| /******************************************************************************* |
| * Copyright (c) 2000, 2003 IBM Corporation and others. |
| * All rights reserved. This program and the accompanying materials |
| * are made available under the terms of the Common Public License v1.0 |
| * which accompanies this distribution, and is available at |
| * http://www.eclipse.org/legal/cpl-v10.html |
| * |
| * Contributors: |
| * IBM Corporation - initial API and implementation |
| *******************************************************************************/ |
| package org.eclipse.team.internal.core.streams; |
| |
| import java.io.BufferedOutputStream; |
| import java.io.FilterOutputStream; |
| import java.io.IOException; |
| import java.io.InterruptedIOException; |
| import java.io.OutputStream; |
| |
| import org.eclipse.team.internal.core.Policy; |
| |
| /** |
| * Wraps an output stream that blocks indefinitely to simulate timeouts on write(), |
| * flush(), and close(). The resulting output stream is buffered and supports |
| * retrying operations that failed due to an InterruptedIOException. |
| * |
| * Supports resuming partially completed operations after an InterruptedIOException |
| * REGARDLESS of whether the underlying stream does unless the underlying stream itself |
| * generates InterruptedIOExceptions in which case it must also support resuming. |
| * Check the bytesTransferred field to determine how much of the operation completed; |
| * conversely, at what point to resume. |
| */ |
| public class TimeoutOutputStream extends FilterOutputStream { |
| // unsynchronized variables |
| private final long writeTimeout; // write() timeout in millis |
| private final long closeTimeout; // close() timeout in millis, or -1 |
| |
| // requests for the thread (synchronized) |
| private byte[] iobuffer; // circular buffer |
| private int head = 0; // points to first unwritten byte |
| private int length = 0; // number of remaining unwritten bytes |
| private boolean closeRequested = false; // if true, close requested |
| private boolean flushRequested = false; // if true, flush requested |
| |
| // responses from the thread (synchronized) |
| private Thread thread; |
| private boolean waitingForClose = false; // if true, the thread is waiting for close() |
| private IOException ioe = null; |
| |
| /** |
| * Creates a timeout wrapper for an output stream. |
| * @param out the underlying input stream |
| * @param bufferSize the buffer size in bytes; should be large enough to mitigate |
| * Thread synchronization and context switching overhead |
| * @param writeTimeout the number of milliseconds to block for a write() or flush() before |
| * throwing an InterruptedIOException; 0 blocks indefinitely |
| * @param closeTimeout the number of milliseconds to block for a close() before throwing |
| * an InterruptedIOException; 0 blocks indefinitely, -1 closes the stream in the background |
| */ |
| public TimeoutOutputStream(OutputStream out, int bufferSize, long writeTimeout, long closeTimeout) { |
| super(new BufferedOutputStream(out, bufferSize)); |
| this.writeTimeout = writeTimeout; |
| this.closeTimeout = closeTimeout; |
| this.iobuffer = new byte[bufferSize]; |
| thread = new Thread(new Runnable() { |
| public void run() { |
| runThread(); |
| } |
| }, "TimeoutOutputStream");//$NON-NLS-1$ |
| thread.setDaemon(true); |
| thread.start(); |
| } |
| |
| /** |
| * Wraps the underlying stream's method. |
| * It may be important to wait for a stream to actually be closed because it |
| * holds an implicit lock on a system resoure (such as a file) while it is |
| * open. Closing a stream may take time if the underlying stream is still |
| * servicing a previous request. |
| * @throws InterruptedIOException if the timeout expired, bytesTransferred will |
| * reflect the number of bytes flushed from the buffer |
| * @throws IOException if an i/o error occurs |
| */ |
| public void close() throws IOException { |
| Thread oldThread; |
| synchronized (this) { |
| if (thread == null) return; |
| oldThread = thread; |
| closeRequested = true; |
| thread.interrupt(); |
| checkError(); |
| } |
| if (closeTimeout == -1) return; |
| try { |
| oldThread.join(closeTimeout); |
| } catch (InterruptedException e) { |
| Thread.currentThread().interrupt(); // we weren't expecting to be interrupted |
| } |
| synchronized (this) { |
| checkError(); |
| if (thread != null) throw new InterruptedIOException(); |
| } |
| } |
| |
| /** |
| * Writes a byte to the stream. |
| * @throws InterruptedIOException if the timeout expired and no data was sent, |
| * bytesTransferred will be zero |
| * @throws IOException if an i/o error occurs |
| */ |
