Struct LfudaCacheMetrics

pub struct LfudaCacheMetrics {
    pub core: CoreCacheMetrics,
    pub global_age: u64,
    pub total_aging_events: u64,
    pub min_priority: u64,
    pub max_priority: u64,
    pub total_frequency_increments: u64,
    pub items_benefited_from_aging: u64,
    pub total_age_distributed: u64,
}

LFUDA-specific metrics (extends CoreCacheMetrics)

This struct contains metrics specific to the LFUDA (Least Frequently Used with Dynamic Aging) cache algorithm. LFUDA combines frequency tracking with aging to prevent old frequently-used items from blocking new items indefinitely.

Fields

core: CoreCacheMetrics

Core metrics common to all cache algorithms

global_age: u64

Current global age value

total_aging_events: u64

Total number of aging events (when global age is increased)

min_priority: u64

Current minimum priority in the cache

max_priority: u64

Current maximum priority in the cache

total_frequency_increments: u64

Total number of frequency increments (every cache hit increases frequency)

items_benefited_from_aging: u64

Number of items that benefited from aging (had their effective priority boosted)

total_age_distributed: u64

Total age value distributed to items at insertion time

Implementations

impl LfudaCacheMetrics

pub fn new(max_cache_size_bytes: u64) -> Self

Creates a new LfudaCacheMetrics instance with the specified maximum cache size

Arguments

• max_cache_size_bytes - The maximum allowed cache size in bytes

pub fn record_aging_event(&mut self, new_global_age: u64)

Records an aging event (when global age is increased due to eviction)

Arguments

• new_global_age - The new global age value

pub fn record_frequency_increment(&mut self, new_priority: u64)

Records a frequency increment (when an item is accessed and its frequency increases)

Arguments

• new_priority - The new priority value for the accessed item

pub fn record_aging_benefit(&mut self, age_benefit: u64)

Records when an item benefits from aging (gets age boost at insertion)

Arguments

• age_benefit - The age value added to the item’s priority

pub fn average_aging_benefit(&self) -> f64

Calculates the average aging benefit per item

Returns

Average age benefit per item that received aging boost, or 0.0 if none

pub fn priority_range(&self) -> u64

Calculates the priority range (max - min)

Returns

The range of priorities currently in the cache

pub fn aging_effectiveness(&self) -> f64

Calculates the aging effectiveness (aging events / evictions)

Returns

How often evictions trigger aging events, or 0.0 if no evictions

pub fn aging_contribution_ratio(&self) -> f64

Calculates the frequency advantage due to aging

Returns

How much of the total priority comes from aging vs raw frequency

pub fn to_btreemap(&self) -> BTreeMap<String, f64>

Converts LFUDA metrics to a BTreeMap for reporting

This method returns all metrics relevant to the LFUDA cache algorithm, including both core metrics and LFUDA-specific aging and priority metrics.

Uses BTreeMap to ensure consistent, deterministic ordering of metrics.

Returns

A BTreeMap containing all LFUDA cache metrics as key-value pairs

Trait Implementations

impl CacheMetrics for LfudaCacheMetrics

fn metrics(&self) -> BTreeMap<String, f64>

Returns all LFUDA cache metrics as key-value pairs in deterministic order

Returns

A BTreeMap containing all metrics tracked by this LFUDA cache instance

fn algorithm_name(&self) -> &'static str

Returns the algorithm name for this cache implementation

Returns

“LFUDA” - identifying this as a Least Frequently Used with Dynamic Aging cache

impl Clone for LfudaCacheMetrics

fn clone(&self) -> LfudaCacheMetrics

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for LfudaCacheMetrics

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

Formats the value using the given formatter.