Struct LocalCache 

pub struct LocalCache { /* private fields */ }

Holds arbitrary query results which are namespaced by arbitrary scope types. Usually used through SharedLocalCache::cache_with and SharedLocalCache::gc.

Query types

Note: the types referenced in this documentation are only visible on individual methods, as LocalCache is not itself a generic type.

Storage is sharded by the type of the query. The type of a query has three parts:

The query scope is the value which indexes the storage for a particular query type, it has the bound Scope: 'static + Eq + Hash.

Each Scope corresponds to at most a single Input: 'static and a single Output: 'static value at any given time.

Reading stored values

See LocalCache::get which accepts borrowed forms of Scope and Input: Key and Arg respectively. Arg must satisfy PartialEq<Input> to determine whether to return a stored output.

Garbage Collection

Each time LocalCache::gc is called it removes any values which haven’t been referenced since the prior call.

After each GC, all values still in the cache are marked garbage. They are marked live again when inserted with LocalCache::store or read with LocalCache::get.

Implementations

impl LocalCache

pub fn get<'k, Key, Scope, Arg, Input, Output>( &self, key: &'k Key, arg: &Arg, ) -> Result<&Output, CacheMiss<'k, Key, Scope, Input, Output>>

where Key: Eq + Hash + ToOwned<Owned = Scope> + ?Sized, Scope: 'static + Borrow<Key> + Eq + Hash, Arg: PartialEq<Input> + ToOwned<Owned = Input> + ?Sized, Input: 'static + Borrow<Arg>, Output: 'static,

Return a reference to a query’s stored output if a result is stored and arg equals the previously-stored Input. If a reference is returned, the stored input/output is marked as a root and will not be GC’d the next call.

If no reference is found, a CacheMiss is returned. Call CacheMiss::init to get a CacheEntry to pass to LocalCache::store.

pub fn store<Key, Scope, Input, Output>( &mut self, entry: CacheEntry<'_, Key, Scope, Input, Output>, )

where Key: Eq + Hash + ToOwned<Owned = Scope> + ?Sized, Scope: 'static + Borrow<Key> + Eq + Hash, Input: 'static, Output: 'static,

Stores a fresh CacheEntry whose input/output will not be GC’d at the next call. Call LocalCache::get to get a CacheMiss and CacheMiss::init to get a CacheEntry.

pub fn gc(&mut self)

Drop any values which have not been marked alive since the last call to this method.

Trait Implementations

impl Debug for LocalCache

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for LocalCache

fn default() -> LocalCache

Returns the “default value” for a type.

impl From<LocalCache> for SharedLocalCache

fn from(inner: LocalCache) -> Self

Converts to this type from the input type.

impl RefUnwindSafe for LocalCache

impl UnwindSafe for LocalCache