refac: removed 7 direct and 12 indirect go modules for custom code instead

internal/infrastructure/useCases/ServeVariant.go

@@ -11,8 +11,6 @@ import (
 	"slices"
 	"strings"
 	"time"
-
-	"golang.org/x/sync/singleflight"
 )
 
 const (
@@ -54,7 +52,7 @@ type ServeVariantUseCase struct {
 	maxSourceBytes  int64
 	maxSourcePixels int64
 	renderSlots     chan struct{}
-	flights         singleflight.Group
+	flights         flightGroup
 	tracker         image.VariantUsageTracker
 }
 
@@ -214,11 +212,11 @@ func (u *ServeVariantUseCase) lookupCached(variantName string, storedName string
 func (u *ServeVariantUseCase) generated(ctx context.Context, variant image.Variant, storedName string, fingerprint string, previous image.VariantFile) (image.VariantFile, error) {
 	key := strings.Join([]string{variant.Name, fingerprint, storedName}, flightKeySep)
 	for {
-		file, err, _ := u.flights.Do(key, func() (any, error) {
+		file, err := u.flights.do(key, func() (image.VariantFile, error) {
 			return u.generate(ctx, variant, storedName, fingerprint, previous)
 		})
 		if err == nil {
-			return file.(image.VariantFile), nil
+			return file, nil
 		}
 		if ctx.Err() != nil || !errors.Is(err, context.Canceled) {
 			return image.VariantFile{}, err

internal/infrastructure/useCases/flightGroup.go

@@ -0,0 +1,45 @@
+package useCases
+
+import (
+	"RenewCMS/internal/domain/image"
+	"errors"
+	"sync"
+)
+
+var errFlightAbandoned = errors.New("shared call ended without a result")
+
+type flightCall struct {
+	done  chan struct{}
+	value image.VariantFile
+	err   error
+}
+
+type flightGroup struct {
+	mu    sync.Mutex
+	calls map[string]*flightCall
+}
+
+func (g *flightGroup) do(key string, work func() (image.VariantFile, error)) (image.VariantFile, error) {
+	g.mu.Lock()
+	if existing, running := g.calls[key]; running {
+		g.mu.Unlock()
+		<-existing.done
+		return existing.value, existing.err
+	}
+	if g.calls == nil {
+		g.calls = map[string]*flightCall{}
+	}
+	call := &flightCall{done: make(chan struct{}), err: errFlightAbandoned}
+	g.calls[key] = call
+	g.mu.Unlock()
+
+	defer func() {
+		g.mu.Lock()
+		delete(g.calls, key)
+		g.mu.Unlock()
+		close(call.done)
+	}()
+
+	call.value, call.err = work()
+	return call.value, call.err
+}