Having trouble using std::rc::Rc values within a Mutation object.

[ruseinov]

Here's an example:

fn ipfs_client(ctx: &Context<'_>) -> Result<IpfsClient, InvalidUri> {
    let app_data = ctx.data::<AppData>();
    IpfsClient::from_str(&app_data.ipfs_url)
}

    async fn create_asset(
        &self,
        ctx: &Context<'_>,
        file: Upload,
    ) -> FieldResult<Asset> {

        if true {
            let reader = File::open(file.path)?;

            let ipfs_client = ipfs_client(ctx)?;

            let resp = ipfs_client.add(reader).await.map_err(|err| {
                ErrorKind::Fatal(format!("Failed to add a file to IPFS: {:?}", err))
            })?;

            ipfs_hash = resp.hash;
        }
}

The Object macro on MutationRoot

#[Object]
impl MutationRoot {

Would throw an error:

69  | #[Object]
    | ^^^^^^^^^ future returned by `__resolve_field` is not `Send`
    |
    = help: within `impl core::future::future::Future`, the trait `std::marker::Send` is not implemented for `std::rc::Rc<awc::ClientConfig>`

and also

   | `std::rc::Rc<std::cell::RefCell<actix_http::h1::payload::Inner>>` cannot be sent between threads safely

For the result of the add operation.

For the record: I'm not trying to pass the ipfs_client around, I instantiate it when it's needed, get a result and throw it away.

[ruseinov]

I can't help but wonder why Rc is used there anyway as the library provides async api, I guess my best bet is to fork this and introduce an Arc instead. But if you have other suggestions - that'd be much appreciated!

[ruseinov]

After digging deeper it seems like the library I mentioned is using awc::Client, which is always an Rc.

[sunli829]

Don't use awc, it is based on actix_rt, all its Future is !Send, because it is based on single-threaded runtime.

[sunli829]

I do not recommend the use of actix, which is incompatible with other asynchronous ecology.

[ruseinov]

Yeah, I have figured as much. Learned the hard way:)

[ruseinov]

I ended up using hyper, which works nicely with my actix-web runtime. Works like a charm now! I did not realize initially that the actix feature of the lib referred to actix actor framework.

[lastmjs]

Hey, I'm running into a similar problem: Rc<RefCell<call::CallFutureState<std::vec::Vec<u8>>>> cannot be sent between threads safely. I'm developing for DFINITY's Internet Computer, which compiles to WebAssembly and thus (for now) is a single-threaded environment. I'm trying to use their ic_cdk::api::call::call function from within an async mutation resolver, and I'm getting all kinds of craziness. What should I do? Or what should I ask the implementers of ic-cdk to do? Here's a link to the ic-cdk crate: https://crates.io/crates/ic-cdk

Here is more error detail:

