| /* |
| * 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 java.io.DataInput; |
| import java.io.DataOutput; |
| import java.io.IOException; |
| import java.util.Iterator; |
| import java.util.NoSuchElementException; |
| |
| import org.apache.giraph.conf.ImmutableClassesGiraphConfigurable; |
| import org.apache.giraph.conf.ImmutableClassesGiraphConfiguration; |
| import org.apache.giraph.types.ops.PrimitiveIdTypeOps; |
| import org.apache.giraph.types.ops.TypeOpsUtils; |
| import org.apache.giraph.types.ops.collections.array.WArrayList; |
| import org.apache.giraph.utils.EdgeIterables; |
| import org.apache.hadoop.io.NullWritable; |
| import org.apache.hadoop.io.Writable; |
| import org.apache.hadoop.io.WritableComparable; |
| |
| /** |
| * Implementation of {@link OutEdges} with IDs and null edge values having |
| * their TypeOps. |
| * Backed by a dynamic primitive array. Parallel edges are allowed. |
| * Note: this implementation is optimized for space |
| * usage, but random access and edge removals are expensive. |
| * |
| * @param <I> Vertex id type |
| */ |
| public class IdAndNullArrayEdges<I extends WritableComparable> |
| implements ReuseObjectsOutEdges<I, NullWritable>, |
| MutableOutEdges<I, NullWritable>, |
| ImmutableClassesGiraphConfigurable<I, Writable, NullWritable> { |
| |
| /** Array of target vertex ids. */ |
| private WArrayList<I> neighbors; |
| |
| @Override |
| public |
| ImmutableClassesGiraphConfiguration<I, Writable, NullWritable> getConf() { |
| throw new UnsupportedOperationException(); |
| } |
| |
| @Override |
| public void setConf( |
| ImmutableClassesGiraphConfiguration<I, Writable, NullWritable> conf) { |
| PrimitiveIdTypeOps<I> idTypeOps = |
| TypeOpsUtils.getPrimitiveIdTypeOps(conf.getVertexIdClass()); |
| neighbors = idTypeOps.createArrayList(10); |
| if (!conf.getEdgeValueClass().equals(NullWritable.class)) { |
| throw new IllegalArgumentException( |
| "IdAndNullArrayEdges can be used only with NullWritable " + |
| "as edgeValueClass, not with " + conf.getEdgeValueClass()); |
| } |
| } |
| |
| @Override |
| public void initialize(Iterable<Edge<I, NullWritable>> edges) { |
| EdgeIterables.initialize(this, edges); |
| } |
| |
| @Override |
| public void initialize(int capacity) { |
| neighbors.clear(); |
| neighbors.setCapacity(capacity); |
| } |
| |
| @Override |
| public void initialize() { |
| initialize(10); |
| } |
| |
| @Override |
| public void add(Edge<I, NullWritable> edge) { |
| neighbors.addW(edge.getTargetVertexId()); |
| } |
| |
| /** |
| * If the backing array is more than four times as big as the number of |
| * elements, reduce to 2 times current size. |
| */ |
| private void trim() { |
| if (neighbors.capacity() > 4 * neighbors.size()) { |
| neighbors.setCapacity(neighbors.size() * 2); |
| } |
| } |
| |
| /** |
| * Remove edge at position i. |
| * |
| * @param i Position of edge to be removed |
| */ |
| private void removeAt(int i) { |
| // The order of the edges is irrelevant, so we can simply replace |
| // the deleted edge with the rightmost element, thus achieving constant |
| // time. |
| I tmpValue = neighbors.getElementTypeOps().create(); |
| neighbors.popIntoW(tmpValue); |
| if (i != neighbors.size()) { |
| neighbors.setW(i, tmpValue); |
| } |
| // If needed after the removal, trim the array. |
| trim(); |
| } |
| |
| @Override |
| public void remove(I targetVertexId) { |
| // Thanks to the constant-time implementation of removeAt(int), |
| // we can remove all matching edges in linear time. |
| I tmpValue = neighbors.getElementTypeOps().create(); |
| for (int i = neighbors.size() - 1; i >= 0; --i) { |
| neighbors.getIntoW(i, tmpValue); |
| if (tmpValue.equals(targetVertexId)) { |
| removeAt(i); |
| } |
| } |
| } |
| |
| @Override |
| public int size() { |
| return neighbors.size(); |
| } |
| |
| @Override |
| public Iterator<Edge<I, NullWritable>> iterator() { |
| // Returns an iterator that reuses objects. |
| // The downcast is fine because all concrete Edge implementations are |
| // mutable, but we only expose the mutation functionality when appropriate. |
| return (Iterator) mutableIterator(); |
| } |
| |
| @Override |
| public Iterator<MutableEdge<I, NullWritable>> mutableIterator() { |
| return new Iterator<MutableEdge<I, NullWritable>>() { |
| /** Current position in the array. */ |
| private int offset = 0; |
| /** Representative edge object. */ |
| private final MutableEdge<I, NullWritable> representativeEdge = |
| EdgeFactory.createReusable(neighbors.getElementTypeOps().create()); |
| |
| @Override |
| public boolean hasNext() { |
| return offset < neighbors.size(); |
| } |
| |
| @Override |
| public MutableEdge<I, NullWritable> next() { |
| if (!hasNext()) { |
| throw new NoSuchElementException(); |
| } |
| neighbors.getIntoW(offset++, representativeEdge.getTargetVertexId()); |
| return representativeEdge; |
| } |
| |
| @Override |
| public void remove() { |
| // Since removeAt() might replace the deleted edge with the last edge |
| // in the array, we need to decrease the offset so that the latter |
| // won't be skipped. |
| removeAt(--offset); |
| } |
| }; |
| } |
| |
| @Override |
| public void write(DataOutput out) throws IOException { |
| neighbors.write(out); |
| } |
| |
| @Override |
| public void readFields(DataInput in) throws IOException { |
| neighbors.readFields(in); |
| } |
| } |