/*
* Licensed to Elasticsearch under one or more contributor
* license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright
* ownership. Elasticsearch licenses this file to you 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 org.elasticsearch.cluster.routing;
import org.apache.lucene.util.StringHelper;
/**
* Hash function based on the Murmur3 algorithm, which is the default as of Elasticsearch 2.0.
*/
public final class Murmur3HashFunction {
private Murmur3HashFunction() {
//no instance
}
public static int hash(String routing) {
final byte[] bytesToHash = new byte[routing.length() * 2];
for (int i = 0; i < routing.length(); ++i) {
final char c = routing.charAt(i);
final byte b1 = (byte) c, b2 = (byte) (c >>> 8);
assert ((b1 & 0xFF) | ((b2 & 0xFF) << 8)) == c; // no information loss
bytesToHash[i * 2] = b1;
bytesToHash[i * 2 + 1] = b2;
}
return hash(bytesToHash, 0, bytesToHash.length);
}
public static int hash(byte[] bytes, int offset, int length) {
return StringHelper.murmurhash3_x86_32(bytes, offset, length, 0);
}
}