// Copyright Joyent, Inc. and other Node contributors. // // Permission is hereby granted, free of charge, to any person obtaining a // copy of this software and associated documentation files (the // "Software"), to deal in the Software without restriction, including // without limitation the rights to use, copy, modify, merge, publish, // distribute, sublicense, and/or sell copies of the Software, and to permit // persons to whom the Software is furnished to do so, subject to the // following conditions: // // The above copyright notice and this permission notice shall be included // in all copies or substantial portions of the Software. // // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS // OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN // NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, // DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR // OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE // USE OR OTHER DEALINGS IN THE SOFTWARE. #include "async_wrap-inl.h" #include "env-inl.h" #include "node_internals.h" #include "util-inl.h" #include "tracing/traced_value.h" #include "v8.h" #include "v8-profiler.h" using v8::Context; using v8::Function; using v8::FunctionCallbackInfo; using v8::FunctionTemplate; using v8::HandleScope; using v8::Integer; using v8::Isolate; using v8::Local; using v8::MaybeLocal; using v8::Number; using v8::Object; using v8::ObjectTemplate; using v8::Promise; using v8::PromiseHookType; using v8::PropertyCallbackInfo; using v8::String; using v8::Uint32; using v8::Undefined; using v8::Value; using AsyncHooks = node::Environment::AsyncHooks; namespace node { static const char* const provider_names[] = { #define V(PROVIDER) \ #PROVIDER, NODE_ASYNC_PROVIDER_TYPES(V) #undef V }; struct AsyncWrapObject : public AsyncWrap { static inline void New(const FunctionCallbackInfo& args) { Environment* env = Environment::GetCurrent(args); CHECK(args.IsConstructCall()); CHECK(env->async_wrap_constructor_template()->HasInstance(args.This())); CHECK(args[0]->IsUint32()); auto type = static_cast(args[0].As()->Value()); new AsyncWrapObject(env, args.This(), type); } inline AsyncWrapObject(Environment* env, Local object, ProviderType type) : AsyncWrap(env, object, type) {} void MemoryInfo(MemoryTracker* tracker) const override { tracker->TrackThis(this); } }; static void DestroyAsyncIdsCallback(Environment* env, void* data) { Local fn = env->async_hooks_destroy_function(); FatalTryCatch try_catch(env); do { std::vector destroy_async_id_list; destroy_async_id_list.swap(*env->destroy_async_id_list()); if (!env->can_call_into_js()) return; for (auto async_id : destroy_async_id_list) { // Want each callback to be cleaned up after itself, instead of cleaning // them all up after the while() loop completes. HandleScope scope(env->isolate()); Local async_id_value = Number::New(env->isolate(), async_id); MaybeLocal ret = fn->Call( env->context(), Undefined(env->isolate()), 1, &async_id_value); if (ret.IsEmpty()) return; } } while (!env->destroy_async_id_list()->empty()); } static void DestroyAsyncIdsCallback(void* arg) { Environment* env = static_cast(arg); if (!env->destroy_async_id_list()->empty()) DestroyAsyncIdsCallback(env, nullptr); } void Emit(Environment* env, double async_id, AsyncHooks::Fields type, Local fn) { AsyncHooks* async_hooks = env->async_hooks(); if (async_hooks->fields()[type] == 0 || !env->can_call_into_js()) return; v8::HandleScope handle_scope(env->isolate()); Local async_id_value = Number::New(env->isolate(), async_id); FatalTryCatch try_catch(env); USE(fn->Call(env->context(), Undefined(env->isolate()), 1, &async_id_value)); } void AsyncWrap::EmitPromiseResolve(Environment* env, double