org.apache.mahout.h2obindings.drm.H2OBCast.java Source code

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Here is the source code for org.apache.mahout.h2obindings.drm.H2OBCast.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.mahout.h2obindings.drm;

import org.apache.mahout.math.drm.BCast;
import org.apache.mahout.math.Matrix;
import org.apache.mahout.math.Vector;
import org.apache.mahout.math.MatrixWritable;
import org.apache.mahout.math.VectorWritable;

import org.apache.hadoop.io.Writable;

import java.io.Serializable;
import java.io.ByteArrayOutputStream;
import java.io.ByteArrayInputStream;
import java.io.ObjectOutputStream;
import java.io.ObjectInputStream;

/**
 * Broadcast class wrapper around Matrix and Vector.
 *
 * Use MatrixWritable and VectorWritable internally.
 * Even though the class is generically typed, we do runtime
 * enforcement to assert the type is either Matrix or Vector.
 *
 * H2OBCast object is created around a Matrix or Vector. Matrix or Vector
 * objects cannot be freely referred in closures. Instead create and refer the
 * corresponding H2OBCast object. The original Matrix or Vector can be
 * obtained by calling the ->value() method on the H2OBCast object within a
 * closure.
 */
public class H2OBCast<T> implements BCast<T>, Serializable {
    private transient T obj;
    private byte buf[];
    private boolean isMatrix;

    /**
     * Class constructor.
     */
    public H2OBCast(T o) {
        obj = o;

        if (o instanceof Matrix) {
            buf = serialize(new MatrixWritable((Matrix) o));
            isMatrix = true;
        } else if (o instanceof Vector) {
            buf = serialize(new VectorWritable((Vector) o));
            isMatrix = false;
        } else {
            throw new IllegalArgumentException("Only Matrix or Vector supported for now");
        }
    }

    /**
     * Get the serialized object.
     */
    public T value() {
        if (obj == null) {
            obj = deserialize(buf);
        }
        return obj;
    }

    /**
     * Internal method to serialize the object.
     *
     * @param w Either MatrixWritable or VectorWritable corresponding to
     *          either Matrix or Vector as the class is typed.
     * @return serialized sequence of bytes.
     */
    private byte[] serialize(Writable w) {
        ByteArrayOutputStream bos = new ByteArrayOutputStream();
        try {
            ObjectOutputStream oos = new ObjectOutputStream(bos);
            w.write(oos);
            oos.close();
        } catch (java.io.IOException e) {
            return null;
        }
        return bos.toByteArray();
    }

    /**
     * Internal method to deserialize a sequence of bytes.
     *
     * @param buf Sequence of bytes previously serialized by serialize() method.
     * @return The original Matrix or Vector object.
     */
    private T deserialize(byte buf[]) {
        T ret = null;
        ByteArrayInputStream bis = new ByteArrayInputStream(buf);
        try {
            ObjectInputStream ois = new ObjectInputStream(bis);
            if (isMatrix) {
                MatrixWritable w = new MatrixWritable();
                w.readFields(ois);
                ret = (T) w.get();
            } else {
                VectorWritable w = new VectorWritable();
                w.readFields(ois);
                ret = (T) w.get();
            }
        } catch (java.io.IOException e) {
            System.out.println("Caught exception: " + e);
        }
        return ret;
    }
}