Module Uwt_preemptive

module Uwt_preemptive: sig .. end

This module allows to mix preemptive threads with Lwt cooperative threads. It maintains an extensible pool of preemptive threads to which you can detach computations.

val detach : ('a -> 'b) -> 'a -> 'b Lwt.t

detach f x runs the computation f x in a separate preemptive thread. detach evaluates to an Lwt thread, which waits for the preemptive thread to complete.

Note that Lwt thread-local storage (i.e., Lwt.with_key) cannot be safely used from within f x. The same goes for most of the rest of Lwt. If you need to run an Lwt thread in f x, use Uwt_preemptive.run_in_main.

val run_in_main : (unit -> 'a Lwt.t) -> 'a

run_in_main f can be called from a detached computation to execute f () in the main preemptive thread, i.e. the one executing Lwt_main.run. run_in_main f blocks until f () completes, then returns its result. If f () raises an exception, run_in_main f raises the same exception.

Lwt.with_key may be used inside f (). Lwt.get can correctly retrieve values set inside f (), but not values set outside the detach invocation that is calling run_in_main.

val init : int -> int -> (string -> unit) -> unit

init min max log initialises this module. i.e. it launches the minimum number of preemptive threads and starts the dispatcher.

val simple_init : unit -> unit

simple_init () does a simple initialization. i.e. with default parameters if the library is not yet initialised.

Note: this function is automatically called Uwt_preemptive.detach.

val get_bounds : unit -> int * int

get_bounds () returns the minimum and the maximum number of preemptive threads.

val set_bounds : int * int -> unit

set_bounds (min, max) set the minimum and the maximum number of preemptive threads.

val set_max_number_of_threads_queued : int -> unit

Sets the size of the waiting queue, if no more preemptive threads are available. When the queue is full, Uwt_preemptive.detach will sleep until a thread is available.

val get_max_number_of_threads_queued : unit -> int

Returns the size of the waiting queue, if no more threads are available