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This component provides the means to set up a cluster of Neo4j instances that act together as a cluster, providing Master-Slave replication and other features.

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/*
 * Copyright (c) 2002-2016 "Neo Technology,"
 * Network Engine for Objects in Lund AB [http://neotechnology.com]
 *
 * This file is part of Neo4j.
 *
 * Neo4j is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as
 * published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 *
 * This program 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 Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program. If not, see .
 */
package org.neo4j.kernel.ha;

import java.util.concurrent.TimeUnit;

import org.neo4j.kernel.impl.util.JobScheduler;
import org.neo4j.kernel.lifecycle.LifecycleAdapter;
import org.neo4j.logging.Log;
import org.neo4j.logging.LogProvider;

import static org.neo4j.kernel.impl.util.JobScheduler.Groups.pullUpdates;

/**
 * This scheduler is part of slave lifecycle that will schedule periodic pulling on slave switch
 * and turn them off during slave shutdown.
 *
 * @see UpdatePuller
 */
public class UpdatePullerScheduler extends LifecycleAdapter
{
    private final JobScheduler scheduler;
    private final Log log;
    private final UpdatePuller updatePuller;
    private final long pullIntervalMillis;
    private JobScheduler.JobHandle intervalJobHandle;

    public UpdatePullerScheduler( JobScheduler scheduler, LogProvider logProvider, UpdatePuller updatePullingThread,
            long pullIntervalMillis )
    {
        this.scheduler = scheduler;
        this.log = logProvider.getLog( getClass() );
        this.updatePuller = updatePullingThread;
        this.pullIntervalMillis = pullIntervalMillis;
    }

    @Override
    public void init() throws Throwable
    {
        if ( pullIntervalMillis > 0 )
        {
            intervalJobHandle = scheduler.scheduleRecurring( pullUpdates, new Runnable()
            {
                @Override
                public void run()
                {
                    try
                    {
                        updatePuller.pullUpdates();
                    }
                    catch ( InterruptedException e )
                    {
                        log.error( "Pull updates failed", e );
                    }
                }
            }, pullIntervalMillis, pullIntervalMillis, TimeUnit.MILLISECONDS );
        }
    }

    @Override
    public void shutdown() throws Throwable
    {
        if ( intervalJobHandle != null )
        {
            intervalJobHandle.cancel( false );
        }
    }
}