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 java.nio.channels.Channel specification. Implementations of the implCloseChannel method need not synchronize against
other threads that might be attempting to close the channel.
implements