0 if everything worked as expected or - ENOENT if the client was already unregistered or - EBADF if the I/O device file descriptor does not refer to a useable device (i.e. it was closed already or not opened yet). In any case the I/O device is not registered with epoll.
EpollException on error.
Unregisters the I/O device.
You need to call this method if you close and then reopen or otherwise reassign the I/O device's file descriptor *without* suspending and resuming or terminating and restarting the task in between. You may call this method at any time, even if the I/O device is not (yet or any more) usable, in which case it will not throw.
Calling unregister is needed if the file descriptor is closed and reopened because when closing the OS unregisters it from epoll behind this instance's back. However, - suspending or terminating the task has the same effect as calling unregister and - if the file descriptor is not going to be closed then unregistering is harmless, as ioWait this will re-register it on the next call.