, -111, 4, 125, -41, 114, -124, -64, -43};  

    protected long interval = 1000; //1 second

    protected boolean useThread = false;
    protected boolean staticOnly = false;
    protected boolean running = true;
    protected PingThread thread = null;
    protected static AtomicInteger cnt = new AtomicInteger(0);
    
    WeakReference<TcpFailureDetector> failureDetector = null;
    WeakReference<StaticMembershipInterceptor> staticMembers = null;
    
    public synchronized void start(int svc) throws ChannelException {
        super.start(svc);
        running = true;
        if ( thread == null ) {
            thread = new PingThread();
            thread.setDaemon(true);
            thread.setName("TcpPingInterceptor.PingThread-"+cnt.addAndGet(1));
            thread.start();
        }
        
        //acquire the interceptors to invoke on send ping events
        ChannelInterceptor next = getNext();
        while ( next != null ) {
            if ( next instanceof TcpFailureDetector ) 
                failureDetector = new WeakReference<TcpFailureDetector>((TcpFailureDetector)next);
            if ( next instanceof StaticMembershipInterceptor ) 
                staticMembers = new WeakReference<StaticMembershipInterceptor>((StaticMembershipInterceptor)next);
            next = next.getNext();
        }
        
    }
    
    public void stop(int svc) throws ChannelException {
        running = false;
        if ( thread != null ) thread.interrupt();
        thread = null;
        super.stop(svc);
    }
    
    public void heartbeat() {
        super.heartbeat();
        if (!getUseThread()) sendPing();
    }

    public long getInterval() {
        return interval;
    }

    public void setInterval(long interval) {
        this.interval = interval;
    }

    public void setUseThread(boolean useThread) {
        this.useThread = useThread;
    }

    public void setStaticOnly(boolean staticOnly) {
        this.staticOnly = staticOnly;
    }

    public boolean getUseThread() {
        return useThread;
    }

    public boolean getStaticOnly() {
        return staticOnly;
    }

    protected void sendPing() {
        if (failureDetector.get()!=null) {
            //we have a reference to the failure detector
            //piggy back on that dude
            failureDetector.get().checkMembers(true);
        }else {
            if (staticOnly && staticMembers.get()!=null) {
                sendPingMessage(staticMembers.get().getMembers());
            } else {
                sendPingMessage(getMembers());
            }
        }
    }

    protected void sendPingMessage(Member[] members) {
        if ( members == null || members.length == 0 ) return;
        ChannelData data = new ChannelData(true);//generates a unique Id
        data.setAddress(getLocalMember(false));
        data.setTimestamp(System.currentTimeMillis());
        data.setOptions(getOptionFlag());
        try {
            super.sendMessage(members, data, null);
        }catch (ChannelException x) {
            log.warn("Unable to send TCP ping.",x);
        }
    }
    
    public void messageReceived(ChannelMessage msg) {
        //catch incoming 
        boolean process = true;
        if ( okToProcess(msg.getOptions()) ) {
            //check to see if it is a ping message, if so, process = false
            process = ( (msg.getMessage().getLength() != TCP_PING_DATA.length) ||
                        (!Arrays.equals(TCP_PING_DATA,msg.getMessage().getBytes()) ) );
        }//end if

        //ignore the message, it doesnt have the flag set
        if ( process ) super.messageReceived(msg);
        else if ( log.isDebugEnabled() ) log.debug("Received a TCP ping packet:"+msg);
    }//messageReceived
    
    protected class PingThread extends Thread {
        public void run() {
            while (running) {
                try {
                    sleep(interval);
                    sendPing();
                }catch ( InterruptedException ix ) {
                    interrupted();
                }catch ( Exception x )  {
                    log.warn("Unable to send ping from TCP ping thread.",x);
                }
            }
        }
    }

    
    

}