A purely functional synchronization primitive which represents a single value which may not yet be available.
When created, a Deferred
is empty. It can then be completed exactly once, and never be made empty again.
get
on an empty Deferred
will block until the Deferred
is completed. get
on a completed Deferred
will always immediately return its content.
complete(a)
on an empty Deferred
will set it to a
, notify any and all readers currently blocked on a call to get
, and return true. complete(a)
on a Deferred
that has already been completed will not modify its content, and return false.
Albeit simple, Deferred
can be used in conjunction with Ref to build complex concurrent behaviour and data structures like queues and semaphores.
Finally, the blocking mentioned above is semantic only, no actual threads are blocked by the implementation.
Attributes
- Companion
- object
- Source
- Deferred.scala
- Graph
-
- Supertypes
-
trait Serializableclass Objecttrait Matchableclass Any
- Known subtypes
-