[][src]Crate flo_stream

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)));

Structs

BlockingPublisher

A blocking publisher is a publisher that blocks messages until it has enough subscribers

ExpiringPublisher

An 'expiring' publisher is one that responds to backpressure from its subscribers by expiring the most recent message.

Publisher

A publisher represents a sink that sends messages to zero or more subscribers

SinglePublisher

A single publisher is a publisher that sends each message to only a single subscriber rather than all of them

Subscriber

Represents a subscriber stream from a publisher sink

Traits

PubSubSpawn
PublisherSink

Trait implemented by sinks that act as a publisher