/*

  * 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.giraph.block_app.framework.piece.global_comm;

 import org.apache.giraph.block_app.framework.api.BlockMasterApi;

 import org.apache.giraph.master.MasterGlobalCommUsage;

 /**

  * Handle to a reducer.

  *

  * @param <S> Single value type

  * @param <R> Reduced value type

  */

 public interface ReducerHandle<S, R> {

   /** Reduce single value */

   void reduce(S valueToReduce);

   /** Get reduced value */

   R getReducedValue(MasterGlobalCommUsage master);

   /**

    * Broadcast reduced value from master

    *

    * @return Handle to the broadcasted value.

    */

   BroadcastHandle<R> broadcastValue(BlockMasterApi master);

 }