| /******************************************************************************* |
| * Copyright (c) 2000, 2004 IBM Corporation and others. |
| * All rights reserved. This program and the accompanying materials |
| * are made available under the terms of the Eclipse Public License v1.0 |
| * which accompanies this distribution, and is available at |
| * http://www.eclipse.org/legal/epl-v10.html |
| * |
| * Contributors: |
| * IBM Corporation - initial API and implementation |
| *******************************************************************************/ |
| package org.eclipse.team.internal.core.streams; |
| |
| import java.io.FilterInputStream; |
| import java.io.IOException; |
| import java.io.InputStream; |
| import java.io.InterruptedIOException; |
| |
| import org.eclipse.core.runtime.IProgressMonitor; |
| import org.eclipse.core.runtime.IStatus; |
| import org.eclipse.core.runtime.OperationCanceledException; |
| import org.eclipse.team.internal.core.*; |
| import org.eclipse.team.internal.core.Policy; |
| import org.eclipse.team.internal.core.TeamPlugin; |
| |
| /** |
| * 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 reads (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 PollingInputStream extends FilterInputStream { |
| private static final boolean DEBUG = Policy.DEBUG_STREAMS; |
| private int numAttempts; |
| private IProgressMonitor monitor; |
| private boolean cancellable; |
| |
| /** |
| * Creates a new polling input stream. |
| * @param in the underlying input 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 PollingInputStream(InputStream in, int numAttempts, IProgressMonitor monitor) { |
| super(in); |
| this.numAttempts = numAttempts; |
| this.monitor = monitor; |
| this.cancellable = true; |
| } |
| |
| /** |
| * Wraps the underlying stream's method. |
| * It may be important to wait for an input stream to 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 OperationCanceledException if the progress monitor is canceled |
| * @throws InterruptedIOException if the underlying operation times out numAttempts times |
| * @throws IOException if an i/o error occurs |
| */ |
| public void close() throws IOException { |
| int attempts = 0; |
| try { |
| readPendingInput(); |
| } catch (IOException e) { |
| // We shouldn't get an exception when we're getting the available input. |
| // If we do, just log it so we can close. |
| TeamPlugin.log(IStatus.ERROR, e.getMessage(), e); |
| } finally { |
| boolean stop = false; |
| while (!stop) { |
| try { |
| in.close(); |
| stop = true; |
| } catch (InterruptedIOException e) { |
| if (checkCancellation()) throw new OperationCanceledException(); |
| if (++attempts == numAttempts) |
| throw new InterruptedIOException(Messages.PollingInputStream_closeTimeout); //$NON-NLS-1$ |
| if (DEBUG) System.out.println("close 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 |
| * and no data was received, bytesTransferred will be zero |
| * @throws IOException if an i/o error occurs |
| */ |
| public int read() throws IOException { |
| int attempts = 0; |
| for (;;) { |
| if (checkCancellation()) throw new OperationCanceledException(); |
| try { |
| return in.read(); |
| } catch (InterruptedIOException e) { |
| if (++attempts == numAttempts) |
| throw new InterruptedIOException(Messages.PollingInputStream_readTimeout); //$NON-NLS-1$ |
| if (DEBUG) System.out.println("read 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 |
| * and no data was received, bytesTransferred will be zero |
| * @throws IOException if an i/o error occurs |
| */ |
| public int read(byte[] buffer, int off, int len) throws IOException { |
| int attempts = 0; |
| for (;;) { |
| if (checkCancellation()) throw new OperationCanceledException(); |
| try { |
| return in.read(buffer, off, len); |
| } catch (InterruptedIOException e) { |
| if (e.bytesTransferred != 0) return e.bytesTransferred; // keep partial transfer |
| if (++attempts == numAttempts) |
| throw new InterruptedIOException(Messages.PollingInputStream_readTimeout); //$NON-NLS-1$ |
| if (DEBUG) System.out.println("read 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 |
| * and no data was received, bytesTransferred will be zero |
| * @throws IOException if an i/o error occurs |
| */ |
| public long skip(long count) throws IOException { |
| int attempts = 0; |
| for (;;) { |
| if (checkCancellation()) throw new OperationCanceledException(); |
| try { |
| return in.skip(count); |
| } catch (InterruptedIOException e) { |
| if (e.bytesTransferred != 0) return e.bytesTransferred; // keep partial transfer |
| if (++attempts == numAttempts) |
| throw new InterruptedIOException(Messages.PollingInputStream_readTimeout); //$NON-NLS-1$ |
| if (DEBUG) System.out.println("read retry=" + attempts); //$NON-NLS-1$ |
| } |
| } |
| } |
| |
| /** |
| * Reads any pending input from the input stream so that |
| * the stream can savely be closed. |
| */ |
| protected void readPendingInput() throws IOException { |
| byte[] buffer= new byte[2048]; |
| while (true) { |
| int available = in.available(); |
| if (available < 1) break; |
| if (available > buffer.length) available = buffer.length; |
| if (in.read(buffer, 0, available) < 1) break; |
| } |
| } |
| |
| /** |
| * 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; |
| } |
| } |
| } |