“类型不能满足要求的寿命".在线程中使用方法时 [英] "the type does not fulfill the required lifetime" when using a method in a thread

问题描述

我正在尝试在Rust的线程中使用方法，但收到以下错误消息

I am trying to use a method in a thread in Rust, but I get the following error message

:21:10:21:23错误:类型[closure@<anon>:21:24: 23:14 tx:std::sync::mpsc::Sender<i32>, self:&MyStruct, adder:i32, a:i32] 无法满足要求的寿命:21
thread :: spawn(move || { ^ ~~~~~~~~~~~~~:18:9:24:10注意:在此for循环扩展中注意:类型必须超过静态 终身错误:由于先前的错误而中止

:21:10: 21:23 error: the type [closure@<anon>:21:24: 23:14 tx:std::sync::mpsc::Sender<i32>, self:&MyStruct, adder:i32, a:i32] does not fulfill the required lifetime :21
thread::spawn(move || { ^~~~~~~~~~~~~ :18:9: 24:10 note: in this expansion of for loop expansion note: type must outlive the static lifetime error: aborting due to previous error

这是示例代码:

use std::thread;
use std::sync::mpsc;

struct MyStruct {
    field: i32
}

impl MyStruct {
    fn my_fn(&self, adder1: i32, adder2: i32) -> i32 {
        self.field + adder1 + adder2
    }

    fn threade_test(&self) {
        let (tx, rx) = mpsc::channel();
        let adder = 1;
        let lst_adder = vec!(2, 2, 2);

        for a in lst_adder {
            let tx = tx.clone();

            thread::spawn(move || {
                let _ = tx.send(self.my_fn(adder, a));
            });
        }

        println!("{}", rx.recv().unwrap());
    }
}

fn main() {
    let ms = MyStruct{field: 42};
    ms.threade_test();
}

在Rust游乐场上进行测试.

推荐答案

问题在于，每个移至线程的变量都必须具有生存期'static.即线程不能引用该线程不拥有的值.

The problem is that every variable moved to the thread must have the lifetime 'static. i.e. threads can't reference values which are not owned by the thread.

在这种情况下，问题是self是对MyStruct实例的引用.

In this case the problem is that self is a reference to an instance of MyStruct.

要解决此问题，请删除所有引用并克隆结构，然后再将其发送给线程.

To solve it, remove every reference and clone the structure before sending it to the thread.

use std::thread;
use std::sync::mpsc;

#[derive(Clone)]
struct MyStruct {
    field: i32
}

impl MyStruct {
    fn my_fn(&self, adder1: i32, adder2: i32) -> i32 {
        self.field + adder1 + adder2
    }

    fn threade_test(&self) {
        let (tx, rx) = mpsc::channel();
        let adder = 1;
        let lst_adder = vec!(2, 2, 2);

        for a in lst_adder {
            let tx = tx.clone();

            let self_clone = self.clone();
            thread::spawn(move || {
                let _ = tx.send(self_clone.my_fn(adder, a));
            });
        }

        println!("{}", rx.recv().unwrap());
    }
}

fn main() {
    let ms = MyStruct{field: 42};
    ms.threade_test();
}

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