| /* |
| * 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.edge; |
| |
| import com.google.common.collect.ArrayListMultimap; |
| import com.google.common.collect.UnmodifiableIterator; |
| import org.apache.hadoop.io.Writable; |
| import org.apache.hadoop.io.WritableComparable; |
| |
| import java.io.DataInput; |
| import java.io.DataOutput; |
| import java.io.IOException; |
| import java.util.Collection; |
| import java.util.Iterator; |
| import java.util.Map; |
| |
| /** |
| * {@link OutEdges} implementation backed by an {@link ArrayListMultimap}. |
| * Parallel edges are allowed. |
| * Note: this implementation is optimized for fast mutations, |
| * but uses more space. |
| * |
| * @param <I> Vertex id |
| * @param <E> Edge value |
| */ |
| public class HashMultimapEdges<I extends WritableComparable, E extends Writable> |
| extends ConfigurableOutEdges<I, E> |
| implements MultiRandomAccessOutEdges<I, E> { |
| /** Multimap from target vertex id to edge values. */ |
| private ArrayListMultimap<I, E> edgeMultimap; |
| |
| @Override |
| public void initialize(Iterable<Edge<I, E>> edges) { |
| // If the iterable is actually a collection, we can cheaply get the |
| // size and initialize the hash-multimap with the expected capacity. |
| if (edges instanceof Collection) { |
| initialize(((Collection<Edge<I, E>>) edges).size()); |
| } else { |
| initialize(); |
| } |
| for (Edge<I, E> edge : edges) { |
| add(edge); |
| } |
| } |
| |
| /** |
| * Additional initialization method tailored to the underlying multimap |
| * implementation. |
| * |
| * @param expectedNeighbors Expected number of unique neighbors |
| * @param expectedEdgesPerNeighbor Expected number of edges per neighbor |
| */ |
| public void initialize(int expectedNeighbors, int expectedEdgesPerNeighbor) { |
| edgeMultimap = ArrayListMultimap.create(expectedNeighbors, |
| expectedEdgesPerNeighbor); |
| } |
| |
| @Override |
| public void initialize(int capacity) { |
| // To be conservative in terms of space usage, we assume that the initial |
| // number of values per key is 1. |
| initialize(capacity, 1); |
| } |
| |
| @Override |
| public void initialize() { |
| edgeMultimap = ArrayListMultimap.create(); |
| } |
| |
| @Override |
| public void add(Edge<I, E> edge) { |
| edgeMultimap.put(edge.getTargetVertexId(), edge.getValue()); |
| } |
| |
| @Override |
| public void remove(I targetVertexId) { |
| edgeMultimap.removeAll(targetVertexId); |
| } |
| |
| @Override |
| public Iterable<E> getAllEdgeValues(I targetVertexId) { |
| return edgeMultimap.get(targetVertexId); |
| } |
| |
| @Override |
| public int size() { |
| return edgeMultimap.size(); |
| } |
| |
| @Override |
| public Iterator<Edge<I, E>> iterator() { |
| // Returns an iterator that reuses objects. |
| return new UnmodifiableIterator<Edge<I, E>>() { |
| /** Wrapped map iterator. */ |
| private Iterator<Map.Entry<I, E>> mapIterator = |
| edgeMultimap.entries().iterator(); |
| /** Representative edge object. */ |
| private ReusableEdge<I, E> representativeEdge = |
| getConf().createReusableEdge(); |
| |
| @Override |
| public boolean hasNext() { |
| return mapIterator.hasNext(); |
| } |
| |
| @Override |
| public Edge<I, E> next() { |
| Map.Entry<I, E> nextEntry = mapIterator.next(); |
| representativeEdge.setTargetVertexId(nextEntry.getKey()); |
| representativeEdge.setValue(nextEntry.getValue()); |
| return representativeEdge; |
| } |
| }; |
| } |
| |
| @Override |
| public void write(DataOutput out) throws IOException { |
| // We write both the total number of edges and the number of unique |
| // neighbors. |
| out.writeInt(edgeMultimap.size()); |
| out.writeInt(edgeMultimap.keys().size()); |
| for (Map.Entry<I, E> edge : edgeMultimap.entries()) { |
| edge.getKey().write(out); |
| edge.getValue().write(out); |
| } |
| } |
| |
| @Override |
| public void readFields(DataInput in) throws IOException { |
| // Given the total number of pairs and the number of unique neighbors, |
| // we are able to compute the average number of edges per neighbors. |
| int numEdges = in.readInt(); |
| int numNeighbors = in.readInt(); |
| initialize(numEdges, numNeighbors == 0 ? 0 : numEdges / numNeighbors); |
| for (int i = 0; i < numEdges; ++i) { |
| I targetVertexId = getConf().createVertexId(); |
| targetVertexId.readFields(in); |
| E edgeValue = getConf().createEdgeValue(); |
| edgeValue.readFields(in); |
| edgeMultimap.put(targetVertexId, edgeValue); |
| } |
| } |
| } |