Message Bus

Async Message Bus for Rust

Inspired by Actix ### Basics 1. Can deliver messages between actors using receivers (usually a queue implementations) 2. Messages distincts and delivers by TypeId 3. Messages delivers in a broadcast fashion to many receivers (Cloned) 4. There are different kind of receivers implemented: - BufferUnordered Receiver (sync and async) - Synchronized (sync and async) - BatchedBufferUnordered Receiver (sync and async) - BatchedSynchronized (sync and async) 5. Request/response api. There is an example is [demo_req_resp.rs](./examples/demo_req_resp.rs) Here are the list of implmented handler kinds: ```rust pub trait Handler: Send + Sync { type Error: crate::Error; type Response: Message; fn handle(&self, msg: M, bus: &Bus) -> Result; fn sync(&self, _bus: &Bus) -> Result<(), Self::Error> { Ok(()) } } #[async_trait] pub trait AsyncHandler: Send + Sync { type Error: crate::Error; type Response: Message; async fn handle(&self, msg: M, bus: &Bus) -> Result; async fn sync(&self, _bus: &Bus) -> Result<(), Self::Error> { Ok(()) } } pub trait SynchronizedHandler: Send { type Error: crate::Error; type Response: Message; fn handle(&mut self, msg: M, bus: &Bus) -> Result; fn sync(&mut self, _bus: &Bus) -> Result<(), Self::Error> { Ok(()) } } #[async_trait] pub trait AsyncSynchronizedHandler: Send { type Error: crate::Error; type Response: Message; async fn handle(&mut self, msg: M, bus: &Bus) -> Result; async fn sync(&mut self, _bus: &Bus) -> Result<(), Self::Error> { Ok(()) } } pub trait BatchHandler: Send + Sync { type Error: crate::Error; type Response: Message; fn handle(&self, msg: Vec, bus: &Bus) -> Result, Self::Error>; fn sync(&self, _bus: &Bus) -> Result<(), Self::Error> { Ok(()) } } #[async_trait] pub trait AsyncBatchHandler: Send + Sync { type Error: crate::Error; type Response: Message; async fn handle(&self, msg: Vec, bus: &Bus) -> Result, Self::Error>; async fn sync(&self, _bus: &Bus) -> Result<(), Self::Error> { Ok(()) } } pub trait BatchSynchronizedHandler: Send { type Error: crate::Error; type Response: Message; fn handle(&mut self, msg: Vec, bus: &Bus) -> Result, Self::Error>; fn sync(&mut self, _bus: &Bus) -> Result<(), Self::Error> { Ok(()) } } #[async_trait] pub trait AsyncBatchSynchronizedHandler: Send { type Error: crate::Error; type Response: Message; async fn handle(&mut self, msg: Vec, bus: &Bus) -> Result, Self::Error>; async fn sync(&mut self, _bus: &Bus) -> Result<(), Self::Error> { Ok(()) } } ``` 6. Implemented handler kinds: 1. No Synchronization needed (Handler implements `Send` and `Sync`) * Not batched operations - sync (spawn_blocking) - async (spawn) * Batched - sync (spawn_blocking) - async (spawn) 2. Synchronization needed (Handler implements only `Send` but not implements `Sync`) * Not batched operations - sync (spawn_blocking) - async (spawn) * Batched - sync (spawn_blocking) - async (spawn) 7. Not yet implemented handler kinds: 1. Synchronization needed and thread dedicated (Handler is `!Sync` and `!Send`) * Not batched operations - sync (spawn_blocking) - async (spawn) * Batched - sync (spawn_blocking) - async (spawn) 8. Example: ```rust use messagebus::{error::Error, receivers, AsyncHandler, Bus}; use async_trait::async_trait; struct TmpReceiver; #[async_trait] impl AsyncHandler for TmpReceiver { type Error = Error; type Response = (); async fn handle(&self, msg: i32, bus: &Bus) -> Result { println!("---> i32 {}", msg); bus.send(2i64).await?; Ok(()) } } #[async_trait] impl AsyncHandler for TmpReceiver { type Error = Error; type Response = (); async fn handle(&self, msg: i64, _bus: &Bus) -> Result { println!("---> i64 {}", msg); Ok(()) } } #[tokio::main] async fn main() { let (b, poller) = Bus::build() .register(TmpReceiver) .subscribe::, _, _>(8, Default::default()) .subscribe::, _, _>(8, Default::default()) .done() .build(); b.send(1i32).await.unwrap(); println!("flush"); b.flush().await; println!("close"); b.close().await; println!("closed"); poller.await; println!("[done]"); } ```