一、使用async搭建简单的web服务
1、修改cargo.toml文件添加依赖
[dependencies]
futures = "0.3"
tokio = { version = "1", features = ["full"] }
[dependencies.async-std]
version = "1.6"
features = ["attributes"]
2、搭建web服务
(1)单线程并发处理请求
这里解释一下,单线程并发处理请求,其实每一个请求都是一个future,如果一个future卡了,会去处理别的future,async原理可以去看我关于async的博客
use async_std::net::TcpListener;
use async_std::net::TcpStream;
use futures::stream::StreamExt;
use std::fs;
use async_std::prelude::*;
use std::time::Duration;
use async_std::task;
#[async_std::main]
async fn main() {
let listener = TcpListener::bind("127.0.0.1:7878").await.unwrap(); // 创建 TCP 监听器,绑定到本地 7878 端口
listener
.incoming() // 监听传入的连接
.for_each_concurrent(/* limit */ None, |tcpstream| async move {//stream 流异步并发处理
let tcpstream = tcpstream.unwrap(); // 获取传入连接
handle_connection(tcpstream).await; // 处理连接的异步任务
})
.await; // 等待所有连接处理完毕
}
async fn handle_connection(mut stream: TcpStream) {
let mut buffer = [0; 1024];
stream.read(&mut buffer).await.unwrap(); // 读取 TCP 流数据到缓冲区
let get = b"GET / HTTP/1.1\r\n";
let sleep = b"GET /sleep HTTP/1.1\r\n";
// 判断请求内容,确定响应状态行和文件名
let (status_line, filename) = if buffer.starts_with(get) {
("HTTP/1.1 200 OK\r\n\r\n", "hello.html") // 如果请求是 GET /,返回 200 OK 状态和 hello.html 文件
} else if buffer.starts_with(sleep) {
task::sleep(Duration::from_secs(5)).await; // 如果请求是 GET /sleep,等待 5 秒钟
("HTTP/1.1 200 OK\r\n\r\n", "hello.html") // 然后返回 200 OK 状态和 hello.html 文件
} else {
("HTTP/1.1 404 NOT FOUND\r\n\r\n", "404.html") // 其他情况返回 404 NOT FOUND 状态和 404.html 文件
};
// 读取文件内容到字符串
let contents = fs::read_to_string(filename).unwrap();
let response = format!("{status_line}{contents}"); // 构建响应字符串
// 将响应字符串写入 TCP 流,并刷新
stream.write(response.as_bytes()).await.unwrap();
stream.flush().await.unwrap();
}
(2)多线程并发处理请求
lib.rs
// src/lib.rs
use std::{
sync::{mpsc, Arc, Mutex},
thread,
};
pub struct ThreadPool {
workers: Vec<Worker>,
sender: Option<mpsc::Sender<Job>>,
}
type Job = Box<dyn FnOnce() + Send + 'static>;
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: Some(sender),
}
}
pub fn execute<F>(&self, f: F)
where
F: FnOnce() + Send + 'static,
{
let job = Box::new(f);
self.sender.as_ref().unwrap().send(job).unwrap();
}
}
impl Drop for ThreadPool {
fn drop(&mut self) {
drop(self.sender.take());
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<Job>>>) -> Worker {
let thread = thread::spawn(move || loop {
let message = receiver.lock().unwrap().recv();
match message {
Ok(job) => {
println!("Worker {id} got a job; executing.");
job();
}
Err(_) => {
println!("Worker {id} disconnected; shutting down.");
break;
}
}
});
Worker {
id,
thread: Some(thread),
}
}
}
main.rs
// src/main.rs
use hello_package::ThreadPool;
use std::fs;
use std::io::prelude::*;
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 = ThreadPool::new(4);
for stream in listener.incoming().take(4) {//take限制请求次数
let stream = stream.unwrap();
pool.execute(|| {
handle_connection(stream);
});
}
println!("Shutting down.");
}
fn handle_connection(mut stream: TcpStream) {
let mut buffer = [0; 1024];
stream.read(&mut buffer).unwrap();
let get = b"GET / HTTP/1.1\r\n";
let sleep = b"GET /sleep HTTP/1.1\r\n";
let (status_line, filename) = if buffer.starts_with(get) {
("HTTP/1.1 200 OK", "hello.html")
} else if buffer.starts_with(sleep) {
thread::sleep(Duration::from_secs(5));
("HTTP/1.1 200 OK", "hello.html")
} else {
("HTTP/1.1 404 NOT FOUND", "404.html")
};
let contents = fs::read_to_string(filename).unwrap();
let response = format!(
"{}\r\nContent-Length: {}\r\n\r\n{}",
status_line,
contents.len(),
contents
);
stream.write_all(response.as_bytes()).unwrap();
stream.flush().unwrap();
}