Struct LruQueue 

pub struct LruQueue<K: Eq + Hash + Clone, V> { /* private fields */ }

Provides a Least Recently Used queue with unbounded capacity.

Examples

use datafusion_execution::cache::lru_queue::LruQueue;

let mut lru_queue: LruQueue<i32, i32> = LruQueue::new();
lru_queue.put(1, 10);
lru_queue.put(2, 20);
lru_queue.put(3, 30);
assert_eq!(lru_queue.get(&2), Some(&20));
assert_eq!(lru_queue.pop(), Some((1, 10)));
assert_eq!(lru_queue.pop(), Some((3, 30)));
assert_eq!(lru_queue.pop(), Some((2, 20)));
assert_eq!(lru_queue.pop(), None);

Implementations

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

pub fn new() -> Self

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

Returns a reference to value mapped by key, if it exists. If the entry exists, it becomes the most recently used.

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

Returns a reference to value mapped by key, if it exists. Does not affect the queue order.

pub fn contains_key(&self, key: &K) -> bool

Checks whether there is an entry with key key in the queue. Does not affect the queue order.

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

Inserts an entry in the queue, becoming the most recently used. If the entry already exists, returns the previous value.

pub fn pop(&mut self) -> Option<(K, V)>

Removes and returns the least recently used value. Returns None if the queue is empty.

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

Removes a specific entry from the queue, if it exists.

pub fn len(&self) -> usize

Returns the number of entries in the queue.

pub fn is_empty(&self) -> bool

Checks whether the queue has no items.

pub fn clear(&mut self)

Removes all entries from the queue.

pub fn list_entries(&self) -> HashMap<&K, &V>

Returns a reference to the entries currently in the queue.

Trait Implementations

impl<K: Default + Eq + Hash + Clone, V: Default> Default for LruQueue<K, V>

fn default() -> LruQueue<K, V>

Returns the “default value” for a type.