pub const fn from_generator<T>(gen: T) -> impl Future<Output = T::Return>
   |                                           ------------------------------- within this `impl std::future::Future`
   |
   = help: within `impl std::future::Future`, the trait `std::marker::Send` is not implemented for `Rc<RefCell<call::CallFutureState<std::vec::Vec<u8>>>>`
   = note: required because it appears within the type `call::CallFuture<std::vec::Vec<u8>>`
   = note: required because it appears within the type `impl std::future::Future`
   = note: required because it appears within the type `for<'r> {ResumeTy, sudograph::ic_cdk::export::Principal, &'r str, (), std::vec::Vec<u8>, i64, impl std::future::Future, ()}`
   = note: required because it appears within the type `[static generator@sudograph::ic_cdk::call<(), (std::vec::Vec<u8>,)>::{closure#0} for<'r> {ResumeTy, sudograph::ic_cdk::export::Principal, &'r str, (), std::vec::Vec<u8>, i64, impl std::future::Future, ()}]`
   = note: required because it appears within the type `from_generator::GenFuture<[static generator@sudograph::ic_cdk::call<(), (std::vec::Vec<u8>,)>::{closure#0} for<'r> {ResumeTy, sudograph::ic_cdk::export::Principal, &'r str, (), std::vec::Vec<u8>, i64, impl std::future::Future, ()}]>`
   = note: required because it appears within the type `impl std::future::Future`
   = note: required because it appears within the type `impl std::future::Future`
   = note: required because it appears within the type `for<'r, 's> {ResumeTy, sudograph::ic_cdk::export::Principal, &'r str, (), impl std::future::Future}`
   = note: required because it appears within the type `[static generator@canisters/graphql/src/graphql.rs:8:1: 8:59 for<'r, 's> {ResumeTy, sudograph::ic_cdk::export::Principal, &'r str, (), impl std::future::Future}]`
   = note: required because it appears within the type `for<'r, 's, 't0, 't1> {ResumeTy, &'r MutationGenerated, &'s ContextBase<'t0, &'t1 Positioned<sudograph::async_graphql::async_graphql_parser::types::Field>>, [static generator@canisters/graphql/src/graphql.rs:8:1: 8:59 for<'t2, 't3> {ResumeTy, sudograph::ic_cdk::export::Principal, &'t2 str, (), impl std::future::Future}], impl std::future::Future, ()}`
   = note: required because it appears within the type `[static generator@canisters/graphql/src/graphql.rs:8:1: 8:59 for<'r, 's, 't0, 't1> {ResumeTy, &'r MutationGenerated, &'s ContextBase<'t0, &'t1 Positioned<sudograph::async_graphql::async_graphql_parser::types::Field>>, [static generator@canisters/graphql/src/graphql.rs:8:1: 8:59 for<'t2, 't3> {ResumeTy, sudograph::ic_cdk::export::Principal, &'t2 str, (), impl std::future::Future}], impl std::future::Future, ()}]`
   = note: required because it appears within the type `from_generator::GenFuture<[static generator@canisters/graphql/src/graphql.rs:8:1: 8:59 for<'r, 's, 't0, 't1> {ResumeTy, &'r MutationGenerated, &'s ContextBase<'t0, &'t1 Positioned<sudograph::async_graphql::async_graphql_parser::types::Field>>, [static generator@canisters/graphql/src/graphql.rs:8:1: 8:59 for<'t2, 't3> {ResumeTy, sudograph::ic_cdk::export::Principal, &'t2 str, (), impl std::future::Future}], impl std::future::Future, ()}]>`
   = note: required because it appears within the type `impl std::future::Future`
   = note: required because it appears within the type `impl std::future::Future`