| public synchronized void write(int b) throws IOException { |
| syncCommit(true); |
| iobuffer[(head + length) % iobuffer.length] = (byte) b; |
| length++; |
| notify(); |
| } |
| |
| /** |
| * Writes multiple bytes to the stream. |
| * @throws InterruptedIOException if the timeout expired, bytesTransferred will |
| * reflect the number of bytes sent |
| * @throws IOException if an i/o error occurs |
| */ |
| public synchronized void write(byte[] buffer, int off, int len) throws IOException { |
| int amount = 0; |
| try { |
| do { |
| syncCommit(true); |
| while (amount < len && length != iobuffer.length) { |
| iobuffer[(head + length) % iobuffer.length] = buffer[off++]; |
| length++; |
| amount++; |
| } |
| } while (amount < len); |
| } catch (InterruptedIOException e) { |
| e.bytesTransferred = amount; |
| throw e; |
| } |
| notify(); |
| } |
| |
| /** |
| * Flushes the stream. |
| * @throws InterruptedIOException if the timeout expired, bytesTransferred will |
| * reflect the number of bytes flushed from the buffer |
| * @throws IOException if an i/o error occurs |
| */ |
| public synchronized void flush() throws IOException { |
| int oldLength = length; |
| flushRequested = true; |
| try { |
| syncCommit(false); |
| } catch (InterruptedIOException e) { |
| e.bytesTransferred = oldLength - length; |
| throw e; |
| } |
| notify(); |
| } |
| |
| /** |
| * Waits for the buffer to drain if it is full. |
| * @param partial if true, waits until the buffer is partially empty, else drains it entirely |
| * @throws InterruptedIOException if the buffer could not be drained as requested |
| */ |
| private void syncCommit(boolean partial) throws IOException { |
| checkError(); // check errors before allowing the addition of new bytes |
| if (partial && length != iobuffer.length || length == 0) return; |
| if (waitingForClose) throw new IOException(Policy.bind("TimeoutOutputStream.cannotWriteToStream")); //$NON-NLS-1$ |
| notify(); |
| try { |
| wait(writeTimeout); |
| } catch (InterruptedException e) { |
| Thread.currentThread().interrupt(); // we weren't expecting to be interrupted |
| } |
| checkError(); // check errors before allowing the addition of new bytes |
| if (partial && length != iobuffer.length || length == 0) return; |
| throw new InterruptedIOException(); |
| } |
| |
| /** |
| * If an exception is pending, throws it. |
| */ |
| private void checkError() throws IOException { |
| if (ioe != null) { |
| IOException e = ioe; |
| ioe = null; |
| throw e; |
| } |
| } |
| |
| /** |
| * Runs the thread in the background. |
| */ |
| private void runThread() { |
| try { |
| writeUntilDone(); |
| } catch (IOException e) { |
| synchronized (this) { ioe = e; } |
| } finally { |
| waitUntilClosed(); |
| try { |
| out.close(); |
| } catch (IOException e) { |
| synchronized (this) { ioe = e; } |
| } finally { |
| synchronized (this) { |
| thread = null; |
| notify(); |
| } |
| } |
| } |
| } |
| |
| /** |
| * Waits until we have been requested to close the stream. |
| */ |
| private synchronized void waitUntilClosed() { |
| waitingForClose = true; |
| notify(); |
| while (! closeRequested) { |
| try { |
| wait(); |
| } catch (InterruptedException e) { |
| closeRequested = true; // alternate quit signal |
| } |
| } |
| } |
| |
| /** |
| * Writes bytes from the buffer until closed and buffer is empty |
| */ |
| private void writeUntilDone() throws IOException { |
| int bytesUntilFlush = -1; // if > 0, then we will flush after that many bytes have been written |
| for (;;) { |
| int off, len; |
| synchronized (this) { |
| for (;;) { |
| if (closeRequested && length == 0) return; // quit signal |
| if (length != 0 || flushRequested) break; |
| try { |
| wait(); |
| } catch (InterruptedException e) { |
| closeRequested = true; // alternate quit signal |
| } |
| } |
| off = head; |
| len = iobuffer.length - head; |
| if (len > length) len = length; |
| if (flushRequested && bytesUntilFlush < 0) { |
| flushRequested = false; |
| bytesUntilFlush = length; |
| } |
| } |
| if (len != 0) { |
| // write out all remaining bytes from the buffer before flushing |
| try { |
| // the i/o operation might block without releasing the lock, |
| // so we do this outside of the synchronized block |
| out.write(iobuffer, off, len); |
| } catch (InterruptedIOException e) { |
| len = e.bytesTransferred; |
| } |
| synchronized (this) { |
| head = (head + len) % iobuffer.length; |
| length -= len; |
| notify(); |
| } |
| } |
| if (bytesUntilFlush >= 0) { |
| bytesUntilFlush -= len; |
| if (bytesUntilFlush <= 0) { |
| // flush the buffer now |
| try { |
| out.flush(); |
| } catch (InterruptedIOException e) { |
| } |
| bytesUntilFlush = -1; // might have been 0 |
| } |
| } |
| } |
| } |
| } |