env: introduce AsyncWrapScope for MakeCallback

Do not go through async wrap hooks if we are already within the
`MakeCallback`. This commit allows calling `MakeCallback` recursively.

src/async-wrap.cc

@@ -176,10 +176,25 @@ Local<Value> AsyncWrap::MakeCallback(const Local<Function> cb,
                                       int argc,
                                       Local<Value>* argv) {
   CHECK(env()->context() == env()->isolate()->GetCurrentContext());
+  Local<Object> context = object();
+
+  if (env()->in_async_callback()) {
+    TryCatch try_catch(env()->isolate());
+    try_catch.SetVerbose(true);
+
+    Local<Value> ret = cb->Call(context, argc, argv);
+
+    if (try_catch.HasCaught()) {
+      return Undefined(env()->isolate());
+    }
+
+    return ret;
+  }
+
+  Environment::AsyncCallbackScope async_scope(env());
 
   Local<Function> pre_fn = env()->async_hooks_pre_function();
   Local<Function> post_fn = env()->async_hooks_post_function();
-  Local<Object> context = object();
   Local<Object> process = env()->process_object();
   Local<Object> domain;
   bool has_domain = false;

src/env-inl.h

@@ -88,6 +88,15 @@ inline void Environment::AsyncHooks::set_enable_callbacks(uint32_t flag) {
   fields_[kEnableCallbacks] = flag;
 }
 
+inline Environment::AsyncCallbackScope::AsyncCallbackScope(Environment* env) :
+    env_(env) {
+  env_->set_in_async_callback(true);
+}
+
+inline Environment::AsyncCallbackScope::~AsyncCallbackScope() {
+  env_->set_in_async_callback(false);
+}
+
 inline Environment::DomainFlag::DomainFlag() {
   for (int i = 0; i < kFieldsCount; ++i) fields_[i] = 0;
 }
@@ -206,6 +215,7 @@ inline Environment::Environment(v8::Local<v8::Context> context,
                                 uv_loop_t* loop)
     : isolate_(context->GetIsolate()),
       isolate_data_(IsolateData::GetOrCreate(context->GetIsolate(), loop)),
+      in_async_callback_(false),
       timer_base_(uv_now(loop)),
       using_domains_(false),
       printed_error_(false),
@@ -323,6 +333,14 @@ inline Environment::AsyncHooks* Environment::async_hooks() {
   return &async_hooks_;
 }
 
+inline bool Environment::in_async_callback() const {
+  return in_async_callback_;
+}
+
+inline void Environment::set_in_async_callback(bool value) {
+  in_async_callback_ = value;
+}
+
 inline Environment::DomainFlag* Environment::domain_flag() {
   return &domain_flag_;
 }

src/env.h

@@ -305,6 +305,15 @@ class Environment {
     DISALLOW_COPY_AND_ASSIGN(AsyncHooks);
   };
 
+  class AsyncCallbackScope {
+   public:
+    explicit AsyncCallbackScope(Environment* env);
+    ~AsyncCallbackScope();
+
+   private:
+    Environment* env_;
+  };
+
   class DomainFlag {
    public:
     inline uint32_t* fields();
@@ -435,6 +444,9 @@ class Environment {
   inline void FinishHandleCleanup(uv_handle_t* handle);
 
   inline AsyncHooks* async_hooks();
+  inline bool in_async_callback() const;
+  inline void set_in_async_callback(bool value);
+
   inline DomainFlag* domain_flag();
   inline TickInfo* tick_info();
   inline ArrayBufferAllocatorInfo* array_buffer_allocator_info();
@@ -542,6 +554,7 @@ class Environment {
   uv_prepare_t idle_prepare_handle_;
   uv_check_t idle_check_handle_;
   AsyncHooks async_hooks_;
+  bool in_async_callback_;
   DomainFlag domain_flag_;
   TickInfo tick_info_;
   ArrayBufferAllocatorInfo array_buffer_allocator_info_;

src/node.cc

@@ -3196,6 +3196,8 @@ void LoadEnvironment(Environment* env) {
   // thrown during process startup.
   try_catch.SetVerbose(true);
 
+  Environment::AsyncCallbackScope async_scope(env);
+
   env->SetMethod(env->process_object(), "_rawDebug", RawDebug);
 
   Local<Value> arg = env->process_object();