/*
* Copyright (C) 2015 SoftIndex LLC.
*
* 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 io.datakernel.stream.processor;
/**
* Static utility methods pertaining to Sharders
*/
public final class Sharders {
private Sharders() {
}
/**
* Instance of this class shares objects by hashcode to shards
*/
public static final class HashSharder<K> implements Sharder<K> {
private final int partitions;
/**
* Creates the sharder which contains specified number of parts
*
* @param partitions number of parts
*/
public HashSharder(int partitions) {
assert partitions >= 0;
this.partitions = partitions;
}
/**
* Returns number of part which must contains this object. It counts it with hash code
*
* @param object object for sharding
*/
@Override
public int shard(K object) {
int hash = object.hashCode();
int hashAbs = hash < 0 ? (hash == Integer.MIN_VALUE ? Integer.MAX_VALUE : -hash) : hash;
return hashAbs % partitions;
}
}
}