org.apache.hama.bsp.BSPMessageBundle.java Source code

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Here is the source code for org.apache.hama.bsp.BSPMessageBundle.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;

import java.io.DataInput;
import java.io.DataOutput;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Collection;
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;
import org.apache.hama.util.ReflectionUtils;

/**
 * BSPMessageBundle stores a group of messages so that they can be sent in batch
 * rather than individually.
 * 
 */
public class BSPMessageBundle<M extends Writable> implements Writable, Iterable<M>, BSPMessageBundleInterface<M> {

    public static final Log LOG = LogFactory.getLog(BSPMessageBundle.class);

    private List<M> messages = new ArrayList<M>();

    public BSPMessageBundle() {
    }

    /**
     * Add message to this bundle.
     * 
     * @param message BSPMessage to add.
     */
    public void addMessage(M message) {
        messages.add(message);
    }

    public void addMessages(Collection<M> msgs) {
        messages.addAll(msgs);
    }

    public Iterator<M> iterator() {
        return messages.iterator();
    }

    public int size() {
        return messages.size();
    }

    @SuppressWarnings("unchecked")
    @Override
    public void write(DataOutput out) throws IOException {
        out.writeInt(messages.size());

        if (messages.size() > 0) {
            Class<M> clazz = (Class<M>) messages.get(0).getClass();
            out.writeUTF(clazz.getName());

            for (M m : messages) {
                m.write(out);
            }
        }
    }

    @SuppressWarnings("unchecked")
    @Override
    public void readFields(DataInput in) throws IOException {
        int num = in.readInt();

        if (num > 0) {
            Class<M> clazz = null;
            try {
                clazz = (Class<M>) Class.forName(in.readUTF());
            } catch (ClassNotFoundException e) {
                LOG.error("Class was not found.", e);
            }

            for (int i = 0; i < num; i++) {
                M msg = ReflectionUtils.newInstance(clazz);
                msg.readFields(in);
                messages.add(msg);
            }
        }
    }

}