feat(tracer): export add to pending event function (#394)

src/tracer.js

@@ -75,6 +75,20 @@ const session = axios.create({
  * @param {Promise} [promise] A promise that resolves when the event handling is Done, if required.
  */
 module.exports.addEvent = function addEvent(event, promise) {
+    const tracerObj = module.exports.getTrace();
+    if (!tracerObj) {
+        return;
+    }
+    this.addPendingEvent(event, promise);
+    tracerObj.trace.addEvent(event);
+};
+
+/**
+ * Add promise event result to pendingEvents map.
+ * @param {proto.event_pb.Event} event The event
+ * @param {Promise} [promise] A promise that resolves when the event handling is Done
+ */
+module.exports.addPendingEvent = function addPendingEvent(event, promise) {
     const tracerObj = module.exports.getTrace();
     if (!tracerObj) {
         return;
@@ -87,8 +101,6 @@ module.exports.addEvent = function addEvent(event, promise) {
             }))
         );
     }
-
-    tracerObj.trace.addEvent(event);
 };
 
 /**