refactor(timeout): unify and enhance timeout middleware

middleware/timeout/timeout.go

@@ -8,23 +8,43 @@ import (
 	"github.com/gofiber/fiber/v3"
 )
 
-// New implementation of timeout middleware. Set custom errors(context.DeadlineExceeded vs) for get fiber.ErrRequestTimeout response.
-func New(h fiber.Handler, t time.Duration, tErrs ...error) fiber.Handler {
+// New enforces a timeout for each incoming request. If the timeout expires or
+// any of the specified errors occur, fiber.ErrRequestTimeout is returned.
+func New(h fiber.Handler, timeout time.Duration, tErrs ...error) fiber.Handler {
 	return func(ctx fiber.Ctx) error {
-		timeoutContext, cancel := context.WithTimeout(ctx.Context(), t)
+		// Create a context with the specified timeout; any operation exceeding
+		// this deadline will be canceled automatically.
+		timeoutContext, cancel := context.WithTimeout(ctx.Context(), timeout)
 		defer cancel()
+
+		// Attach the timeout-bound context to the current Fiber context.
 		ctx.SetContext(timeoutContext)
-		if err := h(ctx); err != nil {
-			if errors.Is(err, context.DeadlineExceeded) {
+
+		// Execute the wrapped handler synchronously.
+		err := h(ctx)
+
+		// If the context has timed out, return a request timeout error.
+		if timeoutContext.Err() != nil && errors.Is(timeoutContext.Err(), context.DeadlineExceeded) {
+			return fiber.ErrRequestTimeout
+		}
+
+		// If the handler returned an error, check whether it's a deadline exceeded
+		// error or any other listed timeout-triggering error.
+		if err != nil {
+			if errors.Is(err, context.DeadlineExceeded) || isCustomError(err, tErrs) {
 				return fiber.ErrRequestTimeout
 			}
-			for i := range tErrs {
-				if errors.Is(err, tErrs[i]) {
-					return fiber.ErrRequestTimeout
-				}
-			}
-			return err
 		}
-		return nil
+		return err
+	}
+}
+
+// isCustomError checks whether err matches any error in errList using errors.Is.
+func isCustomError(err error, errList []error) bool {
+	for _, e := range errList {
+		if errors.Is(err, e) {
+			return true
+		}
 	}
+	return false
 }