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 package org.apache.giraph.function; 19 20 /** 21 * Default object holder, intermediary between producers and consumers. 22 * 23 * Holds value in memory, so can be used only when producer and consumer 24 * are in the same context. 25 * 26 * Useful when value is set on the master, and later read in block logic 27 * (RepeatUntilBlock), or in a different Piece, either on worker or master. 28 * If it is read within the same piece - just use local field. 29 * 30 * @param <T> Type of object to hold. 31 */ 32 public class ObjectHolder<T> implements Supplier<T>, Consumer<T> { 33 /** value */ 34 private T value; 35 36 /** 37 * Constructor 38 * @param value initial value 39 */ 40 public ObjectHolder(T value) { 41 this.value = value; 42 } 43 44 /** Constructor */ 45 public ObjectHolder() { 46 } 47 48 @Override 49 public T get() { 50 return value; 51 } 52 53 @Override 54 public void apply(T value) { 55 this.value = value; 56 } 57 58 @Override 59 public String toString() { 60 return getClass() + " [value=" + value + "]"; 61 } 62 }