Async disk cache

[Ben Schreck]

I saw #145 was only merged recently but an async version would be really useful for me

[Omid Rad]

Disk cache for async functions is there already if you mean that:
https://github.com/jaemk/cached/blob/master/tests/cached.rs#L1298

If you mean async disk access, nope AFAICS

[Ben Schreck]

Hmm what am I doing wrong here? The macro works, but I need to specify custom keys. So the following breaks and does not attempt to use the IOCachedAsync trait:

#[io_cached(
   type = "DiskCache<String, Result<String, TrimItClientError>>",
   map_error = r##"|e| TrimItClientError::DiskError(format!("{:?}", e))"##,
   create = r##" {
        DiskCache::new("uploaded_videos_from_disk_cache")
            .build()
            .expect("error building disk cache")
   } "##,
   convert = r#"{ format!("{}-{}-{}", &project_name.unwrap_or(""), base_url, _email) }"#
)]
async fn uploaded_videos_from_disk_cache(client: &Client, project_name: Option<&str>, base_url: &str, _email: &str) -> Result<String, TrimItClientError> {
    uploaded_videos(client, project_name, base_url, _email).await
}

But I can use:

#[io_cached(
    disk = true,
    time = 30,
    map_error = r##"|e| TrimItClientError::DiskError(format!("{:?}", e))"##,
)]
``` if I don't need to change the default keys.

I get two errors with the first snippet: ```error[E0277]: `Result<std::option::Option<Result<std::string::String, TrimItClientError>>, DiskCacheError>` is not a future
   --> src/modal_client.rs:208:1
    |
208 | /  #[io_cached(
209 | |     type = "DiskCache<String, Result<String, TrimItClientError>>",
210 | |     map_error = r##"|e| TrimItClientError::DiskError(format!("{:?}", e))"##,
211 | |     create = r##" {
...   |
217 | |     convert = r#"{ format!("{}-{}-{}", &project_name.unwrap_or(""), base_url, _email) }"#
218 | |  )]
    | | __^-
    | ||__|
    |  |  `Result<std::option::Option<Result<std::string::String, TrimItClientError>>, DiskCacheError>` is not a future
219 |  | async fn uploaded_videos_from_disk_cache(client: &Client, project_name: Option<&str>, base_u...
    |  |_ help: remove the `.await`
    |
    = help: the trait `Future` is not implemented for `Result<std::option::Option<Result<std::string::String, TrimItClientError>>, DiskCacheError>`, which is required by `Result<std::option::Option<Result<std::string::String, TrimItClientError>>, DiskCacheError>: IntoFuture`
    = note: Result<std::option::Option<Result<std::string::String, TrimItClientError>>, DiskCacheError> must be a future or must implement `IntoFuture` to be awaited
    = note: required for `Result<std::option::Option<Result<std::string::String, TrimItClientError>>, DiskCacheError>` to implement `IntoFuture`

error[E0308]: mismatched types
   --> src/modal_client.rs:208:1
    |
208 | / #[io_cached(
209 | |    type = "DiskCache<String, Result<String, TrimItClientError>>",
210 | |    map_error = r##"|e| TrimItClientError::DiskError(format!("{:?}", e))"##,
211 | |    create = r##" {
...   |
217 | |    convert = r#"{ format!("{}-{}-{}", &project_name.unwrap_or(""), base_url, _email) }"#
218 | | )]
    | |  ^
    | |  |
    | |__expected `Result<String, ...>`, found `String`
    |    arguments to this method are incorrect
    |
    = note: expected enum `Result<std::string::String, TrimItClientError>`
             found struct `std::string::String`
help: the return type of this call is `std::string::String` due to the type of the argument passed
   --> src/modal_client.rs:208:1
    |
208 | / #[io_cached(
209 | |    type = "DiskCache<String, Result<String, TrimItClientError>>",
210 | |    map_error = r##"|e| TrimItClientError::DiskError(format!("{:?}", e))"##,
211 | |    create = r##" {
...   |
217 | |    convert = r#"{ format!("{}-{}-{}", &project_name.unwrap_or(""), base_url, _email) }"#
218 | | )]
    | |__^ this argument influences the return type of `cache_set`
note: method defined here
   --> /Users/ben/.cargo/registry/src/index.crates.io-6f17d22bba15001f/cached-0.49.2/src/lib.rs:404:8
    |
404 |     fn cache_set(&self, k: K, v: V) -> Result<Option<V>, Self::Error>;
    |        ^^^^^^^^^
    = note: this error originates in the attribute macro `io_cached` (in Nightly builds, run with -Z macro-backtrace for more info)

warning: unused import: `cached::IOCachedAsync`
  --> src/modal_client.rs:12:5
   |
12 | use cached::IOCachedAsync;
   |     ^^^^^^^^^^^^^^^^^^^^^
   |
   = note: `#[warn(unused_imports)]` on by default

[Ben Schreck]

Ah had to change the type to just be DiskCache<String, String> without the Result<> (even though my function returns a Result)

   disk = true,
   type = "DiskCache<String, String>",
   map_error = r##"|e| TrimItClientError::DiskError(format!("{:?}", e))"##,
   create = r##" {
        DiskCache::new("uploaded_videos_from_disk_cache")
            .build()
            .expect("error building disk cache")
   } "##,
   convert = r#"{ format!("{}-{}-{}", &project_name.unwrap_or(""), base_url, _email) }"#
)]
async fn uploaded_videos_from_disk_cache(client: &Client, project_name: Option<&str>, base_url: &str, _email: &str) -> Result<String, TrimItClientError> {
    uploaded_videos(client, project_name, base_url, _email).await
}```

[Omid Rad]

@bschreck so if it's solved, let's close this