rust使用lazy_static对全局变量多线程并发读写示例

首先需要在项目依赖Cargo.toml添加lazy_static依赖项

[dependencies]
lazy_static = "1.4.0"

示例代码如下：

use lazy_static::lazy_static;
use std::sync::{RwLock, RwLockReadGuard, RwLockWriteGuard};
use std::thread;

#[derive(Debug)]
struct SharedData {
    version: i32,
    data: Vec<u8>,
}

impl SharedData {
    fn new() -> Self {
        SharedData {
            version: 0,
            data: Vec::new(),
        }
    }

    fn display(&self) {
        println!("{:?}", self);
    }

    fn add_version(&mut self) {
        self.version = self.version + 1;
    }

    fn add_item(&mut self, item: u8) {
        self.data.push(item);
        self.add_version();
    }

    fn remove_item(&mut self, item: u8) {
        self.data.retain(|&x| x != 42);
        self.add_version();
    }
}

lazy_static! {
    static ref GLOBAL_DATA: RwLock<SharedData> = RwLock::new(SharedData::new());
}

fn get_write_shared_data() -> RwLockWriteGuard<'static, SharedData> {
    GLOBAL_DATA.write().unwrap()
}

fn get_read_shared_data() -> RwLockReadGuard<'static, SharedData> {
    GLOBAL_DATA.read().unwrap()
}

fn main() {
    // 读取最初的数据
    thread::spawn(|| {
        let shared_data = get_read_shared_data();
        shared_data.display();
    })
    .join()
    .unwrap();

    // 添加一个元素
    thread::spawn(|| {
        let mut shared_data = get_write_shared_data();
        shared_data.add_item(42);
    })
    .join()
    .unwrap();

    // 读取修改后的数据
    thread::spawn(|| {
        let shared_data = get_read_shared_data();
        shared_data.display();
    })
    .join()
    .unwrap();

    // 移除一个元素
    thread::spawn(|| {
        let mut shared_data = get_write_shared_data();
        shared_data.remove_item(42);
    })
    .join()
    .unwrap();

    // 读取修改后的数据
    thread::spawn(|| {
        let shared_data = get_read_shared_data();
        shared_data.display();
    })
    .join()
    .unwrap();
}