Fix egg issue (#29)

lib/plugins/egg-core/file_loader.js

@@ -99,7 +99,7 @@ module.exports = function(fileLoaderModule, instrumentation, contextManager) {
     function wrapServiceMethod(origin) {
         const methodName = origin.name + "(" + functionArguments(origin) + ")";
         if (origin && origin[Symbol.toStringTag] === "AsyncFunction") {
-            return async function() {
+            return function() {
                 let previousActiveContext = contextManager.activeTraceContext();
                 let curActiveContext = this.ctx[activeContext];
                 contextManager.active(curActiveContext);
@@ -107,14 +107,20 @@ module.exports = function(fileLoaderModule, instrumentation, contextManager) {
                 let ret = undefined;
                 try {
                     ret = origin.apply(this, arguments);
+                    Promise.all([ret]).then(function() {
+                        contextManager.finishSpan(runningSpan);
+                        contextManager.active(previousActiveContext);
+                    }).catch(function(e) {
+                        runningSpan.errorOccurred();
+                        runningSpan.log(e);
+                        contextManager.finishSpan(runningSpan);
+                        contextManager.active(previousActiveContext);
+                    });
                     return ret;
                 } catch (e) {
                     runningSpan.errorOccurred();
                     runningSpan.log(e);
                     throw e;
-                } finally {
-                    contextManager.finishSpan(runningSpan);
-                    contextManager.active(previousActiveContext);
                 }
                 return ret;
             };