Crate flo_stream
source ·Expand description
flo_stream is a crate providing some extra utilities for streams in Rust’s futures library, in particular the ‘pubsub’ pattern.
The primary new feature is a “pubsub” mechanism - a way to subscribe to updates sent to a futures Sink. This differs
from the Sender/Receiver mechanism provided in the main futures library in two key ways: it’s possible to have
multiple receivers, and messages sent when there is no subscriber connected will be ignored.
PubSub
The sink type provided is Publisher. You can create one with let publisher = Publisher::new(10). This implements
the Sink trait so can be used in a very similar way to send messages. The number passed in is the maximum number
of waiting messages allowed for any given subscriber.
A subscription can be created using let subscription = publisher.subscribe(). Any messages sent to the sink after
this is called is relayed to all subscriptions. A subscription is a Stream so can interact with other parts of the
futures library in the usual way.
Here’s a full worked example with a single subscriber.
let publisher = Publisher::new(10);
let mut publisher = executor::spawn(publisher);
let subscriber = publisher.subscribe();
let mut subscriber = executor::spawn(subscriber);
publisher.wait_send(1).unwrap();
publisher.wait_send(2).unwrap();
publisher.wait_send(3).unwrap();
assert!(subscriber.wait_stream() == Some(Ok(1)));
assert!(subscriber.wait_stream() == Some(Ok(2)));
assert!(subscriber.wait_stream() == Some(Ok(3)));