AbstractInterruptibleChannel

public abstract class AbstractInterruptibleChannel extends Object
implements Channel InterruptibleChannel
Known Direct Subclasses
Known Indirect Subclasses

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 begin and end methods before and after, respectively, invoking an I/O operation that might block indefinitely. In order to ensure that the 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);
 }

The completed argument to the end method tells whether or not the I/O operation actually completed, that is, whether it had any effect that would be visible to the invoker. In the case of an operation that reads bytes, for example, this argument should be true if, and only if, some bytes were actually transferred into the invoker's target buffer.

A concrete channel class must also implement the implCloseChannel method in such a way that if it is invoked while another thread is blocked in a native I/O operation upon the channel then that operation will immediately return, either by throwing an exception or by returning normally. If a thread is interrupted or the channel upon which it is blocked is asynchronously closed then the channel's end method will throw the appropriate exception.

This class performs the synchronization required to implement the Channel specification. Implementations of the implCloseChannel method need not synchronize against other threads that might be attempting to close the channel.

Protected Constructor Summary

AbstractInterruptibleChannel()
Initializes a new instance of this class.

Public Method Summary

final void
close()
Closes this channel.
final boolean
isOpen()
Tells whether or not this channel is open.

Protected Method Summary

final void
begin()
Marks the beginning of an I/O operation that might block indefinitely.
final void
end(boolean completed)
Marks the end of an I/O operation that might block indefinitely.
abstract void
implCloseChannel()
Closes this channel.

Inherited Method Summary

Protected Constructors

protected AbstractInterruptibleChannel ()

Initializes a new instance of this class.

Public Methods

public final void close ()

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 implCloseChannel method in order to complete the close operation.

Throws