Module async_utils::stream

Additional Useful Stream Combinators and Utilities Streams always signal exhaustion with None return values. A stream epitaph can be used when a specific value is desired as the last item returned by a stream before it is exhausted.

Example usecase: often streams will be used without having direct access to the stream itself such as from a streammap::StreamMap or a futures::stream::FuturesUnordered. Occasionally, it is necessary to perform some cleanup procedure outside of a stream when it is exhausted. An epitaph can be used to uniquely identify which stream has ended within a collection of streams.

Structs

• FlattenUnordered
  A stream that selects items from a [Stream] of [Stream]s.
• FutureMap
  A collection of Future indexed by key, allowing removal by Key. When polled, a FutureMap yields from whichever member future is ready first. The Future type Fut can be ?Unpin, as all futures are stored as pins inside the map. The Key type K must be Unpin; it is unlikely that an !Unpin type would ever be needed as a Key. FutureMap yields items of type Fut::Output.
• OneOrMany
  A collection of multiple futures that optimizes for the single-future case.
• StreamMap
  A collection of Stream indexed by key, allowing removal by Key. When polled, a StreamMap yields from whichever member stream is ready first. The Stream type St can be ?Unpin, as all streams are stored as pins inside the map. The Key type K must be Unpin; it is unlikely that an !Unpin type would ever be needed as a Key. StreamMap yields items of type St::Item; For a stream that yields messages tagged with their Key, consider using the IndexedStreams type alias or using the Tagged combinator.
• StreamWithEpitaph
  A Stream that returns the values of the wrapped stream until the wrapped stream is exhausted. Then it returns a single epitaph value before being exhausted
• Tagged
  A Stream where each yielded item is tagged with a uniform key Items yielded are (K, St::Item)
• TryFlattenUnordered
  A try stream that selects items from a [TryStream] of [TryStream]s.

Enums

• StreamItem
  Values returned from a stream with an epitaph are of type StreamItem.

Traits

• FlattenUnorderedExt
  Extension trait to allow for easy creation of a FlattenUnordered stream from a Stream.
• TryFlattenUnorderedExt
  Extension trait to allow for easy creation of a TryFlattenUnordered stream from a Stream.
• WithEpitaph
  Extension trait to allow for easy creation of a StreamWithEpitaph from a Stream.
• WithTag
  Extension trait to allow for easy creation of a Tagged stream from a Stream.

Type Definitions

• IndexedStreams
  Convenient alias for a collection of Streams indexed by key where each message is tagged and stream termination is notified by key. This is especially useful for maintaining a collection of fidl client request streams, and being notified when each terminates