binding.cc

#include <cppgc/allocation.h>
#include <cppgc/garbage-collected.h>
#include <cppgc/heap.h>
#include <node.h>
#include <v8-cppgc.h>
#include <v8.h>
#include <algorithm>

class CppGCed : public cppgc::GarbageCollected<CppGCed> {
 public:
  static uint16_t states[2];
  static constexpr int kDestructCount = 0;
  static constexpr int kTraceCount = 1;

  static void New(const v8::FunctionCallbackInfo<v8::Value>& args) {
    v8::Isolate* isolate = args.GetIsolate();
    v8::Local<v8::Object> js_object = args.This();
    CppGCed* gc_object = cppgc::MakeGarbageCollected<CppGCed>(
        isolate->GetCppHeap()->GetAllocationHandle());
    node::SetCppgcReference(isolate, js_object, gc_object);
    args.GetReturnValue().Set(js_object);
  }

  static v8::Local<v8::Function> GetConstructor(
      v8::Local<v8::Context> context) {
    auto ft = v8::FunctionTemplate::New(context->GetIsolate(), New);
    auto ot = ft->InstanceTemplate();
    v8::WrapperDescriptor descriptor =
        context->GetIsolate()->GetCppHeap()->wrapper_descriptor();
    uint16_t required_size = std::max(descriptor.wrappable_instance_index,
                                      descriptor.wrappable_type_index);
    ot->SetInternalFieldCount(required_size + 1);
    return ft->GetFunction(context).ToLocalChecked();
  }

  CppGCed() = default;

  ~CppGCed() { states[kDestructCount]++; }

  void Trace(cppgc::Visitor* visitor) const { states[kTraceCount]++; }
};

uint16_t CppGCed::states[] = {0, 0};

void InitModule(v8::Local<v8::Object> exports) {
  v8::Isolate* isolate = v8::Isolate::GetCurrent();
  auto context = isolate->GetCurrentContext();

  auto store = v8::ArrayBuffer::NewBackingStore(
      CppGCed::states,
      sizeof(uint16_t) * 2,
      [](void*, size_t, void*) {},
      nullptr);
  auto ab = v8::ArrayBuffer::New(isolate, std::move(store));

  exports
      ->Set(context,
            v8::String::NewFromUtf8(isolate, "CppGCed").ToLocalChecked(),
            CppGCed::GetConstructor(context))
      .FromJust();
  exports
      ->Set(context,
            v8::String::NewFromUtf8(isolate, "states").ToLocalChecked(),
            v8::Uint16Array::New(ab, 0, 2))
      .FromJust();
  exports
      ->Set(context,
            v8::String::NewFromUtf8(isolate, "kDestructCount").ToLocalChecked(),
            v8::Integer::New(isolate, CppGCed::kDestructCount))
      .FromJust();
  exports
      ->Set(context,
            v8::String::NewFromUtf8(isolate, "kTraceCount").ToLocalChecked(),
            v8::Integer::New(isolate, CppGCed::kTraceCount))
      .FromJust();
}

NODE_MODULE(NODE_GYP_MODULE_NAME, InitModule)