org.eclipse.ecf.provider.filetransfer.util
Class PollingInputStream

java.lang.Object
  java.io.InputStream
      java.io.FilterInputStream
          org.eclipse.ecf.provider.filetransfer.util.PollingInputStream

All Implemented Interfaces:

java.io.Closeable

public class PollingInputStream
extends java.io.FilterInputStream

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.

Since:

3.0

Field Summary

Fields inherited from class java.io.FilterInputStream

in

Constructor Summary

PollingInputStream(java.io.InputStream in, int numAttempts, org.eclipse.core.runtime.IProgressMonitor monitor)
Creates a new polling input stream.

PollingInputStream(java.io.InputStream in, int numAttempts, org.eclipse.core.runtime.IProgressMonitor monitor, java.lang.String readTimeoutMessage, java.lang.String closeTimeoutMessage)
Creates a new polling input stream.

Method Summary

void	close() Wraps the underlying stream's method.
int	read() Wraps the underlying stream's method.
int	read(byte[] buffer, int off, int len) Wraps the underlying stream's method.
protected void	readPendingInput() Reads any pending input from the input stream so that the stream can savely be closed.
void	setIsCancellable(boolean cancellable) Called to set whether cancellation will be checked by this stream.
long	skip(long count) Wraps the underlying stream's method.

Methods inherited from class java.io.FilterInputStream

available, mark, markSupported, read, reset

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

PollingInputStream

public PollingInputStream(java.io.InputStream in,
                          int numAttempts,
                          org.eclipse.core.runtime.IProgressMonitor monitor)

Creates a new polling input stream.

Parameters:

in - the underlying input stream

numAttempts - the number of attempts before issuing an InterruptedIOException, if 0, retries indefinitely until canceled

monitor - the progress monitor to be polled for cancellation

PollingInputStream

public PollingInputStream(java.io.InputStream in,
                          int numAttempts,
                          org.eclipse.core.runtime.IProgressMonitor monitor,
                          java.lang.String readTimeoutMessage,
                          java.lang.String closeTimeoutMessage)

Creates a new polling input stream.

Parameters:

in - the underlying input stream

numAttempts - the number of attempts before issuing an InterruptedIOException, if 0, retries indefinitely until canceled

monitor - the progress monitor to be polled for cancellation

readTimeoutMessage - message to go with InteruptedIOException if read timeout

closeTimeoutMessage - message to go with InteruptedIOException if close timeout

Since:

3.1

Method Detail

close

public void close()
           throws java.io.InterruptedIOException

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 resource (such as a file) while it is open. Closing a stream may take time if the underlying stream is still servicing a previous request.

Specified by:

close in interface java.io.Closeable

Overrides:

close in class java.io.FilterInputStream

Throws:

org.eclipse.core.runtime.OperationCanceledException - if the progress monitor is canceled

java.io.InterruptedIOException - if the underlying operation times out numAttempts times

read

public int read()
         throws java.io.IOException

Wraps the underlying stream's method.

Overrides:

read in class java.io.FilterInputStream

Returns:

the next byte of data, or -1 if the end of the stream is reached.

Throws:

org.eclipse.core.runtime.OperationCanceledException - if the progress monitor is canceled

java.io.InterruptedIOException - if the underlying operation times out numAttempts times and no data was received, bytesTransferred will be zero

java.io.IOException - if an i/o error occurs

read

public int read(byte[] buffer,
                int off,
                int len)
         throws java.io.IOException

Wraps the underlying stream's method.

Overrides:

read in class java.io.FilterInputStream

Parameters:

buffer - - the buffer into which the data is read.

off - - the start offset of the data.

len - - the maximum number of bytes read.

Returns:

the total number of bytes read into the buffer, or -1 if there is no more data because the end of the stream has been reached.

Throws:

org.eclipse.core.runtime.OperationCanceledException - if the progress monitor is canceled

java.io.InterruptedIOException - if the underlying operation times out numAttempts times and no data was received, bytesTransferred will be zero

java.io.IOException - if an i/o error occurs

skip

public long skip(long count)
          throws java.io.IOException

Wraps the underlying stream's method.

Overrides:

skip in class java.io.FilterInputStream

Parameters:

count - - the number of bytes to be skipped.

Returns:

the actual number of bytes skipped.

Throws:

org.eclipse.core.runtime.OperationCanceledException - if the progress monitor is canceled

java.io.InterruptedIOException - if the underlying operation times out numAttempts times and no data was received, bytesTransferred will be zero

java.io.IOException - if an i/o error occurs

readPendingInput

protected void readPendingInput()
                         throws java.io.IOException

Reads any pending input from the input stream so that the stream can savely be closed.

Throws:

java.io.IOException

setIsCancellable

public void setIsCancellable(boolean cancellable)

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.

Parameters:

cancellable - a flag controlling whether this stream will check for cancellation.