Crate tiny_pubsub 

In-process, topic-based publish/subscribe message bus.

A subscriber is a function called with (topic, data). You register it against a topic string and get back a Token. A publisher sends a value to a topic. Every subscriber whose topic matches runs.

Topics are hierarchical and dot-delimited. Publishing a.b.c notifies subscribers of a.b.c, then a.b, then a, then the wildcard *. A subscriber on an ancestor topic receives the original leaf topic as its first argument, not the ancestor it matched.

Delivery modes

PubSub::publish is deferred. It queues delivery and returns right away. Subscribers run later, when you call PubSub::process_deferred. This mirrors a non-blocking publisher that does not wait on subscriber work.

PubSub::publish_sync runs every matching subscriber before it returns.

Both return true if the topic had at least one matching subscriber (direct, ancestor, or *), else false. The return value is computed before any subscriber runs.

Panics during delivery

Default mode catches a panicking subscriber, finishes delivery to the rest, then re-raises the first panic after the dispatch. Set PubSub::immediate_exceptions to true to stop at the first panic and let it propagate, skipping the remaining subscribers.

Example

use tiny_pubsub::PubSub;
use std::cell::Cell;
use std::rc::Rc;

let bus: PubSub<&str> = PubSub::new();
let hits = Rc::new(Cell::new(0));
let h = hits.clone();
bus.subscribe("car.engine", move |_topic, _data| h.set(h.get() + 1));

assert!(bus.publish_sync("car.engine", "start"));
assert_eq!(hits.get(), 1);

Structs

PubSub

An in-process hierarchical-topic pub/sub message bus.

Token

A handle to one subscription, returned by PubSub::subscribe.

Constants

WILDCARD

The wildcard topic. A subscriber here receives every published message.