module DLS:sig
..end
Domain-local Storage
type 'a
key
Type of a DLS key
val new_key : ?split_from_parent:('a -> 'a) -> (unit -> 'a) -> 'a key
new_key f
returns a new key bound to initialiser f
for accessing
, domain-local variables.
If split_from_parent
is not provided, the value for a new
domain will be computed on-demand by the new domain: the first
get
call will call the initializer f
and store that value.
If split_from_parent
is provided, spawning a domain will
derive the child value (for this key) from the parent
value. This computation happens in the parent domain and it
always happens, regardless of whether the child domain will
use it.
If the splitting function is expensive or requires
child-side computation, consider using 'a Lazy.t key
:
let init () = ...
let split_from_parent parent_value =
... parent-side computation ...;
lazy (
... child-side computation ...
)
let key = Domain.DLS.new_key ~split_from_parent init
let get () = Lazy.force (Domain.DLS.get key)
In this case a part of the computation happens on the child
domain; in particular, it can access parent_value
concurrently with the parent domain, which may require
explicit synchronization to avoid data races.
val get : 'a key -> 'a
get k
returns v
if a value v
is associated to the key k
on
the calling domain's domain-local state. Sets k
's value with its
initialiser and returns it otherwise.
val set : 'a key -> 'a -> unit
set k v
updates the calling domain's domain-local state to associate
the key k
with value v
. It overwrites any previous values associated
to k
, which cannot be restored later.