Struct TwoQueueCache 

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

A 2Q cache with configurable total capacity and A1in/A1out sizing.

Type parameters

• K — key type (must be Eq + Hash + Clone).
• V — value type.

Implementations

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

pub fn new(capacity: usize) -> Self

Create a new 2Q cache with the given capacity.

A1in is sized to ~25% of capacity and A1out to ~50%.

pub fn with_queue_sizes( capacity: usize, a1in_capacity: usize, a1out_capacity: usize, ) -> Self

Create a 2Q cache with explicit A1in and A1out sizing.

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

Look up key. On a hit in Am, promote to MRU. On a hit in A1in, the entry stays in place (FIFO semantics).

pub fn insert(&mut self, key: K, value: V)

Insert (key, value) into the cache.

• If key is already in Am or A1in, its value is updated.
• If key is in A1out (ghost hit), it is admitted to Am.
• Otherwise it enters A1in.

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

Remove key from the cache entirely (including ghost list).

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

Returns true if the cache contains key (not counting ghosts).

pub fn len(&self) -> usize

Total number of live entries.

pub fn is_empty(&self) -> bool

Returns true when the cache has no live entries.

pub fn stats(&self) -> TwoQueueStats

Return a statistics snapshot.

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

Peek at key without updating access metadata or LRU order.

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

Return a mutable reference to the value for key without changing queue positions.

pub fn clear(&mut self)

Remove all entries, ghost list included.

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

Return true if key is in the ghost list (A1out).

pub fn a1in_len(&self) -> usize

Return the number of entries in A1in.

pub fn am_len(&self) -> usize

Return the number of entries in Am.

pub fn a1out_len(&self) -> usize

Return the number of ghost entries in A1out.