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/singleflight.go

@@ -0,0 +1,103 @@
+package engine
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/ungluedlabs/go-jdenticon/internal/util"
+)
+
+// Generate creates an identicon with the specified hash and size
+// This method includes caching and singleflight to prevent duplicate work
+func (g *Generator) Generate(ctx context.Context, hash string, size float64) (*Icon, error) {
+	// Basic validation
+	if hash == "" {
+		return nil, fmt.Errorf("jdenticon: engine: generation failed: hash cannot be empty")
+	}
+	if size <= 0 {
+		return nil, fmt.Errorf("jdenticon: engine: generation failed: invalid size: %f", size)
+	}
+
+	// Check icon size limits
+	if g.maxIconSize > 0 && int(size) > g.maxIconSize {
+		return nil, fmt.Errorf("jdenticon: engine: generation failed: icon size %d exceeds maximum allowed size %d", int(size), g.maxIconSize)
+	}
+
+	// Validate hash format
+	if !util.IsValidHash(hash) {
+		return nil, fmt.Errorf("jdenticon: engine: generation failed: invalid hash format: %s", hash)
+	}
+
+	// Check for context cancellation before proceeding
+	if err := ctx.Err(); err != nil {
+		return nil, err
+	}
+
+	// Generate cache key
+	key := g.cacheKey(hash, size)
+
+	// Check cache first (with read lock)
+	g.mu.RLock()
+	if cached, ok := g.cache.Get(key); ok {
+		g.mu.RUnlock()
+		g.metrics.recordHit()
+		return cached, nil
+	}
+	g.mu.RUnlock()
+
+	// Use singleflight to prevent multiple concurrent generations for the same key
+	result, err, _ := g.sf.Do(key, func() (interface{}, error) {
+		// Check cache again inside singleflight (another goroutine might have populated it)
+		g.mu.RLock()
+		if cached, ok := g.cache.Get(key); ok {
+			g.mu.RUnlock()
+			g.metrics.recordHit()
+			return cached, nil
+		}
+		g.mu.RUnlock()
+
+		// Generate the icon
+		icon, err := g.generateIcon(ctx, hash, size)
+		if err != nil {
+			return nil, err
+		}
+
+		// Store in cache (with write lock)
+		g.mu.Lock()
+		g.cache.Add(key, icon)
+		g.mu.Unlock()
+
+		g.metrics.recordMiss()
+		return icon, nil
+	})
+
+	if err != nil {
+		return nil, err
+	}
+
+	return result.(*Icon), nil
+}
+
+// GenerateWithoutCache creates an identicon without using cache
+// This method is useful for testing or when caching is not desired
+func (g *Generator) GenerateWithoutCache(ctx context.Context, hash string, size float64) (*Icon, error) {
+	// Basic validation
+	if hash == "" {
+		return nil, fmt.Errorf("jdenticon: engine: generation failed: hash cannot be empty")
+	}
+	if size <= 0 {
+		return nil, fmt.Errorf("jdenticon: engine: generation failed: invalid size: %f", size)
+	}
+
+	// Validate hash format
+	if !util.IsValidHash(hash) {
+		return nil, fmt.Errorf("jdenticon: engine: generation failed: invalid hash format: %s", hash)
+	}
+
+	// Check for context cancellation
+	if err := ctx.Err(); err != nil {
+		return nil, err
+	}
+
+	return g.generateIcon(ctx, hash, size)
+}