| /******************************************************************************* |
| * Copyright (c) 2000, 2017 IBM Corporation and others. |
| * |
| * This program and the accompanying materials |
| * are made available under the terms of the Eclipse Public License 2.0 |
| * which accompanies this distribution, and is available at |
| * https://www.eclipse.org/legal/epl-2.0/ |
| * |
| * SPDX-License-Identifier: EPL-2.0 |
| * |
| * Contributors: |
| * IBM Corporation - initial API and implementation |
| *******************************************************************************/ |
| package org.eclipse.team.internal.core.streams; |
| |
| import java.io.FilterOutputStream; |
| import java.io.IOException; |
| import java.io.InterruptedIOException; |
| import java.io.OutputStream; |
| |
| import org.eclipse.core.runtime.IProgressMonitor; |
| import org.eclipse.core.runtime.OperationCanceledException; |
| import org.eclipse.team.internal.core.Messages; |
| import org.eclipse.team.internal.core.Policy; |
| |
| /** |
| * Polls a progress monitor periodically and handles timeouts over extended durations. |
| * For this class to be effective, a high numAttempts should be specified, and the |
| * underlying stream should time out frequently on writes (every second or so). |
| * |
| * Supports resuming partially completed operations after an InterruptedIOException |
| * if the underlying stream does. Check the bytesTransferred field to determine how |
| * much of the operation completed; conversely, at what point to resume. |
| */ |
| public class PollingOutputStream extends FilterOutputStream { |
| private int numAttempts; |
| private IProgressMonitor monitor; |
| private boolean cancellable; |
| |
| /** |
| * Creates a new polling output stream. |
| * @param out the underlying output stream |
| * @param numAttempts the number of attempts before issuing an InterruptedIOException, |
| * if 0, retries indefinitely until canceled |
| * @param monitor the progress monitor to be polled for cancellation |
| */ |
| public PollingOutputStream(OutputStream out, int numAttempts, IProgressMonitor monitor) { |
| super(out); |
| this.numAttempts = numAttempts; |
| this.monitor = monitor; |
| this.cancellable = true; |
| } |
| |
| /** |
| * Wraps the underlying stream's method. |
| * @throws OperationCanceledException if the progress monitor is canceled |
| * @throws InterruptedIOException if the underlying operation times out numAttempts times |
| * and no data was sent, bytesTransferred will be zero |
| * @throws IOException if an i/o error occurs |
| */ |
| @Override |
| public void write(int b) throws IOException { |
| int attempts = 0; |
| for (;;) { |
| if (checkCancellation()) throw new OperationCanceledException(); |
| try { |
| out.write(b); |
| return; |
| } catch (InterruptedIOException e) { |
| if (++attempts == numAttempts) |
| throw new InterruptedIOException(Messages.PollingOutputStream_writeTimeout); |
| if (Policy.DEBUG_STREAMS) System.out.println("write retry=" + attempts); //$NON-NLS-1$ |
| } |
| } |
| } |
| |
| /** |
| * Wraps the underlying stream's method. |
| * @throws OperationCanceledException if the progress monitor is canceled |
| * @throws InterruptedIOException if the underlying operation times out numAttempts times, |
| * bytesTransferred will reflect the number of bytes sent |
| * @throws IOException if an i/o error occurs |
| */ |
| @Override |
| public void write(byte[] buffer, int off, int len) throws IOException { |
| int count = 0; |
| int attempts = 0; |
| for (;;) { |
| if (checkCancellation()) throw new OperationCanceledException(); |
| try { |
| out.write(buffer, off, len); |
| return; |
| } catch (InterruptedIOException e) { |
| int amount = e.bytesTransferred; |
| if (amount != 0) { // keep partial transfer |
| len -= amount; |
| if (len <= 0) return; |
| off += amount; |
| count += amount; |
| attempts = 0; // made some progress, don't time out quite yet |
| } |
| if (++attempts == numAttempts) { |
| e = new InterruptedIOException(Messages.PollingOutputStream_writeTimeout); |
| e.bytesTransferred = count; |
| throw e; |
| } |
| if (Policy.DEBUG_STREAMS) System.out.println("write retry=" + attempts); //$NON-NLS-1$ |
| } |
| } |
| } |
| |
| /** |
| * Wraps the underlying stream's method. |
| * @throws OperationCanceledException if the progress monitor is canceled |
| * @throws InterruptedIOException if the underlying operation times out numAttempts times, |
| * bytesTransferred will reflect the number of bytes sent |
| * @throws IOException if an i/o error occurs |
| */ |
| @Override |
| public void flush() throws IOException { |
| int count = 0; |
| int attempts = 0; |
| for (;;) { |
| if (checkCancellation()) throw new OperationCanceledException(); |
| try { |
| out.flush(); |
| return; |
| } catch (InterruptedIOException e) { |
| int amount = e.bytesTransferred; |
| if (amount != 0) { // keep partial transfer |
| count += amount; |
| attempts = 0; // made some progress, don't time out quite yet |
| } |
| if (++attempts == numAttempts) { |
| e = new InterruptedIOException(Messages.PollingOutputStream_writeTimeout); |
| e.bytesTransferred = count; |
| throw e; |
| } |
| if (Policy.DEBUG_STREAMS) System.out.println("write retry=" + attempts); //$NON-NLS-1$ |
| } |
| } |
| } |
| |
| /** |
| * Calls flush() then close() on the underlying stream. |
| * @throws OperationCanceledException if the progress monitor is canceled |
| * @throws InterruptedIOException if the underlying operation times out numAttempts times, |
| * bytesTransferred will reflect the number of bytes sent during the flush() |
| * @throws IOException if an i/o error occurs |
| */ |
| @Override |
| public void close() throws IOException { |
| int attempts = numAttempts - 1; // fail fast if flush() does times out |
| try { |
| out.flush(); |
| attempts = 0; |
| } finally { |
| boolean stop = false; |
| while (!stop) { |
| try { |
| out.close(); |
| stop = true; |
| } catch (InterruptedIOException e) { |
| if (checkCancellation()) throw new OperationCanceledException(); |
| if (++attempts == numAttempts) |
| throw new InterruptedIOException(Messages.PollingOutputStream_closeTimeout); |
| if (Policy.DEBUG_STREAMS) System.out.println("close retry=" + attempts); //$NON-NLS-1$ |
| } |
| } |
| } |
| } |
| |
| /** |
| * Called to set whether cancellation will be checked by this stream. Turning cancellation checking |
| * off can be very useful for protecting critical portions of a protocol that shouldn't be interrupted. |
| * For example, it is often necessary to protect login sequences. |
| * @param cancellable a flag controlling whether this stream will check for cancellation. |
| */ |
| public void setIsCancellable(boolean cancellable) { |
| this.cancellable = cancellable; |
| } |
| |
| /** |
| * Checked whether the monitor for this stream has been cancelled. If the cancellable |
| * flag is <code>false</code> then the monitor is never cancelled. |
| * @return <code>true</code> if the monitor has been cancelled and <code>false</code> |
| * otherwise. |
| */ |
| private boolean checkCancellation() { |
| if(cancellable) { |
| return monitor.isCanceled(); |
| } else { |
| return false; |
| } |
| } |
| } |