com.almende.eve.algorithms.DAAValueBean.java Source code

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Here is the source code for com.almende.eve.algorithms.DAAValueBean.java

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/*
 * Copyright: Almende B.V. (2014), Rotterdam, The Netherlands
 * License: The Apache Software License, Version 2.0
 */
package com.almende.eve.algorithms;

import java.util.Arrays;

import org.joda.time.DateTime;

import com.fasterxml.jackson.annotation.JsonIgnore;

/**
 * The Class ValueBean.
 */
public class DAAValueBean {
    protected int evictionFactor = 10;
    protected int width = 0;
    protected double offset = 0.0;
    protected double[] valueArray = null;
    protected long[] ttlArray = null;

    /**
     * Instantiates a new value bean.
     */
    public DAAValueBean() {
    }

    /**
     * Instantiates a new value bean.
     *
     * @param width
     *            the width
     * @param evictionFactor
     *            the eviction factor
     */
    public DAAValueBean(final int width, final int evictionFactor) {
        this.width = width;
        this.evictionFactor = evictionFactor;
        valueArray = new double[width];
        ttlArray = new long[width];
    }

    /**
     * Gets the eviction factor.
     *
     * @return the eviction factor
     */
    public int getEvictionFactor() {
        return evictionFactor;
    }

    /**
     * Sets the eviction factor.
     *
     * @param evictionFactor
     *            the new eviction factor
     */
    public void setEvictionFactor(int evictionFactor) {
        this.evictionFactor = evictionFactor;
    }

    /**
     * Gets the width.
     *
     * @return the width
     */
    public int getWidth() {
        return width;
    }

    /**
     * Sets the width.
     *
     * @param width
     *            the new width
     */
    public void setWidth(int width) {
        this.width = width;
    }

    /**
     * Gets the value array.
     *
     * @return the value array
     */
    public double[] getValueArray() {
        return valueArray;
    }

    /**
     * Sets the value array.
     *
     * @param valueArray
     *            the new value array
     */
    public void setValueArray(final double[] valueArray) {
        this.valueArray = valueArray;
    }

    /**
     * Gets the ttl array.
     *
     * @return the ttl array
     */
    public long[] getTtlArray() {
        return ttlArray;
    }

    /**
     * Sets the ttl array.
     *
     * @param ttlArray
     *            the new ttl array
     */
    public void setTtlArray(final long[] ttlArray) {
        this.ttlArray = ttlArray;
    }

    /**
     * Gets the offset.
     *
     * @return the offset
     */
    @JsonIgnore
    public double getOffset() {
        return offset;
    }

    /**
     * Compute sum.
     *
     * @return the double
     */
    public Double computeSum() {
        return (1.0 / computeMean());
    }

    private double computeMean() {
        double result = 0.0;
        for (double i : valueArray) {
            result += Math.abs(i);
        }
        return result / width;
    }

    /**
     * Generate the random array to represent this value;.
     *
     * @param value
     *            the value
     * @return the value bean
     */
    public DAAValueBean generate(final double value) {
        if (value <= 0.0) {
            Arrays.fill(valueArray, Double.MAX_VALUE);
        } else {
            for (int i = 0; i < width; i++) {
                Double expRand = -Math.log(Math.random()) / value;
                valueArray[i] = expRand;
            }
            // Noise cancelation:
            final Double mean = computeMean();
            final Double goal = 1.0 / value;
            offset = goal / mean;
            for (int i = 0; i < width; i++) {
                valueArray[i] = valueArray[i] * offset;
            }
        }
        return this;
    }

    /**
     * Sets the ttl.
     *
     * @param initialTTL
     *            the initial ttl
     * @return the DAA value bean
     */
    public DAAValueBean setTTL(final long initialTTL) {
        Arrays.fill(ttlArray, initialTTL);
        return this;
    }

    /**
     * Make this ValueBean represent the minimum with regard to the given other.
     * Returns reference to itself, for chaining.
     *
     * @param other
     *            the other
     * @return the value bean
     * @throws IllegalArgumentException
     *             the illegal argument exception
     */
    public DAAValueBean minimum(final DAAValueBean other) throws IllegalArgumentException {
        if (this.width != other.width) {
            throw new IllegalArgumentException(
                    "ValueBeans aren't of the same length:(" + this.width + "/" + other.width + ")!");
        }
        for (int i = 0; i < width; i++) {
            if (other.valueArray[i] == valueArray[i]) {
                ttlArray[i] = Math.max(ttlArray[i], other.ttlArray[i]);
            } else {
                ttlArray[i] = Math.min(ttlArray[i], other.ttlArray[i]);
                if (other.valueArray[i] < valueArray[i]) {
                    valueArray[i] = other.valueArray[i];
                    ttlArray[i] = other.ttlArray[i];
                }
            }
            final long now = DateTime.now().getMillis();
            if (ttlArray[i] < now && other.ttlArray[i] > now) {
                valueArray[i] = other.valueArray[i];
                ttlArray[i] = other.ttlArray[i];
            }
        }
        return this;
    }

    /**
     * Avg ttl.
     *
     * @return the int
     */
    public long avgTTL() {
        long res = 0;
        for (int i = 0; i < ttlArray.length; i++) {
            res += ttlArray[i];
        }
        return res / ttlArray.length;
    }
}