node.js-nan

Invoking some callback function twice leads to Segmentation fault: Nan

六眼飞鱼酱① — Tue, 10 Dec 2019 19:35:16 +0000

Invoking some callback function twice leads to Segmentation fault: Nan 六眼飞鱼酱① 2019-12-11 03:35:16

问题

I am writing C++ addon using nbind - GitHub link for most thing and Nan - GitHub link for calling callbacks asynchronous. When I invoke callback only once, it works perfect. But When I invoke callback twice it gives Segmentation fault (core dumped). Couldn't find error using gdb. Here is JS and C++ codes(compiling using node-gyp configure build):

//main.js code
var nbind = require('nbind');
var lib = nbind.init().lib;

lib.HeaderExample.callJS(function(a) {
console.log("result" + a);
});

lib.HeaderExample.startThread();
lib.HeaderExample.startThread();

C++ addon's code

//c++ code
class CallbackRunner : public Nan::AsyncWorker {
public:
    CallbackRunner(Nan::Callback *callback)
            : AsyncWorker(callback) {}
    void Execute () {}
    void HandleOKCallback () {
        std::cout << "running HandleOKCallback in thread " << std::this_thread::get_id() << std::endl;
        Nan::HandleScope scope;
        v8::Local<v8::Value> argv[] = {
                Nan::New<v8::Number>(10)
        };
        callback->Call(1, argv);
    }
};

class HeaderExample {
public:
    static void callJS(nbind::cbFunction &callback) {
        std::cout << "running callJS in thread " << std::this_thread::get_id() << std::endl;
        m_onInitialisationStarted = new nbind::cbFunction(callback);
        Nan::Callback *callbackNan = new Nan::Callback(m_onInitialisationStarted->getJsFunction());
        runner = new CallbackRunner(callbackNan);
    }
    static void startThread() {
        std::cout << "it is here";
        std::thread threadS(some);
        threadS.join();
    }
    static void some() {
        std::cout << "running some in thread: " << std::this_thread::get_id() << std::endl;
        if(runner){
        AsyncQueueWorker(runner);
        }
    }
    inline static nbind::cbFunction *m_onInitialisationStarted = 0;
    inline static CallbackRunner *runner;
};

回答1:

Your class uses AsyncQueueWorker to invoke the CallbackRunner, but AsyncQueueWorker calls AsyncExecuteComplete after the callback is done, which in turn calls worker->Destroy(). See the AsyncQueueWorker code from nan.h:

inline void AsyncExecute (uv_work_t* req) {
  AsyncWorker *worker = static_cast<AsyncWorker*>(req->data);
  worker->Execute();
}

inline void AsyncExecuteComplete (uv_work_t* req) {
  AsyncWorker* worker = static_cast<AsyncWorker*>(req->data);
  worker->WorkComplete();
  worker->Destroy();
}

inline void AsyncQueueWorker (AsyncWorker* worker) {
  uv_queue_work(
      uv_default_loop()
    , &worker->request
    , AsyncExecute
    , reinterpret_cast<uv_after_work_cb>(AsyncExecuteComplete)
  );
}

worker->Destroy() will delete the CallbackRunner class, along with the Nan::Callback that you fed to its constructor. That is the reason why you get a segmentation fault when attempting to call this callback a second time.

You might be better off basing your class on Nan::AsyncProgressQueueWorker instead of Nan::AsyncWorker. AsyncProgressQueueWorker inherits AsyncWorker and it allows you to schedule work from the main thread just as AsyncWorker does, but it provides you with an ExecutionProgress class that allows you to use any thread to call back into the main thread any number of times while the original scheduled job is running.

Nan::AsyncProgressQueueWorker was added to NAN in version 2.8.0

回答2:

You can't have two threads calling into the same V8 instance concurrently. You'll need careful locking to make sure that only one thread interacts with V8 at any point in time.

来源：https://stackoverflow.com/questions/45589254/invoking-some-callback-function-twice-leads-to-segmentation-fault-nan

标签

c++

node.js

libuv

node.js-nan

Return a Nan::ObjectWrap from another Nan::ObjectWrap

六月ゝ毕业季﹏ — Sat, 07 Dec 2019 00:22:07 +0000

Return a Nan::ObjectWrap from another Nan::ObjectWrap 六月ゝ毕业季﹏ 2019-12-07 08:22:07

问题

I have two subclasses of Nan::ObjectWrap

class Zyre: public Nan::ObjectWrap {...}

class ZyreEvent: public Nan::ObjectWrap {...}

How can I return a ZyreEvent javascript object from a method in Zyre?

I have the following method, in which I create a ZyreEvent:

NAN_METHOD (Zyre::_recv) {
  Zyre *node = Nan::ObjectWrap::Unwrap <Zyre> (info.Holder ());
  ZyreEvent *zyre_event = new ZyreEvent (node->self);
  info.GetReturnValue().Set(zyre_event->Wrap(info.This()));
}

But I can't Wrap the zyre_event because Wrap is a protected member.

