ml.grafos.okapi.common.graph.SortedOutEdges.java Source code

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Here is the source code for ml.grafos.okapi.common.graph.SortedOutEdges.java

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/**
 * Copyright 2014 Grafos.ml
 *
 * Licensed 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 ml.grafos.okapi.common.graph;

import java.io.DataInput;
import java.io.DataOutput;
import java.io.IOException;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Map.Entry;
import java.util.SortedSet;

import org.apache.giraph.edge.ConfigurableOutEdges;
import org.apache.giraph.edge.Edge;
import org.apache.giraph.edge.MapMutableEdge;
import org.apache.giraph.edge.MutableEdge;
import org.apache.giraph.edge.MutableOutEdges;
import org.apache.giraph.edge.OutEdges;
import org.apache.giraph.edge.StrictRandomAccessOutEdges;
import org.apache.giraph.utils.EdgeIterables;
import org.apache.hadoop.io.WritableComparable;
import org.weakref.jmx.com.google.common.collect.Sets;

import com.google.common.collect.Maps;

/**
 * {@link OutEdges} implementation backed by a {@link HashMap}
 * with entries sorted by value.
 * Useful when the edges are accessed in value order. 
 *
 * @param <I> Vertex id
 * @param <E> Edge value
 */
@SuppressWarnings("rawtypes")
public class SortedOutEdges<I extends WritableComparable, E extends WritableComparable>
        extends ConfigurableOutEdges<I, E> implements StrictRandomAccessOutEdges<I, E>, MutableOutEdges<I, E> {

    /** Map from target vertex id to edge value. */
    private HashMap<I, E> edgeMap;

    @Override
    public void initialize(Iterable<Edge<I, E>> edges) {
        EdgeIterables.initialize(this, edges);
    }

    @Override
    public void initialize(int capacity) {
        edgeMap = Maps.newHashMapWithExpectedSize(capacity);
    }

    @Override
    public void initialize() {
        edgeMap = Maps.newHashMap();
    }

    @Override
    public void add(Edge<I, E> edge) {
        edgeMap.put(edge.getTargetVertexId(), edge.getValue());
    }

    @Override
    public void remove(I targetVertexId) {
        edgeMap.remove(targetVertexId);
    }

    @Override
    public E getEdgeValue(I targetVertexId) {
        return edgeMap.get(targetVertexId);
    }

    @Override
    public void setEdgeValue(I targetVertexId, E edgeValue) {
        if (edgeMap.containsKey(targetVertexId)) {
            edgeMap.put(targetVertexId, edgeValue);
        }
    }

    @Override
    public int size() {
        return edgeMap.size();
    }

    @SuppressWarnings("unchecked")
    @Override
    public Iterator<Edge<I, E>> 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, E>> mutableIterator() {
        return new Iterator<MutableEdge<I, E>>() {
            /** Wrapped map iterator. */
            @SuppressWarnings("unchecked")
            private Iterator<Map.Entry<I, E>> mapIterator = entriesSortedByValues(edgeMap).iterator();
            /** Representative edge object. */
            private MapMutableEdge<I, E> representativeEdge = new MapMutableEdge<I, E>();

            @Override
            public boolean hasNext() {
                return mapIterator.hasNext();
            }

            @Override
            public MutableEdge<I, E> next() {
                representativeEdge.setEntry(mapIterator.next());
                return representativeEdge;
            }

            @Override
            public void remove() {
                mapIterator.remove();
            }
        };
    }

    @Override
    public void write(DataOutput out) throws IOException {
        out.writeInt(edgeMap.size());
        for (Map.Entry<I, E> entry : edgeMap.entrySet()) {
            entry.getKey().write(out);
            entry.getValue().write(out);
        }
    }

    @Override
    public void readFields(DataInput in) throws IOException {
        int numEdges = in.readInt();
        initialize(numEdges);
        for (int i = 0; i < numEdges; ++i) {
            I targetVertexId = getConf().createVertexId();
            targetVertexId.readFields(in);
            E edgeValue = getConf().createEdgeValue();
            edgeValue.readFields(in);
            edgeMap.put(targetVertexId, edgeValue);
        }
    }

    static <K extends Comparable, V extends Comparable<? super V>> SortedSet<Entry<K, V>> entriesSortedByValues(
            Map<K, V> map) {
        SortedSet<Entry<K, V>> sortedEntries = Sets.newTreeSet(new EdgeValueComparator<K, V>());
        sortedEntries.addAll(map.entrySet());
        return sortedEntries;
    }
}