The Little Book of Semaphores

This directory contains examples, exercises, and experiments based on Allen Downey's The Little Book of Semaphores.

Semaphore method names

Below are some semaphore method names mentioned by Prof. Downey in section 2.2; the names of the methods in the Semaphore classes in Python and Java; and the corresponding POSIX semaphore functions.

Dykstra	action	used for	Python/Java	POSIX	meaning
P	decrement	wait	acquire	sem_wait	decrement and block if the result is negative
V	increment	signal	release	sem_post	increment and wake a waiting process if any

Prof. Downey adopted the names wait and signal.

I prefer acquire and release, which are consistent with similar methods in the Lock class.