com.bigdata.service.AbstractServiceLoadHelper Maven / Gradle / Ivy

Go to download
package com.bigdata.service;

import java.util.UUID;
import java.util.concurrent.TimeUnit;


/**
 * Base class for abstract implementations with integration points for the
 * {@link LoadBalancerService}.
 * 
 * @author Bryan Thompson
 * @version $Id$
 */
abstract public class AbstractServiceLoadHelper implements IServiceLoadHelper {
    
    final protected long joinTimeout;
    
    /**
     * 
     * @param joinTimeout
     */
    protected AbstractServiceLoadHelper(final long joinTimeout) {
       
        if (joinTimeout <= 0L)
            throw new IllegalArgumentException();
        
        this.joinTimeout = joinTimeout;
        
    }

    /**
     * Return true iff the service is under-utilized.
     * 
     * @param score
     *            The score for the service.
     * @param scores
     *            The set of scores for the known services.
     */
    abstract protected boolean isUnderUtilizedDataService(
            final ServiceScore score, final ServiceScore[] scores);
    
    /**
     * Return true iff the given serviceUUID identifies an
     * active {@link IDataService}.
     * 
     * @param serviceUUID
     *            The service UUID.
     */
    abstract protected boolean isActiveDataService(UUID serviceUUID);

    /**
     * Await the join of an {@link IDataService}.
     * 
     * @param timeout
     *            The timeout.
     * @param unit
     *            The unit for the timeout.
     */
    abstract protected void awaitJoin(long timeout, TimeUnit unit)
            throws InterruptedException;

    /**
     * Return an array of service UUIDs for all of the active
     * {@link IDataService}s that we know about right now (snapshot).
     * 
     * @return The array and never null.
     */
    abstract protected UUID[] getActiveServices();
    
}