Rust 编程视频教程(进阶)——018_2 互斥器示例

视频地址

头条地址:https://www.ixigua.com/i677586170644791348...
B站地址:https://www.bilibili.com/video/av81202308/

源码地址

github地址:https://github.com/anonymousGiga/learn_rus...

讲解内容

1、线程间共享Mutex
(1)错误例子:

use std::sync::Mutex;
use std::thread;
fn main() {
    let counter = Mutex::new(0);
    let mut handles = vec![];
    for _ in 0..10 {
        let handle = thread::spawn(move || {
            let mut num = counter.lock().unwrap();
            *num += 1;
        });
        handles.push(handle);
    }
    for handle in handles {
        handle.join().unwrap();
    }
    println!("Result: {}", *counter.lock().unwrap());
}

错误原因:不能将counter锁的所有权移动到多个线程中。

(2)错误例子2:通过Rc来创建引用计数的值

use std::rc::Rc;
use std::sync::Mutex;
use std::thread;
fn main() {
    let counter = Rc::new(Mutex::new(0));
    let mut handles = vec![];
    for _ in 0..10 {
        let counter = Rc::clone(&counter);
        let handle = thread::spawn(move || {
            let mut num = counter.lock().unwrap();
            *num += 1;
        });
        handles.push(handle);
    }
    for handle in handles {
        handle.join().unwrap();
    }
    println!("Result: {}", *counter.lock().unwrap());
}

错误原因:Rc不是线程安全的

(3)例子3:使用Arc
说明: Arc是一个类似于Rc并可以安全的用于并发环境的类型,代码如下:

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

fn main() {
    let counter = Arc::new(Mutex::new(0));
    let mut handles = vec![];

    for _ in 0..10 {
        let counter = Arc::clone(&counter);
        let handle = thread::spawn(move || {
            let mut num = counter.lock().unwrap();

            *num += 1;
        });
        handles.push(handle);
    }

    for handle in handles {
        handle.join().unwrap();
    }

    println!("Result: {}", *counter.lock().unwrap());
}

2、RefCell/Rc 与 Mutex/Arc 的相似性
(1)Mutex提供内部可变性,类似于RefCell;
(2)RefCell/Rc是非线程安全的,而Mutex/Arc是线程安全的。

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