When starting an Actor 'spawn_local called from outside of a task::LocalSet'

[marcus-pousette]

I am trying to learn how actors work by creating database connection actor. But I have trouble creating an Actor even without a database in mind

[dependencies]
actix-web = { version = "3", features=["rustls"] }
actix-rt = "1"
backoff = "0.3.0"
actix = "0.12"

use actix::prelude::*;
use backoff::ExponentialBackoff;

pub struct Database {
    addr: String,
    backoff: ExponentialBackoff,
    //client: Option<Some kind of client>
}

impl Database {
    pub fn start<S: Into<String>>(addr: S) -> Addr<Database> {
        let addr = addr.into();
        let mut backoff = ExponentialBackoff::default();
        backoff.max_elapsed_time = None;

        Context::new().run(Database {
            addr,
            backoff,
            //   client: None,
        })
    }
}

impl Actor for Database {
    type Context = Context<Self>;

    fn started(&mut self, ctx: &mut Context<Self>) {
        dbg!("Create client!");

        // TODO
    }
}
#[cfg(test)]
mod tests {
    use super::*;
    use actix_web::{get, post, test, App, Responder};
    use actix_web::{web, HttpResponse};

    #[get("/{number}")]
    pub async fn test_endpoint(
        number: web::Path<u64>,
        database: web::Data<Database>,
    ) -> impl Responder {
        // Do things with database
        // TODO

        return HttpResponse::Ok().json(number.0);
    }

    #[actix_rt::test]
    async fn it_works() {
        let mut app = test::init_service(
            App::new()
                .data(Database::start("ADDRESS"))
                .service(test_endpoint),
        )
        .await;

        // Make some request to test endpoint
        let req = test::TestRequest::default().uri("/123").to_request();
        let response: u64 = test::read_response_json(&mut app, req).await;
        assert_eq!(response, 123);
    }
}

When running the test, I get:

running 1 test
thread 'dummy::tests::it_works' panicked at '`spawn_local` called from outside of a `task::LocalSet`', C:\Users\Marcus\.cargo\registry\src\github.com-1ecc6299db9ec823\tokio-1.10.1\src\task\local.rs:305:18
stack backtrace:
   0: rust_begin_unwind
             at /rustc/a178d0322ce20e33eac124758e837cbd80a6f633\/library\std\src/panicking.rs:515:5
   1: core::panicking::panic_fmt
             at /rustc/a178d0322ce20e33eac124758e837cbd80a6f633\/library\core\src/panicking.rs:92:14
   2: core::option::expect_failed
             at /rustc/a178d0322ce20e33eac124758e837cbd80a6f633\/library\core\src/option.rs:1243:5
   3: core::option::Option<T>::expect
             at /rustc/a178d0322ce20e33eac124758e837cbd80a6f633\library\core\src/option.rs:351:21
   4: tokio::task::local::spawn_local_inner::{{closure}}
             at .\C:\Users\Marcus\.cargo\registry\src\github.com-1ecc6299db9ec823\tokio-1.10.1\src\task/local.rs:304:22
   5: tokio::macros::scoped_tls::ScopedKey<T>::with
             at .\C:\Users\Marcus\.cargo\registry\src\github.com-1ecc6299db9ec823\tokio-1.10.1\src\macros/scoped_tls.rs:72:13
   6: tokio::task::local::spawn_local_inner
             at .\C:\Users\Marcus\.cargo\registry\src\github.com-1ecc6299db9ec823\tokio-1.10.1\src\task/local.rs:303:9
   7: tokio::task::local::spawn_local
             at .\C:\Users\Marcus\.cargo\registry\src\github.com-1ecc6299db9ec823\tokio-1.10.1\src\task/local.rs:295:9
   8: actix_rt::spawn
             at .\C:\Users\Marcus\.cargo\registry\src\github.com-1ecc6299db9ec823\actix-rt-2.2.0\src/lib.rs:167:5
   9: actix::context::Context<A>::run
             at .\C:\Users\Marcus\.cargo\registry\src\github.com-1ecc6299db9ec823\actix-0.12.0\src/context.rs:146:9
  10: test_project::dummy::Database::start
             at .\src/dummy.rs:16:9
  11: test_project::dummy::tests::it_works::{{closure}}
             at .\src/dummy.rs:54:23
             
    ....

How I understand it is that we spawn threads outside some local set (?) and that is not allowed. But I don't see how I could change this. I have been somewhat following the RedisActor implementation
https://docs.rs/actix-redisactor/0.3.1/src/actix_redisactor/redis.rs.html#27-33

I also tried removing the custom start method and using the default one provided with Actor, but same result.

[marcus-pousette]

I did not the understand the concept of the Actor system good enough.

The endpoint should consume web::Data<Addr<Database>> rather than web::Data<Database>

[fakeshadow]

https://crates.io/crates/actix/0.12.0/dependencies

actix 0.12 depend on actix-rt 2.0.

Instead you can use actix 0.10

[siedentop]

This error happened for me, too.

The error was that I used #[tokio::main] on async fn main(), not #[actix_web::main] on async fn main(). (Took me ~8 hours to find this.)

Here are my versions:

# Via: cargo tree --frozen --prefix none | sort -u, and manual filtered.
actix v0.13.0
actix-codec v0.5.0
actix-files v0.6.0
actix-http v3.0.4
actix-macros v0.2.3 (proc-macro)
actix-router v0.5.0
actix-rt v2.7.0
actix-server v2.1.1
actix-service v2.0.2
actix-utils v3.0.0
actix-web v4.0.1
actix-web-actors v4.1.0
actix-web-codegen v4.0.0 (proc-macro)
actix_derive v0.6.0 (proc-macro)
tokio v1.17.0
tokio-macros v1.7.0 (proc-macro)
tokio-tungstenite v0.17.1
tokio-util v0.7.1
tokio v1.17.0

[robjtede]

https://github.com/actix/actix-web/blob/master/actix-web/MIGRATION-4.0.md#actix_webmain-and-tokiomain

[siedentop]

Thanks for the link, @robjtede !

[lithbitren]

took me one night when using awc...

[Warchant]

And for tests use #[actix_rt::test] instead of #[tokio::main]