hibench.ZipfRandom.java Source code

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Here is the source code for hibench.ZipfRandom.java

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/**
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.
 */

package hibench;

import org.apache.hadoop.mapred.JobConf;

public class ZipfRandom extends RandSimulate {

    public int agents;
    public int reds;
    public long agentelems;
    public double exponent;

    ZipfRandom(int numAgents, int numReds, long numElems, double exp) {
        type = RandType.ZIPFIAN;
        agents = numAgents;
        reds = numReds;
        elems = numElems;
        exponent = exp;

        agentelems = (long) Math.ceil(elems * 1.0 / agents);
    }

    @Override
    public double massfunc(double var) {
        return 1.0 / Math.pow(var, exponent);
    }

    @Override
    public void setVirtElems(long numVirtElems) {
        velems = numVirtElems;
    }

    public double estimateZipfSum() {
        double p0 = 1, x0 = 1, x1, p1, estSum = 0, logstep = 1.5;

        /***
         * Estimate scale, sum, and required space to simulate zipf sampling 
         */
        do {
            x1 = Math.ceil(x0 * logstep);
            p1 = massfunc(x1);
            estSum = estSum + (p0 + p1) * (x1 - x0) / 2.0;

            x0 = x1;
            p0 = p1;
        } while (x0 <= elems);

        return estSum;
    }

    @Override
    public void calcScale(long samples, double zoom) {

        samps = samples;
        ratio = zoom;

        double estSum = estimateZipfSum();

        double estScale = Math.ceil(1.0 / massfunc(elems));
        double estSpace = estScale * estSum;

        double limit = ratio * samps;
        if (MAX_SPACE < limit) {
            limit = MAX_SPACE;
        }

        if (limit < estSpace) {
            estSpace = limit;
        }

        scale = estSpace / estSum;
    }

    public void setJobConf(JobConf job) {
        job.setInt("agents", agents);
        job.setLong("elems", elems);
        job.setLong("agentelems", agentelems);
        job.setFloat("exponent", (float) exponent);
        job.setFloat("scale", (float) scale);
    }

    public String debugInfo() {

        return "[elems: " + elems + "] [velems: " + velems + "] [samps: " + samps + "] [ratio: " + ratio
                + "] [agentelems: " + agentelems + "] [exponent: " + exponent + "] [scale: " + scale + "]";
    }
}