Module Domain

module Domain: sig .. end


See 'Parallel programming' chapter in the manual.

type !'a t 

A domain of type 'a t runs independently, eventually producing a result of type 'a, or an exception

val spawn : (unit -> 'a) -> 'a t

spawn f creates a new domain that runs in parallel with the current domain.

val join : 'a t -> 'a

join d blocks until domain d runs to completion. If d results in a value, then that is returned by join d. If d raises an uncaught exception, then that is re-raised by join d.

type id = private int 

Domains have unique integer identifiers

val get_id : 'a t -> id

get_id d returns the identifier of the domain d

val self : unit -> id

self () is the identifier of the currently running domain

val before_first_spawn : (unit -> unit) -> unit

before_first_spawn f registers f to be called before the first domain is spawned by the program. The functions registered with before_first_spawn are called on the main (initial) domain. The functions registered with before_first_spawn are called in 'first in, first out' order: the oldest function added with before_first_spawn is called first.

val at_exit : (unit -> unit) -> unit

at_exit f registers f to be called when the current domain exits. Note that at_exit callbacks are domain-local and only apply to the calling domain. The registered functions are called in 'last in, first out' order: the function most recently added with at_exit is called first. An example:

let temp_file_key = Domain.DLS.new_key (fun _ ->
  let tmp = snd (Filename.open_temp_file "" "") in
  Domain.at_exit (fun () -> close_out_noerr tmp);

The snippet above creates a key that when retrieved for the first time will open a temporary file and register an at_exit callback to close it, thus guaranteeing the descriptor is not leaked in case the current domain exits.

val cpu_relax : unit -> unit

If busy-waiting, calling cpu_relax () between iterations will improve performance on some CPU architectures

val is_main_domain : unit -> bool

is_main_domain () returns true if called from the initial domain.

val recommended_domain_count : unit -> int

The recommended maximum number of domains which should be running simultaneously (including domains already running).

The value returned is at least 1.

module DLS: sig .. end