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(* *)
(* Open Source License *)
(* Copyright (c) 2018 Dynamic Ledger Solutions, Inc. <contact@tezos.com> *)
(* *)
(* Permission is hereby granted, free of charge, to any person obtaining a *)
(* copy of this software and associated documentation files (the "Software"),*)
(* to deal in the Software without restriction, including without limitation *)
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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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(** A 'dropbox' with a single element. *)
(** Type of dropbox holding a value of type ['a] *)
type 'a t
(** The exception returned when trying to access a 'closed' dropbox. *)
exception Closed
(** Create an empty dropbox. *)
val create : unit -> 'a t
(** [put t e] puts the element [e] inside the dropbox [t]. If the dropbox
already held an element, the old element is discarded and replaced by the
new one.
@raise Closed if [close t] has been called. *)
val put : 'a t -> 'a -> unit
(** [take t] is a promise that resolves as soon as an element is held by [t].
The element is removed from [t] when the promise resolves.
If [t] already holds an element when [take t] is called, the promise
resolves immediately. Otherwise, the promise resolves when an element is
[put] there.
@raise Closed if [close t] has been called. *)
val take : 'a t -> 'a Lwt.t
(** [take_with_timeout timeout t] behaves like [take t] except that it returns
[None] if [timeout] resolves before an element is [put].
Note that [timeout] is canceled (i.e., fails with [Canceled]) if an element
is [put] in time (or if one is already present).
@raise Closed if [close t] has been called. *)
val take_with_timeout : unit Lwt.t -> 'a t -> 'a option Lwt.t
(** [peek t] is [Some e] if [t] holds [e] and [None] if [t] does not hold any
element.
@raise Closed if [close t] has been called. *)
val peek : 'a t -> 'a option
(** [close t] closes the dropbox [t]. It terminates all the waiting reader with
the exception [Closed]. All further read or write will also immediately
fail with [Closed], except if the dropbox is not empty when
[close] is called. In that case, a single (and last) [take] will
succeed. *)
val close : 'a t -> unit