package lsp

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package lsp
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Concurrency library

This module implements "structured concurrency".

Generals

type 'a t

Type of fiber. A fiber represent a suspended computation. Note that using the same fiber twice will execute it twice, which is probably not what you want. To share the result of a fiber, use an Ivar.t.

val return : 'a -> 'a t

Create a fiber that has already terminated.

val of_thunk : (unit -> 'a t) -> 'a t

Converts a thunk to a fiber, making sure the thunk runs in the context of the fiber (rather than applied in the current context).

Equivalent to (>>=) (return ()), but more explicit.

val never : 'a t

Fiber that never completes.

module O : sig ... end
val map : 'a t -> f:('a -> 'b) -> 'b t
val bind : 'a t -> f:('a -> 'b t) -> 'b t

Joining

The following combinators are helpers to combine the result of several fibers into one. Note that they do not introduce parallelism.

val both : 'a t -> 'b t -> ('a * 'b) t
val sequential_map : 'a list -> f:('a -> 'b t) -> 'b list t
val sequential_iter : 'a list -> f:('a -> unit t) -> unit t

Forking + joining

The following functions combine forking 2 or more fibers followed by joining the results. The execution of the various fibers might be interleaved, however once the combining fiber has terminated, it is guaranteed that there are no fibers lingering around.

val fork_and_join : (unit -> 'a t) -> (unit -> 'b t) -> ('a * 'b) t

Start two fibers and wait for their results.

val fork_and_join_unit : (unit -> unit t) -> (unit -> 'a t) -> 'a t

Same but assume the first fiber returns unit.

val parallel_map : 'a list -> f:('a -> 'b t) -> 'b list t

Map a list in parallel.

val parallel_iter : 'a list -> f:('a -> unit t) -> unit t

Iter over a list in parallel.

Local storage

module Var : sig ... end

Variables local to a fiber

Error handling

val with_error_handler : (unit -> 'a t) -> on_error:(Stdune.Exn_with_backtrace.t -> unit) -> 'a t

with_error_handler f ~on_error calls on_error for every exception raised during the execution of f. This include exceptions raised when calling f () or during the execution of fibers after f () has returned. Exceptions raised by on_error are passed on to the parent error handler.

It is guaranteed that after the fiber has returned a value, on_error will never be called.

val fold_errors : (unit -> 'a t) -> init:'b -> on_error:(Stdune.Exn_with_backtrace.t -> 'b -> 'b) -> ('a, 'b) Stdune.Result.t t

fold_errors f ~init ~on_error calls on_error for every exception raised during the execution of f. This include exceptions raised when calling f () or during the execution of fibers after f () has returned.

Exceptions raised by on_error are passed on to the parent error handler.

val collect_errors : (unit -> 'a t) -> ('a, Stdune.Exn_with_backtrace.t list) Stdune.Result.t t

collect_errors f is: fold_errors f ~init:[] ~on_error:(fun e l -> e :: l)

val finalize : (unit -> 'a t) -> finally:(unit -> unit t) -> 'a t

finalize f ~finally runs finally after f () has terminated, whether it fails or succeeds.

Synchronization

module Ivar : sig ... end

Write once variables

module Mvar : sig ... end

Mailbox variables

module Mutex : sig ... end
module Throttle : sig ... end

Limit the number of jobs

module Sequence : sig ... end

Running fibers

type fill =
  1. | Fill : 'a Ivar.t * 'a -> fill
val run : 'a t -> iter:(unit -> fill) -> 'a

run t ~iter runs a fiber until it terminates. iter is used to implement the scheduler, it should block waiting for an event and return an ivar to fill.

val fork_and_race : (unit -> 'a t) -> (unit -> 'b t) -> ('a, 'b) Stdune.Either.t t