randomroutingpolicy.java

来自「High performance DB query」· Java 代码 · 共 83 行

/*
 * @(#)$Id: RandomRoutingPolicy.java,v 1.7 2004/07/02 23:59:21 huebsch Exp $
 *
 * Copyright (c) 2001-2004 Regents of the University of California.
 * All rights reserved.
 *
 * This file is distributed under the terms in the attached BERKELEY-LICENSE
 * file. If you do not find these files, copies can be found by writing to:
 * Computer Science Division, Database Group, Universite of California,
 * 617 Soda Hall #1776, Berkeley, CA 94720-1776. Attention: Berkeley License
 *
 * Copyright (c) 2003-2004 Intel Corporation. All rights reserved.
 *
 * This file is distributed under the terms in the attached INTEL-LICENSE file.
 * If you do not find these files, copies can be found by writing to:
 * Intel Research Berkeley, 2150 Shattuck Avenue, Suite 1300,
 * Berkeley, CA, 94704.  Attention:  Intel License Inquiry.
 */


package pier.helpers.routingpolicy;

import java.util.ArrayList;
import java.util.HashMap;
import org.apache.log4j.Logger;
import pier.data.Tuple;
import pier.operators.Eddy;
import services.LocalNode;
import services.Output;
import util.BitID;
import util.logging.LogMessage;

/**
 * Class RandomRoutingPolicy
 *
 * Uses the nextOp map from BasicRoutingPolicy, but routes to random op, rather than first
 */
public class RandomRoutingPolicy extends BasicRoutingPolicy {

    private static Logger logger = Logger.getLogger(RandomRoutingPolicy.class);

    /**
     * Constructor RandomRoutingPolicy
     *
     *
     * @param sourceInitMap
     * @param doneReadyMap
     */
    public RandomRoutingPolicy(HashMap sourceInitMap, HashMap doneReadyMap) {
        super(sourceInitMap, doneReadyMap);
    }

    /**
     * Method getNextOperator
     *
     *
     * Based on the ready bits, find
     * the next operator to route to according to the routing policy
     *
     * @param item the tuple to determine the next op for
     * @return the index of the operator to send the tuple to
     */
    public int getNextOperator(Tuple item) {
        if (Output.debuggingEnabled) {
            logger.debug(new LogMessage(new Object[]{
                "getNextOperator for tuple from table: ",
                item.getTableName()}));
        }

        // pull out the array of possible operators - this corresponds exactly to the ready bits, but
        // for simplicity/efficiency at runtime, this is the index into the eddy's operator list
        // The "optimal" operator should be at the front of the list.  In this case, its random
        ArrayList possibleOps = (ArrayList) nextOperatorMap.get(
                                    (BitID) item.getMetadata(Eddy.READY_BITS));

        // randomly pick one of the possible operators
        Integer nextOp = (Integer) possibleOps.get(
                             LocalNode.myRandom.nextInt(possibleOps.size()));

        return nextOp.intValue();
    }
}