| /* |
| * Copyright (C) 2016, 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.InterruptedIOException; |
| import java.io.OutputStream; |
| import java.util.concurrent.ArrayBlockingQueue; |
| import java.util.concurrent.Callable; |
| import java.util.concurrent.ExecutionException; |
| import java.util.concurrent.ExecutorService; |
| import java.util.concurrent.Future; |
| import java.util.concurrent.RejectedExecutionException; |
| import java.util.concurrent.ThreadFactory; |
| import java.util.concurrent.ThreadPoolExecutor; |
| import java.util.concurrent.TimeUnit; |
| import java.util.concurrent.TimeoutException; |
| import java.util.concurrent.atomic.AtomicInteger; |
| |
| import org.eclipse.jgit.internal.JGitText; |
| |
| /** |
| * OutputStream isolated from interrupts. |
| * <p> |
| * Wraps an OutputStream to prevent interrupts during writes from being made |
| * visible to that stream instance. This works around buggy or difficult |
| * OutputStream implementations like JSch that cannot gracefully handle an |
| * interrupt during write. |
| * <p> |
| * Every write (or flush) requires a context switch to another thread. Callers |
| * should wrap this stream with {@code BufferedOutputStream} using a suitable |
| * buffer size to amortize the cost of context switches. |
| * |
| * @since 4.6 |
| */ |
| public class IsolatedOutputStream extends OutputStream { |
| private final OutputStream dst; |
| private final ExecutorService copier; |
| private Future<Void> pending; |
| |
| /** |
| * Wraps an OutputStream. |
| * |
| * @param out |
| * stream to send all writes to. |
| */ |
| public IsolatedOutputStream(OutputStream out) { |
| dst = out; |
| copier = new ThreadPoolExecutor(1, 1, 0, TimeUnit.MILLISECONDS, |
| new ArrayBlockingQueue<Runnable>(1), new NamedThreadFactory()); |
| } |
| |
| @Override |
| public void write(int ch) throws IOException { |
| write(new byte[] { (byte) ch }, 0, 1); |
| } |
| |
| @Override |
| public void write(final byte[] buf, final int pos, final int cnt) |
| throws IOException { |
| checkClosed(); |
| execute(new Callable<Void>() { |
| @Override |
| public Void call() throws IOException { |
| dst.write(buf, pos, cnt); |
| return null; |
| } |
| }); |
| } |
| |
| @Override |
| public void flush() throws IOException { |
| checkClosed(); |
| execute(new Callable<Void>() { |
| @Override |
| public Void call() throws IOException { |
| dst.flush(); |
| return null; |
| } |
| }); |
| } |
| |
| @Override |
| public void close() throws IOException { |
| if (!copier.isShutdown()) { |
| try { |
| if (pending == null || tryCleanClose()) { |
| cleanClose(); |
| } else { |
| dirtyClose(); |
| } |
| } finally { |
| copier.shutdown(); |
| } |
| } |
| } |
| |
| private boolean tryCleanClose() { |
| /* |
| * If the caller stopped waiting for a prior write or flush, they could |
| * be trying to close a stream that is still in-use. Check if the prior |
| * operation ended in a predictable way. |
| */ |
| try { |
| pending.get(0, TimeUnit.MILLISECONDS); |
| pending = null; |
| return true; |
| } catch (TimeoutException | InterruptedException e) { |
| return false; |
| } catch (ExecutionException e) { |
| pending = null; |
| return true; |
| } |
| } |
| |
| private void cleanClose() throws IOException { |
| execute(new Callable<Void>() { |
| @Override |
| public Void call() throws IOException { |
| dst.close(); |
| return null; |
| } |
| }); |
| } |
| |
| private void dirtyClose() throws IOException { |
| /* |
| * Interrupt any still pending write or flush operation. This may cause |
| * massive failures inside of the stream, but its going to be closed as |
| * the next step. |
| */ |
| pending.cancel(true); |
| |
| Future<Void> close; |
| try { |
| close = copier.submit(new Callable<Void>() { |
| @Override |
| public Void call() throws IOException { |
| dst.close(); |
| return null; |
| } |
| }); |
| } catch (RejectedExecutionException e) { |
| throw new IOException(e); |
| } |
| try { |
| close.get(200, TimeUnit.MILLISECONDS); |
| } catch (InterruptedException | TimeoutException e) { |
| close.cancel(true); |
| throw new IOException(e); |
| } catch (ExecutionException e) { |
| throw new IOException(e.getCause()); |
| } |
| } |
| |
| private void checkClosed() throws IOException { |
| if (copier.isShutdown()) { |
| throw new IOException(JGitText.get().closed); |
| } |
| } |
| |
| private void execute(Callable<Void> task) throws IOException { |
| if (pending != null) { |
| // Check (and rethrow) any prior failed operation. |
| checkedGet(pending); |
| } |
| try { |
| pending = copier.submit(task); |
| } catch (RejectedExecutionException e) { |
| throw new IOException(e); |
| } |
| checkedGet(pending); |
| pending = null; |
| } |
| |
| private static void checkedGet(Future<Void> future) throws IOException { |
| try { |
| future.get(); |
| } catch (InterruptedException e) { |
| throw interrupted(e); |
| } catch (ExecutionException e) { |
| throw new IOException(e.getCause()); |
| } |
| } |
| |
| private static InterruptedIOException interrupted(InterruptedException c) { |
| InterruptedIOException e = new InterruptedIOException(); |
| e.initCause(c); |
| return e; |
| } |
| |
| private static class NamedThreadFactory implements ThreadFactory { |
| private static final AtomicInteger cnt = new AtomicInteger(); |
| |
| @Override |
| public Thread newThread(Runnable r) { |
| int n = cnt.incrementAndGet(); |
| String name = IsolatedOutputStream.class.getSimpleName() + '-' + n; |
| return new Thread(r, name); |
| } |
| } |
| } |