feat(module-loader): add caching for ngModuleLoader on load

Author: brandyscarney

src/util/module-loader.ts

@@ -1,4 +1,4 @@
-import { ComponentFactoryResolver, Injectable, Injector, OpaqueToken, Type } from '@angular/core';
+import { ComponentFactoryResolver, Injectable, Injector, NgModuleFactory, OpaqueToken, Type } from '@angular/core';
 import { DeepLinkConfig } from '../navigation/nav-util';
 import { NgModuleLoader } from './ng-module-loader';
 
@@ -15,6 +15,8 @@ export class ModuleLoader {
   /** @internal */
   _cfrMap = new Map<any, ComponentFactoryResolver>();
 
+  _promiseMap = new Map<string, Promise<NgModuleFactory<any>>>();
+
   constructor(
     private _ngModuleLoader: NgModuleLoader,
     private _injector: Injector) {}
@@ -25,7 +27,15 @@ export class ModuleLoader {
 
     const splitString = modulePath.split(SPLITTER);
 
-    return this._ngModuleLoader.load(splitString[0], splitString[1]).then(loadedModule => {
+    let promise = this._promiseMap.get(modulePath);
+    if (!promise) {
+      promise = this._ngModuleLoader.load(splitString[0], splitString[1]);
+      this._promiseMap.set(modulePath, promise);
+    }
+
+    return promise.then(loadedModule => {
+      // clear it from the cache
+      this._promiseMap.delete(modulePath);
       console.timeEnd(`ModuleLoader, load: ${modulePath}'`);
       const ref = loadedModule.create(this._injector);
 

src/util/test/module-loader.spec.ts

@@ -1,7 +1,5 @@
-import { DeepLinkConfig } from '../../navigation/nav-util';
-import { DeepLinker } from '../../navigation/deep-linker';
 import { ModuleLoader } from '../module-loader';
-import { mockDeepLinkConfig, mockDeepLinker, mockModuleLoader, mockNgModuleLoader } from '../mock-providers';
+import { mockModuleLoader, mockNgModuleLoader } from '../mock-providers';
 import { NgModuleLoader } from '../ng-module-loader';
 
 
@@ -47,22 +45,16 @@ describe('module-loader', () => {
         // we would expect the same promise to be returned both times
         expect(promise).toEqual(secondPromise);
 
-        // TODO enable this with caching
-        // expect(ngModuleLoader.load).toHaveBeenCalledTimes(1);
+        expect(ngModuleLoader.load).toHaveBeenCalledTimes(1);
     });
 
   });
 
-  var deepLinker: DeepLinker;
-  var deepLinkConfig: DeepLinkConfig;
   var moduleLoader: ModuleLoader;
   var ngModuleLoader: NgModuleLoader;
 
   beforeEach(() => {
-    deepLinkConfig = mockDeepLinkConfig();
-    deepLinker = mockDeepLinker(deepLinkConfig);
     ngModuleLoader = mockNgModuleLoader();
-
     moduleLoader = mockModuleLoader(ngModuleLoader);
   });