Tokio 0.2 and lifetimes

help
1

Hello.
I have a problem with wrapping tokio runtime in my impl trait.
How to fix it?

My code:

use async_trait::async_trait;

#[async_trait]
trait MyTrait
{
    async fn run(&mut self);
    async fn test(&mut self);
}

struct MyStruct{}

#[async_trait]
impl MyTrait for MyStruct
{
    async fn test(&mut self)
    {
       ///... any code
    }

    async fn run(&mut self)
    {
        let mut rt = Runtime::new().unwrap();

        rt.block_on(async move {
            ///... any code
            tokio::spawn(async move { self.test(); });
          });
     }
}

Error:

error: cannot infer an appropriate lifetime
   --> src/main.rs:833:23
    |
833 |     async fn run(&mut self)
    |                       ^^^^ ...but this borrow...
...
840 |             tokio::spawn(async move {
    |             ------------ this return type evaluates to the `'static` lifetime...
    |
note: ...can't outlive the lifetime `'_` as defined on the function body at 725:1
2

You should not create a runtime inside an async fn, since to call an async fn, you must already be on a runtime.

3

Ok. How to fix? How wrap tokio::runtime?

4

Since you want run to move self into a spawned task, it must take self by value.

trait MyTrait
{
    async fn run(self);
    async fn test(&mut self);
}

struct MyStruct{}

#[async_trait]
impl MyTrait for MyStruct
{
    async fn test(&mut self) {
       /// ... any code
    }

    async fn run(self) {
        tokio::spawn(async move {
            self.test();
        });
    }
}

This means that run owns self, so it is allowed to move it to another task.

5

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