The self-pipe trick<http://cr.yp.to/docs/selfpipe.html>, used to wake up the main loop from another thread or a signal handler.
_FDWaker is a base class for waker implementations based on writing to a pipe being monitored by the reactor.
|Close both ends of my pipe.
|Read some bytes from the pipe and discard them.
|The file descriptor which should be monitored in order to be awoken by this waker.
|The file descriptor for the end of the pipe which can be written to wake up a reactor monitoring this waker.
|Override this method to insert custom logging behavior. Its return value will be inserted in front of every line. It may be called more times than the number of output lines.
Close both ends of my pipe.
|The platform-specified representation of a file descriptor number. Or -1 if the descriptor no longer has a valid file descriptor number associated with it. As long as the descriptor is valid, calls to this method on a particular instance must return the same value.
The file descriptor which should be monitored in order to be awoken by this waker.