/*
* 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.tinkerpop.gremlin.process.computer;
import java.io.Serializable;
/**
* A MessageCombiner allows two messages in route to the same vertex to be aggregated into a single message.
* Message combining can reduce the number of messages sent between vertices and thus, reduce network traffic.
* Not all messages can be combined and thus, this is an optional feature of a {@link VertexProgram}.
*
* @author Marko A. Rodriguez (http://markorodriguez.com)
*/
public interface MessageCombiner<M> extends Serializable {
/**
* Combine two messages and return a message containing the combination.
* In many instances, it is possible to simply merge the data in the second message into the first message.
* Such an optimization can limit the amount of object creation.
*
* @param messageA the first message
* @param messageB the second message
* @return the combination of the two messages
*/
public M combine(final M messageA, final M messageB);
}