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Accepted
Dolphin
Asked: 2023-09-01 17:35:20 +0800 CST

借用是由于对 `std::sync::Mutex<UnboundedSender<SSEMessage>>` 的解引用强制而发生的

  • 772

我正在使用 tokiotokio = { version = "1.17.0", features = ["full"] } unbounded_channel通道发送一些 sse 消息，因为我需要从不同的位置发送消息，所以我定义了这样的发送消息函数（这是显示错误的最小重现演示）：

use std::sync::{Arc, Mutex};
use tokio::{
    sync::mpsc::{UnboundedReceiver, UnboundedSender},
    task,
};

#[tokio::main]
async fn main() {
    let (tx, rx): (UnboundedSender<String>, UnboundedReceiver<String>) =
        tokio::sync::mpsc::unbounded_channel();
    task::spawn_blocking(move || {
        let shared_tx = Arc::new(Mutex::new(tx));
        shared_tx.lock().unwrap().send("l".to_string());
    });
    tx.send("d".to_string());
}

编译器显示错误：

   > cargo build
   Compiling rust-learn v0.1.0 (/Users/xiaoqiangjiang/source/reddwarf/backend/rust-learn)
warning: unused variable: `rx`
 --> src/main.rs:9:14
  |
9 |     let (tx, rx): (UnboundedSender<String>, UnboundedReceiver<String>) =
  |              ^^ help: if this is intentional, prefix it with an underscore: `_rx`
  |
  = note: `#[warn(unused_variables)]` on by default

error[E0382]: borrow of moved value: `tx`
  --> src/main.rs:15:5
   |
9  |     let (tx, rx): (UnboundedSender<String>, UnboundedReceiver<String>) =
   |          -- move occurs because `tx` has type `UnboundedSender<String>`, which does not implement the `Copy` trait
10 |         tokio::sync::mpsc::unbounded_channel();
11 |     task::spawn_blocking(move || {
   |                          ------- value moved into closure here
12 |         let shared_tx = Arc::new(Mutex::new(tx));
   |                                             -- variable moved due to use in closure
...
15 |     tx.send("d".to_string());
   |     ^^^^^^^^^^^^^^^^^^^^^^^^ value borrowed here after move

For more information about this error, try `rustc --explain E0382`.
warning: `rust-learn` (bin "rust-learn") generated 1 warning
error: could not compile `rust-learn` due to previous error; 1 warning emitted

我已经尝试添加.as_ref()但shared_tx仍然没有解决这个问题。我应该怎么做才能解决这个问题？这是cargo.toml：

[package]
name = "rust-learn"
version = "0.1.0"
edition = "2018"

[dependencies]
tokio = { version = "1.17.0", features = ["full"] }
serde = { version = "1.0.64", features = ["derive"] }
serde_json = "1.0.64"
rust

1 个回答

  1. Best Answer

    MPSC 代表多个生产者，单个消费者。您不需要将发件人包装在 中Arc<Mutex>，只需将其包装即可clone()。

    #[tokio::main]
async fn main() {
    let (tx, rx): (UnboundedSender<String>, UnboundedReceiver<String>) =
        tokio::sync::mpsc::unbounded_channel();
    task::spawn_blocking({
        let tx = tx.clone();
        move || {
            let shared_tx = Arc::new(Mutex::new(tx));
            shared_tx.lock().unwrap().send("l".to_string()).unwrap();
        }
    });
    tx.send("d".to_string()).unwrap();
}
    • 1

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