org.jgroups.util.Average Maven / Gradle / Ivy

Go to download

Show more of this group Show more artifacts with this name
Show all versions of wildfly-client-all

This artifact provides a single jar that contains all classes required to use remote Jakarta Enterprise Beans and Jakarta Messaging, including all dependencies. It is intended for use by those not using maven, maven users should just import the Jakarta Enterprise Beans and Jakarta Messaging BOM's instead (shaded JAR's cause lots of problems with maven, as it is very easy to inadvertently end up with different versions on classes on the class path).

There is a newer version: 35.0.1.Final

Show newest version

package org.jgroups.util;

import java.util.concurrent.atomic.AtomicInteger;

/**
 * A class which uses a simple array (of configurable length) to store stats samples. The average is then taken as
 * the sum of all values >= 0 (the array is initialized with -1 values) divided by the number of non -1 values. This is
 * best used in cases where we have a lot of sample data entered by different threads. Each thread picks a random
 * array index and sets the value at the index. This will be an approximation of an average as all values
 * are updated after some time.
 * @author Bela Ban
 * @since  3.4
 */
public class Average {
    protected final long[]  samples;
    protected AtomicInteger index=new AtomicInteger(0);

    public Average() {
        this(64);
    }

    public Average(int size) {
        samples=new long[Util.getNextHigherPowerOfTwo(size)];
        for(int i=0; i < samples.length; i++)
            samples[i]=-1;
    }

    public void add(long sample) {
        // samples[((int)Util.random(samples.length) -1)]=sample;
        int tmp_index=index.getAndIncrement();
        int real_index=tmp_index & (samples.length -1); // fast modulo operation
        samples[real_index]=sample;
        if(tmp_index >= samples.length)
            index.set(0);
    }

    public double getAverage() {
        int  num=0;
        long total=0;
        for(int i=0; i < samples.length; i++) {
            long sample=samples[i];
            if(sample >= 0) {
                num++;
                total+=sample;
            }
        }
        return num > 0? total / (double)num : 0;
    }

    public void clear() {
        for(int i=0; i < samples.length; i++)
            samples[i]=-1;
    }

    public String toString() {
        return String.valueOf(getAverage());
    }
}