I'm making a room reservation system in Web2Py over Google App Engine. When a user is booking a Room the system must be sure that this room is really available and no one else have reserved it just a moment before. To be sure I make a query to see if the room is available, then I make the reservation. The problem is how can I do this transaction in a kind of "Mutual exclusion" to be sure that this room is really for this user?
Thank you!! :) --
