RFC: Distributed Semaphore

[debuggerpk]

First of all, thank-you for creating this awesome library. 😍

We need to control the number of parallel running jobs. For a single machine, We would use a semaphore to implement this. However, for our current requirements, the semaphore needs to be central. Our team thought of using etcd to implement the said semaphore using a combination of distributed lock and the key/value store before we came across this library.

The question here is, would it make sense to add a distributed semaphore primitive here or the concept can be implemented using atomix.Counter with atomix.Mutex.

PS: my understanding of semaphore and mutex is, A Mutex is a Semaphore with size 1.

Thank-you again.