Source.unfoldAsync
Just like unfold
but the fold function returns a Future
CompletionStage
.
Description
Just like unfold
but the fold function returns a Future
CompletionStage
which will cause the source to complete or emit when it completes.
Can be used to implement many stateful sources without having to touch the more low level GraphStage
API.
emits when there is demand and unfold state returned future completes with some value
completes when the future CompletionStage returned by the unfold function completes with an empty value