Initial release: Go Jdenticon library v0.1.0

- Core library with SVG and PNG generation
- CLI tool with generate and batch commands
- Cross-platform path handling for Windows compatibility
- Comprehensive test suite with integration tests

internal/engine/cache.go

@@ -0,0 +1,131 @@
+package engine
+
+import (
+	"fmt"
+	"strconv"
+	"sync/atomic"
+
+	lru "github.com/hashicorp/golang-lru/v2"
+	"github.com/ungluedlabs/go-jdenticon/internal/constants"
+)
+
+// CacheMetrics holds cache performance metrics using atomic operations for efficiency
+type CacheMetrics struct {
+	hits   int64 // Use atomic operations, no mutex needed
+	misses int64 // Use atomic operations, no mutex needed
+}
+
+// GetHits returns the number of cache hits
+func (m *CacheMetrics) GetHits() int64 {
+	return atomic.LoadInt64(&m.hits)
+}
+
+// GetMisses returns the number of cache misses
+func (m *CacheMetrics) GetMisses() int64 {
+	return atomic.LoadInt64(&m.misses)
+}
+
+// recordHit records a cache hit atomically
+func (m *CacheMetrics) recordHit() {
+	atomic.AddInt64(&m.hits, 1)
+}
+
+// recordMiss records a cache miss atomically
+func (m *CacheMetrics) recordMiss() {
+	atomic.AddInt64(&m.misses, 1)
+}
+
+// cacheKey generates a cache key from hash and size
+func (g *Generator) cacheKey(hash string, size float64) string {
+	// Use a simple concatenation approach for better performance
+	// Convert float64 size to string with appropriate precision
+	return hash + ":" + strconv.FormatFloat(size, 'f', 1, 64)
+}
+
+// ClearCache removes all entries from the cache and resets metrics
+func (g *Generator) ClearCache() {
+	g.mu.Lock()
+	defer g.mu.Unlock()
+
+	g.cache.Purge()
+	// Reset metrics
+	atomic.StoreInt64(&g.metrics.hits, 0)
+	atomic.StoreInt64(&g.metrics.misses, 0)
+}
+
+// GetCacheSize returns the number of items currently in the cache
+func (g *Generator) GetCacheSize() int {
+	g.mu.RLock()
+	defer g.mu.RUnlock()
+	return g.cache.Len()
+}
+
+// GetCacheCapacity returns the maximum number of items the cache can hold
+func (g *Generator) GetCacheCapacity() int {
+	g.mu.RLock()
+	defer g.mu.RUnlock()
+	// LRU cache doesn't expose capacity, return the configured capacity from config
+	return g.config.CacheSize
+}
+
+// GetCacheMetrics returns the cache hit and miss counts
+func (g *Generator) GetCacheMetrics() (hits int64, misses int64) {
+	return g.metrics.GetHits(), g.metrics.GetMisses()
+}
+
+// SetConfig updates the generator's color configuration and clears the cache
+func (g *Generator) SetConfig(colorConfig ColorConfig) {
+	g.mu.Lock()
+	defer g.mu.Unlock()
+
+	g.config.ColorConfig = colorConfig
+	g.cache.Purge() // Clear cache since config changed
+}
+
+// SetGeneratorConfig updates the generator's configuration, including cache size
+func (g *Generator) SetGeneratorConfig(config GeneratorConfig) error {
+	g.mu.Lock()
+	defer g.mu.Unlock()
+
+	// Validate cache size
+	if config.CacheSize <= 0 {
+		return fmt.Errorf("jdenticon: engine: invalid cache size: %d", config.CacheSize)
+	}
+
+	// Create new cache with updated size if necessary
+	if config.CacheSize != g.config.CacheSize {
+		newCache, err := lru.New[string, *Icon](config.CacheSize)
+		if err != nil {
+			return fmt.Errorf("jdenticon: engine: failed to create new cache: %w", err)
+		}
+		g.cache = newCache
+	} else {
+		// Same cache size, just clear existing cache
+		g.cache.Purge()
+	}
+
+	g.config = config
+
+	// Update resolved max icon size
+	if config.MaxIconSize > 0 {
+		g.maxIconSize = config.MaxIconSize
+	} else {
+		g.maxIconSize = constants.DefaultMaxIconSize
+	}
+
+	return nil
+}
+
+// GetConfig returns the current color configuration
+func (g *Generator) GetConfig() ColorConfig {
+	g.mu.RLock()
+	defer g.mu.RUnlock()
+	return g.config.ColorConfig
+}
+
+// GetGeneratorConfig returns the current generator configuration
+func (g *Generator) GetGeneratorConfig() GeneratorConfig {
+	g.mu.RLock()
+	defer g.mu.RUnlock()
+	return g.config
+}