I have written my first Node.JS N-Api addon but it crashes with log:
internal/modules/cjs/loader.js:718
return process.dlopen(module, path.toNamespacedPath(filename));
^
Error: /home/d/Projects/engine/build/Release/engine.node: undefined symbol: _ZTV6Config
at Object.Module._extensions..node (internal/modules/cjs/loader.js:718:18)
at Module.load (internal/modules/cjs/loader.js:599:32)
at tryModuleLoad (internal/modules/cjs/loader.js:538:12)
at Function.Module._load (internal/modules/cjs/loader.js:530:3)
at Module.require (internal/modules/cjs/loader.js:637:17)
at require (internal/modules/cjs/helpers.js:22:18)
at Object.<anonymous> (/home/d/Projects/engine/index.js:1:78)
at Module._compile (internal/modules/cjs/loader.js:689:30)
at Object.Module._extensions..js (internal/modules/cjs/loader.js:700:10)
at Module.load (internal/modules/cjs/loader.js:599:32)
Below is my code:
wrapper.h:
#include <napi.h>
#include "types.hpp"
using namespace std;
class Config: public Napi::ObjectWrap<Config> {
config_t _cfg;
public:
explicit Config(const Napi::CallbackInfo &info);
~Config();
static Napi::FunctionReference constructor;
static Napi::Object Init(Napi::Env &env, Napi::Object &exports);
config_t Get();
private:
Napi::Value GetTimeAccuracy(const Napi::CallbackInfo &info);
void SetTimeAccuracy(const Napi::CallbackInfo &info, const Napi::Value &value);
};
wrapper.cc:
Config::Config(const Napi::CallbackInfo &info): Napi::ObjectWrap<Config>(info) {
}
Napi::Object Config::Init(Napi::Env &env, Napi::Object &exports) {
// This method is used to hook the accessor and method callbacks
Napi::Function func = DefineClass(env, "Config", {
InstanceAccessor("timeAccuracy", &Config::GetTimeAccuracy, &Config::SetTimeAccuracy)
});
// Create a peristent 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);
// Call the SuppressDestruct() method on the static data prevent the calling
// to this destructor to reset the reference when the environment is no longer
// available.
constructor.SuppressDestruct();
exports.Set("Config", func);
return exports;
}
Napi::FunctionReference Config::constructor;
config_t Config::Get() {
return _cfg;
}
Napi::Value Config::GetTimeAccuracy(const Napi::CallbackInfo &info) {
Napi::Env env = info.Env();
return Napi::Number::New(env, _cfg.time_accuracy);
}
void Config::SetTimeAccuracy(const Napi::CallbackInfo &info, const Napi::Value &value) {
_cfg.time_accuracy = value.As<Napi::Number>().FloatValue();
}
engine.cc:
#include <napi.h>
#include "wrapper.h"
Napi::Object init(Napi::Env env, Napi::Object exports) {
Config::Init(env, exports);
return exports;
}
NODE_API_MODULE(engine, init);
binding.gyp:
{
"targets": [{
"cflags_cc": ["-std=c++17"],
"include_dirs": [
"<!@(node -p \"require('node-addon-api').include\")"
],
"target_name": "engine",
"sources": [
"wrapper.cc",
"engine.cc",
"types.cpp",
],
"defines": ["NAPI_DISABLE_CPP_EXCEPTIONS"]
}]
}
When I rebuild the project it hasn't any errors. Before I wrote a simple Hello, World! where I've just registered function that prints a text and all worked well. But now I am getting errors (see above) when I try to import my module as const engine = require('./build/Release/engine.node');
.
As I get my module registers but after Node.JS can't find an implementation of Config
.
How can I fix it?
_ZTV6Config
is the mangled name for vtable for Config
.
Confusingly this is actually caused by a missing implementation of the destructor method for Config
.
The compiler defines the vtable in the same translation unit as it finds the destructor definition.