feat(log): Prevent log.Helper sprintf from running early #3209

log/helper.go

@@ -66,18 +66,33 @@ func (h *Helper) WithContext(ctx context.Context) *Helper {
 	}
 }
 
+// Enabled returns true if the given level above this level.
+// It delegates to the underlying *Filter.
+func (h *Helper) Enabled(level Level) bool {
+	if l, ok := h.logger.(*Filter); ok {
+		return level >= l.level
+	}
+	return true
+}
+
 // Log Print log by level and keyvals.
 func (h *Helper) Log(level Level, keyvals ...interface{}) {
 	_ = h.logger.Log(level, keyvals...)
 }
 
 // Debug logs a message at debug level.
 func (h *Helper) Debug(a ...interface{}) {
+	if !h.Enabled(LevelDebug) {
+		return
+	}
 	_ = h.logger.Log(LevelDebug, h.msgKey, h.sprint(a...))
 }
 
 // Debugf logs a message at debug level.
 func (h *Helper) Debugf(format string, a ...interface{}) {
+	if !h.Enabled(LevelDebug) {
+		return
+	}
 	_ = h.logger.Log(LevelDebug, h.msgKey, h.sprintf(format, a...))
 }
 
@@ -88,11 +103,17 @@ func (h *Helper) Debugw(keyvals ...interface{}) {
 
 // Info logs a message at info level.
 func (h *Helper) Info(a ...interface{}) {
+	if !h.Enabled(LevelInfo) {
+		return
+	}
 	_ = h.logger.Log(LevelInfo, h.msgKey, h.sprint(a...))
 }
 
 // Infof logs a message at info level.
 func (h *Helper) Infof(format string, a ...interface{}) {
+	if !h.Enabled(LevelInfo) {
+		return
+	}
 	_ = h.logger.Log(LevelInfo, h.msgKey, h.sprintf(format, a...))
 }
 
@@ -103,11 +124,17 @@ func (h *Helper) Infow(keyvals ...interface{}) {
 
 // Warn logs a message at warn level.
 func (h *Helper) Warn(a ...interface{}) {
+	if !h.Enabled(LevelWarn) {
+		return
+	}
 	_ = h.logger.Log(LevelWarn, h.msgKey, h.sprint(a...))
 }
 
 // Warnf logs a message at warnf level.
 func (h *Helper) Warnf(format string, a ...interface{}) {
+	if !h.Enabled(LevelWarn) {
+		return
+	}
 	_ = h.logger.Log(LevelWarn, h.msgKey, h.sprintf(format, a...))
 }
 
@@ -118,11 +145,17 @@ func (h *Helper) Warnw(keyvals ...interface{}) {
 
 // Error logs a message at error level.
 func (h *Helper) Error(a ...interface{}) {
+	if !h.Enabled(LevelError) {
+		return
+	}
 	_ = h.logger.Log(LevelError, h.msgKey, h.sprint(a...))
 }
 
 // Errorf logs a message at error level.
 func (h *Helper) Errorf(format string, a ...interface{}) {
+	if !h.Enabled(LevelError) {
+		return
+	}
 	_ = h.logger.Log(LevelError, h.msgKey, h.sprintf(format, a...))
 }
 

log/helper_test.go

@@ -46,13 +46,27 @@ func BenchmarkHelperPrint(b *testing.B) {
 	}
 }
 
+func BenchmarkHelperPrintFilterLevel(b *testing.B) {
+	log := NewHelper(NewFilter(NewStdLogger(io.Discard), FilterLevel(LevelDebug)))
+	for i := 0; i < b.N; i++ {
+		log.Debug("test")
+	}
+}
+
 func BenchmarkHelperPrintf(b *testing.B) {
 	log := NewHelper(NewStdLogger(io.Discard))
 	for i := 0; i < b.N; i++ {
 		log.Debugf("%s", "test")
 	}
 }
 
+func BenchmarkHelperPrintfFilterLevel(b *testing.B) {
+	log := NewHelper(NewFilter(NewStdLogger(io.Discard), FilterLevel(LevelInfo)))
+	for i := 0; i < b.N; i++ {
+		log.Debugf("%s", "test")
+	}
+}
+
 func BenchmarkHelperPrintw(b *testing.B) {
 	log := NewHelper(NewStdLogger(io.Discard))
 	for i := 0; i < b.N; i++ {