"The basic idea behind an actor is to spawn a self-contained task that performs some job independently of other parts of the program. Typically these actors communicate with the rest of the program through the use of message passing channels. Since each actor runs independently, programs designed using them are naturally parallel." - Alice Ryhl
For a comprehensive understanding of the underlying
concepts and implementation details of the Actor Model,
it's recommended to read the article Actors with Tokio
by Alice Ryhl ( also known as Darksonn ).
This article not only inspired the development of the
interthread crate but also serves as foundation
for the Actor Model implementation logic in it.
To achieve parallel execution of individual objects within the same program, it is challenging due to the need for various types that are capable of working across threads. The main difficulty lies in the fact that as you introduce thread-related types, you can quickly lose sight of the main program idea as the focus shifts to managing thread-related concerns. It involves using constructs like threads, locks, channels, and other synchronization primitives. These additional types and mechanisms introduce complexity and can obscure the core logic of the program.
Moreover, existing libraries like actix, axiom,
designed to simplify working within the Actor Model,
often employ specific concepts, vocabulary, traits and types that may
be unfamiliar to users who are less experienced with
asynchronous programming and futures.
The actor macro - when applied to the
implementation block of a given "MyActor" object,
generates additional types and functions
that enable communication between threads.
A notable outcome of applying this macro is the
creation of the MyActorLive struct ("ActorName" + "Live"),
which acts as an interface/handle to the MyActor object.
MyActorLive retains the exact same public method signatures
as MyActor, allowing users to interact with the actor as if
they were directly working with the original object.
Filename: Cargo.toml
text
interthread = "0.1.4"
oneshot = "0.1.5"
Filename: main.rs ```rust
pub struct MyActor { value: i8, }
impl MyActor {
pub fn new( v: i8 ) -> Self {
Self { value: v }
}
pub fn increment(&mut self) {
self.value += 1;
}
pub fn add_number(&mut self, num: i8) -> i8 {
self.value += num;
self.value
}
pub fn get_value(&self) -> i8 {
self.value
}
}
fn main() {
let actor = MyActorLive::new(5);
let mut actor_a = actor.clone();
let mut actor_b = actor.clone();
let handle_a = std::thread::spawn( move || {
actor_a.increment();
});
let handle_b = std::thread::spawn( move || {
actor_b.add_number(5)
});
let _ = handle_a.join();
let hb = handle_b.join().unwrap();
// we never know which thread will
// be first to call the actor so
// hb = 10 or 11
assert!(hb >= 10);
assert_eq!(actor.get_value(), 11);
}
```
An essential point to highlight is that when invoking
MyActorLive::new, not only does it return an instance
of MyActorLive, but it also spawns a new thread that
contains an instance of MyActor in it.
This introduces parallelism to the program.
The code generated by actor takes
care of the underlying message routing and synchronization,
allowing developers to rapidly prototype their application's
core functionality. This fast sketching capability is
particularly useful when exploring different design options,
experimenting with concurrency models, or implementing
proof-of-concept systems.
The same example can be run in
tokio,
async-std,
and smol,
with the only difference being that the methods will
be marked as async and need to be awaited for
asynchronous execution.
Filename: Cargo.toml
text
interthread = "0.1.4"
tokio = { version="1.28.2",features=["full"]}
Filename: main.rs
```rust
pub struct MyActor { value: i8, }
impl MyActor {
pub fn new( v: i8 ) -> Self {
Self { value: v }
}
// if the "lib" is defined
// object methods can be "async"
pub async fn increment(&mut self) {
self.value += 1;
}
pub fn add_number(&mut self, num: i8) -> i8 {
self.value += num;
self.value
}
pub fn get_value(&self) -> i8 {
self.value
}
}
async fn main() {
let actor = MyActorLive::new(5);
let mut actor_a = actor.clone();
let mut actor_b = actor.clone();
let handle_a = tokio::spawn( async move {
actor_a.increment().await;
});
let handle_b = tokio::spawn( async move {
actor_b.add_number(5).await
});
let _ = handle_a.await;
let hb = handle_b.await.unwrap();
// hb = 10 or 11
assert!(hb >= 10);
assert_eq!(actor.get_value().await, 11);
}
``
The crate also includes a powerful macro called [example](https://docs.rs/interthread/latest/interthread/attr.example.html) that can expand the [actor](https://docs.rs/interthread/latest/interthread/attr.actor.html) macro, ensuring that users always have the opportunity to visualize and interact with the generated code. Which makes [actor`](https://docs.rs/interthread/latest/interthread/attr.actor.html) 100% transparent macro .
For more details, check out interthread on
Docs.rs.
You've paid for 5 cores, don't code on one.