/*
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* Copyright 2011 gitblit.com.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.gitblit.utils;
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import java.io.ByteArrayInputStream;
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import java.io.ByteArrayOutputStream;
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import java.io.IOException;
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import java.io.InputStream;
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import java.io.ObjectInputStream;
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import java.io.ObjectOutputStream;
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import java.io.PipedInputStream;
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import java.io.PipedOutputStream;
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public class DeepCopier {
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/**
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* Produce a deep copy of the given object. Serializes the entire object to
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* a byte array in memory. Recommended for relatively small objects.
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*/
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@SuppressWarnings("unchecked")
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public static <T> T copy(T original) {
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T o = null;
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try {
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ByteArrayOutputStream byteOut = new ByteArrayOutputStream();
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ObjectOutputStream oos = new ObjectOutputStream(byteOut);
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oos.writeObject(original);
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ByteArrayInputStream byteIn = new ByteArrayInputStream(byteOut.toByteArray());
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ObjectInputStream ois = new ObjectInputStream(byteIn);
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try {
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o = (T) ois.readObject();
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} catch (ClassNotFoundException cex) {
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// actually can not happen in this instance
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}
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} catch (IOException iox) {
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// doesn't seem likely to happen as these streams are in memory
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throw new RuntimeException(iox);
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}
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return o;
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}
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/**
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* This conserves heap memory!!!!! Produce a deep copy of the given object.
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* Serializes the object through a pipe between two threads. Recommended for
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* very large objects. The current thread is used for serializing the
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* original object in order to respect any synchronization the caller may
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* have around it, and a new thread is used for deserializing the copy.
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*
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*/
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public static <T> T copyParallel(T original) {
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try {
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PipedOutputStream outputStream = new PipedOutputStream();
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PipedInputStream inputStream = new PipedInputStream(outputStream);
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ObjectOutputStream ois = new ObjectOutputStream(outputStream);
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Receiver<T> receiver = new Receiver<T>(inputStream);
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try {
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ois.writeObject(original);
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} finally {
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ois.close();
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}
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return receiver.getResult();
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} catch (IOException iox) {
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// doesn't seem likely to happen as these streams are in memory
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throw new RuntimeException(iox);
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}
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}
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private static class Receiver<T> extends Thread {
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private final InputStream inputStream;
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private volatile T result;
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private volatile Throwable throwable;
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public Receiver(InputStream inputStream) {
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this.inputStream = inputStream;
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start();
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}
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@SuppressWarnings("unchecked")
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public void run() {
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try {
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ObjectInputStream ois = new ObjectInputStream(inputStream);
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try {
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result = (T) ois.readObject();
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try {
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// Some serializers may write more than they actually
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// need to deserialize the object, but if we don't
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// read it all the PipedOutputStream will choke.
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while (inputStream.read() != -1) {
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}
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} catch (IOException e) {
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// The object has been successfully deserialized, so
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// ignore problems at this point (for example, the
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// serializer may have explicitly closed the inputStream
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// itself, causing this read to fail).
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}
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} finally {
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ois.close();
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}
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} catch (Throwable t) {
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throwable = t;
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}
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}
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public T getResult() throws IOException {
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try {
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join();
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} catch (InterruptedException e) {
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throw new RuntimeException("Unexpected InterruptedException", e);
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}
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// join() guarantees that all shared memory is synchronized between
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// the two threads
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if (throwable != null) {
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if (throwable instanceof ClassNotFoundException) {
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// actually can not happen in this instance
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}
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throw new RuntimeException(throwable);
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}
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return result;
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}
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}
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}
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