/***********************************************************************************************************************
* Copyright (C) 2010-2013 by the Stratosphere project (http://stratosphere.eu)
*
* 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 eu.stratosphere.pact.runtime.hash.util;
/**
* Takes the last m bits of a hash as bucket number
*
*
*/
public class LastBitsToRange implements RangeCalculator {
private final int mask;
private final int bucketCount;
/**
* Create object which calculates bucket number according to the last m bits
*
* @param numberOfLastBits
* Number of bits to be used for bucket calculation
*/
public LastBitsToRange(int numberOfLastBits) {
bucketCount = (int) Math.pow(2, numberOfLastBits);
mask = bucketCount - 1;
}
@Override
public int getBucket(int hash) {
return hash & mask;
}
public int getBucketCount() {
return bucketCount;
}
}