com.datatorrent.lib.util.KryoCloneUtils.java Source code

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Here is the source code for com.datatorrent.lib.util.KryoCloneUtils.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 com.datatorrent.lib.util;

import java.io.ByteArrayOutputStream;
import java.lang.reflect.Array;

import org.apache.commons.io.IOUtils;

import com.esotericsoftware.kryo.Kryo;
import com.esotericsoftware.kryo.io.Input;
import com.esotericsoftware.kryo.io.Output;

/**
 *
 * A Kryo Clone Util class that clone object by using Kryo serializer and deserializer
 * The class has static method that are can be used directly to clone one object
 * Or it can be used as util instance to clone as many objects as you need from the one source object
 *
 * @since 3.4.0
 */
public class KryoCloneUtils<T> {

    /**
     * Reusable Kryo object as deserializer
     */
    private final Kryo kryo;

    /**
     * Reusable binary data for object that would be deserialized from
     */
    private final byte[] bin;

    /**
     * The class of the object
     */
    private final Class<T> clazz;

    @SuppressWarnings("unchecked")
    private KryoCloneUtils(Kryo kryo, T t) {
        this.kryo = kryo;
        ByteArrayOutputStream bos = null;
        Output output = null;
        try {
            bos = new ByteArrayOutputStream();
            output = new Output(bos);
            kryo.writeObject(output, t);
            output.close();
            bin = bos.toByteArray();
        } finally {
            IOUtils.closeQuietly(output);
            IOUtils.closeQuietly(bos);
        }
        clazz = (Class<T>) t.getClass();
        kryo.setClassLoader(clazz.getClassLoader());
    }

    /**
     * Clone from the binary data of the source object
     * @return T
     */
    public T getClone() {
        try (Input input = new Input(bin)) {
            return kryo.readObject(input, clazz);
        }
    }

    /**
     * Clone array of objects from source object
     * @param num size of the return array
     * @return array of T
     */
    @SuppressWarnings("unchecked")
    public T[] getClones(int num) {
        T[] ts = (T[]) Array.newInstance(clazz, num);
        try (Input input = new Input(bin)) {
            for (int i = 0; i < ts.length; i++) {
                input.rewind();
                ts[i] = kryo.readObject(input, clazz);
            }
        }
        return ts;
    }

    /**
     * Clone object by serializing and deserializing using Kryo.
     * Note this is different from using {@link Kryo#copy(Object)}, which will attempt to also clone transient fields.
     *
     * @param kryo kryo object used to clone objects
     * @param src src object that copy from
     * @return
     */
    @SuppressWarnings("unchecked")
    public static <SRC> SRC cloneObject(Kryo kryo, SRC src) {
        kryo.setClassLoader(src.getClass().getClassLoader());
        ByteArrayOutputStream bos = null;
        Output output;
        Input input = null;
        try {
            bos = new ByteArrayOutputStream();
            output = new Output(bos);
            kryo.writeObject(output, src);
            output.close();
            input = new Input(bos.toByteArray());
            return (SRC) kryo.readObject(input, src.getClass());
        } finally {
            IOUtils.closeQuietly(input);
            IOUtils.closeQuietly(bos);
        }
    }

    /**
     * Clone object by serializing and deserializing using default Kryo.
     * Note this is different from using {@link Kryo#copy(Object)}, which will attempt to also clone transient fields.
     *
     * @param src src object that copy from
     * @return
     */
    public static <SRC> SRC cloneObject(SRC src) {
        return cloneObject(new Kryo(), src);
    }

    /**
     * Factory function to return CloneUtils object
     * @param template
     * @param <SRC>
     * @return
     */
    public static <SRC> KryoCloneUtils<SRC> createCloneUtils(SRC template) {
        return createCloneUtils(new Kryo(), template);
    }

    /**
     * Factory function to return CloneUtils object with customized Kryo
     * @param kryo
     * @param template
     * @param <SRC>
     * @return
     */
    public static <SRC> KryoCloneUtils<SRC> createCloneUtils(Kryo kryo, SRC template) {
        return new KryoCloneUtils<>(kryo, template);
    }

}