For context, I started with this question. I need to call the callback for the emitter in another thread. I made a minimal example but it segfaults on emit.Call({cb, result});
My first instinct is that I have a problem with the lifetimes of env
or the emit
function.
addon.cpp
#include <napi.h>
#include <iostream>
#include <thread>
#include <memory>
#include <functional>
#include <chrono>
std::shared_ptr<std::thread> thread;
bool running = true;
void generate(Napi::Env& env, Napi::Function& emit)
{
while(running)
{
Napi::Array result = Napi::Array::New(env);
for(int i = 0; i < 3; ++i)
{
result[i] = rand()%100;
}
auto cb = Napi::String::New(env, "onFeedData");
emit.Call({cb, result});
std::this_thread::sleep_for(std::chrono::seconds(1));
}
}
Napi::Value Start(const Napi::CallbackInfo& info)
{
Napi::Env env = info.Env();
Napi::Function emit = info[0].As<Napi::Function>();
auto cb = std::bind(generate, env, emit);
thread = std::make_shared<std::thread>(cb);
return Napi::String::New(env, "OK");
}
Napi::Value Stop(const Napi::CallbackInfo& info)
{
Napi::Env env = info.Env();
Napi::Function emit = info[0].As<Napi::Function>();
running = false;
thread->join();
return Napi::String::New(env, "OK");
}
Napi::Object Init(Napi::Env env, Napi::Object exports)
{
exports.Set(
Napi::String::New(env, "Start"),
Napi::Function::New(env, Start));
exports.Set(Napi::String::New(env, "Stop"),
Napi::Function::New(env, Stop));
return exports;
}
NODE_API_MODULE(addon, Init)
index.js
'use strict'
const EventEmitter = require('events').EventEmitter;
const addon = require('./build/addon.node');
function Main() {
const emitter = new EventEmitter();
emitter.on('onFeedData', (evt) => {
console.log(evt);
})
setTimeout(() => {
addon.Stop( emitter.emit.bind(emitter) );
}, 5000);
addon.Start( emitter.emit.bind(emitter) );
}
Main();
I have not tried this, still I know the The node.js v10.6 has introduce Asynchronous Thread-safe Function Calls, it is still in experimental state with Stability level 1. The usage has certain limitation too, here is the snippet from the node.js documentation.
You can get the full documentation about it from. Asynchronous Thread-safe Function Calls