This library allows you to build Rust applications that run on top of Lunatic.

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Why would you want to run on top of Lunatic?

Lunatic provides an Erlang like runtime for all programming languages that compile to WebAssembly. It's all about spawning super lightweight processes, also known as green threads or go-routines in other runtimes. Lunatic processes are fast to create, have a small memory footprint and a low scheduling overhead. They are designed for MASSIVE concurrency.

Lunatic processes are completely isolated from each other, they have their own stack, heap and even syscalls. If one process fails it will not affect the rest of the system. This allows you to create very powerful and fault-tolerant abstraction.

All processes running on Lunatic are preemptively scheduled and executed by a work stealing async executor. This gives you the freedom to write simple blocking code, but the runtime is going to make sure it actually never blocks a thread if waiting on I/O.

To learn more about Lunatic's architecture check out the runtime repository. It's written in Rust :)

Example

This example application spawns a process and waits for it to print a message on the screen.

use  lunatic::Process;

fn main() {
    Process::spawn_with((), |_: ()| {
        println!("Hello from inside the new process!");
    })
    .join()
    .unwrap();
}

Check out more examples here.

Requirements

To run the example you will first need to download the Lunatic runtime by following the installation steps in this repository.

Lunatic applications need to be compiled to WebAssembly before they can be executed by the runtime. Rust has great support for WebAssembly and you can build a Lunatic compatible application just by passing the --target=wasm32-wasi flag to cargo, e.g:

cargo build --release --target=wasm32-wasi

This will generate a .wasm file in the target/wasm32-wasi/release/ folder inside your project. You can now run your application by passing the generated .wasm file to Lunatic, e.g:

lunatic target/wasm32-wasi/release/<name>.wasm

Supported Features

Some features are directly supported through Rust's standard library, like filesystem access (std::fs::File). Others are specific to Lunatic, like process spawning (lunatic::Process).

Some features that are usually available in Rust's standard library (like TCP, e.g. std::net::TcpListener) are not standardised yet by WASI. So we made them available through this library (e.g. lunatic::net::TcpListener). Once WASI gets support for this features you will be able to just use the standard library versions.

What currently works:

• Process creation & joining (with this library)
• Fine-grained process permissions (with this library)
• Channel based message passing (with this library)
• TCP networking (with this library)
• Filesystem access
• Environment variables
• Multithreading

NOTE: Some libraries currently don't compile under the target wasm32-wasi and can't be used inside Lunatic applications.