RusotoFuture does not implement Future

help
1

I'm attempting to list the objects of an S3 bucket using rusoto_s3 and have run against an error I think I understand, but would like validation on.

Below are the vitals:

  • Rust version: rustc 1.58.1 (db9d1b20b 2022-01-20)
  • rusoto_s3 = "0.42.0"
  • tokio = { version = "1", features = ["rt-multi-thread", "macros"] }

Minimal Example:

#[tokio::main]
async fn main() {
    let args = Opts::from_args();

    let client = S3Client::new(Region::UsEast1);
    let resp = client.list_objects_v2(ListObjectsV2Request {
		bucket: args.location.bucket,
		prefix: args.location.path,
        ..Default::default()
    }).await;
}

Attempting to compile the above snippet results in the following error:

error[E0277]: `rusoto_core::future::RusotoFuture<ListObjectsV2Output, ListObjectsV2Error>` is not a future
  --> src/bin/list_objects/main.rs:47:16
   |
47 |       let resp = client.list_objects_v2(ListObjectsV2Request {
   |  ________________^
48 | |         bucket: args.location.bucket,
49 | |         prefix: args.location.path,
50 | |         ..Default::default()
51 | |     }).await;
   | |____________^ `rusoto_core::future::RusotoFuture<ListObjectsV2Output, ListObjectsV2Error>` is not a future
   |
   = help: the trait `Future` is not implemented for `rusoto_core::future::RusotoFuture<ListObjectsV2Output, ListObjectsV2Error>`

My assumption is that there's a mismatch between Future here. RusotoFuture implements futures::Future but I'm guessing the Future referenced in the error message is actually std::futures::Future. Does this seem plausible?

I feel like this worked as is at some point in the past ( I don't have evidence to back that up, so it's entirely possible I'm misremembering). I noticed rusoto is in maintenance mode; is it possible this is drift between rust version and a potentially aging crate? Am I just doing it wrong?

Whatever the case, this issue has afforded an interesting challenge: How could I implement std::future::Future for RusotoFuture given that the struct is not in my crate, and the trait is in the std library? Define some form of adapter struct/enum in my own create and implement std::future::Future for that construct? I'd love to hear some thoughts.

2

It seems you're using an old version of rusoto that predates the addition of Future to the standard library. rusoto_core 0.43.0 and later use std::future::Future, so upgrading rusoto_s3 to a recent release—if one exists—should fix this problem.

3 Likes
3

It sure does! I don't know why I thought I was on the latest version of rusoto. Long day I guess.

For a more hypothetical question, how would one solve this issue there wasn't a version of rusoto that used std::future::Future ? I assume I'd need to have my own wrapper type that implements future to get around the orphan rule. Are there any other patterns that would mitigate this theoretical issue?

4

There generally isn't a good way to do it if the crate is that old.

5

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