A default PoolCounter, which provides no locking.
release()
I have successfully finished my task.
acquireForMe( $timeout=null)
I want to do this task and I need to do it myself.
acquireForAnyone( $timeout=null)
I want to do this task, but if anyone else does it instead, it's also fine for me.
Semaphore semantics to restrict how many workers may concurrently perform a task.
int $timeout
Maximum time in seconds to wait for the lock.