如何将非静态数据发送到Rust中的线程，在此示例中是否需要? [英] How can I send non-static data to a thread in Rust and is it needed in this example?

问题描述

我正在尝试使用Rust中的一些堆数据来启动一个新线程，并且由于出现需要使用'static生命周期的数据，我遇到了一堆错误.我已经按照自己的方式将程序向后退了，但是遇到了问题.

I am trying to fire up a new thread using some heap data in Rust and I am getting a bunch of errors that stem from the need of the data to have 'static lifetime. I've worked my way backwards up my program but hit a problem.

use std::sync::Arc;
use std::thread;

struct ThreadData {
    vector_of_strings: Vec<String>,
    terms: Vec<&'static str>,
    quotient: usize,
}

fn perform_search(slice: &[String], terms: &[&str]) {
    /* ... */
}

fn threaded_search(td_arc: &Arc<ThreadData>) {
    let no_of_lines = td_arc.vector_of_strings.len();
    let new_tda1 = td_arc.clone();

    let strings_as_slice1 = new_tda1.vector_of_strings.as_slice();   

    thread::spawn(move || {
        perform_search(&strings_as_slice1[0..td_arc.quotient], &new_tda1.terms);
    });
}

fn main() {
    let td = ThreadData {
        vector_of_strings: Vec::new(),
        terms: Vec::new(),
        quotient: 0,
    };

    let td_arc = Arc::new(td);
    threaded_search(&td_arc);
}

错误:

error[E0621]: explicit lifetime required in the type of `td_arc`               
  --> src/main.rs:20:5                                                         
   |                                                                           
14 | fn threaded_search(td_arc: &Arc<ThreadData>) {                            
   |                            ---------------- help: add explicit lifetime `'static` to the type of `td_arc`: `&'static std::sync::Arc<ThreadData>`
...                                                                            
20 |     thread::spawn(move || {                                               
   |     ^^^^^^^^^^^^^ lifetime `'static` required

推荐答案

关于'static的错误是因为在thread::spawn中创建的新线程可能会在最初创建该线程的threaded_search调用中失效.意味着不允许该线程使用threaded_search中寿命短于'static的任何局部变量.

The error about 'static is because the new thread created within thread::spawn may outlive the invocation of threaded_search during which the thread is initially created, which means the thread must not be permitted to use any local variables from threaded_search with a lifetime shorter than 'static.

在您的代码中，新线程引用了strings_as_slice1和td_arc.

In your code the new thread is referring to strings_as_slice1 and td_arc.

通常使用thread::spawn和Arc，您将需要将一个引用计数的所有权移入线程，并使该线程可以通过该引用计数指针(而不是直接从短暂的作用域中直接访问)来访问它所需要的任何内容. /p>

Generally with thread::spawn and Arc you will want to move ownership of one reference count into the thread and have the thread access whatever it needs through that reference counted pointer rather than from the enclosing short-lived scope directly.

fn threaded_search(td_arc: &Arc<ThreadData>) {
    // Increment reference count that we can move into the new thread.
    let td_arc = td_arc.clone();

    thread::spawn(move || {
        perform_search(&td_arc.vector_of_strings[0..td_arc.quotient], &td_arc.terms);
    });
}

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