nz.net.orcon.kanban.automation.ClusterManagerImpl.java Source code

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Here is the source code for nz.net.orcon.kanban.automation.ClusterManagerImpl.java

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/**
 * GRAVITY WORKFLOW AUTOMATION
 * (C) Copyright 2015 Orcon Limited
 * 
 * This file is part of Gravity Workflow Automation.
 *
 * Gravity Workflow Automation is free software: you can redistribute it 
 * and/or modify it under the terms of the GNU General Public License as 
 * published by the Free Software Foundation, either version 3 of the License,
 * or (at your option) any later version.
 *
 * Gravity Workflow Automation is distributed in the hope that it will be 
 * useful, but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *    
 * You should have received a copy of the GNU General Public License
 * along with Gravity Workflow Automation.  
 * If not, see <http://www.gnu.org/licenses/>. 
 */

package nz.net.orcon.kanban.automation;

import javax.jms.Message;
import javax.jms.ObjectMessage;

import nz.net.orcon.kanban.model.Coup;
import nz.net.orcon.kanban.model.IdRequest;
import nz.net.orcon.kanban.model.IdResponse;

import org.apache.commons.lang.RandomStringUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.jms.core.JmsTemplate;
import org.springframework.scheduling.annotation.Scheduled;

/**
 * The purpose of the Cluster manager is to manage all the functions that need to be
 * coordinated across the Cluster.
 * 
 * - Invalidation of Caches.
 * - Phase Updates
 * - Getting Identifiers.
 * - Master Server Protocol
 * 
 * @author peter
 *
 */
public class ClusterManagerImpl implements ClusterManager {

    private static final Logger LOG = LoggerFactory.getLogger(ClusterManagerImpl.class);

    private boolean leader;

    private long startTime = System.currentTimeMillis();

    private String serverId = RandomStringUtils.random(10, true, true);

    @Autowired
    @Qualifier("idJmsTemplate")
    private JmsTemplate idTemplate;

    @Autowired
    @Qualifier("idSyncReceiver")
    private SyncReceive idSyncReceiever;

    @Autowired
    JcrObserver jcrObserver;

    @Autowired
    TimerManager timerManager;

    public Long getId(String path, String field) throws Exception {
        if (LOG.isDebugEnabled()) {
            LOG.debug("Generating ID from " + path + "." + field);
        }

        Message message = requestId(path, field);

        if (message == null) {
            executeChallenge();
            message = requestId(path, field);
        }

        ObjectMessage objectMessage = (ObjectMessage) message;
        IdResponse idResponse = (IdResponse) objectMessage.getObject();
        return idResponse.getId();
    }

    private Message requestId(String path, String field) {
        String requestId = RandomStringUtils.random(10, true, true);
        SyncMessage idSync = idSyncReceiever.register(requestId);

        IdRequest request = new IdRequest();
        request.setField(field);
        request.setPath(path);
        request.setRequestId(requestId);
        idTemplate.convertAndSend(request);

        return idSync.receiveMessage(10000l);
    }

    public String getIdString(String path, String field, String prefix) throws Exception {
        Long id = getId(path, field);
        return prefix + id.toString();
    }

    /**
     * Note that this method is simply a wrapper to eat the return value of executeChallenge.
     * This is needed to be able to schedule the task.
     * 
     * @throws Exception
     */
    @Scheduled(fixedDelay = 30000l)
    public void pollLeader() throws Exception {
        if (!isLeader()) {
            this.executeChallenge();
        }
    }

    public synchronized boolean executeChallenge() throws Exception {

        SyncMessage coupSync = idSyncReceiever.register(this.serverId);

        Coup coup = new Coup();
        coup.setRequestId(this.serverId);
        coup.setCoupTime(this.startTime);

        idTemplate.convertAndSend(coup);

        if (LOG.isDebugEnabled()) {
            LOG.debug("Sending Heatbeat: " + this.serverId + ", Time: " + coup.getCoupTime() + ", ID: "
                    + coup.getRequestId());
        }

        Message coupMessage = coupSync.receiveMessage(10000l);
        boolean newLeader = (coupMessage == null);

        if (isLeader() != newLeader) {
            if (newLeader) {
                LOG.warn("FAILOVER: Node promoted to MASTER.");
                setLeader(true);
                this.jcrObserver.start();
                this.timerManager.startup();
            } else {
                LOG.warn("FAILOVER: Node demoted to worker.");
                setLeader(false);
                this.jcrObserver.stop();
                this.timerManager.stopAll();
            }
        }

        return isLeader();
    }

    public synchronized void setLeader(boolean leader) {
        this.leader = leader;
    }

    public synchronized boolean isLeader() {
        return leader;
    }

    public long getStartTime() {
        return startTime;
    }

    public String getServerId() {
        return serverId;
    }

}