async_id) { Emit(env, async_id, AsyncHooks::kPromiseResolve, env->async_hooks_promise_resolve_function()); } void AsyncWrap::EmitTraceEventBefore() { switch (provider_type()) { #define V(PROVIDER) \ case PROVIDER_ ## PROVIDER: \ TRACE_EVENT_NESTABLE_ASYNC_BEGIN0( \ TRACING_CATEGORY_NODE1(async_hooks), \ #PROVIDER "_CALLBACK", static_cast(get_async_id())); \ break; NODE_ASYNC_PROVIDER_TYPES(V) #undef V default: UNREACHABLE(); } } void AsyncWrap::EmitBefore(Environment* env, double async_id) { Emit(env, async_id, AsyncHooks::kBefore, env->async_hooks_before_function()); } void AsyncWrap::EmitTraceEventAfter(ProviderType type, double async_id) { switch (type) { #define V(PROVIDER) \ case PROVIDER_ ## PROVIDER: \ TRACE_EVENT_NESTABLE_ASYNC_END0( \ TRACING_CATEGORY_NODE1(async_hooks), \ #PROVIDER "_CALLBACK", static_cast(async_id)); \ break; NODE_ASYNC_PROVIDER_TYPES(V) #undef V default: UNREACHABLE(); } } void AsyncWrap::EmitAfter(Environment* env, double async_id) { // If the user's callback failed then the after() hooks will be called at the // end of _fatalException(). Emit(env, async_id, AsyncHooks::kAfter, env->async_hooks_after_function()); } class PromiseWrap : public AsyncWrap { public: PromiseWrap(Environment* env, Local object, bool silent) : AsyncWrap(env, object, PROVIDER_PROMISE, -1, silent) { MakeWeak(); } void MemoryInfo(MemoryTracker* tracker) const override { tracker->TrackThis(this); } static constexpr int kPromiseField = 1; static constexpr int kIsChainedPromiseField = 2; static constexpr int kInternalFieldCount = 3; static PromiseWrap* New(Environment* env, Local promise, PromiseWrap* parent_wrap, bool silent); static void GetPromise(Local property, const PropertyCallbackInfo& info); static void getIsChainedPromise(Local property, const PropertyCallbackInfo& info); }; PromiseWrap* PromiseWrap::New(Environment* env, Local promise, PromiseWrap* parent_wrap, bool silent) { Local object = env->promise_wrap_template() ->NewInstance(env->context()).ToLocalChecked(); object->SetInternalField(PromiseWrap::kPromiseField, promise); object->SetInternalField(PromiseWrap::kIsChainedPromiseField, parent_wrap != nullptr ? v8::True(env->isolate()) : v8::False(env->isolate())); CHECK_EQ(promise->GetAlignedPointerFromInternalField(0), nullptr); promise->SetInternalField(0, object); return new PromiseWrap(env, object, silent); } void PromiseWrap::GetPromise(Local property, const PropertyCallbackInfo& info) { info.GetReturnValue().Set(info.Holder()->GetInternalField(kPromiseField)); } void PromiseWrap::getIsChainedPromise(Local property, const PropertyCallbackInfo& info) { info.GetReturnValue().Set( info.Holder()->GetInternalField(kIsChainedPromiseField)); } static PromiseWrap* extractPromiseWrap(Local promise) { Local resource_object_value = promise->GetInternalField(0); if (resource_object_value->IsObject()) { return Unwrap(resource_object_value.As()); } return nullptr; } static void PromiseHook(PromiseHookType type, Local promise, Local parent, void* arg) { Environment* env = static_cast(arg); PromiseWrap* wrap = extractPromiseWrap(promise); if (type == PromiseHookType::kInit || wrap == nullptr) { bool silent = type != PromiseHookType::kInit; // set parent promise's async Id as this promise's triggerAsyncId if (parent->IsPromise()) { // parent promise exists, current promise // is a chained promise, so we set parent promise's id as // current promise's triggerAsyncId Local parent_promise = parent.As(); PromiseWrap* parent_wrap = extractPromiseWrap(parent_promise); if (parent_wrap == nullptr) { parent_wrap = PromiseWrap::New(env, parent_promise, nullptr, true); } AsyncHooks::DefaultTriggerAsyncIdScope trigger_scope(parent_wrap); wrap = PromiseWrap::New(env, promise, parent_wrap, silent); } else { wrap = PromiseWrap::New(env, promise, nullptr, silent); } } CHECK_NOT_NULL(wrap); if (type == PromiseHookType::kBefore) { env->async_hooks()->push_async_ids( wrap->get_async_id(), wrap->get_trigger_async_id()); wrap->EmitTraceEventBefore(); AsyncWrap::EmitBefore(wrap->env(), wrap->get_async_id()); } else if (type == PromiseHookType::kAfter) { wrap->EmitTraceEventAfter(wrap->provider_type(), wrap->get_async_id()); AsyncWrap::EmitAfter(wrap->env(), wrap->get_async_id()); if (env->execution_async_id() == wrap->get_async_id()) { // This condition might not be true if async_hooks was enabled during // the promise callback execution. // Popping it off the stack can be skipped in that case, because it is // known that it would correspond to exactly one call with // PromiseHookType::kBefore that was not witnessed by the PromiseHook. env->async_hooks()->pop_async_id(wrap->get_async_id()); } } else if (type == PromiseHookType::kResolve) { AsyncWrap::EmitPromiseResolve(wrap->env(), wrap->get_async_id()); } } static void SetupHooks(const FunctionCallbackInfo& args) { Environment* env = Environment::GetCurrent(args); CHECK(args[0]->IsObject()); // All of init, before, after, destroy are supplied by async_hooks // internally, so this should every only be called once. At which time all // the functions should be set. Detect this by checking if init !IsEmpty(). CHECK(env->async_hooks_init_function().IsEmpty()); Local fn_obj = args[0].As(); #define SET_HOOK_FN(name) \ Local name##_v = fn_obj->Get( \ env->context(), \ FIXED_ONE_BYTE_STRING(env->isolate(), #name)).ToLocalChecked(); \ CHECK(name##_v->IsFunction()); \ env->set_async_hooks_##name##_function(name##_v.As()); SET_HOOK_FN(init); SET_HOOK_FN(before); SET_HOOK_FN(after); SET_HOOK_FN(destroy); SET_HOOK_FN(promise_resolve); #undef SET_HOOK_FN { Local ctor = FunctionTemplate::New(env->isolate()); ctor->SetClassName(FIXED_ONE_BYTE_STRING(env->isolate(), "PromiseWrap")); Local promise_wrap_template = ctor->InstanceTemplate(); promise_wrap_template->SetInternalFieldCount( PromiseWrap::kInternalFieldCount); promise_wrap_template->SetAccessor( FIXED_ONE_BYTE_STRING(env->isolate(), "promise"), PromiseWrap::GetPromise); promise_wrap_template->SetAccessor( FIXED_ONE_BYTE_STRING(env->isolate(), "isChainedPromise"), PromiseWrap::getIsChainedPromise); env->set_promise_wrap_template(promise_wrap_template); } } static void EnablePromiseHook(const FunctionCallbackInfo& args) { Environment* env = Environment::GetCurrent(args); env->AddPromiseHook(PromiseHook, static_cast(env)); } static void DisablePromiseHook(const FunctionCallbackInfo& args) { Environment* env = Environment::GetCurrent(args); // Delay the call to `RemovePromiseHook` because we might currently be // between the `before` and `after` calls of a Promise. env->isolate()->EnqueueMicrotask([](void* data) { Environment* env = static_cast(data); env->RemovePromiseHook(PromiseHook, data); }, static_cast(env)); } class DestroyParam { public: double asyncId; Environment* env; Persistent target; Persistent propBag; }; void AsyncWrap::WeakCallback(const v8::WeakCallbackInfo& info) { HandleScope scope(info.GetIsolate()); std::unique_ptr p{info.GetParameter()}; Local prop_bag = PersistentToLocal(info.GetIsolate(), p->propBag); Local val = prop_bag->Get(p->env->destroyed_string()); if (val->IsFalse()) { AsyncWrap::EmitDestroy(p->env, p->asyncId); } // unique_ptr goes out of scope here and pointer is deleted. } static void RegisterDestroyHook(const FunctionCallbackInfo& args) { CHECK(args[0]->IsObject()); CHECK(args[1]->IsNumber()); CHECK(args[2]->IsObject()); Isolate* isolate = args.GetIsolate(); DestroyParam* p = new DestroyParam(); p->asyncId = args[1].As()->Value(); p->env = Environment::GetCurrent(args); p->target.Reset(isolate, args[0].As()); p->propBag.Reset(isolate, args[2].As()); p->target.SetWeak( p, AsyncWrap::WeakCallback, v8::WeakCallbackType::kParameter); } void AsyncWrap::GetAsyncId(const FunctionCallbackInfo& args) { AsyncWrap* wrap; args.GetReturnValue().Set(-1); ASSIGN_OR_RETURN_UNWRAP(&wrap, args.Holder()); args.GetReturnValue().Set(wrap->get_async_id()); } void AsyncWrap::PushAsyncIds(const FunctionCallbackInfo& args) { Environment* env = Environment::GetCurrent(args); // No need for CHECK(IsNumber()) on args because if FromJust() doesn't fail // then the checks in push_async_ids() and pop_async_id() will. double async_id = args[0]->NumberValue(env->context()).FromJust(); double trigger_async_id = args[1]->NumberValue(env->context()).FromJust(); env->async_hooks()->push_async_ids(async_id, trigger_async_id); } void AsyncWrap::PopAsyncIds(const FunctionCallbackInfo& args) { Environment* env = Environment::GetCurrent(args); double async_id = args[0]->NumberValue(env->context()).FromJust(); args.GetReturnValue().Set(env->async_hooks()->pop_async_id(async_id)); } void AsyncWrap::AsyncReset(const FunctionCallbackInfo& args) { AsyncWrap* wrap; ASSIGN_OR_RETURN_UNWRAP(&wrap, args.Holder()); double execution_async_id = args[0]->IsNumber() ? args[0].As()->Value() : -1; wrap->AsyncReset(execution_async_id); } void AsyncWrap::QueueDestroyAsyncId(const FunctionCallbackInfo& args) { CHECK(args[0]->IsNumber()); AsyncWrap::EmitDestroy( Environment::GetCurrent(args), args[0].As()->Value()); } void AsyncWrap::AddWrapMethods(Environment* env, Local constructor, int flag) { env->SetProtoMethod(constructor, "getAsyncId", AsyncWrap::GetAsyncId); if (flag & kFlagHasReset) env->SetProtoMethod(constructor, "asyncReset", AsyncWrap::AsyncReset); } void AsyncWrap::Initialize(Local target, Local unused, Local context) { Environment* env = Environment::GetCurrent(context); Isolate* isolate = env->isolate(); HandleScope scope(isolate); env->BeforeExit(DestroyAsyncIdsCallback, env); env->SetMethod(target, "setupHooks", SetupHooks); env->SetMethod(target, "pushAsyncIds", PushAsyncIds); env->SetMethod(target, "popAsyncIds", PopAsyncIds); env->SetMethod(target, "queueDestroyAsyncId", QueueDestroyAsyncId); env->SetMethod(target, "enablePromiseHook", EnablePromiseHook); env->SetMethod(target, "disablePromiseHook", DisablePromiseHook); env->SetMethod(target, "registerDestroyHook", RegisterDestroyHook); v8::PropertyAttribute ReadOnlyDontDelete = static_cast(v8::ReadOnly | v8::DontDelete); #define FORCE_SET_TARGET_FIELD(obj, str, field) \ (obj)->DefineOwnProperty(context, \ FIXED_ONE_BYTE_STRING(isolate, str), \ field, \ ReadOnlyDontDelete).FromJust() // Attach the uint32_t[] where each slot contains the count of the number of // callbacks waiting to be called on a particular event. It can then be // incremented/decremented from JS quickly to communicate to C++ if there are // any callbacks waiting to be called. FORCE_SET_TARGET_FIELD(target, "async_hook_fields", env->async_hooks()->fields().GetJSArray()); // The following v8::Float64Array has 5 fields. These fields are shared in // this way to allow JS and C++ to read/write each value as quickly as // possible. The fields are represented as follows: // // kAsyncIdCounter: Maintains the state of the next unique id to be assigned. // // kDefaultTriggerAsyncId: Write the id of the resource responsible for a // handle's creation just before calling the new handle's constructor. // After the new handle is constructed kDefaultTriggerAsyncId is set back // to -1. FORCE_SET_TARGET_FIELD(target, "async_id_fields", env->async_hooks()->async_id_fields().GetJSArray()); target->Set(context, env->async_ids_stack_string(), env->async_hooks()->async_ids_stack().GetJSArray()).FromJust(); target->Set(context, FIXED_ONE_BYTE_STRING(env->isolate(), "owner_symbol"), env->owner_symbol()).FromJust(); Local