.TH "Semaphore.Counting" 3o 2023-02-12 OCamldoc "OCaml library"
.SH NAME
Semaphore.Counting \- no description
.SH Module
Module   Semaphore.Counting
.SH Documentation
.sp
Module
.BI "Counting"
 : 
.B sig end

.sp

.sp

.sp
.sp
.I type t 

.sp
The type of counting semaphores\&.

.sp

.I val make 
: 
.B int -> t
.sp

.ft B
make n
.ft R
returns a new counting semaphore, with initial value 
.ft B
n
.ft R
\&.
The initial value 
.ft B
n
.ft R
must be nonnegative\&.

.sp
.B "Raises Invalid_argument"
if 
.ft B
n < 0
.ft R


.sp

.I val release 
: 
.B t -> unit
.sp

.ft B
release s
.ft R
increments the value of semaphore 
.ft B
s
.ft R
\&.
If other threads are waiting on 
.ft B
s
.ft R
, one of them is restarted\&.
If the current value of 
.ft B
s
.ft R
is equal to 
.ft B
max_int
.ft R
, the value of
the semaphore is unchanged and a 
.ft B
Sys_error
.ft R
exception is raised
to signal overflow\&.

.sp
.B "Raises Sys_error"
if the value of the semaphore would overflow 
.ft B
max_int
.ft R


.sp

.I val acquire 
: 
.B t -> unit
.sp

.ft B
acquire s
.ft R
blocks the calling thread until the value of semaphore 
.ft B
s
.ft R
is not zero, then atomically decrements the value of 
.ft B
s
.ft R
and returns\&.

.sp

.I val try_acquire 
: 
.B t -> bool
.sp

.ft B
try_acquire s
.ft R
immediately returns 
.ft B
false
.ft R
if the value of semaphore 
.ft B
s
.ft R
is zero\&.  Otherwise, the value of 
.ft B
s
.ft R
is atomically decremented
and 
.ft B
try_acquire s
.ft R
returns 
.ft B
true
.ft R
\&.

.sp

.I val get_value 
: 
.B t -> int
.sp

.ft B
get_value s
.ft R
returns the current value of semaphore 
.ft B
s
.ft R
\&.
The current value can be modified at any time by concurrent
.ft B
Semaphore\&.Counting\&.release
.ft R
and 
.ft B
Semaphore\&.Counting\&.acquire
.ft R
operations\&.  Hence, the 
.ft B
get_value
.ft R
operation is racy, and its result should only be used for debugging
or informational messages\&.

.sp