This is an implementation of "Dining Savages" problem as described in 
"The Little Book of Semaphores" by Allen B. Downey Version 2.1.5.

Problem Description:
  
  A tribe of savages eats communal dinners from a large pot that 
  can hold M servings of stewed missionary1. When a savage wants to 
  eat, he helps himself from the pot, unless it is empty. If the pot is 
  empty, the savage wakes up the cook and then waits until the cook 
  has refilled the pot.