org.apache.hama.bsp.message.bundle.POJOMessageBundle.java Source code

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Here is the source code for org.apache.hama.bsp.message.bundle.POJOMessageBundle.java

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/**
 * 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.hama.bsp.message.bundle;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.io.Writable;

public class POJOMessageBundle<M extends Writable> implements BSPMessageBundle<M>, Iterable<M> {

    protected static final Log LOG = LogFactory.getLog(POJOMessageBundle.class);

    protected HashMap<String, List<M>> messages = new HashMap<String, List<M>>();
    protected HashMap<String, Class<M>> classCache = new HashMap<String, Class<M>>();

    protected int numElements;

    private static class BundleIterator<M extends Writable> implements Iterator<M> {

        private Iterator<List<M>> listIterator;
        private Iterator<M> messageIterator;

        public BundleIterator(Iterator<List<M>> listIterator) {
            this.listIterator = listIterator;
        }

        @Override
        public boolean hasNext() {
            return listIterator.hasNext() || messageIterator.hasNext();
        }

        @Override
        public M next() {
            while (true) {
                if (messageIterator != null && messageIterator.hasNext()) {
                    return messageIterator.next();
                } else {
                    if (listIterator.hasNext()) {
                        messageIterator = listIterator.next().iterator();
                    } else {
                        return null;
                    }
                }
            }
        }

        @Override
        public void remove() {
        }

    }

    public POJOMessageBundle() {
    }

    /**
     * Add message to this bundle.
     * 
     * @param message BSPMessage to add.
     */
    public void addMessage(M message) {
        String className = message.getClass().getName();
        List<M> list = messages.get(className);
        ++numElements;
        if (list == null) {
            list = new ArrayList<M>();
            messages.put(className, list);
        }

        list.add(message);
    }

    public List<M> getMessages() {
        // here we use an arraylist, because we know the size and outside may need
        // random access
        List<M> mergeList = new ArrayList<M>(messages.size());
        for (List<M> c : messages.values()) {
            mergeList.addAll(c);
        }
        return mergeList;
    }

    @Override
    public Iterator<M> iterator() {
        return new BundleIterator<M>(this.messages.values().iterator());
    }

    @Override
    public long getSize() {
        return numElements;
    }

    @Override
    public int getNumElements() {
        return numElements;
    }
}