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.edge; 20 21 import org.apache.hadoop.io.NullWritable; 22 import org.apache.hadoop.io.Writable; 23 import org.apache.hadoop.io.WritableComparable; 24 25 /** 26 * Factory for creating Edges 27 */ 28 public class EdgeFactory { 29 /** Do not construct */ 30 private EdgeFactory() { } 31 32 /** 33 * Create an edge pointing to a given ID with a value 34 * 35 * @param id target ID 36 * @param value edge value 37 * @param <I> Vertex ID type 38 * @param <E> Edge Value type 39 * @return Edge pointing to ID with value 40 */ 41 public static <I extends WritableComparable, 42 E extends Writable> 43 Edge<I, E> create(I id, E value) { 44 return createReusable(id, value); 45 } 46 47 /** 48 * Create an edge pointing to a given ID without a value 49 * 50 * @param id target ID 51 * @param <I> Vertex ID type 52 * @return Edge pointing to ID without a value 53 */ 54 public static <I extends WritableComparable> 55 Edge<I, NullWritable> create(I id) { 56 return createReusable(id); 57 } 58 59 /** 60 * Create a reusable edge pointing to a given ID with a value 61 * 62 * @param id target ID 63 * @param value edge value 64 * @param <I> Vertex ID type 65 * @param <E> Edge Value type 66 * @return Edge pointing to ID with value 67 */ 68 public static <I extends WritableComparable, 69 E extends Writable> 70 ReusableEdge<I, E> createReusable(I id, E value) { 71 if (value instanceof NullWritable) { 72 return (ReusableEdge<I, E>) createReusable(id); 73 } else { 74 return new DefaultEdge<I, E>(id, value); 75 } 76 } 77 78 /** 79 * Create a reusable edge pointing to a given ID with a value 80 * 81 * @param id target ID 82 * @param <I> Vertex ID type 83 * @return Edge pointing to ID with value 84 */ 85 public static <I extends WritableComparable> 86 ReusableEdge<I, NullWritable> createReusable(I id) { 87 return new EdgeNoValue<I>(id); 88 } 89 }