Crate streamunordered
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A stream that efficiently multiplexes multiple streams.
This “combinator” provides the ability to maintain and drive a set of streams to completion, while also providing access to each stream as it yields new elements.
Streams are pushed into this set and their realized values are yielded as they are produced.
This structure is optimized to manage a large number of streams. Streams managed by
StreamUnordered will only be polled when they generate notifications. This reduces the
required amount of work needed to coordinate large numbers of streams.
When a StreamUnordered is first created, it does not contain any streams. Calling poll in
this state will result in Ok(Async::Ready(None)) to be returned. Streams are submitted to the
set using push; however, the stream will not be polled at this point. StreamUnordered
will only poll managed streams when StreamUnordered::poll is called. As such, it is important
to call poll after pushing new streams.
If StreamUnordered::poll returns Ok(Async::Ready(None)) this means that the set is
currently not managing any streams. A stream may be submitted to the set at a later time. At
that point, a call to StreamUnordered::poll will either return the stream’s resolved value
or Ok(Async::NotReady) if the stream has not yet completed.
Whenever a value is yielded, the yielding stream’s index is also included. A reference to the
stream that originated the value is obtained by using StreamUnordered::get or
StreamUnordered::get_mut.
In normal operation, poll will yield a StreamYield::Item when it completes successfully.
This value indicates that an underlying stream (the one indicated by the included index)
produced an item. If an underlying stream yields Async::Ready(None) to indicate termination,
a StreamYield::Finished is returned instead. Note that as soon as a stream is returned in
StreamYield::Finished, its token may be reused for new streams that are added.
Structs
StreamUnordered.