Module Async_kernel__.Ivar
A write-once cell that can be empty or full (i.e., hold a single value).
One can read
an ivar to obtain a deferred that becomes determined when the ivar is filled. An ivar is similar to an 'a option ref
, except it is an error to fill an already full ivar.
type 'a t
= 'a Async_kernel__.Types.Ivar.t
type 'a ivar
= 'a t
val equal : 'a t -> 'a t -> bool
equal t t'
is physical equality of t
and t'
.
val create : unit -> 'a t
create ()
returns an empty ivar.
val create_full : 'a -> 'a t
create_full v
returns an ivar filled with v
.
val fill : 'a t -> 'a -> unit
fill t v
fills t
with value v
if t
was empty. If t
was full, fill
raises an exception. It is guaranteed that immediately after calling fill t
, is_some
(Deferred.peek (read t))
.
val fill_if_empty : 'a t -> 'a -> unit
fill_if_empty t v
fills t
with v
if t
is currently empty. If t
is full, then fill_if_empty
does nothing.
val is_empty : 'a t -> bool
is_empty t
returns true if t
is empty.
val is_full : 'a t -> bool
is_full t
returns true if t
is full.
val read : 'a t -> 'a Async_kernel__.Deferred0.t
read t
returns a deferred that becomes enabled with value v
after the ivar is filled with v
.
val peek : 'a t -> 'a option
peek t
returns Some v
iff t
is full with value v
.
val value_exn : 'a t -> 'a
value_exn t
returns v
if t
is full with value v
, and raises otherwise.
val has_handlers : _ t -> bool
has_handlers t
returns true
if t
has handlers waiting on read t
.