constants = Object::New(isolate); #define SET_HOOKS_CONSTANT(name) \ FORCE_SET_TARGET_FIELD( \ constants, #name, Integer::New(isolate, AsyncHooks::name)); SET_HOOKS_CONSTANT(kInit); SET_HOOKS_CONSTANT(kBefore); SET_HOOKS_CONSTANT(kAfter); SET_HOOKS_CONSTANT(kDestroy); SET_HOOKS_CONSTANT(kPromiseResolve); SET_HOOKS_CONSTANT(kTotals); SET_HOOKS_CONSTANT(kCheck); SET_HOOKS_CONSTANT(kExecutionAsyncId); SET_HOOKS_CONSTANT(kTriggerAsyncId); SET_HOOKS_CONSTANT(kAsyncIdCounter); SET_HOOKS_CONSTANT(kDefaultTriggerAsyncId); SET_HOOKS_CONSTANT(kStackLength); #undef SET_HOOKS_CONSTANT FORCE_SET_TARGET_FIELD(target, "constants", constants); Local async_providers = Object::New(isolate); #define V(p) \ FORCE_SET_TARGET_FIELD( \ async_providers, #p, Integer::New(isolate, AsyncWrap::PROVIDER_ ## p)); NODE_ASYNC_PROVIDER_TYPES(V) #undef V FORCE_SET_TARGET_FIELD(target, "Providers", async_providers); #undef FORCE_SET_TARGET_FIELD env->set_async_hooks_init_function(Local()); env->set_async_hooks_before_function(Local()); env->set_async_hooks_after_function(Local()); env->set_async_hooks_destroy_function(Local()); env->set_async_hooks_promise_resolve_function(Local()); env->set_async_hooks_binding(target); { auto class_name = FIXED_ONE_BYTE_STRING(env->isolate(), "AsyncWrap"); auto function_template = env->NewFunctionTemplate(AsyncWrapObject::New); function_template->SetClassName(class_name); AsyncWrap::AddWrapMethods(env, function_template); auto instance_template = function_template->InstanceTemplate(); instance_template->SetInternalFieldCount(1); auto function = function_template->GetFunction(env->context()).ToLocalChecked(); target->Set(env->context(), class_name, function).FromJust(); env->set_async_wrap_constructor_template(function_template); } } AsyncWrap::AsyncWrap(Environment* env, Local object, ProviderType provider, double execution_async_id) : AsyncWrap(env, object, provider, execution_async_id, false) {} AsyncWrap::AsyncWrap(Environment* env, Local object, ProviderType provider, double execution_async_id, bool silent) : BaseObject(env, object), provider_type_(provider) { CHECK_NE(provider, PROVIDER_NONE); CHECK_GE(object->InternalFieldCount(), 1); // Shift provider value over to prevent id collision. persistent().SetWrapperClassId(NODE_ASYNC_ID_OFFSET + provider_type_); // Use AsyncReset() call to execute the init() callbacks. AsyncReset(execution_async_id, silent); } AsyncWrap::~AsyncWrap() { EmitTraceEventDestroy(); EmitDestroy(env(), get_async_id()); } void AsyncWrap::EmitTraceEventDestroy() { switch (provider_type()) { #define V(PROVIDER) \ case PROVIDER_ ## PROVIDER: \ TRACE_EVENT_NESTABLE_ASYNC_END0( \ TRACING_CATEGORY_NODE1(async_hooks), \ #PROVIDER, static_cast(get_async_id())); \ break; NODE_ASYNC_PROVIDER_TYPES(V) #undef V default: UNREACHABLE(); } } void AsyncWrap::EmitDestroy(Environment* env, double async_id) { if (env->async_hooks()->fields()[AsyncHooks::kDestroy] == 0 || !env->can_call_into_js()) { return; } if (env->destroy_async_id_list()->empty()) { env->SetUnrefImmediate(DestroyAsyncIdsCallback, nullptr); } env->destroy_async_id_list()->push_back(async_id); } // Generalized call for both the constructor and for handles that are pooled // and reused over their lifetime. This way a new uid can be assigned when // the resource is pulled out of the pool and put back into use. void AsyncWrap::AsyncReset(double execution_async_id, bool silent) { async_id_ = execution_async_id == -1 ? env()->new_async_id() : execution_async_id; trigger_async_id_ = env()->get_default_trigger_async_id(); switch (provider_type()) { #define V(PROVIDER) \ case PROVIDER_ ## PROVIDER: \ if (*TRACE_EVENT_API_GET_CATEGORY_GROUP_ENABLED( \ TRACING_CATEGORY_NODE1(async_hooks))) { \ auto data = tracing::TracedValue::Create(); \ data->SetInteger("executionAsyncId", \ static_cast(env()->execution_async_id())); \ data->SetInteger("triggerAsyncId", \ static_cast(get_trigger_async_id())); \ TRACE_EVENT_NESTABLE_ASYNC_BEGIN1( \ TRACING_CATEGORY_NODE1(async_hooks), \ #PROVIDER, static_cast(get_async_id()), \ "data", std::move(data)); \ } \ break; NODE_ASYNC_PROVIDER_TYPES(V) #undef V default: UNREACHABLE(); } if (silent) return; EmitAsyncInit(env(), object(), env()->async_hooks()->provider_string(provider_type()), async_id_, trigger_async_id_); } void AsyncWrap::EmitAsyncInit(Environment* env, Local object, Local type, double async_id, double trigger_async_id) { CHECK(!object.IsEmpty()); CHECK(!type.IsEmpty()); AsyncHooks* async_hooks = env->async_hooks(); // Nothing to execute, so can continue normally. if (async_hooks->fields()[AsyncHooks::kInit] == 0) { return; } HandleScope scope(env->isolate()); Local init_fn = env->async_hooks_init_function(); Local argv[] = { Number::New(env->isolate(), async_id), type, Number::New(env->isolate(), trigger_async_id), object, }; FatalTryCatch try_catch(env); USE(init_fn->Call(env->context(), object, arraysize(argv), argv)); } MaybeLocal AsyncWrap::MakeCallback(const Local cb, int argc, Local* argv) { EmitTraceEventBefore(); ProviderType provider = provider_type(); async_context context { get_async_id(), get_trigger_async_id() }; MaybeLocal ret = InternalMakeCallback( env(), object(), cb, argc, argv, context); // This is a static call with cached values because the `this` object may // no longer be alive at this point. EmitTraceEventAfter(provider, context.async_id); return ret; } /* Public C++ embedder API */ async_id AsyncHooksGetExecutionAsyncId(Isolate* isolate) { return Environment::GetCurrent(isolate)->execution_async_id(); } async_id AsyncHooksGetTriggerAsyncId(Isolate* isolate) { return Environment::GetCurrent(isolate)->trigger_async_id(); } async_context EmitAsyncInit(Isolate* isolate, Local resource, const char* name, async_id trigger_async_id) { Local type = String::NewFromUtf8(isolate, name, v8::NewStringType::kInternalized) .ToLocalChecked(); return EmitAsyncInit(isolate, resource, type, trigger_async_id); } async_context EmitAsyncInit(Isolate* isolate, Local resource, v8::Local name, async_id trigger_async_id) { Environment* env = Environment::GetCurrent(isolate); // Initialize async context struct if (trigger_async_id == -1) trigger_async_id = env->get_default_trigger_async_id(); async_context context = { env->new_async_id(), // async_id_ trigger_async_id // trigger_async_id_ }; // Run init hooks AsyncWrap::EmitAsyncInit(env, resource, name, context.async_id, context.trigger_async_id); return context; } void EmitAsyncDestroy(Isolate* isolate, async_context asyncContext) { AsyncWrap::EmitDestroy( Environment::GetCurrent(isolate), asyncContext.async_id); } std::string AsyncWrap::MemoryInfoName() const { return provider_names[provider_type()]; } std::string AsyncWrap::diagnostic_name() const { return MemoryInfoName() + " (" + std::to_string(env()->thread_id()) + ":" + std::to_string(static_cast(async_id_)) + ")"; } Local AsyncWrap::GetOwner() { return GetOwner(env(), object()); } Local AsyncWrap::GetOwner(Environment* env, Local obj) { v8::EscapableHandleScope handle_scope(env->isolate()); CHECK(!obj.IsEmpty()); v8::TryCatch ignore_exceptions(env->isolate()); while (true) { Local owner; if (!obj->Get(env->context(), env->owner_symbol()).ToLocal(&owner) || !owner->IsObject()) { return handle_scope.Escape(obj); } obj = owner.As(); } } } // namespace node NODE_MODULE_CONTEXT_AWARE_INTERNAL(async_wrap, node::AsyncWrap::Initialize)