module Netsys_sem:sig..end
Netsys_posix.
Note that on OS X named semaphores have a max name length of
31 characters (including the / at the beginning), and that
Netsys_sem uses 9 characters for its own purposes, leaving
22 characters for the prefix. (On other OS this is less restricted.)
val have_anon_semaphores : unit -> booltrue if anonymous semaphores are supported on this
system, either natively or emulated via named semaphores.val sem_value_max : intmax_intval sem_size : intsizeof(sem_t))type container
typeprefix =string
type anon_semaphore
typesem_open_flag =Netsys_posix.sem_open_flag=
| |
SEM_O_CREAT |
| |
SEM_O_EXCL |
val container : prefix -> containercontainer prefix: The prefix shall identify the container uniquely.
Once can e.g. use the path of the shared memory object. The prefix
is used to construct names for persistent objects.
Note that containers have kernel persistence! They are not
automatically deleted when the process finishes. Call drop
to delete containers, or create_container to force their
creation as fresh objects.
If the container does not exist yet, it is created. Otherwise the
container is just opened.
val create_container : prefix -> containercreate_container prefix: Like container, but the container is
always created. A previous instance is first deleted.val prefix : container -> prefixval drop : container -> unit
This function is a no-op if the OS supports anonymous semaphores
directly (because in this case the deletion of the container will
automatically destroy the semaphores).
val unlink : prefix -> unitval sem_init : container ->
Netsys_types.memory -> int -> bool -> int -> anon_semaphoresem_init cont mem pos pshared init_value: Initializes the memory
at position pos to pos + sem_size() - 1 as anonymous semaphore.
If pshared the semaphore is shared between processes.
init_value is the initial non-negative value (max is
sem_value_max).val sem_destroy : container -> anon_semaphore -> unitval as_sem : container ->
Netsys_types.memory -> int -> anon_semaphoreas_sem mem pos: Interprets the memory at position pos
to pos + sem_size() - 1 as anonymous semaphore.
The memory region must already have been initialized.val sem_getvalue : anon_semaphore -> intint, an EINVAL error is returned.
The returned value is non-negative - if the underlying POSIX function reports a negative value zero is returned instead.
Unavailable on MacOS.
val sem_post : anon_semaphore -> unittypesem_wait_behavior =Netsys_posix.sem_wait_behavior=
| |
SEM_WAIT_BLOCK |
| |
SEM_WAIT_NONBLOCK |
val sem_wait : anon_semaphore -> sem_wait_behavior -> unitSEM_WAIT_BLOCK is given, the function
waits until another process or thread posts. If SEM_WAIT_NONBLOCK
the error EAGAIN is returned.
sem_wait may be interrupted by signals.
module Debug:sig..end