event_bus.rs

A runtime-agnostic, async, and thread-safe event bus for Rust. Designed to be efficient, simple, and easy to use, allowing you to publish and subscribe to messages across threads and async tasks.

Features

• Runtime-agnostic: works with any async runtime (Tokio, async-std, smol, etc.)
• Thread-safe: multiple publishers and subscribers can safely coexist
• Async & Stream-based: subscribers implement futures::Stream
• Automatic cleanup: topics are removed when the last subscriber drops
• Minimal & simple API: just EventBus::subscribe and EventBus::publish

Topic capacity

The EventBus is build on top of bounded channels, which means that each time a topic is created, we need to specify a capacity.

The default one is set to an arbitrary value which is available and documented in the docs.

To know more about how the bounded channels work, check async_broadcast

Installation

Add to your Cargo.toml:

[dependencies]
event_bus_rs = "0.1"
futures = "0.3"

Usage Example

use event_bus_rs::EventBus;
use futures::StreamExt;

#[tokio::main]
async fn main() {
    let bus = EventBus::new_with_topic_capacity(50);

    // Subscribe to a topic
    let mut sub = bus.subscribe("my_topic");

    // Spawn a subscriber task
    tokio::spawn(async move {
        while let Some(msg) = sub.next().await {
            println!("Received: {}", String::from_utf8_lossy(&msg));
        }
    });

    // Publish a message
    bus.publish("my_topic", b"Hello, EventBus!").unwrap();
}

Notes:

• Messages are published as &[u8]; encoding/decoding is the user's responsibility.
• Multiple subscribers to the same topic each get a copy of every message.
• When all subscribers of a topic are dropped, the topic is automatically cleaned up.

API Overview

• EventBus::new() -> EventBus – create a new bus
• EventBus::new_with_topic_capacity() -> EventBus - create a new but with a configure topic capacity
• EventBus::subscribe(&self, topic: &str) -> Subscription – subscribe to a topic
• EventBus::publish(&self, topic: &str, data: &[u8]) -> Result<(), PublishError> – publish a message
• Subscription implements futures::Stream<Item = Arc<[u8]>>

License

MIT OR Apache-2.0