Add worker_threads to import and start to implement

Author: hegelocampus

lib/src/node.dart

@@ -81,16 +81,14 @@ Future<RenderResult> _renderAsync(RenderOptions options) async {
   var file = options.file == null ? null : p.absolute(options.file);
   CompileResult result;
 
-  print(StackTrace.current);
-
   if (isMainThread == true) {
-    print(p.current);
+    print("Creating worker thread");
     final worker = Worker(p.current, WorkerOptions(workerData: {options}));
     worker.on('message', (CompileResult msg) => result = msg);
     worker.on('error', (JSError error) {
       jsThrow(_wrapException(error));
     });
-  } else {
+  } else if (isMainThread == false) {
     if (options.data != null) {
       result = await compileStringAsync(options.data,
           nodeImporter: _parseImporter(options, start),
@@ -115,7 +113,9 @@ Future<RenderResult> _renderAsync(RenderOptions options) async {
     } else {
       throw ArgumentError("Either options.data or options.file must be set.");
     }
-    parentPort.postMessage(result);
+    parentPort?.postMessage(result);
+  } else {
+    throw UnsupportedError("Failed to create worker thread.");
   }
 
   return _newRenderResult(options, result, start);

lib/src/node/worker_threads.dart

@@ -1,17 +1,13 @@
-// Copyright 2017 Google Inc. Use of this source code is governed by an
+// Copyright 2018 Google Inc. Use of this source code is governed by an
 // MIT-style license that can be found in the LICENSE file or at
 // https://opensource.org/licenses/MIT.
-@JS("workerThreads")
-library worker_threads;
-//Import is failing here
-
 import 'package:js/js.dart';
 
-@JS()
-external WorkerThreads get workerThreads;
+@JS("worker_threads")
+external WorkerThreads get worker_threads;
 
-bool isMainThread = workerThreads.isMainThread;
-ParentPort parentPort = workerThreads.parentPort;
+bool isMainThread = worker_threads?.isMainThread;
+ParentPort parentPort = worker_threads?.parentPort;
 
 @JS()
 abstract class WorkerThreads {

package/package.json

@@ -14,7 +14,7 @@
     "url": "https://github.com/nex3"
   },
   "engines": {
-    "node": ">=12.14.1"
+    "node": ">=11.7.0"
   },
   "dependencies": {
     "chokidar": ">=2.0.0 <4.0.0"

tool/grind.dart

@@ -26,7 +26,12 @@ void main(List<String> args) {
   pkg.chocolateyNuspec = _nuspec;
   pkg.homebrewRepo = "sass/homebrew-sass";
   pkg.homebrewFormula = "sass.rb";
-  pkg.jsRequires = {"fs": "fs", "chokidar": "chokidar", "readline": "readline"};
+  pkg.jsRequires = {
+    "fs": "fs",
+    "chokidar": "chokidar",
+    "readline": "readline",
+    "workerThreads": "worker_threads"
+  };
   pkg.jsModuleMainLibrary = "lib/src/node.dart";
   pkg.npmPackageJson =
       json.decode(File("package/package.json").readAsStringSync())