Switch JSchSession to simple isolated OutputStream

Work around issues with JSch not handling interrupts by
isolating the JSch interactions onto another thread.

Run write and flush on a single threaded Executor using
simple Callable operations wrapping the method calls,
waiting on the future to determine the outcome before
allowing the caller to continue.

If any operation was interrupted the state of the stream
becomes fuzzy at close time. The implementation tries to
interrupt the pending write or flush, but this is very
likely to corrupt the stream object, so exceptions are
ignored during such a dirty close.

Change-Id: I42e3ba3d8c35a2e40aad340580037ebefbb99b53

5 files changed, 249 insertions, 27 deletions

diff --git a/org.eclipse.jgit/resources/org/eclipse/jgit/internal/JGitText.properties b/org.eclipse.jgit/resources/org/eclipse/jgit/internal/JGitText.properties
index aa73b44848..0f2c8b3d1d 100644
--- a/org.eclipse.jgit/resources/org/eclipse/jgit/internal/JGitText.properties
+++ b/org.eclipse.jgit/resources/org/eclipse/jgit/internal/JGitText.properties
@@ -116,6 +116,7 @@ checkoutConflictWithFiles=Checkout conflict with files: {0}
 checkoutUnexpectedResult=Checkout returned unexpected result {0}
 classCastNotA=Not a {0}
 cloneNonEmptyDirectory=Destination path "{0}" already exists and is not an empty directory
+closed=closed
 collisionOn=Collision on {0}
 commandRejectedByHook=Rejected by "{0}" hook.\n{1}
 commandWasCalledInTheWrongState=Command {0} was called in the wrong state
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/internal/JGitText.java b/org.eclipse.jgit/src/org/eclipse/jgit/internal/JGitText.java
index 29b319fe65..212cb7fdef 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/internal/JGitText.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/internal/JGitText.java
@@ -175,6 +175,7 @@ public class JGitText extends TranslationBundle {
 	/***/ public String checkoutUnexpectedResult;
 	/***/ public String classCastNotA;
 	/***/ public String cloneNonEmptyDirectory;
+	/***/ public String closed;
 	/***/ public String collisionOn;
 	/***/ public String commandRejectedByHook;
 	/***/ public String commandWasCalledInTheWrongState;
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/transport/JschSession.java b/org.eclipse.jgit/src/org/eclipse/jgit/transport/JschSession.java
index 1dfe5d9797..fa27bfce5f 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/transport/JschSession.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/transport/JschSession.java
@@ -48,15 +48,14 @@
 
 package org.eclipse.jgit.transport;
 
+import java.io.BufferedOutputStream;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.OutputStream;
-import java.io.PipedInputStream;
-import java.io.PipedOutputStream;
 
 import org.eclipse.jgit.errors.TransportException;
 import org.eclipse.jgit.internal.JGitText;
-import org.eclipse.jgit.util.io.StreamCopyThread;
+import org.eclipse.jgit.util.io.IsolatedOutputStream;
 
 import com.jcraft.jsch.Channel;
 import com.jcraft.jsch.ChannelExec;
@@ -178,33 +177,12 @@ public class JschSession implements RemoteSession {
 			// that we spawn a background thread to shuttle data through a pipe,
 			// as we can issue an interrupted write out of that. Its slower, so
 			// we only use this route if there is a timeout.
-			final OutputStream out = channel.getOutputStream();
+			OutputStream out = channel.getOutputStream();
 			if (timeout <= 0) {
 				outputStream = out;
 			} else {
-				final PipedInputStream pipeIn = new PipedInputStream();
-				final StreamCopyThread copier = new StreamCopyThread(pipeIn,
-						out);
-				final PipedOutputStream pipeOut = new PipedOutputStream(pipeIn) {
-					@Override
-					public void flush() throws IOException {
-						super.flush();
-						copier.flush();
-					}
-
-					@Override
-					public void close() throws IOException {
-						super.close();
-						try {
-							copier.join(timeout * 1000);
-						} catch (InterruptedException e) {
-							// Just wake early, the thread will terminate
-							// anyway.
-						}
-					}
-				};
-				copier.start();
-				outputStream = pipeOut;
+				IsolatedOutputStream i = new IsolatedOutputStream(out);
+				outputStream = new BufferedOutputStream(i, 16 * 1024);
 			}
 
 			errStream = channel.getErrStream();
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/util/io/IsolatedOutputStream.java b/org.eclipse.jgit/src/org/eclipse/jgit/util/io/IsolatedOutputStream.java
new file mode 100644
index 0000000000..cdc4a4d863
--- /dev/null
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/util/io/IsolatedOutputStream.java
@@ -0,0 +1,241 @@
+/*
+ * 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.
+ */
+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);
+		}
+	}
+}
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/util/io/StreamCopyThread.java b/org.eclipse.jgit/src/org/eclipse/jgit/util/io/StreamCopyThread.java
index ae760e3b8e..506330eb08 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/util/io/StreamCopyThread.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/util/io/StreamCopyThread.java
@@ -88,6 +88,7 @@ public class StreamCopyThread extends Thread {
 	 * happen at some future point in time, when the thread wakes up to process
 	 * the request.
 	 */
+	@Deprecated
 	public void flush() {
 		flushCount.incrementAndGet();
 		synchronized (writeLock) {