1 /* 2 * Licensed to the Apache Software Foundation (ASF) under one 3 * or more contributor license agreements. See the NOTICE file 4 * distributed with this work for additional information 5 * regarding copyright ownership. The ASF licenses this file 6 * to you under the Apache License, Version 2.0 (the 7 * "License"); you may not use this file except in compliance 8 * with the License. You may obtain a copy of the License at 9 * 10 * http://www.apache.org/licenses/LICENSE-2.0 11 * 12 * Unless required by applicable law or agreed to in writing, software 13 * distributed under the License is distributed on an "AS IS" BASIS, 14 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 15 * See the License for the specific language governing permissions and 16 * limitations under the License. 17 */ 18 19 package org.apache.giraph.master; 20 21 import org.apache.giraph.reducers.ReduceOperation; 22 import org.apache.hadoop.io.Writable; 23 24 /** 25 * Master compute can access reduce and broadcast methods 26 * through this interface, from masterCompute method. 27 */ 28 public interface MasterGlobalCommUsageAggregators { 29 /** 30 * Register reducer to be reduced in the next worker computation, 31 * using given name and operations. 32 * @param name Name of the reducer 33 * @param reduceOp Reduce operations 34 * @param <S> Single value type 35 * @param <R> Reduced value type 36 */ 37 <S, R extends Writable> void registerReducer( 38 String name, ReduceOperation<S, R> reduceOp); 39 40 /** 41 * Register reducer to be reduced in the next worker computation, using 42 * given name and operations, starting globally from globalInitialValue. 43 * (globalInitialValue is reduced only once, each worker will still start 44 * from neutral initial value) 45 * 46 * @param name Name of the reducer 47 * @param reduceOp Reduce operations 48 * @param globalInitialValue Global initial value 49 * @param <S> Single value type 50 * @param <R> Reduced value type 51 */ 52 <S, R extends Writable> void registerReducer( 53 String name, ReduceOperation<S, R> reduceOp, R globalInitialValue); 54 55 /** 56 * Get reduced value from previous worker computation. 57 * @param name Name of the reducer 58 * @return Reduced value 59 * @param <R> Reduced value type 60 */ 61 <R extends Writable> R getReduced(String name); 62 63 /** 64 * Broadcast given value to all workers for next computation. 65 * @param name Name of the broadcast object 66 * @param value Value 67 */ 68 void broadcast(String name, Writable value); 69 }