javascript - 节点C ++插件保留JS回调以供以后使用(Node C++ addon persist JS callback for later use)

Question

I'm working on a littler node addon using node 12 and NAN.

(我正在使用节点12和NAN开发一个littler节点插件。)

I've an issue when I try to save a JS callback to execute later.

(我尝试保存JS回调以便稍后执行时遇到问题。)

This is the c++ code (simplified version)

(这是C ++代码（简体版）)

#include <nan.h>

static MyObject *object;
Nan::Persistent<v8::Function> reloadCallback;

class Example : public Nan::ObjectWrap
{
public:
  static NAN_MODULE_INIT(Init)
  {
    v8::Local<v8::FunctionTemplate> tpl = Nan::New<v8::FunctionTemplate>(New);
    tpl->InstanceTemplate()->SetInternalFieldCount(1);

    constructor().Reset(Nan::GetFunction(tpl).ToLocalChecked());
  }

  static NAN_METHOD(NewInstance)
  {
    v8::Local<v8::Function> cons = Nan::New(constructor());

    const int argc = 1;
    v8::Local<v8::Value> argv[1] = {info[0]};
    info.GetReturnValue().Set(Nan::NewInstance(cons, argc, argv).ToLocalChecked());
  }

private:
  static void updateCallback()
  {
       // HERE is the place where I want to call the JS callback
      if (!reloadCallback.IsEmpty())
      {
        printf("Callback set");
      }
  }

  static NAN_METHOD(New)
  {
    if (info.IsConstructCall())
    {

      // This is the JS callback, if I execute if right here (when JS init this module) all works well, with the Nan:: Callback
      v8::Local<v8::Function> cbFunc = v8::Local<v8::Function>::Cast(info[0]);
      // Nan::Callback cb(cbFunc);
      // cb.Call(0, NULL);

      // But, if I persist it here and try to recover later (don't know when this will be called, could be at any time) I have a Segmentation Error
      // reloadCallback.Reset(cbFunc);

      try
      {
        // This object will call this updateCallback function with something happens
        object->setCallbackInfo(updateCallback, NULL);
      }
      catch (Error &e)
      {
        Nan::ThrowError("Error");
      }
    }
    else
    {...}
  }

  static inline Nan::Persistent<v8::Function> &constructor()
  {
    static Nan::Persistent<v8::Function> my_constructor;
    return my_constructor;
  }
};

NAN_MODULE_INIT(Init)
{
  Example::Init(target);
  Nan::Set(target,
           Nan::New<v8::String>("init").ToLocalChecked(),
           Nan::GetFunction(
               Nan::New<v8::FunctionTemplate>(Example::NewInstance))
               .ToLocalChecked());
}

NODE_MODULE(module, Init)

The JS code

(JS代码)

const example = require('bindings')('module');
function log(a) {
    console.log('Hi from JS', a);
}
example.init(example, log);

I don't know why I can't persist a function and call it later without getting a 'Segmentation Fault' error, any clues?

(我不知道为什么我不能持久保存一个函数，以后再调用它而没有收到“ Segmentation Fault”错误，有什么线索吗？)

Thanks!

(谢谢！)

  ask by Sergio translate from so

Answer 1

等待大神答复