回答1:

If I understand correctly, you want to return from (subclass of) Nan::ObjectWrap's method instance of another (subclass of) Nan::ObjectWrap.

Note: I'm not experienced so this may have faults or be wrong. I've put my sources in brackets where are examples how it's is done I guess.

Create static NewInstance method in a first class which receives pointer of itself (NewInstance)
Use v8::External to wrap first class' C++ object and pass it as an argument for New with argc and argv to first class' constructor (using v8::External) (v8::External doc)
Edit first class' New method and handle info.Length() == 1 && info[0]->IsExternal() case which is basically copy constructor in this case (copying passed pointer)
Use ...::NewInstance() in second class to set return value

来源：https://stackoverflow.com/questions/38794789/return-a-nanobjectwrap-from-another-nanobjectwrap

标签

Error: Cannot find module 'nan'

荒凉一梦 — Thu, 05 Dec 2019 21:01:31 +0000

Error: Cannot find module 'nan' 荒凉一梦 2019-12-06 05:01:31

问题

I'm working on native Node.js addon and following nan docs

I included nan into binding.gyp like: "include_dirs" : [ "<!(node -e \"require('nan')\")" ]

Also nan is in npm dependencies.

But when I install the package inside the another node module node-gyp is failed with error

> nnb@1.0.2 install /Users/Shopgate/sandbox/stress/node_modules/nnb
> node-gyp rebuild

module.js:338
    throw err;
          ^
Error: Cannot find module 'nan'
    at Function.Module._resolveFilename (module.js:336:15)
    at Function.Module._load (module.js:278:25)
    at Module.require (module.js:365:17)
    at require (module.js:384:17)
    at [eval]:1:1
    at Object.exports.runInThisContext (vm.js:74:17)
    at Object.<anonymous> ([eval]-wrapper:6:22)
    at Module._compile (module.js:460:26)
    at evalScript (node.js:431:25)
    at startup (node.js:90:7)
gyp: Call to 'node -e "require('nan')"' returned exit status 1. while trying to load binding.gyp

回答1:

Not ideal but it works if you install nan first.

$ npm install nan

回答2:

Install nan globally:

npm i -g nan

And then,

export NODE_PATH=$(npm root -g)

回答3:

Unfortunately I had this issue, anything that had 'npm' in it was immediately returned with thrown error.

module.js:471
    throw err;
    ^

Error: Cannot find module 'number-is-nan'
    at Function.Module._resolveFilename (module.js:469:15)
    at Function.Module._load (module.js:417:25)
    at Module.require (module.js:497:17)
    at require (internal/module.js:20:19)
    at Object.<anonymous> (/usr/local/lib/node_modules/npm/node_modules/npmlog/node_modules/gauge/node_modules/string-width/node_modules/code-point-at/index.js:2:19)
    at Module._compile (module.js:570:32)
    at Object.Module._extensions..js (module.js:579:10)
    at Module.load (module.js:487:32)
    at tryModuleLoad (module.js:446:12)
    at Function.Module._load (module.js:438:3)
cd: no such file or directory: /npm

I had to remove my node & npm files

uninstall and reinstall instruction I followed were here (stackoverflow):

How do I completely uninstall Node.js, and reinstall from beginning (Mac OS X)

I then followed the rabbit trail all the way through every issue!

Don't immediately jump to SO (stackoverflow) at the first sign of friction, the command window (cli) will "oddly enough" give you the right answers to everything (I did however hit about 2 hurdles I referred to SO for, mainly to be on the safe side).

When going through the install of node, npm, & grunt via Install Node.js and npm with Homebrew.

-- I ran into some friction with a python framework file being in a place that made homebrew throw a warning resolve with.

-- and a kegs link warning resolved with my own write up here.

Then when I needed to run: brew install node

-- I had another brew link issue, easy enough, as my write-up above for kegs link warning would just need to be walked through again, so I thought. I then was getting an error saying I can not brew link --overwrite node that file (privileges or something if I recall, none-the-less resolved here).

Finally

It was at this point everything was working well. -- Remember! there were simple steps inbetween that I literally just obeyed the command prompts in the cli, such as:
brew wanting me to delete files via a given path:

-- open finder> [at top of MacBook "monitor tool bar"] Go>go to folder...>copy&paste the path supplied by brew in cli window>it will find that director/file then delete appropriate directory/file

-- continue these steps until brew update is completely satisfied.

As I said this final part was just simple following of direction from brew responses directly.
I hope this walkthrough helps someone bypass the issues I had a bit faster, and thank you to the community that spent their time helping me with solutions that I have linked to in this answer.
don't cry over spilt code, keep supporting the community.

回答4:

I am little bit late for a party. But what worked for me was to re-install all node_modules using rm -rf node_modules && npm install

来源：https://stackoverflow.com/questions/34464673/error-cannot-find-module-nan

标签

Return a Nan::ObjectWrap from another Nan::ObjectWrap

帅比萌擦擦* — Thu, 05 Dec 2019 09:10:25 +0000

Return a Nan::ObjectWrap from another Nan::ObjectWrap 帅比萌擦擦* 2019-12-05 17:10:25

I have two subclasses of Nan::ObjectWrap

class Zyre: public Nan::ObjectWrap {...}

class ZyreEvent: public Nan::ObjectWrap {...}

How can I return a ZyreEvent javascript object from a method in Zyre?

