IATGen.java

/* 
 * Copyright 2016 christopher.metter.
 *
 * Licensed 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 de.uniwuerzburg.info3.ofcprobe.vswitch.trafficgen;

import org.apache.commons.math3.distribution.AbstractRealDistribution;
import org.apache.commons.math3.distribution.ChiSquaredDistribution;
import org.apache.commons.math3.distribution.ExponentialDistribution;
import org.apache.commons.math3.distribution.GammaDistribution;
import org.apache.commons.math3.distribution.IntegerDistribution;
import org.apache.commons.math3.distribution.NormalDistribution;
import org.apache.commons.math3.distribution.PoissonDistribution;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * This Class generates random IAT values after a Set Distribution
 *
 * @author Christopher Metter(christopher.metter@informatik.uni-wuerzburg.de)
 *
 */
public class IATGen {

    /**
     * Debugger
     */
    private static final Logger logger = LoggerFactory.getLogger(IATGen.class);
    /**
     * The Distri
     */
    private AbstractRealDistribution distri;
    /**
     * The other Distri
     */
    private IntegerDistribution intDistri;

    /**
     * Constructor
     *
     * @param distribution Distribution as String
     * @param para1 Parameter 1
     * @param para2 Parameter 2 (only needed when applicable)
     */
    public IATGen(String distribution, double para1, double para2) {

        logger.trace("Distribution selected: {} with Parameters {} & {}", distribution, para1, para2);

        switch (distribution) {
            case "ChiSquared":
                this.distri = new ChiSquaredDistribution(para1);
                break;
            case "Exponential":
                this.distri = new ExponentialDistribution(para1);
                break;
            case "Gamma":
                this.distri = new GammaDistribution(para1, para2);
                break;
            case "Poisson":
                this.intDistri = new PoissonDistribution(para1, para2);
                break;
            default:
                this.distri = new NormalDistribution(para1, para2);
                break;
        }
    }

    /**
     * Gets the next IAT after set Distribution
     *
     * @return next IAT
     */
    public int nextIAT() {
        if (this.distri != null) {
            double sample = this.distri.sample();
            if (sample < 0) {
                sample = sample * -1;
            }
            logger.trace("New SampleValue: {}", (int) sample);
            return (int) sample;
        }

        int sample = this.intDistri.sample();
        if (sample < 0) {
            sample = sample * -1;
        }
        logger.trace("New SampleValue: {}", sample);
        return sample;

    }

}