Struct LfuCacheMetrics

pub struct LfuCacheMetrics {
    pub core: CoreCacheMetrics,
    pub min_frequency: u64,
    pub max_frequency: u64,
    pub total_frequency_increments: u64,
    pub active_frequency_levels: u64,
}

LFU-specific metrics (extends CoreCacheMetrics)

This struct contains metrics specific to the LFU (Least Frequently Used) cache algorithm. LFU tracks frequency of access for each item, so these metrics focus on frequency distribution and access patterns.

Fields

core: CoreCacheMetrics

Core metrics common to all cache algorithms

min_frequency: u64

Current minimum frequency in the cache

max_frequency: u64

Current maximum frequency in the cache

total_frequency_increments: u64

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

active_frequency_levels: u64

Number of unique frequency levels currently in use

Implementations

impl LfuCacheMetrics

pub fn new(max_cache_size_bytes: u64) -> Self

Creates a new LfuCacheMetrics instance with the specified maximum cache size

Arguments

• max_cache_size_bytes - The maximum allowed cache size in bytes

pub fn record_frequency_increment( &mut self, _old_frequency: usize, new_frequency: usize, )

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

Arguments

• old_frequency - The previous frequency value
• new_frequency - The new frequency value for the accessed item

pub fn record_frequency_hit(&mut self, object_size: u64, frequency: usize)

Records a cache hit with frequency information

Arguments

• object_size - Size of the object that was served from cache (in bytes)
• frequency - Current frequency of the accessed item

pub fn update_frequency_levels<T>( &mut self, frequency_lists: &BTreeMap<usize, T>, )

Updates the frequency levels based on current frequency lists

Arguments

• frequency_lists - Map of frequency to list of items at that frequency

pub fn record_miss(&mut self, object_size: u64)

Records a cache miss for LFU metrics

Arguments

• object_size - Size of the object that was requested (in bytes)

pub fn update_active_frequency_levels(&mut self, levels: u64)

Updates the count of active frequency levels

Arguments

• levels - The number of different frequency levels currently in use

pub fn average_frequency(&self) -> f64

Calculates the average frequency of accesses

Returns

Average frequency per item access, or 0.0 if no hits have occurred

pub fn frequency_range(&self) -> u64

Calculates the frequency range (max - min)

Returns

The range of frequencies currently in the cache

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

Converts LFU metrics to a BTreeMap for reporting

This method returns all metrics relevant to the LFU cache algorithm, including both core metrics and LFU-specific frequency metrics.

Uses BTreeMap to ensure consistent, deterministic ordering of metrics.

Returns

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

Trait Implementations

impl CacheMetrics for LfuCacheMetrics

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

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

Returns

A BTreeMap containing all metrics tracked by this LFU cache instance

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

Returns the algorithm name for this cache implementation

Returns

“LFU” - identifying this as a Least Frequently Used cache

impl Clone for LfuCacheMetrics

fn clone(&self) -> LfuCacheMetrics

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for LfuCacheMetrics

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

Formats the value using the given formatter.