Um.  This is what an `INTERVAL` of 0 is meant to say.  You *really* don't want an `INTERVAL` of 0 to be passed along to *either* of the reservation methods.  With blocking, it would block forever, preventing other things from happening, such as processing signals to pause, stop, etc.  With polling, to would fire off requests to Redis as fast as the network stack would allow, flooding the network and quickly exhausting resources throughout the system - which is exactly the reason there's an `INTERVAL` in the first place.