diff options
author | Anna Henningsen <anna@addaleax.net> | 2020-06-06 17:11:31 +0300 |
---|---|---|
committer | Anna Henningsen <anna@addaleax.net> | 2020-06-14 15:53:39 +0300 |
commit | 9129cf21ab51432675521ea158191ae3f866cafb (patch) | |
tree | a495ade59782e28a4ba94ddee085349e083cdd09 /src/node_messaging.cc | |
parent | 8ead0211d7ee534015a10cc99c01a14cc38cbd3a (diff) |
worker: allow passing JS wrapper objects via postMessage
Enable JS wrapper objects to be used as transferable or cloneable
objects in `postMessage()` calls, by having them extend a C++-backed
class.
This requires a few internal changes:
- This commit adds the possibility for transferred objects to
read/write JS values at the end of the serialization/deserialization
phases.
- This commit adds the possibility for transferred objects to list
sub-transferables, e.g. typically the public JS wrapper class
would list its C++ handle in there.
- This commit adds usage of `BaseObject` in a few more places, because
now during deserialization weakly held objects can also be involved,
in addition to `MessagePort`s.
PR-URL: https://github.com/nodejs/node/pull/33772
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Diffstat (limited to 'src/node_messaging.cc')
-rw-r--r-- | src/node_messaging.cc | 309 |
1 files changed, 278 insertions, 31 deletions
diff --git a/src/node_messaging.cc b/src/node_messaging.cc index ae7a0fc1750..8a7d6bd474c 100644 --- a/src/node_messaging.cc +++ b/src/node_messaging.cc @@ -10,6 +10,7 @@ #include "util-inl.h" using node::contextify::ContextifyContext; +using node::errors::TryCatchScope; using v8::Array; using v8::ArrayBuffer; using v8::BackingStore; @@ -38,6 +39,8 @@ using v8::WasmModuleObject; namespace node { +using BaseObjectList = std::vector<BaseObjectPtr<BaseObject>>; + BaseObject::TransferMode BaseObject::GetTransferMode() const { return BaseObject::TransferMode::kUntransferable; } @@ -50,8 +53,22 @@ std::unique_ptr<worker::TransferData> BaseObject::CloneForMessaging() const { return {}; } +Maybe<BaseObjectList> BaseObject::NestedTransferables() const { + return Just(BaseObjectList {}); +} + +Maybe<bool> BaseObject::FinalizeTransferRead( + Local<Context> context, ValueDeserializer* deserializer) { + return Just(true); +} + namespace worker { +Maybe<bool> TransferData::FinalizeTransferWrite( + Local<Context> context, ValueSerializer* serializer) { + return Just(true); +} + Message::Message(MallocedBuffer<char>&& buffer) : main_message_buf_(std::move(buffer)) {} @@ -116,21 +133,22 @@ MaybeLocal<Value> Message::Deserialize(Environment* env, // Create all necessary objects for transferables, e.g. MessagePort handles. std::vector<BaseObjectPtr<BaseObject>> host_objects(transferables_.size()); + auto cleanup = OnScopeLeave([&]() { + for (BaseObjectPtr<BaseObject> object : host_objects) { + if (!object) continue; + + // If the function did not finish successfully, host_objects will contain + // a list of objects that will never be passed to JS. Therefore, we + // destroy them here. + object->Detach(); + } + }); + for (uint32_t i = 0; i < transferables_.size(); ++i) { TransferData* data = transferables_[i].get(); host_objects[i] = data->Deserialize( env, context, std::move(transferables_[i])); - if (!host_objects[i]) { - for (BaseObjectPtr<BaseObject> object : host_objects) { - if (!object) continue; - - // Since creating one of the objects failed, we don't want to have the - // other objects lying around in memory. We act as if the object has - // been garbage-collected. - object->Detach(); - } - return MaybeLocal<Value>(); - } + if (!host_objects[i]) return {}; } transferables_.clear(); @@ -162,9 +180,18 @@ MaybeLocal<Value> Message::Deserialize(Environment* env, array_buffers_.clear(); if (deserializer.ReadHeader(context).IsNothing()) - return MaybeLocal<Value>(); - return handle_scope.Escape( - deserializer.ReadValue(context).FromMaybe(Local<Value>())); + return {}; + Local<Value> return_value; + if (!deserializer.ReadValue(context).ToLocal(&return_value)) + return {}; + + for (BaseObjectPtr<BaseObject> base_object : host_objects) { + if (base_object->FinalizeTransferRead(context, &deserializer).IsNothing()) + return {}; + } + + host_objects.clear(); + return handle_scope.Escape(return_value); } void Message::AddSharedArrayBuffer( @@ -240,7 +267,8 @@ class SerializerDelegate : public