/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF 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.apache.kafka.streams.kstream;
import org.apache.kafka.common.annotation.InterfaceStability;
/**
* The interface for merging aggregate values for {@link SessionWindows} with the given key.
*
* @param <K> key type
* @param <V> aggregate value type
*/
@InterfaceStability.Unstable
public interface Merger<K, V> {
/**
* Compute a new aggregate from the key and two aggregates.
*
* @param aggKey the key of the record
* @param aggOne the first aggregate
* @param aggTwo the second aggregate
* @return the new aggregate value
*/
V apply(final K aggKey, final V aggOne, final V aggTwo);
}