如何实现RustBox的同步？

Question

我是Rust的新主题。我正在努力通过线程内的rustbox箱的RustBox type。

欲按q钥匙，而且它在显示2秒钟一个+符号（1,1），而予压瓦特那些2秒内键，其示出了另一+在（1，2符号）。

我写了相同的逻辑一些代码：

extern crate rustbox; 

use std::thread; 
use std::time::Duration; 

use rustbox::{Color, RustBox}; 
use rustbox::Key; 


fn mark_at(x: usize, y: usize, rustbox: &RustBox) { 
    rustbox.print(x, y, rustbox::RB_BOLD, Color::Black, Color::White, "+"); 
    thread::spawn(move || { 
     let delay = Duration::from_millis(2000); 
     thread::sleep(delay); 
     rustbox.print(x, y, rustbox::RB_BOLD, Color::Black, Color::White, " "); 
    }); 
} 


fn main() { 
    let rustbox = match RustBox::init(Default::default()) { 
     Result::Ok(v) => v, 
     Result::Err(e) => panic!("{}", e), 
    }; 
    rustbox.print(1, 1, rustbox::RB_BOLD, Color::Black, Color::White, " "); 
    rustbox.print(1, 2, rustbox::RB_BOLD, Color::Black, Color::White, " "); 

    loop { 
     rustbox.present(); 
     match rustbox.poll_event(false) { 
      Ok(rustbox::Event::KeyEvent(key)) => { 
       match key { 
        Key::Char('q') => { 
         mark_at(1, 1, &rustbox); 
        } 
        Key::Char('w') => { 
         mark_at(1, 2, &rustbox); 
        } 
        Key::Esc => { break; } 
        _ => { } 
       } 
      }, 
      Err(e) => panic!("{}", e), 
      _ => { } 
     } 
    } 
} 

它给我：

error[E0277]: the trait bound `*mut(): std::marker::Sync` is not satisfied in `rustbox::RustBox` 
    --> src/main.rs:12:5 
    | 
12 |  thread::spawn(move || { 
    |  ^^^^^^^^^^^^^ `*mut()` cannot be shared between threads safely 
    | 
    = help: within `rustbox::RustBox`, the trait `std::marker::Sync` is not implemented for `*mut()` 
    = note: required because it appears within the type `std::marker::PhantomData<*mut()>` 
    = note: required because it appears within the type `rustbox::RustBox` 
    = note: required because of the requirements on the impl of `std::marker::Send` for `&rustbox::RustBox` 
    = note: required because it appears within the type `[[email protected]/main.rs:12:19: 16:6 rustbox:&rustbox::RustBox, x:usize, y:usize]` 
    = note: required by `std::thread::spawn` 

error: aborting due to previous error 

如何实现Sync为RustBox类型，这样上面的代码可以工作？

Answer 1

RustBox没有实现Send，所以没有（安全）的方式在线程之间共享（好像你已经找到了尚未合并拉请求https://github.com/gchp/rustbox/pull/65这将支持Send）。

如果合并提取请求，则可以将RustBox包装为Mutex，即Mutex<RustBox>，并且可以在线程之间共享对它的引用。

但是你会遇到一生的问题：你的rustbox引用不够长，不足以产生一个使用它的新线程，所以你必须把它包装在Arc。

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

fn mark_at(x: usize, y: usize, rustbox: &Arc<Mutex<RustBox>>) { 
    rustbox.lock().unwrap().print(x, y, rustbox::RB_BOLD, Color::Black, Color::White, "+"); 
    let rustbox = rustbox.clone(); // increment reference counter 
    thread::spawn(move || { 
     let delay = Duration::from_millis(2000); 
     thread::sleep(delay); 
     rustbox.lock().unwrap().print(x, y, rustbox::RB_BOLD, Color::Black, Color::White, " "); 
    }); 
} 

在你main功能，你必须包裹rustbox：

let rustbox = Arc::new(Mutex::new(rustbox)); 

和lock()它的每一个使用它的时间。

确保你不要把锁保持太久;它可以帮助使用辅助变量，以使这更明确，如：

let pe = rustbox.lock().unwrap().poll_event(false); 
match pe { 
// ... 
}