I have the following method, in which I create a ZyreEvent:

NAN_METHOD (Zyre::_recv) {
  Zyre *node = Nan::ObjectWrap::Unwrap <Zyre> (info.Holder ());
  ZyreEvent *zyre_event = new ZyreEvent (node->self);
  info.GetReturnValue().Set(zyre_event->Wrap(info.This()));
}

But I can't Wrap the zyre_event because Wrap is a protected member.

If I understand correctly, you want to return from (subclass of) Nan::ObjectWrap's method instance of another (subclass of) Nan::ObjectWrap.

Note: I'm not experienced so this may have faults or be wrong. I've put my sources in brackets where are examples how it's is done I guess.

Create static NewInstance method in a first class which receives pointer of itself (NewInstance)
Use v8::External to wrap first class' C++ object and pass it as an argument for New with argc and argv to first class' constructor (using v8::External) (v8::External doc)
Edit first class' New method and handle info.Length() == 1 && info[0]->IsExternal() case which is basically copy constructor in this case (copying passed pointer)
Use ...::NewInstance() in second class to set return value

来源：https://stackoverflow.com/questions/38794789/return-a-nanobjectwrap-from-another-nanobjectwrap

标签

Error: Cannot find module 'nan'

蓝咒 — Wed, 04 Dec 2019 03:36:09 +0000

Error: Cannot find module 'nan' 蓝咒 2019-12-04 11:36:09

I'm working on native Node.js addon and following nan docs

I included nan into binding.gyp like: "include_dirs" : [ "<!(node -e \"require('nan')\")" ]

Also nan is in npm dependencies.

But when I install the package inside the another node module node-gyp is failed with error

> nnb@1.0.2 install /Users/Shopgate/sandbox/stress/node_modules/nnb
> node-gyp rebuild

module.js:338
    throw err;
          ^
Error: Cannot find module 'nan'
    at Function.Module._resolveFilename (module.js:336:15)
    at Function.Module._load (module.js:278:25)
    at Module.require (module.js:365:17)
    at require (module.js:384:17)
    at [eval]:1:1
    at Object.exports.runInThisContext (vm.js:74:17)
    at Object.<anonymous> ([eval]-wrapper:6:22)
    at Module._compile (module.js:460:26)
    at evalScript (node.js:431:25)
    at startup (node.js:90:7)
gyp: Call to 'node -e "require('nan')"' returned exit status 1. while trying to load binding.gyp

Not ideal but it works if you install nan first.

$ npm install nan

Install nan globally:

npm i -g nan

And then,

export NODE_PATH=$(npm root -g)

Unfortunately I had this issue, anything that had 'npm' in it was immediately returned with thrown error.

module.js:471
    throw err;
    ^

Error: Cannot find module 'number-is-nan'
    at Function.Module._resolveFilename (module.js:469:15)
    at Function.Module._load (module.js:417:25)
    at Module.require (module.js:497:17)
    at require (internal/module.js:20:19)
    at Object.<anonymous> (/usr/local/lib/node_modules/npm/node_modules/npmlog/node_modules/gauge/node_modules/string-width/node_modules/code-point-at/index.js:2:19)
    at Module._compile (module.js:570:32)
    at Object.Module._extensions..js (module.js:579:10)
    at Module.load (module.js:487:32)
    at tryModuleLoad (module.js:446:12)
    at Function.Module._load (module.js:438:3)
cd: no such file or directory: /npm

I had to remove my node & npm files

uninstall and reinstall instruction I followed were here (stackoverflow):

How do I completely uninstall Node.js, and reinstall from beginning (Mac OS X)

I then followed the rabbit trail all the way through every issue!

When going through the install of node, npm, & grunt via Install Node.js and npm with Homebrew.

-- I ran into some friction with a python framework file being in a place that made homebrew throw a warning resolve with.

-- and a kegs link warning resolved with my own write up here.

Then when I needed to run: brew install node

Finally

It was at this point everything was working well. -- Remember! there were simple steps inbetween that I literally just obeyed the command prompts in the cli, such as:
brew wanting me to delete files via a given path:

-- open finder> [at top of MacBook "monitor tool bar"] Go>go to folder...>copy&paste the path supplied by brew in cli window>it will find that director/file then delete appropriate directory/file

-- continue these steps until brew update is completely satisfied.

As I said this final part was just simple following of direction from brew responses directly.
I hope this walkthrough helps someone bypass the issues I had a bit faster, and thank you to the community that spent their time helping me with solutions that I have linked to in this answer.
don't cry over spilt code, keep supporting the community.

I am little bit late for a party. But what worked for me was to re-install all node_modules using rm -rf node_modules && npm install

来源：https://stackoverflow.com/questions/34464673/error-cannot-find-module-nan

标签