Shawn Pearce
8 years ago
committed by
Gerrit Code Review @ Eclipse.org
5 changed files with 249 additions and 27 deletions
@ -0,0 +1,241 @@
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/* |
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* Copyright (C) 2016, Google Inc. |
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* and other copyright owners as documented in the project's IP log. |
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* |
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* This program and the accompanying materials are made available |
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* under the terms of the Eclipse Distribution License v1.0 which |
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* accompanies this distribution, is reproduced below, and is |
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* available at http://www.eclipse.org/org/documents/edl-v10.php
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* |
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* All rights reserved. |
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* |
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* Redistribution and use in source and binary forms, with or |
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* without modification, are permitted provided that the following |
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* conditions are met: |
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* |
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* - Redistributions of source code must retain the above copyright |
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* notice, this list of conditions and the following disclaimer. |
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* |
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* - Redistributions in binary form must reproduce the above |
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* copyright notice, this list of conditions and the following |
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* disclaimer in the documentation and/or other materials provided |
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* with the distribution. |
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* |
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* - Neither the name of the Eclipse Foundation, Inc. nor the |
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* names of its contributors may be used to endorse or promote |
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* products derived from this software without specific prior |
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* written permission. |
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* |
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND |
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* CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, |
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* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
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* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR |
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* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; |
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* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER |
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* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, |
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* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) |
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF |
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* ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
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*/ |
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package org.eclipse.jgit.util.io; |
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import java.io.IOException; |
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import java.io.InterruptedIOException; |
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import java.io.OutputStream; |
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import java.util.concurrent.ArrayBlockingQueue; |
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import java.util.concurrent.Callable; |
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import java.util.concurrent.ExecutionException; |
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import java.util.concurrent.ExecutorService; |
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import java.util.concurrent.Future; |
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import java.util.concurrent.RejectedExecutionException; |
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import java.util.concurrent.ThreadFactory; |
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import java.util.concurrent.ThreadPoolExecutor; |
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import java.util.concurrent.TimeUnit; |
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import java.util.concurrent.TimeoutException; |
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import java.util.concurrent.atomic.AtomicInteger; |
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import org.eclipse.jgit.internal.JGitText; |
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/** |
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* OutputStream isolated from interrupts. |
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* <p> |
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* Wraps an OutputStream to prevent interrupts during writes from being made |
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* visible to that stream instance. This works around buggy or difficult |
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* OutputStream implementations like JSch that cannot gracefully handle an |
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* interrupt during write. |
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* <p> |
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* Every write (or flush) requires a context switch to another thread. Callers |
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* should wrap this stream with {@code BufferedOutputStream} using a suitable |
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* buffer size to amortize the cost of context switches. |
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*/ |
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public class IsolatedOutputStream extends OutputStream { |
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private final OutputStream dst; |
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private final ExecutorService copier; |
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private Future<Void> pending; |
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/** |
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* Wraps an OutputStream. |
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* |
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* @param out |
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* stream to send all writes to. |
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*/ |
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public IsolatedOutputStream(OutputStream out) { |
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dst = out; |
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copier = new ThreadPoolExecutor(1, 1, 0, TimeUnit.MILLISECONDS, |
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new ArrayBlockingQueue<Runnable>(1), new NamedThreadFactory()); |
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} |
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@Override |
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public void write(int ch) throws IOException { |
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write(new byte[] { (byte) ch }, 0, 1); |
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} |
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@Override |
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public void write(final byte[] buf, final int pos, final int cnt) |
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throws IOException { |
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checkClosed(); |
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execute(new Callable<Void>() { |
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@Override |
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public Void call() throws IOException { |
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dst.write(buf, pos, cnt); |
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return null; |
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} |
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}); |
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} |
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@Override |
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public void flush() throws IOException { |
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checkClosed(); |
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execute(new Callable<Void>() { |
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@Override |
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public Void call() throws IOException { |
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dst.flush(); |
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return null; |
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} |
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}); |
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} |
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@Override |
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public void close() throws IOException { |
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if (!copier.isShutdown()) { |
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try { |
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if (pending == null || tryCleanClose()) { |
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cleanClose(); |
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} else { |
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dirtyClose(); |
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} |
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} finally { |
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copier.shutdown(); |
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} |
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} |
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} |
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private boolean tryCleanClose() { |
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/* |
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* If the caller stopped waiting for a prior write or flush, they could |
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* be trying to close a stream that is still in-use. Check if the prior |
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* operation ended in a predictable way. |
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*/ |
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try { |
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pending.get(0, TimeUnit.MILLISECONDS); |
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pending = null; |
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return true; |
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} catch (TimeoutException | InterruptedException e) { |
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return false; |
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} catch (ExecutionException e) { |
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pending = null; |
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return true; |
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} |
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} |
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private void cleanClose() throws IOException { |
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execute(new Callable<Void>() { |
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@Override |
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public Void call() throws IOException { |
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dst.close(); |
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return null; |
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} |
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}); |
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} |
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private void dirtyClose() throws IOException { |
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/* |
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* Interrupt any still pending write or flush operation. This may cause |
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* massive failures inside of the stream, but its going to be closed as |
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* the next step. |
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*/ |
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pending.cancel(true); |
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Future<Void> close; |
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try { |
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close = copier.submit(new Callable<Void>() { |
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@Override |
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public Void call() throws IOException { |
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dst.close(); |
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return null; |
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} |
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}); |
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} catch (RejectedExecutionException e) { |
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throw new IOException(e); |
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} |
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try { |
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close.get(200, TimeUnit.MILLISECONDS); |
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} catch (InterruptedException | TimeoutException e) { |
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close.cancel(true); |
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throw new IOException(e); |
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} catch (ExecutionException e) { |
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throw new IOException(e.getCause()); |
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} |
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} |
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private void checkClosed() throws IOException { |
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if (copier.isShutdown()) { |
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throw new IOException(JGitText.get().closed); |
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} |
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} |
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private void execute(Callable<Void> task) throws IOException { |
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if (pending != null) { |
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// Check (and rethrow) any prior failed operation.
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checkedGet(pending); |
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} |
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try { |
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pending = copier.submit(task); |
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} catch (RejectedExecutionException e) { |
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throw new IOException(e); |
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} |
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checkedGet(pending); |
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pending = null; |
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} |
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private static void checkedGet(Future<Void> future) throws IOException { |
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try { |
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future.get(); |
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} catch (InterruptedException e) { |
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throw interrupted(e); |
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} catch (ExecutionException e) { |
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throw new IOException(e.getCause()); |
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} |
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} |
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private static InterruptedIOException interrupted(InterruptedException c) { |
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InterruptedIOException e = new InterruptedIOException(); |
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e.initCause(c); |
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return e; |
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} |
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private static class NamedThreadFactory implements ThreadFactory { |
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private static final AtomicInteger cnt = new AtomicInteger(); |
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@Override |
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public Thread newThread(Runnable r) { |
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int n = cnt.incrementAndGet(); |
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String name = IsolatedOutputStream.class.getSimpleName() + '-' + n; |
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return new Thread(r, name); |
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} |
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} |
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} |
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