package moonpool

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Fiber-local storage.

This storage is associated to the current fiber, just like thread-local storage is associated with the current thread.

See Moonpool.Task_local_storage for more general information, as this is based on it.

NOTE: it's important to note that, while each fiber has its own storage, spawning a sub-fiber f2 from a fiber f1 will only do a shallow copy of the storage. Values inside f1's storage will be physically shared with f2. It is thus recommended to store only persistent values in the local storage.

include module type of struct include Moonpool.Task_local_storage end
type t = Moonpool__.Types_.ls_value array Stdlib.ref

Underlying storage for a task. This is mutable and not thread-safe.

val dummy : t

A key used to access a particular (typed) storage slot on every task.

val new_key : init:(unit -> 'a) -> unit -> 'a key

new_key ~init () makes a new key. Keys are expensive and should never be allocated dynamically or in a loop. The correct pattern is, at toplevel:

  let k_foo : foo Task_ocal_storage.key =
    Task_local_storage.new_key ~init:(fun () -> make_foo ()) ()

(* … *)

(* use it: *)
let … = Task_local_storage.get k_foo
val get : 'a key -> 'a

get k gets the value for the current task for key k. Must be run from inside a task running on a runner.

  • raises Failure


val get_opt : 'a key -> 'a option

get_opt k gets the current task's value for key k, or None if not run from inside the task.

val set : 'a key -> 'a -> unit

set k v sets the storage for k to v. Must be run from inside a task running on a runner.

  • raises Failure


val with_value : 'a key -> 'a -> (unit -> 'b) -> 'b

with_value k v f sets k to v for the duration of the call to f(). When f() returns (or fails), k is restored to its old value.

val get_current : unit -> t option

Access the current storage, or None if not run from within a task.

Direct access to values from a storage handle


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