1_5/modules/clustering/src/org/apache/axis2/clustering/DefaultLoadBalanceEventHandler.java

/*                                                                             
 * Copyright 2004,2005 The Apache Software Foundation.                         
 *                                                                             
 * Licensed 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.axis2.clustering;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import java.io.IOException;
import java.net.InetAddress;
import java.net.InetSocketAddress;
import java.net.Socket;
import java.net.SocketAddress;
import java.util.ArrayList;
import java.util.List;

/**
 * The default implementation of {@link LoadBalanceEventHandler}
 */
public class DefaultLoadBalanceEventHandler implements LoadBalanceEventHandler {

    private static final Log log = LogFactory.getLog(DefaultLoadBalanceEventHandler.class);
    private List<Member> members = new ArrayList<Member>();

    public void applicationMemberAdded(Member member) {
        Thread th = new Thread(new MemberAdder(member));
        th.setPriority(Thread.MAX_PRIORITY);
        th.start();
    }

    public void applicationMemberRemoved(Member member) {
        log.info("Application member " + member + " left cluster.");
        members.remove(member);
    }

    public List<Member> getMembers() {
        return members;
    }

    private class MemberAdder implements Runnable {

        private final Member member;

        private MemberAdder(Member member) {
            this.member = member;
        }

        public void run() {
            if (members.contains(member)) {
                return;
            }
            if (canConnect(member)) {
                //                try
                //                    Thread.sleep(10000);   // Sleep for sometime to allow complete initialization of the node
                //                } catch (InterruptedException e) {
                //                    e.printStackTrace();
                //                }
                if (!members.contains(member)) {
                    members.add(member);
                }
                log.info("Application member " + member + " joined application cluster");
            } else {
                log.error("Could not add application member " + member);
            }
        }

        /**
         * Before adding a member, we will try to verify whether we can connect to it
         *
         * @param member The member whose connectvity needs to be verified
         * @return true, if the member can be contacted; false, otherwise.
         */
        private boolean canConnect(Member member) {
            if (log.isDebugEnabled()) {
                log.debug("Trying to connect to member " + member + "...");
            }
            for (int retries = 30; retries > 0; retries--) {
                try {
                    InetAddress addr = InetAddress.getByName(member.getHostName());
                    int httpPort = member.getHttpPort();
                    if (log.isDebugEnabled()) {
                        log.debug("HTTP Port=" + httpPort);
                    }
                    if (httpPort != -1) {
                        SocketAddress httpSockaddr = new InetSocketAddress(addr, httpPort);
                        new Socket().connect(httpSockaddr, 10000);
                    }
                    int httpsPort = member.getHttpsPort();
                    if (log.isDebugEnabled()) {
                        log.debug("HTTPS Port=" + httpsPort);
                    }
                    if (httpsPort != -1) {
                        SocketAddress httpsSockaddr = new InetSocketAddress(addr, httpsPort);
                        new Socket().connect(httpsSockaddr, 10000);
                    }
                    return true;
                } catch (IOException e) {
                    if (log.isDebugEnabled()) {
                        log.debug("", e);
                    }
                    String msg = e.getMessage();
                    if (msg.indexOf("Connection refused") == -1 && msg.indexOf("connect timed out") == -1) {
                        log.error("Cannot connect to member " + member, e);
                    }
                    try {
                        Thread.sleep(1000);
                    } catch (InterruptedException ignored) {
                    }
                }
            }
            return false;
        }
    }
}