使用 serde_json::from_str 反序列化为带有 &'static 字符串的结构存在生命周期错误

Question

我正在尝试测试我为 Dart、JS 和 Python UI 框架设置的 JSON 桥。它对那些工作正常，但是当我尝试使用 tui-rs 在 Rust 程序中进行相同的 UI/logic 拆分时，在 UI 线程上尝试反序列化逻辑线程结果时出现生命周期错误。

我知道使用 JSON 进行两层之间的通信都用 Rust 编写并不是理想的做事方式，但考虑到我的目标，我希望它是可以理解的。

我已经尝试过克隆，它适用于将事物序列化并从 UI 发送到逻辑，但这不适用于从逻辑反序列化到 UI

use std::sync::mpsc;
use std::sync::mpsc::{Receiver, Sender};
extern crate serde;
extern crate serde_json;
#[macro_use]
extern crate serde_derive;
use serde::{Deserialize, Serialize};

#[macro_export]
macro_rules! BridgeResult {
    ($result:expr, $data:expr) => {
        BridgeResult {
            result: $result,
            data: vec![$data.to_string()],
        }
    };
}

#[derive(Serialize, Deserialize)]
struct BridgeResult {
    result: &'static str,
    data: Vec<String>,
}

#[derive(Serialize, Deserialize)]
struct App {
    state: i64,
}

impl Default for App {
    fn default() -> App {
        App { state: 0 }
    }
}

fn main() {
    let (to_logic, from_ui) = mpsc::channel();
    let (to_ui, from_logic) = mpsc::channel();

    ui(to_logic, from_logic);
    logic(to_ui, from_ui);
}

fn ui(tx: Sender<(String, String)>, rx: Receiver<(String)>) {
    let app = App::default();

    let app_string = serde_json::to_string(&app)
        .expect("failed to encode app struct for sending to logic heard");

    tx.send(("binary_switch".to_string(), app_string))
        .expect("failed to send binary_switch call and data to logic thread");
    let output_string = rx
        .recv()
        .expect("failed to get a result from logic's initialize");
    let output: BridgeResult = serde_json::from_str(&output_string)
        .expect("failed to decode result from logic's binary_switch");

    if output.result != "Ok()" {
        panic!("init failed due to: \n {:?}", output.data);
    } else {
        println!("{:?}", output.data);
    }
}

fn logic(tx: Sender<(String)>, rx: Receiver<(String, String)>) {
    loop {
        let (function, arguments) = rx
            .recv()
            .expect("failed to receive function and arguments from ui thread");
        let result = match function.as_str() {
            "binary_switch" => binary_switch(&arguments),
            _ => {
                BridgeResult! {"Err()", format!("cannot find rust function branch matching {}", function)}
            }
        };

        let output = match serde_json::to_string(&result) {
            Ok(output) => output,
            Err(_) => "{'result' : 'Err()', 'data': 'failed exit encoding!!!'}".to_string(),
        };
        tx.send(output)
            .expect("failed to send the output back to the ui thread");
    }
}

fn binary_switch(data: &String) -> BridgeResult {
    #[derive(Deserialize)]
    struct Arguments {
        state: i64,
    }

    let mut arguments: Arguments = match serde_json::from_str(&data) {
        Ok(data) => data,
        Err(err) => return BridgeResult! {"Err()", format!("failed to parse arguments\n, {}", err)},
    };

    if arguments.state == 0 {
        arguments.state += 1;
    } else {
        arguments.state -= 1;
    }

    BridgeResult! {"Ok()", arguments.state}
}

我希望这会反序列化 BridgeResult 类型并使用其中应包含字符串 1 的数据字段。实际上我得到：

error[E0597]: `output_string` does not live long enough
  --> src/main.rs:55:53
   |
55 |     let output: BridgeResult = serde_json::from_str(&output_string)
   |                                ---------------------^^^^^^^^^^^^^^-
   |                                |                    |
   |                                |                    borrowed value does not live long enough
   |                                argument requires that `output_string` is borrowed for `'static`
...
63 | }
   | - `output_string` dropped here while still borrowed

Answer 1

struct BridgeResult {
    result: &'static str,
    data: Vec<String>,
}

BridgeResult 被定义为保存一个 result，它是一个静态字符串。这与将从输入字符串反序列化的内容不兼容。您要么需要结果是自己拥有的 String，要么是从输入中借来的。

尝试

struct BridgeResult<'a> {
    result: &'a str,
    data: Vec<String>,
}

使用 serde_json::from_str 反序列化为带有 &'static 字符串的结构存在生命周期错误

Using serde_json::from_str to deserialize into a struct with a &'static string has a lifetime error

multithreading

lifetime

rust

serde-json