Node C++ 插件持久化 JS 回调供以后使用

Question

我正在使用节点 12 和 NAN 开发一个更小的节点插件。当我尝试保存 JS 回调以供稍后执行时遇到问题。

这是c++代码（简化版）

#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)

JS代码

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

我不知道为什么我不能持久化一个函数并在以后调用它而不会收到“分段错误”错误，有什么线索吗？

谢谢！

Answer 1

修复了使用 libuv 及其 uv_async_init 和使用 uv_async_send 方法的问题。