Struct LruQueryCache 

pub struct LruQueryCache<T> { /* private fields */ }

Generic LRU cache keyed by CacheFingerprint.

Eviction policy: on evict_oldest, the entry with the oldest last_accessed timestamp is removed. The insertion_order deque maintains insertion ordering for O(1) oldest-insertion eviction fallback.

Hit/miss statistics are tracked across the lifetime of the cache.

Implementations

impl<T: Clone> LruQueryCache<T>

pub fn new(max_size: usize) -> Self

Create a new cache with the given maximum number of entries.

pub fn get(&mut self, key: &CacheFingerprint) -> Option<&T>

Look up a value by fingerprint.

Records a hit or miss and updates the entry’s access time on hit.

pub fn insert(&mut self, key: CacheFingerprint, value: T)

Insert a value into the cache.

If the cache is full and the key is not already present, evict_oldest is called before insertion.

pub fn evict_oldest(&mut self)

Evict the least-recently-used entry (the one with the oldest last_accessed timestamp).

Falls back to evicting the oldest-inserted entry if all timestamps are equal (e.g., in tests).

pub fn hit_rate(&self) -> f64

Fraction of lookups that were cache hits: hits / (hits + misses).

Returns 0.0 if no lookups have occurred.

pub fn total_hits(&self) -> u64

Total number of cache hits.

pub fn total_misses(&self) -> u64

Total number of cache misses.

pub fn len(&self) -> usize

Number of entries currently in the cache.

pub fn is_empty(&self) -> bool

Whether the cache is empty.

pub fn clear(&mut self)

Remove all entries from the cache (does not reset hit/miss counters).

pub fn max_size(&self) -> usize

Maximum number of entries the cache can hold.