.TH "Stdlib.Mutex" 3 2024-05-31 OCamldoc "OCaml library"
.SH NAME
Stdlib.Mutex \- no description
.SH Module
Module   Stdlib.Mutex
.SH Documentation
.sp
Module
.BI "Mutex"
 : 
.B (module Stdlib__Mutex)

.sp

.sp

.sp
.sp
.I type t 

.sp
The type of mutexes\&.

.sp

.I val create 
: 
.B unit -> t
.sp
Return a new mutex\&.

.sp

.I val lock 
: 
.B t -> unit
.sp
Lock the given mutex\&. Only one thread can have the mutex locked
at any time\&. A thread that attempts to lock a mutex already locked
by another thread will suspend until the other thread unlocks
the mutex\&.

.sp
.B "Before4.12"

.ft B
Sys_error
.ft R
was not raised for recursive locking
(platform\-dependent behaviour)


.sp
.B "Raises Sys_error"
if the mutex is already locked by the thread calling
.ft B
Mutex\&.lock
.ft R
\&.

.sp

.I val try_lock 
: 
.B t -> bool
.sp
Same as 
.ft B
Mutex\&.lock
.ft R
, but does not suspend the calling thread if
the mutex is already locked: just return 
.ft B
false
.ft R
immediately
in that case\&. If the mutex is unlocked, lock it and
return 
.ft B
true
.ft R
\&.

.sp

.I val unlock 
: 
.B t -> unit
.sp
Unlock the given mutex\&. Other threads suspended trying to lock
the mutex will restart\&.  The mutex must have been previously locked
by the thread that calls 
.ft B
Mutex\&.unlock
.ft R
\&.

.sp
.B "Before4.12"

.ft B
Sys_error
.ft R
was not raised when unlocking an unlocked mutex
or when unlocking a mutex from a different thread\&.


.sp
.B "Raises Sys_error"
if the mutex is unlocked or was locked by another thread\&.

.sp

.I val protect 
: 
.B t -> (unit -> 'a) -> 'a
.sp

.ft B
protect mutex f
.ft R
runs 
.ft B
f()
.ft R
in a critical section where 
.ft B
mutex
.ft R
is locked (using 
.ft B
Mutex\&.lock
.ft R
); it then takes care of releasing 
.ft B
mutex
.ft R
,
whether 
.ft B
f()
.ft R
returned a value or raised an exception\&.
.sp
The unlocking operation is guaranteed to always takes place,
even in the event an asynchronous exception (e\&.g\&. 
.ft B
Sys\&.Break
.ft R
) is raised
in some signal handler\&.

.sp
.B "Since"
5.1

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