org.elasticsearch.cluster.routing.Murmur3HashFunction Maven / Gradle / Ivy
Go to download
Show more of this group Show more artifacts with this name
Show all versions of elasticsearch Show documentation
Show all versions of elasticsearch Show documentation
Elasticsearch subproject :server
/*
* 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);
}
}