86 lines
3.1 KiB
OCaml
86 lines
3.1 KiB
OCaml
(**************************************************************************)
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(* *)
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(* Copyright (c) 2014 - 2016. *)
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(* Dynamic Ledger Solutions, Inc. <contact@tezos.com> *)
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(* *)
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(* All rights reserved. No warranty, explicit or implicit, provided. *)
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(* *)
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(**************************************************************************)
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(** Data queues similar to the [Pipe] module in Jane Street's [Async]
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library. They are implemented with [Queue]s, limited in size, and
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use lwt primitives for concurrent access. *)
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type 'a t
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(** Type of queues holding values of type ['a]. *)
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val create : ?size:(int * ('a -> int)) -> unit -> 'a t
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(** [create ~size:(max_size, compute_size)] is an empty queue that can
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hold max [size] bytes of data, using [compute_size] to compute the
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size of a datum. *)
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val push : 'a t -> 'a -> unit Lwt.t
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(** [push q v] is a thread that blocks while [q] contains more
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than [size] elements, then adds [v] at the end of [q]. *)
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val pop : 'a t -> 'a Lwt.t
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(** [pop q] is a thread that blocks while [q] is empty, then
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removes and returns the first element in [q]. *)
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val peek : 'a t -> 'a Lwt.t
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(** [peek] is like [pop] except it does not removes the first
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element. *)
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val values_available : 'a t -> unit Lwt.t
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(** [values_available] is like [peek] but it ignores the value
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returned. *)
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val push_now : 'a t -> 'a -> bool
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(** [push_now q v] adds [v] at the ends of [q] immediately and returns
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[false] if [q] is currently full, [true] otherwise. *)
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exception Full
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val push_now_exn : 'a t -> 'a -> unit
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(** [push_now q v] adds [v] at the ends of [q] immediately or
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raise [Full] if [q] is currently full. *)
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val safe_push_now : 'a t -> 'a -> unit
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(** [safe_push_now q v] may adds [v] at the ends of [q]. It does
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nothing if the queue is fulled or closed. *)
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val pop_now : 'a t -> 'a option
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(** [pop_now q] maybe removes and returns the first element in [q] if
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[q] contains at least one element. *)
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exception Empty
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val pop_now_exn : 'a t -> 'a
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(** [pop_now_exn q] removes and returns the first element in [q] if
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[q] contains at least one element, or raise [Empty] otherwise. *)
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val length : 'a t -> int
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(** [length q] is the number of elements in [q]. *)
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val is_empty : 'a t -> bool
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(** [is_empty q] is [true] if [q] is empty, [false] otherwise. *)
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val empty : 'a t -> unit Lwt.t
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(** [empty q] returns when [q] becomes empty. *)
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val iter : 'a t -> f:('a -> unit Lwt.t) -> unit Lwt.t
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(** [iter q ~f] pops all elements of [q] and applies [f] on them. *)
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exception Closed
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val close : 'a t -> unit
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(** [close q] the write end of [q]:
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* Future write attempts will fail with [Closed].
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* If there are reads blocked, they will unblock and fail with [Closed].
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* Future read attempts will drain the data until there is no data left.
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Thus, after a pipe has been closed, reads never block.
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Close is idempotent.
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*)
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