[esnext] prototype runtime implementation for async functions

src/d8.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 
 // Defined when linking against shared lib on Windows.
 #if defined(USING_V8_SHARED) && !defined(V8_SHARED)
 #define V8_SHARED
 #endif
 
@@ skipping 869 matching lines @@
                  const_cast<v8::FunctionCallbackInfo<v8::Value>*>(&args));
 }
 
 
 void Shell::Version(const v8::FunctionCallbackInfo<v8::Value>& args) {
   args.GetReturnValue().Set(
       String::NewFromUtf8(args.GetIsolate(), V8::GetVersion(),
                           NewStringType::kNormal).ToLocalChecked());
 }
 
+void Shell::FlushMicrotasks(const v8::FunctionCallbackInfo<v8::Value>& args) {
+  Isolate* isolate = args.GetIsolate();
+  isolate->RunMicrotasks();
+}
 
 void Shell::ReportException(Isolate* isolate, v8::TryCatch* try_catch) {
   HandleScope handle_scope(isolate);
 #ifndef V8_SHARED
   Local<Context> context;
   bool enter_context = !isolate->InContext();
   if (enter_context) {
     context = Local<Context>::New(isolate, evaluation_context_);
     context->Enter();
   }
@@ skipping 297 matching lines @@
       worker_fun_template);
 #endif  // !V8_SHARED
 
   Local<ObjectTemplate> os_templ = ObjectTemplate::New(isolate);
   AddOSMethods(isolate, os_templ);
   global_template->Set(
       String::NewFromUtf8(isolate, "os", NewStringType::kNormal)
           .ToLocalChecked(),
       os_templ);
 
+  global_template->Set(
+      String::NewFromUtf8(isolate, "flushMicrotasks", NewStringType::kNormal)
+          .ToLocalChecked(),
+      FunctionTemplate::New(isolate, FlushMicrotasks));

[Dan Ehrenberg, 2016/05/04 22:52:36]

I worry that this flushMicrotasks call won't always work so well, as it sort of
violates the microtask model that things don't have to be re-entrant, but I
don't actually have a concrete problem that I can think of here. Existing
Promise tests use an assertLater pattern (found in test/mjsunit/es6/promises.js
for example) and depend on the fact that d8 will not exit until all microtasks
have run. Would that work? Or could you at least guard this behind a special d8
flag so it's not exposed by default?

[caitp (gmail), 2016/05/06 18:45:25]

the assertLater thing is kind of a mess, I would prefer not to rely on a similar
model. It makes tests more complicated, and actually makes it harder to read the
results of the tests when failures occur.

I could put this behind a flag, but I don't believe just exposing it should be a
problem in general.

+
   return global_template;
 }
 
 static void EmptyMessageCallback(Local<Message> message, Local<Value> error) {
   // Nothing to be done here, exceptions thrown up to the shell will be reported
   // separately by {Shell::ReportException} after they are caught.
 }
 
 void Shell::Initialize(Isolate* isolate) {
 #ifndef V8_SHARED
@@ skipping 1309 matching lines @@
 }
 
 }  // namespace v8
 
 
 #ifndef GOOGLE3
 int main(int argc, char* argv[]) {
   return v8::Shell::Main(argc, argv);
 }
 #endif