Semaphore(3o) OCaml library Semaphore(3o)
NAME
Semaphore - Semaphores
Module
Module Semaphore
Documentation
Module Semaphore
: sig end
Semaphores
A semaphore is a thread synchronization device that can be used to con-
trol access to a shared resource.
Two flavors of semaphores are provided: counting semaphores and binary
semaphores.
Since 4.12
Counting semaphores
A counting semaphore is a counter that can be accessed concurrently by
several threads. The typical use is to synchronize producers and con-
sumers of a resource by counting how many units of the resource are
available.
The two basic operations on semaphores are:
-"release" (also called "V", "post", "up", and "signal"), which incre-
ments the value of the counter. This corresponds to producing one more
unit of the shared resource and making it available to others.
-"acquire" (also called "P", "wait", "down", and "pend"), which waits
until the counter is greater than zero and decrements it. This corre-
sponds to consuming one unit of the shared resource.
module Counting : sig end
Binary semaphores
Binary semaphores are a variant of counting semaphores where semaphores
can only take two values, 0 and 1.
A binary semaphore can be used to control access to a single shared re-
source, with value 1 meaning "resource is available" and value 0 mean-
ing "resource is unavailable".
The "release" operation of a binary semaphore sets its value to 1, and
"acquire" waits until the value is 1 and sets it to 0.
A binary semaphore can be used instead of a mutex (see module Mutex )
when the mutex discipline (of unlocking the mutex from the thread that
locked it) is too restrictive. The "acquire" operation corresponds to
locking the mutex, and the "release" operation to unlocking it, but
"release" can be performed in a thread different than the one that per-
formed the "acquire". Likewise, it is safe to release a binary sema-
phore that is already available.
module Binary : sig end
OCamldoc 2023-02-12 Semaphore(3o)
Generated by dwww version 1.15 on Sun Jun 23 03:56:46 CEST 2024.