monoio

Overview of Monoio

Monoio is an advanced runtime system designed specifically for Rust programming language, aimed at handling asynchronous input/output (IO) operations with enhanced efficiency. It utilizes modern system calls like io_uring, epoll, and kqueue to optimize performance, particularly for server applications that require high throughput and low latency.

Design Goals

The primary design objective of Monoio is to offer an efficient runtime for applications that are heavily reliant on IO operations, such as servers dealing with numerous network socket interactions. Unlike other runtimes that might run on top of existing systems, Monoio is built from the ground up with a pure implementation leveraging io_uring, epoll, and kqueue, depending on the platform.

One unique aspect of Monoio's design is its thread-per-core model. This approach allows developers to manage asynchronous tasks without needing to ensure that data structures are Send or Sync, which are typically required to move data safely between threads. In Monoio's model, data remains local to a thread, which eliminates the need for such complications and can result in performance gains, especially in server environments where a thread-per-core setup is advantageous.

Technical Specifics

Monoio is specifically optimized for modern Linux kernels starting from version 5.6, which support io_uring, a new and advanced asynchronous IO API. It can also utilize epoll for earlier versions or where io_uring lacks support. macOS is supported via kqueue, but other operating systems are currently not compatible. This deliberate focus on native, low-level IO interfaces helps maximize throughput and efficiency in network-bound applications.

Quick Start Guide

To begin using Monoio, developers need to ensure they have at least version 1.75 of Rust. For Linux users wishing to employ io_uring, it's vital that the operating system supports it, and necessary configurations such as memlock limitations are appropriately set. For older Linux versions or macOS, developers can use a legacy driver to initiate Monoio.

Here is a simple example demonstrating Monoio in action:

/// A simple echo server example.
///
/// Start the server and then use a command like `nc 127.0.0.1 50002`
/// in another shell to test it. The server will echo back any input.
use monoio::io::{AsyncReadRent, AsyncWriteRentExt};
use monoio::net::{TcpListener, TcpStream};

#[monoio::main]
async fn main() {
    let listener = TcpListener::bind("127.0.0.1:50002").unwrap();
    println!("listening");
    loop {
        let incoming = listener.accept().await;
        match incoming {
            Ok((stream, addr)) => {
                println!("accepted a connection from {}", addr);
                monoio::spawn(echo(stream));
            }
            Err(e) => {
                println!("accepted connection failed: {}", e);
                return;
            }
        }
    }
}

async fn echo(mut stream: TcpStream) -> std::io::Result<()> {
    let mut buf: Vec<u8> = Vec::with_capacity(8 * 1024);
    let mut res;
    loop {
        // read
        (res, buf) = stream.read(buf).await;
        if res? == 0 {
            return Ok(());
        }

        // write all
        (res, buf) = stream.write_all(buf).await;
        res?;

        // clear
        buf.clear();
    }
}

Additional examples and usage details are available in the Monoio repository.

Limitations and Considerations

While Monoio is robust and optimized for a specific range of use cases, it does come with certain limitations. It is only compatible with Linux and macOS at the moment, and on systems with highly unbalanced workloads, its performance might not surpass that of competing runtimes like Tokio.

Community and Contributions

Monoio is part of the larger CloudWeGo project dedicated to fostering cloud-native technologies. Contributions are welcomed, and many developers have already contributed to the project. Visualizations of contributions can be seen in the project's repository.

Related Projects

Monoio is associated with several auxiliary projects that enhance its functionality:

• local-sync: A project providing thread-local synchronization channels.
• monoio-tls: A TLS wrapper designed to work seamlessly with Monoio.
• monoio-codec: A utility to manage data encoding and decoding within Monoio.

Future developments include an HTTP framework and an RPC framework, expanding the capabilities of Monoio even further.

Licensing

Monoio is open-source software available under either the MIT or Apache license. The project has drawn inspiration and components from other popular Rust async libraries including Tokio and mio, recognizing the contributions of their authors.

For more information or to access the project, you can visit the Monoio repository and explore the documentation and other resources provided.