ValueSerializer::Delegate { Maybe<bool> WriteHostObject(Isolate* isolate, Local<Object> object) override { if (env_->base_object_ctor_template()->HasInstance(object)) { - return WriteHostObject(Unwrap<BaseObject>(object)); + return WriteHostObject( + BaseObjectPtr<BaseObject> { Unwrap<BaseObject>(object) }); } ThrowDataCloneError(env_->clone_unsupported_type_str()); @@ -269,31 +297,51 @@ class SerializerDelegate : public ValueSerializer::Delegate { return Just(msg_->AddWASMModule(module->GetCompiledModule())); } - void Finish() { - // Only close the MessagePort handles and actually transfer them - // once we know that serialization succeeded. + Maybe<bool> Finish(Local<Context> context) { for (uint32_t i = 0; i < host_objects_.size(); i++) { - BaseObject* host_object = host_objects_[i]; + BaseObjectPtr<BaseObject> host_object = std::move(host_objects_[i]); std::unique_ptr<TransferData> data; if (i < first_cloned_object_index_) data = host_object->TransferForMessaging(); if (!data) data = host_object->CloneForMessaging(); - CHECK(data); + if (!data) return Nothing<bool>(); + if (data->FinalizeTransferWrite(context, serializer).IsNothing()) + return Nothing<bool>(); msg_->AddTransferable(std::move(data)); } + return Just(true); } - inline void AddHostObject(BaseObject* host_object) { + inline void AddHostObject(BaseObjectPtr<BaseObject> host_object) { // Make sure we have not started serializing the value itself yet. CHECK_EQ(first_cloned_object_index_, SIZE_MAX); - host_objects_.push_back(host_object); + host_objects_.emplace_back(std::move(host_object)); + } + + // Some objects in the transfer list may register sub-objects that can be + // transferred. This could e.g. be a public JS wrapper object, such as a + // FileHandle, that is registering its C++ handle for transfer. + inline Maybe<bool> AddNestedHostObjects() { + for (size_t i = 0; i < host_objects_.size(); i++) { + std::vector<BaseObjectPtr<BaseObject>> nested_transferables; + if (!host_objects_[i]->NestedTransferables().To(&nested_transferables)) + return Nothing<bool>(); + for (auto nested_transferable : nested_transferables) { + if (std::find(host_objects_.begin(), + host_objects_.end(), + nested_transferable) == host_objects_.end()) { + AddHostObject(nested_transferable); + } + } + } + return Just(true); } ValueSerializer* serializer = nullptr; private: - Maybe<bool> WriteHostObject(BaseObject* host_object) { + Maybe<bool> WriteHostObject(BaseObjectPtr<BaseObject> host_object) { for (uint32_t i = 0; i < host_objects_.size(); i++) { if (host_objects_[i] == host_object) { serializer->WriteUint32(i); @@ -325,7 +373,7 @@ class SerializerDelegate : public ValueSerializer::Delegate { Local<Context> context_; Message* msg_; std::vector<Global<SharedArrayBuffer>> seen_shared_array_buffers_; - std::vector<BaseObject*> host_objects_; + std::vector<BaseObjectPtr<BaseObject>> host_objects_; size_t first_cloned_object_index_ = SIZE_MAX; friend class worker::Message; @@ -397,10 +445,11 @@ Maybe<bool> Message::Serialize(Environment* env, "Transfer list contains source port")); return Nothing<bool>(); } - BaseObject* host_object = Unwrap<BaseObject>(entry.As<Object>()); + BaseObjectPtr<BaseObject> host_object { + Unwrap<BaseObject>(entry.As<Object>()) }; if (env->message_port_constructor_template()->HasInstance(entry) && - (host_object == nullptr || - static_cast<MessagePort*>(host_object)->IsDetached())) { + (!host_object || + static_cast<MessagePort*>(host_object.get())->IsDetached())) { ThrowDataCloneException( context, FIXED_ONE_BYTE_STRING( @@ -420,7 +469,7 @@ Maybe<bool> Message::Serialize(Environment* env, entry.As<Object>()->GetConstructorName())); return Nothing<bool>(); } - if (host_object != nullptr && host_object->GetTransferMode() != + if (host_object && host_object->GetTransferMode() != BaseObject::TransferMode::kUntransferable) { delegate.AddHostObject(host_object); continue; @@ -430,6 +479,8 @@ Maybe<bool> Message::Serialize(Environment* env, THROW_ERR_INVALID_TRANSFER_OBJECT(env); return Nothing<bool>(); } + if (delegate.AddNestedHostObjects().IsNothing()) + return Nothing<bool>(); serializer.WriteHeader(); if (serializer.WriteValue(context, input).IsNothing()) { @@ -444,7 +495,8 @@ Maybe<bool> Message::Serialize(Environment* env, array_buffers_.emplace_back(std::move(backing_store)); } - delegate.Finish(); + if (delegate.Finish(context).IsNothing()) + return Nothing<bool>(); // The serializer gave us a buffer allocated using `malloc()`. std::pair<uint8_t*, size_t> data = serializer.Release(); @@ -687,9 +739,10 @@ void MessagePort::OnMessage() { HandleScope handle_scope(env()->isolate()); Context::Scope context_scope(context); + Local<Function> emit_message = PersistentToLocal::Strong(emit_message_fn_); Local<Value> payload; - if (!ReceiveMessage(context, true).ToLocal(&payload)) break; + if (!ReceiveMessage(context, true).ToLocal(&payload)) goto reschedule; if (payload == env()->no_message_symbol()) break; if (!env()->can_call_into_js()) { @@ -698,8 +751,8 @@ void MessagePort::OnMessage() { continue; } - Local<Function> emit_message = PersistentToLocal::Strong(emit_message_fn_); if (MakeCallback(emit_message, 1, &payload).IsEmpty()) { + reschedule: // Re-schedule OnMessage() execution in case of failure. if (data_) TriggerAsync(); @@ -1017,8 +1070,187 @@ Local<FunctionTemplate> GetMessagePortConstructorTemplate(Environment* env) { return GetMessagePortConstructorTemplate(env); } +JSTransferable::JSTransferable(Environment* env, Local<Object> obj) + : BaseObject(env, obj) { + MakeWeak(); +} + +void JSTransferable::New(const FunctionCallbackInfo<Value>& args) { + CHECK(args.IsConstructCall()); + new JSTransferable(Environment::GetCurrent(args), args.This()); +} + +JSTransferable::TransferMode JSTransferable::GetTransferMode() const { + // Implement `kClone in this ? kCloneable : kTransferable`. + HandleScope handle_scope(env()->isolate()); + errors::TryCatchScope ignore_exceptions(env()); + + bool has_clone; + if (!object()->Has(env()->context(), + env()->messaging_clone_symbol()).To(&has_clone)) { + return TransferMode::kUntransferable; + } + + return has_clone ? TransferMode::kCloneable : TransferMode::kTransferable; +} + +std::unique_ptr<TransferData> JSTransferable::TransferForMessaging() { + return TransferOrClone(TransferMode::kTransferable); +} + +std::unique_ptr<TransferData> JSTransferable::CloneForMessaging() const { + return TransferOrClone(TransferMode::kCloneable); +} + +std::unique_ptr<TransferData> JSTransferable::TransferOrClone( + TransferMode mode) const { + // Call `this[symbol]()` where `symbol` is `kClone` or `kTransfer`, + // which should return an object with `data` and `deserializeInfo` properties; + // `data` is written to the serializer later, and `deserializeInfo` is stored + // on the `TransferData` instance as a string. + HandleScope handle_scope(env()->isolate()); + Local<Context> context = env()->isolate()->GetCurrentContext(); + Local<Symbol> method_name = mode == TransferMode::kCloneable ? + env()->messaging_clone_symbol() : env()->messaging_transfer_symbol(); + + Local<Value> method; + if (!object()->Get(context, method_name).ToLocal(&method)) { + return {}; + } + if (method->IsFunction()) { + Local<Value> result_v; + if (!method.As<Function>()->Call( + context, object(), 0, nullptr).ToLocal(&result_v)) { + return {}; + } + + if (result_v->IsObject()) { + Local<Object> result = result_v.As<Object>(); + Local<Value> data; + Local<Value> deserialize_info; + if (!result->Get(context, env()->data_string()).ToLocal(&data) || + !result->Get(context, env()->deserialize_info_string()) + .ToLocal(&deserialize_info)) { + return {}; + } + Utf8Value deserialize_info_str(env()->isolate(), deserialize_info); + if (*deserialize_info_str == nullptr) return {}; + return std::make_unique<Data>( + *deserialize_info_str, Global<Value>(env()->isolate(), data)); + } + } + + if (mode == TransferMode::kTransferable) + return TransferOrClone(TransferMode::kCloneable); + else + return {}; +} + +Maybe<BaseObjectList> +JSTransferable::NestedTransferables() const { + // Call `this[kTransferList]()` and return the resulting list of BaseObjects. + HandleScope handle_scope(env()->isolate()); + Local<Context> context = env()->isolate()->GetCurrentContext(); + Local<Symbol> method_name = env()->messaging_transfer_list_symbol(); + + Local<Value> method; + if (!object()->Get(context, method_name).ToLocal(&method)) { + return Nothing<BaseObjectList>(); + } + if (!method->IsFunction()) return Just(BaseObjectList {}); + + Local<Value> list_v; + if (!method.As<Function>()->Call( + context, object(), 0, nullptr).ToLocal(&list_v)) { + return Nothing<BaseObjectList>(); + } + if (!list_v->IsArray()) return Just(BaseObjectList {}); + Local<Array> list = list_v.As<Array>(); + + BaseObjectList ret; + for (size_t i = 0; i < list->Length(); i++) { + Local<Value> value; + if (!list->Get(context, i).ToLocal(&value)) + return Nothing<BaseObjectList>(); + if (env()->base_object_ctor_template()->HasInstance(value)) + ret.emplace_back(Unwrap<BaseObject>(value)); + } + return Just(ret); +} + +Maybe<bool> JSTransferable::FinalizeTransferRead( + Local<Context> context, ValueDeserializer* deserializer) { + // Call `this[kDeserialize](data)` where `data` comes from the return value + // of `this[kTransfer]()` or `this[kClone]()`. + HandleScope handle_scope(env()->isolate()); + Local<Value> data; + if (!deserializer->ReadValue(context).ToLocal(&data)) return Nothing<bool>(); + + Local<Symbol> method_name = env()->messaging_deserialize_symbol(); + Local<Value> method; + if (!object()->Get(context, method_name).ToLocal(&method)) { + return Nothing<bool>(); + } + if (!method->IsFunction()) return Just(true); + + if (method.As<Function>()->Call(context, object(), 1, &data).IsEmpty()) { + return Nothing<bool>(); + } + return Just(true); +} + +JSTransferable::Data::Data(std::string&& deserialize_info, + v8::Global<v8::Value>&& data) + : deserialize_info_(std::move(deserialize_info)), + data_(std::move(data)) {} + +BaseObjectPtr<BaseObject> JSTransferable::Data::Deserialize( + Environment* env, + Local<Context> context, + std::unique_ptr<TransferData> self) { + // Create the JS wrapper object that will later be filled with data passed to + // the `[kDeserialize]()` method on it. This split is necessary, because here + // we need to create an object with the right prototype and internal fields, + // but the actual JS data stored in the serialized data can only be read at + // the end of the stream, after the main message has been read. + + if (context != env->context()) { + // It would be nice to throw some kind of exception here, but how do we + // pass that to end users? For now, just drop the message silently. + return {}; + } + HandleScope handle_scope(env->isolate()); + Local<Value> info; + if (!ToV8Value(context, deserialize_info_).ToLocal(&info)) return {}; + + Local<Value> ret; + CHECK(!env->messaging_deserialize_create_object().IsEmpty()); + if (!env->messaging_deserialize_create_object()->Call( + context, Null(env->isolate()), 1, &info).ToLocal(&ret) || + !env->base_object_ctor_template()->HasInstance(ret)) { + return {}; + } + + return BaseObjectPtr<BaseObject> { Unwrap<BaseObject>(ret) }; +} + +Maybe<bool> JSTransferable::Data::FinalizeTransferWrite( + Local<Context> context, ValueSerializer* serializer) { + HandleScope handle_scope(context->GetIsolate()); + auto ret = serializer->WriteValue(context, PersistentToLocal::Strong(data_)); + data_.Reset(); + return ret; +} + namespace { +static void SetDeserializerCreateObjectFunction( + const FunctionCallbackInfo<Value>& args) { + Environment* env = Environment::GetCurrent(args); + CHECK(args[0]->IsFunction()); + env->set_messaging_deserialize_create_object(args[0].As<Function>()); +} + static void MessageChannel(const FunctionCallbackInfo<Value>& args) { Environment* env = Environment::GetCurrent(args); if (!args.IsConstructCall()) { @@ -1061,6 +1293,19 @@ static void InitMessaging(Local<Object> target, templ->GetFunction(context).ToLocalChecked()).Check(); } + { + Local<String> js_transferable_string = + FIXED_ONE_BYTE_STRING(env->isolate(), "JSTransferable"); + Local<FunctionTemplate> t = env->NewFunctionTemplate(JSTransferable::New); + t->Inherit(BaseObject::GetConstructorTemplate(env)); + t->SetClassName(js_transferable_string); + t->InstanceTemplate()->SetInternalFieldCount( + JSTransferable::kInternalFieldCount); + target->Set(context, + js_transferable_string, + t->GetFunction(context).ToLocalChecked()).Check(); + } + target->Set(context, env->message_port_constructor_string(), GetMessagePortConstructorTemplate(env) @@ -1073,6 +1318,8 @@ static void InitMessaging(Local<Object> target, env->SetMethod(target, "receiveMessageOnPort", MessagePort::ReceiveMessage); env->SetMethod(target, "moveMessagePortToContext", MessagePort::MoveToContext); + env->SetMethod(target, "setDeserializerCreateObjectFunction", + SetDeserializerCreateObjectFunction); { Local<Function> domexception = GetDOMException(context).ToLocalChecked(); |