Main.java Source code

Introduction

Here is the source code for Main.java

Source

//package com.java2s;

public class Main {
    /**
     * <p>
     * Calculates the bucket id the key should be placed in according to the
     * first n bits of the key where n is the power of 2 numBuckets is defined
     * as. F.e if 1024 buckets are defined the first 10 bits of the key will be
     * taken as the index for the actual bucket (2^10 = 1024, 2^9 = 512, ...)
     * </p>
     * 
     * @param key
     *            The 64bit key whose bucket index should be calculated
     * @param numBuckets
     *            The total number of available buckets. This should be a power
     *            of two (e.g. 2, 4, 8, 16, 32, ...)
     * @return The bucket index the key should be in
     */
    public static int getBucketForKey(long key, final int numBuckets) {
        // test if numBuckets is a power of 2
        int exponent = Math.getExponent(numBuckets);
        if (numBuckets != Math.pow(2, exponent))
            throw new IllegalArgumentException("Number of buckets does not correspond to a power of 2!");
        return (int) (key >> (64 - exponent)) + numBuckets / 2;
    }
}