   = note: required because it appears within the type `for<'r, 's, 't0, 't1, 't2, 't3, 't4, 't5, 't6, 't7, 't8, 't9, 't10, 't11, 't12, 't13, 't14, 't15, 't16, 't17, 't18, 't19, 't20, 't21, 't22, 't23, 't24, 't25, 't26, 't27, 't28, 't29, 't30, 't31, 't32, 't33, 't34, 't35, 't36, 't37, 't38, 't39, 't40> {ResumeTy, &'r MutationGenerated, &'s ContextBase<'t0, &'t1 Positioned<sudograph::async_graphql::async_graphql_parser::types::Field>>, bool, ContextBase<'t2, &'t3 Positioned<SelectionSet>>, impl std::future::Future, (), &'t7 bool, &'t8 ContextBase<'t9, &'t10 Positioned<SelectionSet>>, ContextBase<'t11, &'t12 Positioned<sudograph::async_graphql::async_graphql_parser::types::Field>>, &'t13 Positioned<sudograph::async_graphql::async_graphql_parser::types::Field>, Pin<Box<(dyn std::future::Future<Output = std::result::Result<sudograph::async_graphql::Value, ServerError>> + std::marker::Send + 't14)>>, [closure@canisters/graphql/src/graphql.rs:8:1: 8:59], UpdateBlogPostInput, impl std::future::Future, std::vec::Vec<BlogPost>, &'t26 std::vec::Vec<BlogPost>, [closure@canisters/graphql/src/graphql.rs:8:1: 8:59], DeleteBlogPostInput, impl std::future::Future, impl std::future::Future}`
   = note: required because it appears within the type `[static generator@canisters/graphql/src/graphql.rs:8:1: 8:59 for<'r, 's, 't0, 't1, 't2, 't3, 't4, 't5, 't6, 't7, 't8, 't9, 't10, 't11, 't12, 't13, 't14, 't15, 't16, 't17, 't18, 't19, 't20, 't21, 't22, 't23, 't24, 't25, 't26, 't27, 't28, 't29, 't30, 't31, 't32, 't33, 't34, 't35, 't36, 't37, 't38, 't39, 't40> {ResumeTy, &'r MutationGenerated, &'s ContextBase<'t0, &'t1 Positioned<sudograph::async_graphql::async_graphql_parser::types::Field>>, bool, ContextBase<'t2, &'t3 Positioned<SelectionSet>>, impl std::future::Future, (), &'t7 bool, &'t8 ContextBase<'t9, &'t10 Positioned<SelectionSet>>, ContextBase<'t11, &'t12 Positioned<sudograph::async_graphql::async_graphql_parser::types::Field>>, &'t13 Positioned<sudograph::async_graphql::async_graphql_parser::types::Field>, Pin<Box<(dyn std::future::Future<Output = std::result::Result<sudograph::async_graphql::Value, ServerError>> + std::marker::Send + 't14)>>, [closure@canisters/graphql/src/graphql.rs:8:1: 8:59], UpdateBlogPostInput, impl std::future::Future, std::vec::Vec<BlogPost>, &'t26 std::vec::Vec<BlogPost>, [closure@canisters/graphql/src/graphql.rs:8:1: 8:59], DeleteBlogPostInput, impl std::future::Future, impl std::future::Future}]`
   = note: required because it appears within the type `from_generator::GenFuture<[static generator@canisters/graphql/src/graphql.rs:8:1: 8:59 for<'r, 's, 't0, 't1, 't2, 't3, 't4, 't5, 't6, 't7, 't8, 't9, 't10, 't11, 't12, 't13, 't14, 't15, 't16, 't17, 't18, 't19, 't20, 't21, 't22, 't23, 't24, 't25, 't26, 't27, 't28, 't29, 't30, 't31, 't32, 't33, 't34, 't35, 't36, 't37, 't38, 't39, 't40> {ResumeTy, &'r MutationGenerated, &'s ContextBase<'t0, &'t1 Positioned<sudograph::async_graphql::async_graphql_parser::types::Field>>, bool, ContextBase<'t2, &'t3 Positioned<SelectionSet>>, impl std::future::Future, (), &'t7 bool, &'t8 ContextBase<'t9, &'t10 Positioned<SelectionSet>>, ContextBase<'t11, &'t12 Positioned<sudograph::async_graphql::async_graphql_parser::types::Field>>, &'t13 Positioned<sudograph::async_graphql::async_graphql_parser::types::Field>, Pin<Box<(dyn std::future::Future<Output = std::result::Result<sudograph::async_graphql::Value, ServerError>> + std::marker::Send + 't14)>>, [closure@canisters/graphql/src/graphql.rs:8:1: 8:59], UpdateBlogPostInput, impl std::future::Future, std::vec::Vec<BlogPost>, &'t26 std::vec::Vec<BlogPost>, [closure@canisters/graphql/src/graphql.rs:8:1: 8:59], DeleteBlogPostInput, impl std::future::Future, impl std::future::Future}]>`
   = note: required because it appears within the type `impl std::future::Future`
   = note: required for the cast to the object type `dyn std::future::Future<Output = std::result::Result<std::option::Option<sudograph::async_graphql::Value>, ServerError>> + std::marker::Send`
   = note: this error originates in an attribute macro (in Nightly builds, run with -Z macro-backtrace for more info)

error: aborting due to previous error; 1 warning emitted

For more information about this error, try `rustc --explain E0277`.
error: could not compile `graphql`