perf(runtime): optimize dom write scheduling

Author: manucorporat

src/client/client-load-module.ts

@@ -2,17 +2,27 @@ import * as d from '../declarations';
 import { BUILD } from '@build-conditionals';
 import { consoleError } from './client-log';
 
+export const moduleCache = /*@__PURE__*/new Map<string, {[exportName: string]: d.ComponentConstructor}>();
 
-export const loadModule = (cmpMeta: d.ComponentRuntimeMeta, hostRef: d.HostRef, hmrVersionId?: string): Promise<d.ComponentConstructor> => {
+export const loadModule = (cmpMeta: d.ComponentRuntimeMeta, hostRef: d.HostRef, hmrVersionId?: string): Promise<d.ComponentConstructor> | d.ComponentConstructor => {
   // loadModuleImport
-  const bundleId = (BUILD.mode && typeof cmpMeta.$lazyBundleIds$ !== 'string')
+  const exportName = cmpMeta.$tagName$.replace(/-/g, '_');
+  const bundleId = ((BUILD.mode && typeof cmpMeta.$lazyBundleIds$ !== 'string')
     ? cmpMeta.$lazyBundleIds$[hostRef.$modeName$]
-    : cmpMeta.$lazyBundleIds$;
-
+    : cmpMeta.$lazyBundleIds$) as string;
+  const module = !BUILD.hotModuleReplacement ? moduleCache.get(bundleId) : false;
+  if (module) {
+    return module[exportName];
+  }
   return import(
     /* webpackInclude: /\.entry\.js$/ */
     /* webpackExclude: /\.system\.entry\.js$/ */
     /* webpackMode: "lazy" */
     `./${bundleId}.entry.js${BUILD.hotModuleReplacement && hmrVersionId ? '?s-hmr=' + hmrVersionId : ''}`
-  ).then(importedModule => importedModule[cmpMeta.$tagName$.replace(/-/g, '_')], consoleError);
+  ).then(importedModule => {
+    if (!BUILD.hotModuleReplacement) {
+      moduleCache.set(bundleId, importedModule);
+    }
+    return importedModule[exportName];
+  }, consoleError);
 };

src/client/client-task-queue.ts

@@ -12,7 +12,6 @@ const queueDomWrites: d.RafCallback[] = [];
 const queueDomWritesLow: d.RafCallback[] = [];
 
 const queueTask = (queue: d.RafCallback[]) => (cb: d.RafCallback) => {
-  // queue dom reads
   queue.push(cb);
 
   if (!queuePending) {

src/runtime/initialize-component.ts

@@ -10,7 +10,7 @@ import { fireConnectedCallback } from './connected-callback';
 import { PROXY_FLAGS } from './runtime-constants';
 
 
-export const initializeComponent = async (elm: d.HostElement, hostRef: d.HostRef, cmpMeta: d.ComponentRuntimeMeta, hmrVersionId?: string, Cstr?: d.ComponentConstructor) => {
+export const initializeComponent = async (elm: d.HostElement, hostRef: d.HostRef, cmpMeta: d.ComponentRuntimeMeta, hmrVersionId?: string, Cstr?: any) => {
   // initializeComponent
   if ((BUILD.lazyLoad || BUILD.style) && (hostRef.$flags$ & HOST_FLAGS.hasInitializedComponent) === 0) {
     // we haven't initialized this element yet
@@ -31,7 +31,11 @@ export const initializeComponent = async (elm: d.HostElement, hostRef: d.HostRef
       // lazy loaded components
       // request the component's implementation to be
       // wired up with the host element
-      Cstr = await loadModule(cmpMeta, hostRef, hmrVersionId);
+      Cstr = loadModule(cmpMeta, hostRef, hmrVersionId);
+      if (Cstr.then) {
+        // Await creates a micro-task avoid if possible
+        Cstr = await Cstr;
+      }
       if ((BUILD.isDev || BUILD.isDebug) && !Cstr) {
         throw new Error(`Constructor for "${cmpMeta.$tagName$}#${hostRef.$modeName$}" was not found`);
       }
@@ -88,18 +92,19 @@ export const initializeComponent = async (elm: d.HostElement, hostRef: d.HostRef
 
