Merge pull request #660 from ember-cli/cache-template-compiler-evaluation

Replace `purgeModule` cache busting with `vm` based sandboxing

Author: Robert Jackson

lib/utils.js

@@ -7,6 +7,9 @@ const hashForDep = require('hash-for-dep');
 const debugGenerator = require('heimdalljs-logger');
 const logger = debugGenerator('ember-cli-htmlbars:utils');
 const addDependencyTracker = require('./addDependencyTracker');
+const vm = require('vm');
+
+const TemplateCompilerCache = new Map();
 
 const INLINE_PRECOMPILE_MODULES = Object.freeze({
   'ember-cli-htmlbars': 'hbs',
@@ -92,18 +95,10 @@ function buildParalleizedBabelPlugin(
 function buildOptions(projectConfig, templateCompilerPath, pluginInfo) {
   let EmberENV = projectConfig.EmberENV || {};
 
-  purgeModule(templateCompilerPath);
-
-  // do a full clone of the EmberENV (it is guaranteed to be structured
-  // cloneable) to prevent ember-template-compiler.js from mutating
-  // the shared global config
-  let clonedEmberENV = JSON.parse(JSON.stringify(EmberENV));
-  global.EmberENV = clonedEmberENV; // Needed for eval time feature flag checks
-
   let htmlbarsOptions = {
     isHTMLBars: true,
     EmberENV: EmberENV,
-    templateCompiler: require(templateCompilerPath),
+    templateCompiler: getTemplateCompiler(templateCompilerPath, EmberENV),
     templateCompilerPath: templateCompilerPath,
 
     pluginNames: pluginInfo.pluginNames,
@@ -116,37 +111,47 @@ function buildOptions(projectConfig, templateCompilerPath, pluginInfo) {
     pluginCacheKey: pluginInfo.cacheKeys,
   };
 
-  purgeModule(templateCompilerPath);
-
-  delete global.Ember;
-  delete global.EmberENV;
-
   return htmlbarsOptions;
 }
 
-function purgeModule(templateCompilerPath) {
-  // ensure we get a fresh templateCompilerModuleInstance per ember-addon
-  // instance NOTE: this is a quick hack, and will only work as long as
-  // templateCompilerPath is a single file bundle
-  //
-  // (╯°□°）╯︵ ɹǝqɯǝ
-  //
-  // we will also fix this in ember for future releases
-
-  // Module will be cached in .parent.children as well. So deleting from require.cache alone is not sufficient.
-  let mod = require.cache[templateCompilerPath];
-  if (mod && mod.parent) {
-    let index = mod.parent.children.indexOf(mod);
-    if (index >= 0) {
-      mod.parent.children.splice(index, 1);
-    } else {
-      throw new TypeError(
-        `ember-cli-htmlbars attempted to purge '${templateCompilerPath}' but something went wrong.`
-      );
-    }
+function getTemplateCompiler(templateCompilerPath, EmberENV = {}) {
+  let templateCompilerFullPath = require.resolve(templateCompilerPath);
+  let cacheData = TemplateCompilerCache.get(templateCompilerFullPath);
+
+  if (cacheData === undefined) {
+    let templateCompilerContents = fs.readFileSync(templateCompilerFullPath, { encoding: 'utf-8' });
+    let templateCompilerCacheKey = crypto
+      .createHash('md5')
+      .update(templateCompilerContents)
+      .digest('hex');
+
+    cacheData = {
+      script: new vm.Script(templateCompilerContents, {
+        filename: templateCompilerPath,
+      }),
+
+      templateCompilerCacheKey,
+    };
+
+    TemplateCompilerCache.set(templateCompilerFullPath, cacheData);
   }
 
-  delete require.cache[templateCompilerPath];
+  let { script } = cacheData;
+
+  // do a full clone of the EmberENV (it is guaranteed to be structured
+  // cloneable) to prevent ember-template-compiler.js from mutating
+  // the shared global config
+  let clonedEmberENV = JSON.parse(JSON.stringify(EmberENV));
+
+  let context = vm.createContext({
+    EmberENV: clonedEmberENV,
+    module: { require, exports: {} },
+    require,
+  });
+
+  script.runInContext(context);
+
+  return context.module.exports;
 }
 
 function registerPlugins(templateCompiler, plugins) {
@@ -259,11 +264,10 @@ function setup(pluginInfo, options) {
 
 function makeCacheKey(templateCompilerPath, pluginInfo, extra) {
   let templateCompilerFullPath = require.resolve(templateCompilerPath);
-  let templateCompilerCacheKey = crypto
-    .createHash('md5')
-    .update(fs.readFileSync(templateCompilerFullPath, { encoding: 'utf-8' }))
-    .digest('hex');
+  let { templateCompilerCacheKey } = TemplateCompilerCache.get(templateCompilerFullPath);
+
   let cacheItems = [templateCompilerCacheKey, extra].concat(pluginInfo.cacheKeys.sort());
+
   // extra may be undefined
   return cacheItems.filter(Boolean).join('|');
 }
@@ -332,7 +336,6 @@ function setupPlugins(wrappers) {
 
 module.exports = {
   buildOptions,
-  purgeModule,
   registerPlugins,
   unregisterPlugins,
   initializeEmberENV,
@@ -343,4 +346,5 @@ module.exports = {
   isColocatedBabelPluginRegistered,
   isInlinePrecompileBabelPluginRegistered,
   buildParalleizedBabelPlugin,
+  getTemplateCompiler,
 };