Revision b615df1cabcd074cd216b490e99ec2260a69c324 authored by Corneliu Hoffman on 25 November 2022, 19:52:51 UTC, committed by Corneliu Hoffman on 07 December 2022, 09:16:00 UTC
1 parent dfa2482
lwt_utils.mli
(*****************************************************************************)
(* *)
(* Open Source License *)
(* Copyright (c) 2018 Dynamic Ledger Solutions, Inc. <contact@tezos.com> *)
(* Copyright (c) 2018-2021 Nomadic Labs, <contact@nomadic-labs.com> *)
(* *)
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(* Software is furnished to do so, subject to the following conditions: *)
(* *)
(* The above copyright notice and this permission notice shall be included *)
(* in all copies or substantial portions of the Software. *)
(* *)
(* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR*)
(* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, *)
(* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL *)
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(*****************************************************************************)
val never_ending : unit -> 'a Lwt.t
(** [worker name ~on_event ~run ~cancel] internally calls [run ()] (which
returns a promise [p]) and returns its own promise [work].
If [p] becomes fulfilled, then [work] also becomes fulfilled.
If [p] becomes rejected then [cancel ()] is called and, once its promise is
resolved, [work] is fulfilled. This gives the opportunity for the function
[cancel] to clean-up some resources.
The function [on_event] is called at different times (start, failure, end)
and is mostly meant as a logging mechanism but can also be used for other
purposes such as synchronization between different workers.
If the promises returned by [on_event] or [cancel] raise an exception or
become rejected, the exception/failure is simply ignored and the promise is
treated as having resolved anyway.
Note that the promise [work] returned by the [worker] function is not
cancelable. If you need to cancel the promise returned by [run], you need
to embed your own synchronization system within [run]. E.g.,
[let p, r = Lwt.wait in
let run () =
let main = … in
Lwt.pick [main ; p]
in]
*)
val worker :
string ->
on_event:(string -> [`Ended | `Failed of string | `Started] -> unit Lwt.t) ->
run:(unit -> unit Lwt.t) ->
cancel:(unit -> unit Lwt.t) ->
unit Lwt.t
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