Trait PrefetchFetcher 

pub trait PrefetchFetcher: Send + Sync {
    // Required methods
    fn contains_flat(&self, namespace: &str, key: &str) -> bool;
    fn fetch_block(
        &self,
        namespace: &str,
        key: &str,
    ) -> Result<Option<u64>, String>;
}

Materialization surface for v2 prefetch. The worker holds an Arc<dyn PrefetchFetcher> so the algorithm crate can issue GETs without the block_prefetch module depending on the embed module’s generic WombatKVKvStore<S> shape.

Implementations must be cheap to call (contains_flat should be a single filesystem stat) and fetch_block must populate the local flat tier on success, the whole point of v2 is to warm the flat cache before request time.

Required Methods

fn contains_flat(&self, namespace: &str, key: &str) -> bool

Returns true if the block is already materialized in the local flat tier. The worker skips already-flat blocks to keep cycle cost bounded.

fn fetch_block(&self, namespace: &str, key: &str) -> Result<Option<u64>, String>

Fetch the block. Returns Ok(Some(bytes_len)) on hit (and the implementation populates flat/foyer), Ok(None) on miss, and Err(message) on backend error. The worker logs+continues on error; one bad block does not stop the cycle.

Dyn Compatibility

This trait is dyn compatible.

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

Implementors