org.eclipse.jgit.util.io.StreamCopyThread.java Source code

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Here is the source code for org.eclipse.jgit.util.io.StreamCopyThread.java

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/*
 * Copyright (C) 2009-2010, Google Inc.
 * and other copyright owners as documented in the project's IP log.
 *
 * This program and the accompanying materials are made available
 * under the terms of the Eclipse Distribution License v1.0 which
 * accompanies this distribution, is reproduced below, and is
 * available at http://www.eclipse.org/org/documents/edl-v10.php
 *
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or
 * without modification, are permitted provided that the following
 * conditions are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 *
 * - Redistributions in binary form must reproduce the above
 *   copyright notice, this list of conditions and the following
 *   disclaimer in the documentation and/or other materials provided
 *   with the distribution.
 *
 * - Neither the name of the Eclipse Foundation, Inc. nor the
 *   names of its contributors may be used to endorse or promote
 *   products derived from this software without specific prior
 *   written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
 * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

package org.eclipse.jgit.util.io;

import java.io.IOException;
import java.io.InputStream;
import java.io.InterruptedIOException;
import java.io.OutputStream;

/**
 * Thread to copy from an input stream to an output stream.
 */
public class StreamCopyThread extends Thread {
    private static final int BUFFER_SIZE = 1024;

    private final InputStream src;

    private final OutputStream dst;

    private volatile boolean done;

    /** Lock held by flush to avoid interrupting a write. */
    private final Object writeLock;

    /**
     * Create a thread to copy data from an input stream to an output stream.
     *
     * @param i
     *            stream to copy from. The thread terminates when this stream
     *            reaches EOF. The thread closes this stream before it exits.
     * @param o
     *            stream to copy into. The destination stream is automatically
     *            closed when the thread terminates.
     */
    public StreamCopyThread(InputStream i, OutputStream o) {
        setName(Thread.currentThread().getName() + "-StreamCopy"); //$NON-NLS-1$
        src = i;
        dst = o;
        writeLock = new Object();
    }

    /**
     * Request that the thread terminate, and wait for it.
     * <p>
     * This method signals to the copy thread that it should stop as soon as
     * there is no more IO occurring.
     *
     * @throws java.lang.InterruptedException
     *             the calling thread was interrupted.
     */
    public void halt() throws InterruptedException {
        for (;;) {
            join(250 /* milliseconds */);
            if (isAlive()) {
                done = true;
                interrupt();
            } else
                break;
        }
    }

    /** {@inheritDoc} */
    @Override
    public void run() {
        try {
            final byte[] buf = new byte[BUFFER_SIZE];
            boolean readInterrupted = false;
            for (;;) {
                try {
                    if (readInterrupted) {
                        synchronized (writeLock) {
                            boolean interruptedAgain = Thread.interrupted();
                            dst.flush();
                            if (interruptedAgain) {
                                interrupt();
                            }
                        }
                        readInterrupted = false;
                    }

                    if (done)
                        break;

                    final int n;
                    try {
                        n = src.read(buf);
                    } catch (InterruptedIOException wakey) {
                        readInterrupted = true;
                        continue;
                    }
                    if (n < 0)
                        break;

                    synchronized (writeLock) {
                        boolean writeInterrupted = Thread.interrupted();
                        dst.write(buf, 0, n);
                        if (writeInterrupted) {
                            interrupt();
                        }
                    }
                } catch (IOException e) {
                    break;
                }
            }
        } finally {
            try {
                src.close();
            } catch (IOException e) {
                // Ignore IO errors on close
            }
            try {
                dst.close();
            } catch (IOException e) {
                // Ignore IO errors on close
            }
        }
    }
}