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package posix-semaphore
POSIX semaphore
A semaphore. The type 'a is only a phantom type specifying if the semaphore is a named or unnamed one. This avoids the possible error of closing/destroying a semaphore with the wrong function.
val sem_wait : 'a semaphore -> (unit, [> `EUnix of Unix.error ]) Result.resultsem_wait s decrements (locks) the semaphore s. If the value of s is greater than zero, the decrement proceeds and sem_wait returns immediately. Otherwise the call blocks until either is becomes possible due to a concurrent sem_post or a signal handler interrupts the call.
val sem_wait_exn : 'a semaphore -> unitsem_wait_exn s is identical to sem_wait s but raises a Unix_error on error.
val sem_post : 'a semaphore -> (unit, [> `EUnix of Unix.error ]) Result.resultsem_post s increments (unlocks) the semaphore s.
val sem_post_exn : 'a semaphore -> unitsem_post_exn s is identical to sem_post s but raises a Unix_error on error.
val sem_init :
int ->
([> `Unnamed ] semaphore, [> `EUnix of Unix.error ]) Result.resultsem_init n creates and initializes a new unnamed semaphore. The initial value of the semaphore is n.
val sem_init_exn : int -> [> `Unnamed ] semaphoresem_init_exn n is identical to sem_init n but raises Unix_error on error.
val sem_getvalue :
'a semaphore ->
(int, [> `EUnix of Unix.error ]) Result.resultsem_getvalue s returns the current value of the semaphore s.
val sem_getvalue_exn : 'a semaphore -> intsem_getvalue_exn s is identical to sem_getvalue s but raises a Unix_error on error.
val sem_destroy :
[> `Unnamed ] semaphore ->
(unit, [> `EUnix of Unix.error ]) Result.resultsem_destroy s destroys the unnamed semaphore s.
val sem_destroy_exn : [> `Unnamed ] semaphore -> unitsem_destroy_exn s is identical to sem_destroy s but raises a Unix_error on error.
val sem_close :
[> `Named ] semaphore ->
(unit, [> `EUnix of Unix.error ]) Result.resultsem_close s closes the named semaphore s.
val sem_close_exn : [> `Named ] semaphore -> unitsem_close_exn s is identical to sem_close s but raises a Unix_error on error.
val sem_trywait :
'a semaphore ->
(unit, [> `EUnix of Unix.error ]) Result.resultsem_trywait s is the same as sem_wait s, except that if the decrement cannot be performed immediately, sem_trywait returns an error instead of blocking.
val sem_trywait_exn : 'a semaphore -> unitsem_trywait_exn s is identical to sem_trywait s but raises a Unix_error on error.
val sem_timedwait :
'a semaphore ->
Posix_time.Timespec.t ->
(unit, [> `EUnix of Unix.error ]) Result.resultsem_timedwait s t is the same as sem_wait s except that t specifies the amount of time the call should block if the decrement cannot be immediately perforned. t is an asbolute time; if it has already expired by the time of the call, and the semaphore s could not be locked immediately, sem_timedwait s t fails with a timeout error.
val sem_timedwait_exn : 'a semaphore -> Posix_time.Timespec.t -> unitsem_timedwait_exn s t is identical to sem_timedwait s t but raises a Unix_error on error.
val sem_unlink : string -> (unit, [> `EUnix of Unix.error ]) Result.resultsem_unlink path removes the named semaphore referenced by path. The semaphore is removed immediately but only destroyed once all other processes that have the semaphore open close it.
sem_unlink_exn path is identical to sem_unlink path but raises a Unix_error on error.
val sem_open :
string ->
Unix.open_flag list ->
Unix.file_perm ->
int ->
([> `Named ] semaphore, [> `EUnix of Unix.error ]) Result.resultsem_open path flags perms n creates a new named semaphore with initial value n.
val sem_open_exn :
string ->
Unix.open_flag list ->
Unix.file_perm ->
int ->
[> `Named ] semaphoresem_open_exn path flags perms n is identical to sem_open path flags perms n but raises a Unix_error on error.