   // we've successfully created a lazy instance
   const ancestorComponent = hostRef.$ancestorComponent$;
+  const schedule = () => scheduleUpdate(elm, hostRef, cmpMeta, true);
+
   if (BUILD.lifecycle && BUILD.lazyLoad && ancestorComponent && ancestorComponent['s-lr'] === false && ancestorComponent['s-rc']) {
     // this is the intial load and this component it has an ancestor component
     // but the ancestor component has NOT fired its will update lifecycle yet
     // so let's just cool our jets and wait for the ancestor to continue first
-    ancestorComponent['s-rc'].push(() =>
-      // this will get fired off when the ancestor component
-      // finally gets around to rendering its lazy self
-      // fire off the initial update
-      initializeComponent(elm, hostRef, cmpMeta)
-    );
+
+    // this will get fired off when the ancestor component
+    // finally gets around to rendering its lazy self
+    // fire off the initial update
+    ancestorComponent['s-rc'].push(schedule);
 
   } else {
-    scheduleUpdate(elm, hostRef, cmpMeta, true);
+    schedule();
   }
 };

src/runtime/update-component.ts

@@ -7,21 +7,27 @@ import { HYDRATED_CLASS, PLATFORM_FLAGS } from './runtime-constants';
 import { renderVdom } from './vdom/vdom-render';
 
 
-export const safeCall = async (instance: any, method: string, arg?: any) => {
+export const safeCall = (instance: any, method: string, arg?: any) => {
   if (instance && instance[method]) {
     try {
-      await instance[method](arg);
+      return instance[method](arg);
     } catch (e) {
       consoleError(e);
     }
   }
+  return undefined;
 };
 
-export const scheduleUpdate = async (elm: d.HostElement, hostRef: d.HostRef, cmpMeta: d.ComponentRuntimeMeta, isInitialLoad: boolean) => {
+const then = (promise: Promise<any>, thenFn: () => any) => {
+  return promise && promise.then ? promise.then(thenFn) : thenFn();
+};
+
+export const scheduleUpdate = (elm: d.HostElement, hostRef: d.HostRef, cmpMeta: d.ComponentRuntimeMeta, isInitialLoad: boolean) => {
   if (BUILD.taskQueue && BUILD.updatable) {
     hostRef.$flags$ |= HOST_FLAGS.isQueuedForUpdate;
   }
   const instance = BUILD.lazyLoad ? hostRef.$lazyInstance$ : elm as any;
+  let promise: Promise<void>;
   if (isInitialLoad) {
     if (BUILD.hostListener) {
       hostRef.$flags$ |= HOST_FLAGS.isListenReady;
@@ -32,31 +38,33 @@ export const scheduleUpdate = async (elm: d.HostElement, hostRef: d.HostRef, cmp
     }
     emitLifecycleEvent(elm, 'componentWillLoad');
     if (BUILD.cmpWillLoad) {
-      await safeCall(instance, 'componentWillLoad');
+      promise = safeCall(instance, 'componentWillLoad');
     }
 
   } else {
     emitLifecycleEvent(elm, 'componentWillUpdate');
 
     if (BUILD.cmpWillUpdate) {
-      await safeCall(instance, 'componentWillUpdate');
+      promise = safeCall(instance, 'componentWillUpdate');
     }
   }
 
   emitLifecycleEvent(elm, 'componentWillRender');
   if (BUILD.cmpWillRender) {
-    await safeCall(instance, 'componentWillRender');
+    promise = then(promise, () => safeCall(instance, 'componentWillRender'));
   }
 
   // there is no ancestorc omponent or the ancestor component
   // has already fired off its lifecycle update then
   // fire off the initial update
-  if (BUILD.taskQueue) {
-    writeTask(() => updateComponent(elm, hostRef, cmpMeta, instance, isInitialLoad));
-  } else {
-    // syncronuously write DOM
-    updateComponent(elm, hostRef, cmpMeta, instance, isInitialLoad);
+  const update = () => updateComponent(elm, hostRef, cmpMeta, instance, isInitialLoad);
+  if (promise) {
+    return promise.then(BUILD.taskQueue
+      ? () => writeTask(update)
+      : update
+    );
   }
+  return update();
 };
 
 const updateComponent = (elm: d.RenderNode, hostRef: d.HostRef, cmpMeta: d.ComponentRuntimeMeta, instance: any, isInitialLoad: boolean) => {