Closed
Description
I have got several memory leak issues with this addon library.
I thought it was me who wrote the code wrong. But when I am trying
to run this example, it has the same memory leak too:
https://github.com/nodejs/node-addon-api/blob/main/doc/object_wrap.md
Run the JavaScript code in a while (1) loop will reveal the memory
leak issue.
What is going wrong with this?
C++ code
#include <napi.h>
class Example : public Napi::ObjectWrap<Example> {
public:
static Napi::Object Init(Napi::Env env, Napi::Object exports);
Example(const Napi::CallbackInfo& info);
static Napi::Value CreateNewItem(const Napi::CallbackInfo& info);
private:
double _value;
Napi::Value GetValue(const Napi::CallbackInfo& info);
Napi::Value SetValue(const Napi::CallbackInfo& info);
};
Napi::Object Example::Init(Napi::Env env, Napi::Object exports) {
// This method is used to hook the accessor and method callbacks
Napi::Function func = DefineClass(env, "Example", {
InstanceMethod<&Example::GetValue>("GetValue", static_cast<napi_property_attributes>(napi_writable | napi_configurable)),
InstanceMethod<&Example::SetValue>("SetValue", static_cast<napi_property_attributes>(napi_writable | napi_configurable)),
StaticMethod<&Example::CreateNewItem>("CreateNewItem", static_cast<napi_property_attributes>(napi_writable | napi_configurable)),
});
Napi::FunctionReference* constructor = new Napi::FunctionReference();
// Create a persistent reference to the class constructor. This will allow
// a function called on a class prototype and a function
// called on instance of a class to be distinguished from each other.
*constructor = Napi::Persistent(func);
exports.Set("Example", func);
// Store the constructor as the add-on instance data. This will allow this
// add-on to support multiple instances of itself running on multiple worker
// threads, as well as multiple instances of itself running in different
// contexts on the same thread.
//
// By default, the value set on the environment here will be destroyed when
// the add-on is unloaded using the `delete` operator, but it is also
// possible to supply a custom deleter.
env.SetInstanceData<Napi::FunctionReference>(constructor);
return exports;
}
Example::Example(const Napi::CallbackInfo& info) :
Napi::ObjectWrap<Example>(info) {
Napi::Env env = info.Env();
// ...
Napi::Number value = info[0].As<Napi::Number>();
this->_value = value.DoubleValue();
}
Napi::Value Example::GetValue(const Napi::CallbackInfo& info){
Napi::Env env = info.Env();
return Napi::Number::New(env, this->_value);
}
Napi::Value Example::SetValue(const Napi::CallbackInfo& info){
Napi::Env env = info.Env();
// ...
Napi::Number value = info[0].As<Napi::Number>();
this->_value = value.DoubleValue();
return this->GetValue(info);
}
// Initialize native add-on
Napi::Object Init (Napi::Env env, Napi::Object exports) {
Example::Init(env, exports);
return exports;
}
// Create a new item using the constructor stored during Init.
Napi::Value Example::CreateNewItem(const Napi::CallbackInfo& info) {
// Retrieve the instance data we stored during `Init()`. We only stored the
// constructor there, so we retrieve it here to create a new instance of the
// JS class the constructor represents.
Napi::FunctionReference* constructor =
info.Env().GetInstanceData<Napi::FunctionReference>();
return constructor->New({ Napi::Number::New(info.Env(), 42) });
}
// Register and initialize native add-on
NODE_API_MODULE(NODE_GYP_MODULE_NAME, Init)JavaScript code
const chnet = require('bindings')('chnet');
while (1) {
const example = new chnet.Example(11);
example.GetValue();
example.SetValue(19);
example.GetValue();
}