ElectionListenerManager.java

/**
 * Copyright 2016 vip.com.
 * <p>
 * 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.
 * </p>
 */

package com.vip.saturn.job.internal.election;

import org.apache.curator.framework.recipes.cache.NodeCacheListener;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.vip.saturn.job.basic.JobScheduler;
import com.vip.saturn.job.internal.listener.AbstractListenerManager;
import com.vip.saturn.job.internal.storage.JobNodePath;

/**
 * 主节点选举监听管理器.
 * 
 * 
 */
public class ElectionListenerManager extends AbstractListenerManager {
	static Logger log = LoggerFactory.getLogger(ElectionListenerManager.class);

    private final LeaderElectionService leaderElectionService;
    
    private boolean isShutdown;

	public ElectionListenerManager(final JobScheduler jobScheduler) {
        super(jobScheduler);
        leaderElectionService = new LeaderElectionService(jobScheduler);
    }
    
    @Override
    public void start() {
        // addDataListener(new LeaderElectionJobListener(), jobConfiguration.getJobName());
        zkCacheManager.addNodeCacheListener(new LeaderElectionJobListener(), JobNodePath.getNodeFullPath(jobName, ElectionNode.LEADER_HOST));
    }
    
    @Override
    public void shutdown() {
    	isShutdown = true;
    	leaderElectionService.shutdown();
    	zkCacheManager.closeNodeCache(JobNodePath.getNodeFullPath(jobName, ElectionNode.LEADER_HOST));
    }
    
    class LeaderElectionJobListener implements NodeCacheListener {
       @Override
	    public void nodeChanged() throws Exception {
           zkCacheManager.getExecutorService().execute(new Runnable() {
               @Override
               public void run() {
                   try {
                       log.debug("[{}] msg=Leader host nodeChanged", jobName);
                       if (isShutdown) {
                           log.debug("[{}] msg=ElectionListenerManager has been shutdown", jobName);
                           return;
                       }
                       if (!leaderElectionService.hasLeader()) {
                           log.info("[{}] msg=Leader crashed, elect a new leader now", jobName);
                           leaderElectionService.leaderElection();
                           log.info("[{}] msg=Leader election completed", jobName);
                       } else {
                           log.debug("[{}] msg=Leader is already existing, unnecessary to election", jobName);
                       }
                   } catch (Throwable t) {
                       log.error(t.getMessage(), t);
                   }
               }
           });
	    }
    }
}