feat: add watcher for record code excution time

function/watcher.go

@@ -0,0 +1,30 @@
+package function
+
+import "time"
+
+// Watcher is used for record code excution time
+type Watcher struct {
+	startTime int64
+	stopTime  int64
+	excuting  bool
+}
+
+// Start the watch timer.
+func (w *Watcher) Start() {
+	w.startTime = time.Now().UnixNano()
+	w.excuting = true
+}
+
+// Stop the watch timer.
+func (w *Watcher) Stop() {
+	w.stopTime = time.Now().UnixNano()
+	w.excuting = false
+}
+// GetElapsedTime get excute elapsed time.
+func (w *Watcher) GetElapsedTime() time.Duration {
+	if w.excuting {
+		return time.Duration(time.Now().UnixNano() - w.startTime)
+	} else {
+		return time.Duration(w.stopTime - w.startTime)
+	}
+}