java.nio.channels.spi
class AbstractInterruptibleChannel

java.lang.Object java.nio.channels.spi.AbstractInterruptibleChannel

All Implemented Interfaces:

Channel, InterruptibleChannel

Direct Known Subclasses:

FileChannel, SelectableChannel

public abstract class AbstractInterruptibleChannel
extends Object
implements Channel, InterruptibleChannel

Base implementation class for interruptible channels.

This class encapsulates the low-level machinery required to implement the asynchronous closing and interruption of channels. A concrete channel class must invoke the {@link #begin begin} and {@link #end end} methods before and after, respectively, invoking an I/O operation that might block indefinitely. In order to ensure that the {@link #end end} method is always invoked, these methods should be used within a try ... finally block:

 boolean completed = false;
 try {
     begin();
     completed = ...;    // Perform blocking I/O operation
     return ...;         // Return result
 } finally {
     end(completed);
 }

AbstractInterruptibleChannel

protected AbstractInterruptibleChannel()

Initializes a new instance of this class.

begin

protected final void begin()

Marks the beginning of an I/O operation that might block indefinitely.

This method should be invoked in tandem with the {@link #end end} method, using a try ... finally block as shown above, in order to implement asynchronous closing and interruption for this channel.

close

public final void close()
                 throws IOException

Closes this channel.

If the channel has already been closed then this method returns immediately. Otherwise it marks the channel as closed and then invokes the {@link #implCloseChannel implCloseChannel} method in order to complete the close operation.

Throws:

IOException - If an I/O error occurs

end

protected final void end(boolean completed)
                  throws AsynchronousCloseException

Marks the end of an I/O operation that might block indefinitely.

This method should be invoked in tandem with the {@link #begin begin} method, using a try ... finally block as shown above, in order to implement asynchronous closing and interruption for this channel.

Parameters:

completed - true if, and only if, the I/O operation completed successfully, that is, had some effect that would be visible to the operation's invoker

Throws:

AsynchronousCloseException - If the channel was asynchronously closed

implCloseChannel

protected abstract void implCloseChannel()
                                  throws IOException

Closes this channel.

This method is invoked by the {@link #close close} method in order to perform the actual work of closing the channel. This method is only invoked if the channel has not yet been closed, and it is never invoked more than once.

An implementation of this method must arrange for any other thread that is blocked in an I/O operation upon this channel to return immediately, either by throwing an exception or by returning normally.

Throws:

IOException - If an I/O error occurs while closing the channel

isOpen

public final boolean isOpen()