Struct LRUCache 

pub struct LRUCache<V, K, T, M> { /* private fields */ }

A generational Arena backed LRU cache implementation.

This Cache implementation always evicts the least-recently-used (LRU) key/value pair. It uses a LinkedList for storing the underlying cache block entries to maintain the order in which they were inserted into the cache.

It uses a generational Arena for allocating the underlying LinkedList which stores the cache blocks. It uses a Map for maintaining the mapping from keys to the nodes storing the respective cache blocks in the LinkedList.

Type parameters

• V: Vector<LRUCacheBlockArenaEntry<K, T>> Used as the backing vector for the underlying Arena.
• K The Key type.
• V The Value type.
• M: Map<K, Link> Used to store a mapping from the keys to links in the linked list.

Implementations

impl<V, K, T, M> LRUCache<V, K, T, M>

where V: Vector<LRUCacheBlockArenaEntry<K, T>>, M: Map<K, Link>,

pub fn least_recent(&self) -> Option<(&K, &T)>

Returns the least recently used key/value pair.

pub fn most_recent(&self) -> Option<(&K, &T)>

Returns the most recently used key/value pair.

impl<V, K, T, M> LRUCache<V, K, T, M>

where V: Vector<LRUCacheBlockArenaEntry<K, T>>, M: Map<K, Link>,

pub fn with_backing_vector_and_map(vector: V, map: M) -> Self

Creates an LRUCache instance with the given the backing Vector and Map implementation instances.

impl<V, K, T, M> LRUCache<V, K, T, M>

where V: Vector<LRUCacheBlockArenaEntry<K, T>>, M: Map<K, Link> + Default,

pub fn with_backing_vector(vector: V) -> Self

Creates an LRUCache instance with the given Vector implementation instance and the default Map implementation value.

Trait Implementations

impl<V, K, T, M> Cache<K, T> for LRUCache<V, K, T, M>

where V: Vector<LRUCacheBlockArenaEntry<K, T>>, M: Map<K, Link>, K: Copy,

type Error = LRUCacheError<<V as Vector<Entry<Node<Block<K, T>>>>>::Error, <M as Map<K, Link>>::Error>

Associated error type.

fn insert(&mut self, key: K, value: T) -> Result<Eviction<K, T>, Self::Error>

Inserts the given key/value pair into this cache.

fn remove(&mut self, key: &K) -> Result<Lookup<T>, Self::Error>

Removes the key/value pair associated with the given key from this cache.

fn shrink(&mut self, new_capacity: usize) -> Result<(), Self::Error>

Removes (self.len() - new_capacity) cache blocks to fit the new capacity. If the difference is non-positive no cache blocks are removed.

fn reserve(&mut self, additional: usize) -> Result<(), Self::Error>

Reserves additional memory to accomodate the given number of additional cache blocks.

fn query(&mut self, key: &K) -> Result<Lookup<&T>, Self::Error>

Queries this cache to find the value associated with given key.

fn capacity(&self) -> usize

Returns the current capacity of this cache.

fn len(&self) -> usize

Returns the number of key/value pairs stored in this cache.

fn is_empty(&self) -> bool

Returns whether this cache is empty.

fn clear(&mut self) -> Result<(), Self::Error>

Remove all items from this cache until it’s empty.

fn is_maxed(&self) -> bool

Returns whether this cache is maxed out.

impl<V, K, T, M> Default for LRUCache<V, K, T, M>

where V: Vector<LRUCacheBlockArenaEntry<K, T>> + Default, M: Map<K, Link> + Default,

fn default() -> Self

Returns the “default value” for a type.