Module Fiber.FLS

Fiber local storage

Fiber local storage is intended for use as a low overhead storage mechanism for fiber extensions. For example, one might associate a priority value with each fiber for a scheduler that uses a priority queue or one might use FLS to store unique id values for fibers.

Here is an example of how one might define a fiber id:

let fiber_id_key =
  let next = Atomic.make 0 in
  Fiber.FLS.new_key
  @@ Computed (fun () ->
      Atomic.fetch_and_add next 1)

Here is an example of how one might define a fiber priority:

let fiber_priority_key =
  Fiber.FLS.new_key (Constant 0)

A priority based scheduler could then use get to access the priority of a fiber highly efficiently. Fibers that are fine with the default priority do not necessarily need to store a priority at all.