Crate vin

source ·
Expand description

vin

A lightweight, ergonomic and unconventional actor crate.

Overview

Vin’s goal is to be an ergonomic, unconventional actor library. Vin doesn’t follow the conventional implementations for actor libraries, but tries to be as simple as possible, while still providing an ergonomic and rich interface by integrating itself with [tokio] as much as possible. Each actor gets its own task to poll messages and execute handlers on. Its address is shared by a simple Arc. Vin also provides a way to gracefully shutdown all actors without having to do the manual labour yourself. Actor data is stored in its actor context and is retrievable for reading with Actor::ctx() and for writing with Actor::ctx_mut() which acquire a RwLock to the data. Vin also provides a “task actor” which is simply a [tokio] task spun up and synchronized with Vin’s shutdown system.

Vin completely relies on tokio (for the async runtime), log (for diagnostics) and async_trait.

Examples

Regular actors

Basic usage of [vin].

use vin::prelude::*;
use std::time::Duration;
use tracing::Level;
 
#[vin::message]
#[derive(Debug, Clone)]
pub enum Msg {
    Foo,
    Bar,
    Baz,
}
 
#[vin::message(result = u32, error = String)]
struct MsgWithResult(bool);
 
#[vin::actor]
#[vin::handles(Msg)]
#[vin::handles(MsgWithResult)]
struct MyActor {
    pub number: u32,
}
 
#[async_trait]
impl vin::Hooks for MyActor {}
 
#[async_trait]
impl vin::Handler<Msg> for MyActor {
    async fn handle(&self, msg: Msg) -> Result<(), ()> {
        let ctx = self.ctx().await;
        println!("The message is: {:?} and the number is {}", msg, ctx.number);
 
        Ok(())
    }
}
 
#[async_trait]
impl vin::Handler<MsgWithResult> for MyActor {
    async fn handle(&self, MsgWithResult(should_err): MsgWithResult) -> Result<u32, String> {
		if should_err { Err("error".to_string()) }
        else { Ok(42) }
    }
}
 
#[tokio::main]
async fn main() {
    tracing_subscriber::fmt()
        .with_max_level(Level::TRACE)
        .init();
 
    let ctx = VinContextMyActor { number: 42 };
    let actor = MyActor::start("test", ctx).unwrap();
    actor.send(Msg::Bar).await;
    tokio::time::sleep(Duration::from_millis(500)).await;
	let res = actor.send_and_wait(MsgWithResult(false)).await.unwrap();
	assert_eq!(res, 42);
    vin::shutdown();
    vin::wait_for_shutdowns().await;
}

Task actors

Basic usage of task actors in [vin].

use vin::*;
use std::time::Duration;
use tracing::Level;
 
#[vin::task]
#[derive(Debug, Clone, PartialEq, Eq)]
struct MyTaskActor {
    pub number: u32,
}
#[async_trait]
impl vin::Task for MyTaskActor {
    async fn task(&self, ctx: Self::Context) -> anyhow::Result<()> {
        for i in 0..ctx.number {
            log::info!("{}. iteration", i);
        }
 
        Ok(())
    }
}
 
#[tokio::main]
async fn main() {
    tracing_subscriber::fmt()
        .with_max_level(Level::TRACE)
        .init();
 
	let ctx = VinContextMyTaskActor { number: 5 };
    let actor = MyTaskActor::start("test_task", ctx);
    tokio::time::sleep(Duration::from_millis(100)).await;
	actor.close();
    vin::shutdown();
    vin::wait_for_shutdowns().await;
}

Re-exports

Structs

Enums

Traits

  • Actor
    Actor trait that all generic (non-specialized) actors must implement.
  • Addr
    A restricted interface of Actor that provides send mechanics and state reads.
  • Forwarder
    Forwards the message to the respective mailbox.
  • Handler
    Handler for specifying message handling logic.
  • Hooks
    Used to call arbitrary code on state changes.
  • Message
    Trait indicating that the type is a message.
  • Task
    Used to call arbitrary code on a task actor.
  • TaskActor
    Actor trait that all generic (non-specialized) actors must implement.
  • TaskAddr
    A restricted interface of TaskActor that provides closing and state reads.

Functions

Type Definitions

Attribute Macros

  • actor
    Generates the actor impls and forms necessary fields.
  • handles
    A noop macro attribute used to specify messages to handle. Check [actor] for more information.
  • message
    Implements the [Message] trait for a type. Enables specifying the result type easily.
  • task
    Generates a [vin]-managed [tokio] task. It’s a specialized actor with no handler that runs some piece of code until it’s completed or [vin] has shutdown.