Struct OnceMap 

pub struct OnceMap<K, V> { /* private fields */ }

A process-lifetime cache that maps K → V and computes each entry on first access. See module docs for semantics.

Implementations

impl<K, V> OnceMap<K, V>

pub const fn new() -> Self

Empty cache, suitable for static initializers.

impl<K: Eq + Hash + Clone, V: Clone> OnceMap<K, V>

pub fn get_or_init_with<F>(&self, key: &K, init: F) -> V

where F: FnOnce() -> V,

Return the value for key, computing and caching it with init on first access. The lock is held across init, so concurrent callers for the same key serialize.

pub async fn get_or_init_async<F, Fut>(&self, key: &K, init: F) -> V

where F: FnOnce() -> Fut, Fut: Future<Output = V>,

Async variant of Self::get_or_init_with. The lock is released across the await, so different keys don’t serialize. Two callers for the same key may both run init; the last write wins.

pub fn get(&self, key: &K) -> Option<V>

Read without computing. Returns None if the key was never inserted.

pub fn insert(&self, key: K, value: V) -> Option<V>

Direct insert. Returns the previous value if any.

pub fn remove(&self, key: &K) -> Option<V>

Remove and return the value for key, if any. Used by call sites that need to tear down a cached resource (the mount registry hands the handle back so the caller can unmount it).

Trait Implementations

impl<K, V> Default for OnceMap<K, V>

fn default() -> Self

Returns the “default value” for a type.