Module Lwt_mvar

module Lwt_mvar : sig..end

Mailbox variables

"Mailbox" variables implement a synchronising variable, used for communication between concurrent threads.

This code adapted from Comparing lightweight threads (

type 'a t

The type of a mailbox variable. Mailbox variables are used to communicate values between threads in a synchronous way. The type parameter specifies the type of the value propagated from put to take.

val create : 'a -> 'a t

create v creates a new mailbox variable containing value v.

val create_empty : unit -> 'a t

create () creates a new empty mailbox variable.

val put : 'a t -> 'a -> unit Lwt.t

put mvar value puts a value into a mailbox variable. This value will remain in the mailbox until take is called to remove it. If the mailbox is not empty, the current thread will block until it is emptied.

val take : 'a t -> 'a Lwt.t

take mvar will take any currently available value from the mailbox variable. If no value is currently available, the current thread will block, awaiting a value to be put by another thread.

val take_available : 'a t -> 'a option

take_available mvar immediately takes the value from mvar without blocking, returning None if the mailbox is empty.

val is_empty : 'a t -> bool

is_empty mvar indicates if put mvar can be called without blocking.