Remove for loop from mutex

db/mutex.go

@@ -35,23 +35,31 @@ func (m *mutex) Lock(ctx context.Context, key fmt.Stringer) {
 
 	_, v := m.item(ctx, key)
 
-	for {
+	select {
-		select {
+	case <-ctx.Done():
-		default:
+		return
-			if atomic.LoadUint32(&v.v) < vers(ctx) {
+	case <-v.q:
-				close(v.q)
+		return
-				panic(errRaceCondition)
+	case v.l <- struct{}{}:
-			}
+		atomic.StoreUint32(&v.v, vers(ctx))
-		case <-ctx.Done():
+		return
-			return
+	default:
-		case <-v.q:
+		if atomic.LoadUint32(&v.v) < vers(ctx) {
-			return
+			close(v.q)
-		case v.l <- struct{}{}:
+			panic(errRaceCondition)
-			atomic.StoreUint32(&v.v, vers(ctx))
-			return
 		}
 	}
 
+	select {
+	case <-ctx.Done():
+		return
+	case <-v.q:
+		return
+	case v.l <- struct{}{}:
+		atomic.StoreUint32(&v.v, vers(ctx))
+		return
+	}
+
 }
 
 func (m *mutex) Unlock(ctx context.Context, key fmt.Stringer) {