Share script bytecode across vm contexts.

Avoid reevaluating the app files and vendor files from scratch for each
visit request.

Co-authored-by: Kris Selden <[email protected]>

Author: Robert Jackson

src/ember-app.js

@@ -1,6 +1,7 @@
 'use strict';
 
 const fs = require('fs');
+const vm = require('vm');
 const path = require('path');
 const chalk = require('chalk');
 
@@ -37,8 +38,6 @@ class EmberApp {
     let distPath = (this.distPath = path.resolve(options.distPath));
     let config = this.readPackageJSON(distPath);
 
-    this.appFilePaths = config.appFiles;
-    this.vendorFilePaths = config.vendorFiles;
     this.moduleWhitelist = config.moduleWhitelist;
     this.hostWhitelist = config.hostWhitelist;
     this.config = config.config;
@@ -61,6 +60,11 @@ class EmberApp {
     this.html = fs.readFileSync(config.htmlFile, 'utf8');
 
     this.sandboxRequire = this.buildWhitelistedRequire(this.moduleWhitelist, distPath);
+    let filePaths = [require.resolve('./scripts/install-source-map-support')].concat(
+      config.vendorFiles,
+      config.appFiles
+    );
+    this.scripts = buildScripts(filePaths);
   }
 
   /**
@@ -176,35 +180,6 @@ class EmberApp {
     };
   }
 
-  /**
-   * @private
-   *
-   * Loads the app and vendor files in the sandbox (Node vm).
-   *
-   */
-  loadAppFiles(sandbox) {
-    let appFilePaths = this.appFilePaths;
-    let vendorFilePaths = this.vendorFilePaths;
-
-    sandbox.eval('sourceMapSupport.install(Error);');
-
-    debug('evaluating app and vendor files');
-
-    vendorFilePaths.forEach(function(vendorFilePath) {
-      debug('evaluating vendor file %s', vendorFilePath);
-      let vendorFile = fs.readFileSync(vendorFilePath, 'utf8');
-      sandbox.eval(vendorFile, vendorFilePath);
-    });
-    debug('vendor file evaluated');
-
-    appFilePaths.forEach(function(appFilePath) {
-      debug('evaluating app file %s', appFilePath);
-      let appFile = fs.readFileSync(appFilePath, 'utf8');
-      sandbox.eval(appFile, appFilePath);
-    });
-    debug('app files evaluated');
-  }
-
   /**
    * @private
    *
@@ -247,7 +222,14 @@ class EmberApp {
   async buildAppInstance() {
     let sandbox = this.buildSandbox();
 
-    this.loadAppFiles(sandbox);
+    debug('adding files to sandbox');
+
+    for (let script of this.scripts) {
+      debug('evaluating file %s', script);
+      sandbox.runScript(script);
+    }
+
+    debug('files evaluated');
 
     let app = await this.createEmberApp(sandbox).boot();
 
@@ -525,4 +507,11 @@ function registerFastBootInfo(info, instance) {
   info.register(instance);
 }
 
+function buildScripts(filePaths) {
+  return filePaths.filter(Boolean).map(filePath => {
+    let source = fs.readFileSync(filePath, { encoding: 'utf8' });
+
+    return new vm.Script(source, { filename: filePath });
+  });
+}
 module.exports = EmberApp;

src/install-source-map-support.js

@@ -2,6 +2,8 @@
 
 const chalk = require('chalk');
 const vm = require('vm');
+const sourceMapSupport = require('source-map-support');
+
 
 module.exports = class Sandbox {
   constructor(globals) {
@@ -13,7 +15,6 @@ module.exports = class Sandbox {
 
   buildSandbox() {
     let console = this.buildWrappedConsole();
-    let sourceMapSupport = require('./install-source-map-support');
     let URL = require('url');
     let globals = this.globals;
 
@@ -53,6 +54,10 @@ module.exports = class Sandbox {
     return wrappedConsole;
   }
 
+  runScript(script) {
+    script.runInContext(this.context);
+  }
+
   eval(source, filePath) {
     var fileScript = new vm.Script(source, { filename: filePath });
     fileScript.runInContext(this.context);

src/sandbox.js

@@ -0,0 +1,12 @@
+'use strict';
+/* globals sourceMapSupport */
+
+Error.prepareStackTrace = function prepareStackTrace(error, stack) {
+  return error + stack.map(frame => '\n    at ' + sourceMapSupport.wrapCallSite(frame)).join('');
+};
+Error.stackTraceLimit = Infinity;
+
+sourceMapSupport.install({
+  environment: 'node',
+  handleUncaughtExceptions: false,
+});

src/scripts/install-source-map-support.js

@@ -65,6 +65,29 @@ describe('FastBoot', function() {
       });
   });
 
+  it('can run multiple visits', async function() {
+    this.timeout(3000);
+
+    var fastboot = new FastBoot({
+      distPath: fixture('basic-app'),
+    });
+
+    let result = await fastboot.visit('/');
+    let html = await result.html();
+
+    expect(html).to.match(/Welcome to Ember/);
+
+    result = await fastboot.visit('/');
+    html = await result.html();
+
+    expect(html).to.match(/Welcome to Ember/);
+
+    result = await fastboot.visit('/');
+    html = await result.html();
+
+    expect(html).to.match(/Welcome to Ember/);
+  });
+
   it('can render HTML with array of app files defined in package.json', function() {
     var fastboot = new FastBoot({
       distPath: fixture('multiple-app-files'),