/usr/lib/ocaml/netsys/netsys_sem.mli is in libocamlnet-ocaml-dev 3.7.3-3build2.
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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 | (* $Id: netsys_sem.mli 1802 2012-10-18 23:23:39Z gerd $ *)
(** {1 Generic anonymous semaphores} *)
(** This module purely exists to also support "kind of anonymous"
sempahores on MacOS X (which only has named semaphores). On
other OS, it is just a wrapper for the functions in
{!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 -> bool
(** Returns [true] if anonymous semaphores are supported on this
system, either natively or emulated via named semaphores.
*)
(** {b Constants.} *)
val sem_value_max : int
(** The maximum value of a semaphore, but at most [max_int] *)
val sem_size : int
(** The size of an anonymous semaphore in bytes ([sizeof(sem_t)]) *)
(** {b Types.} *)
type container
(** The container of the semaphore is the shared memory object *)
type prefix = string
(** A name starting with a slash. Must not contain further slashes *)
type anon_semaphore
type sem_open_flag = Netsys_posix.sem_open_flag =
| SEM_O_CREAT
| SEM_O_EXCL
(** {b Container functions.} *)
val container : prefix -> container
(** [container 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.
{b 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 -> container
(** [create_container prefix]: Like [container], but the container is
always created. A previous instance is first deleted.
*)
val prefix : container -> prefix
(** Return the prefix *)
val drop : container -> unit
(** Drop the semaphores in this container, and delete the container.
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).
*)
(** Note that there is a general problem when a container is deleted
or dropped by a process while it is still being used by another one.
This will generally not generate errors, but can cause a lot of
confusion, because the processes will partly access the same
semaphores, and partly different semaphores.
*)
val unlink : prefix -> unit
(** Unlinks the identified container if it exists, and unlinks all
possible named semaphores.
*)
(** {b Semaphore functions.} *)
val sem_init : container -> Netsys_types.memory -> int -> bool -> int ->
anon_semaphore
(** [sem_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 -> unit
(** Destroys the anonymous semaphore *)
val as_sem : container -> Netsys_types.memory -> int -> anon_semaphore
(** [as_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 -> int
(** Returns the value of the semaphore. If the value is bigger than
what can be represented as [int], an [EINVAL] error is returned.
The returned value is non-negative - if the underlying POSIX
function reports a negative value zero is returned instead.
{b Unavailable on MacOS.}
*)
val sem_post : anon_semaphore -> unit
(** Unlocks the semaphore (increases the value by 1) *)
type sem_wait_behavior = Netsys_posix.sem_wait_behavior =
| SEM_WAIT_BLOCK
| SEM_WAIT_NONBLOCK
val sem_wait : anon_semaphore -> sem_wait_behavior -> unit
(** Locks the semaphore (decreases the value by 1). If the semaphore
value is already zero, and [SEM_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
val enable : bool ref
end
(**/**)
val force_emulation : unit -> unit
|