Struct EntropyCache 

pub struct EntropyCache { /* private fields */ }

Entropy result cache for deterministic price sequences (Issue #96 Task #117)

Caches permutation entropy results to avoid redundant computation on identical price sequences. Uses quick_cache::sync::Cache for production-grade LRU eviction with O(1) lookup. Useful for consolidation periods where price sequences repeat frequently.

Performance Impact

• Consolidation periods: 1.5-2.5x speedup (high repetition)
• Trending markets: 1.0-1.2x speedup (low repetition)
• Memory: Automatic LRU eviction (max 128 entries by default)

Implementation

• Uses quick_cache::sync::Cache with automatic LRU eviction (Issue #96 Task #125)
• Hash function: foldhash (captures exact floating-point values, 20-40% faster than ahash)
• Thread-safe via quick_cache’s internal locking
• Metrics: Cache hit/miss/eviction tracking (Issue #96 Task #135)

Implementations

impl EntropyCache

pub fn new() -> EntropyCache

Create new empty entropy cache with LRU eviction and metrics tracking (Task #135)

pub fn with_capacity(capacity: u64) -> EntropyCache

Create entropy cache with custom capacity (Issue #145: Global cache sizing)

Used by global entropy cache to support larger capacity (512-1024 entries) for improved hit ratio on multi-symbol workloads.

Memory Usage

Approximate memory per entry: ~24 bytes (quick_cache overhead + u64 key + f64 value)

• 128 entries ≈ 3KB (default, per-processor)
• 512 entries ≈ 12KB (4x improvement)
• 1024 entries ≈ 24KB (8x improvement, global cache)

pub fn get(&self, prices: &[f64]) -> Option<f64>

Get cached entropy result if available (O(1) operation) Tracks hit/miss metrics for cache effectiveness analysis (Task #135)

pub fn insert(&mut self, prices: &[f64], entropy: f64)

Cache entropy result (O(1) operation, quick_cache handles LRU eviction)

pub fn metrics(&self) -> (usize, usize, f64)

Get cache metrics: (hits, misses, hit_ratio) Returns hit ratio as percentage (0-100) for analysis (Task #135)

pub fn reset_metrics(&mut self)

Reset metrics counters (useful for per-symbol analysis)

Trait Implementations

impl Debug for EntropyCache

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

Formats the value using the given formatter.

impl Default for EntropyCache

fn default() -> EntropyCache

Returns the “default value” for a type.