Hello everyone,
I have a node js service that calls into a native C library. The native
library, fire events repeatedly and continuously. These events are
delivered to a C callback function. My goal is to call a Javascript
callback from this native C callback.
Based on my reading, I am using uv_async_init and uv_async_send to
accomplish this goal.
The problem I am encountering is that my native C callback function gets
called many times and in there uv_async_send is called many times, but the
function passed to uv_async_init is called only once and only when my
program exits.
Here is my C code:
=====================================================
#include "jsaudio.h"
#include <iostream>
using namespace v8;
static void recordAudioCallback(int index);
void asyncmsg(uv_async_t* handle);
Callback* cbPeriodic;
uv_async_t async;
uv_loop_t* loop;
NAN_METHOD(createEngine) {
std::cout << "==> createEngine\n" ;
}
void createAudioRecorder(const Nan::FunctionCallbackInfo<v8::Value>& info) {
std::cout << "==> createAudioRecorder\n";
}
void startRecording(const Nan::FunctionCallbackInfo<v8::Value>& info) {
std::cout << "==> startRecording\n";
cbPeriodic = new Callback(info[0].As<Function>());
loop = uv_default_loop();
*uv_async_init*(loop, &async, *asyncmsg*);
}
void *asyncmsg*(uv_async_t* handle) {
std::cout << "==> asyncmsg \n";
Nan::HandleScope scope;
v8::Isolate* isolate = v8::Isolate::GetCurrent();
Local<Value> argv[] = { v8::String::NewFromUtf8(isolate, "Hello world") };
cbPeriodic->Call(1, argv);
}
/* This my callback that gets called many times, by a native library(/
static void *recordAudioCallback*(int index) {
std::cout << "==> recordAudioCallback " << index << "\n";
*uv_async_send*(&async);
}
======================================================
Here is my test node.js code that calls the above native code
const jsAudio = new JsAudio({sampleRate: 48000, bufferSize: 8192})
function Test () {
jsAudio.createEngine();
jsAudio.createAudioRecorder();
jsAudio.startRecording(function(error, result) {
if (error) {
console.log('startRecording failed: ' + error);
} else {
console.log('startRecording result: ' + result);
}
});
}
Test();
var waitTill = new Date(new Date().getTime() + 3 * 1000);
while(waitTill > new Date()){}
jsAudio.shutdown();
console.log('program exit...');
==========================================================
Here is the out:
==> createEngine
==> createAudioRecorder
==> startRecording
==> recordAudioCallback 0
==> recordAudioCallback 1
==> recordAudioCallback 0
==> recordAudioCallback 1
==> recordAudioCallback 0
==> shutdown
program exit...
==> asyncmsg
startRecording failed: Hello world
===========================================================
Why *asyncmsg* is called only once! even though *recordAudioCallback* is
called several times! Any why is it called after program exits!
Any help is appreciated.
Regards, Shahriar
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