Struct SingleFlight 

pub struct SingleFlight<K, T> { /* private fields */ }

Generation-aware single-flight cache.

Calls for the same key and generation share one in-flight build. A newer generation supersedes an older in-flight build; the older result is not installed if the entry has moved on by the time it finishes.

Implementations

impl<K, T> SingleFlight<K, T>

where K: Clone + Eq + Hash,

pub fn new() -> Self

pub fn get_or_build<E>( &self, id: K, generation: u64, build_fn: impl FnOnce() -> Result<T, E>, ) -> Result<Arc<T>, E>

Return the cached value for id at generation, or build it once.

The build function runs outside the internal lock. Concurrent callers for the same (id, generation) wait for the in-flight build and receive the installed value. If a newer generation supersedes this call while its build is running, this call returns the newer ready value instead of overwriting it with stale work.

If the builder returns an error or panics, the in-flight marker is cleared and waiters are notified so the key can be retried instead of remaining permanently stuck in Building.

Trait Implementations

impl<K, T> Default for SingleFlight<K, T>

where K: Clone + Eq + Hash,

fn default() -> Self

Returns the “default value” for a type.