Trait Loader 

pub trait Loader<K, V>: Send + Sync {
    // Required method
    fn load(
        &self,
        key: &K,
    ) -> impl Future<Output = CacheResult<Option<V>>> + Send;
}

Single-key data loader abstraction.

Design notes:

• This trait is intentionally async because loader implementations are usually IO-bound (DB/HTTP/RPC).
• Methods return impl Future + Send to make the async contract explicit without lint suppression.
• Returning Option<V> allows negative caching semantics: Ok(None) means “query succeeded but row not found”.

Required Methods

fn load(&self, key: &K) -> impl Future<Output = CacheResult<Option<V>>> + Send

Loads one key from the source-of-truth backend.

Dyn Compatibility

This trait is not dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety".

Implementors

impl<K, V, F, Fut> Loader<K, V> for FnLoader<K, V, F, Fut>

where K: Clone + Eq + Hash + Send + Sync + 'static, V: Clone + Send + Sync + 'static, F: Fn(K) -> Fut + Send + Sync + 'static, Fut: Future<Output = CacheResult<Option<V>>> + Send + 'static,

impl<K, V> Loader<K, V> for NoopLoader

where K: Sync,