【Rust】优雅停机

2024-04-05 21:41•css•阅读 3317

环境

Rust 1.56.1
VSCode 1.61.2

概念

参考：https://doc.rust-lang.org/stable/book/ch20-03-graceful-shutdown-and-cleanup.html

示例

main.rs

use std::fs;
use std::io::Read;
use std::io::Write;
use std::net::TcpListener;
use std::net::TcpStream;
use std::thread;
use std::time::Duration;

fn main() {
    let listener = TcpListener::bind("127.0.0.1:7878").unwrap();
    let pool = game::ThreadPool::new(4);

    for stream in listener.incoming() {
        let stream = stream.unwrap();

        pool.execute(|| {
            handle_connection(stream);
        });
    }
}

fn handle_connection(mut stream: TcpStream) {
    println!("sleep 10 seconds");
    thread::sleep(Duration::from_secs(10));
    println!("sleep 10 seconds end");
    let mut buffer = [0; 1024];
    let length = stream.read(&mut buffer).unwrap();

    if length == 0 {
        println!("EOF");
    }

    let contents = fs::read_to_string("hello.html").unwrap();
    let response = format!(
        "HTTP/1.1 200 OK\r\nContent-Length: {}\r\n\r\n{}",
        contents.len(),
        contents
    );

    stream.write_all(response.as_bytes()).unwrap();
    stream.flush().unwrap();
}

lib.rs

use std::sync::{mpsc, Arc, Mutex};
use std::thread;

pub struct ThreadPool {
    workers: Vec<Worker>,
    sender: mpsc::Sender<Message>,
}

type Job = Box<dyn FnOnce() + Send + 'static>;

enum Message {
    NewJob(Job),
    Terminate,
}

impl ThreadPool {
    /// Create a new ThreadPool.
    ///
    /// The size is the number of threads in the pool.
    ///
    /// # Panics
    ///
    /// The `new` function will panic if the size is zero.
    pub fn new(size: usize) -> ThreadPool {
        assert!(size > 0);

        let (sender, receiver) = mpsc::channel();
        let receiver = Arc::new(Mutex::new(receiver));
        let mut workers = Vec::with_capacity(size);

        for id in 0..size {
            workers.push(Worker::new(id, Arc::clone(&receiver)));
        }

        ThreadPool { workers, sender }
    }

    pub fn execute<F>(&self, f: F)
    where
        F: FnOnce() + Send + 'static,
    {
        let job = Box::new(f);

        self.sender.send(Message::NewJob(job)).unwrap();
    }
}

impl Drop for ThreadPool {
    fn drop(&mut self) {
        println!("Sending terminate message to all workers.");

        for _ in &self.workers {
            self.sender.send(Message::Terminate).unwrap();
        }

        println!("Shutting down all workers.");

        for worker in &mut self.workers {
            println!("Shutting down worker {}", worker.id);

            if let Some(thread) = worker.thread.take() {
                thread.join().unwrap();
            }
        }
    }
}

struct Worker {
    id: usize,
    thread: Option<thread::JoinHandle<()>>,
}

impl Worker {
    fn new(id: usize, receiver: Arc<Mutex<mpsc::Receiver<Message>>>) -> Worker {
        let thread = thread::spawn(move || loop {
            let message = receiver.lock().unwrap().recv().unwrap();

            match message {
                Message::NewJob(job) => {
                    println!("Worker {} got a job; executing.", id);
                    job();
                }
                Message::Terminate => {
                    println!("Worker {} was told to terminate.", id);
                    break;
                }
            }
        });

        Worker {
            id,
            thread: Some(thread),
        }
    }
}

hello.html

<!DOCTYPE html>
<html >

<head>
    <meta charset="utf-8">
    <title>Hello!</title>
</head>

<body>
    <h1>Hello!</h1>
    <p>Hi from Rust</p>
</body>

</html>

总结

使用 rust 实现了一个多线程的 web 服务器，并且在停机时进行了资源清理。

附录

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