Added code sample for "Asynchronous C++ addons for Node.js with N-API" blog

Author: tsviatko

asynchronous-c++-addons-for-nodejs-with-napi/Addon.cc

@@ -0,0 +1,21 @@
+#include <napi.h>
+
+#include <DataProcessingAsyncWorker.h>
+
+using namespace Napi;
+
+void ProcessData(const CallbackInfo& info) {
+    Buffer<uint8_t> data = info[0].As<Buffer<uint8_t>>();
+    Function cb = info[1].As<Function>();
+
+    DataProcessingAsyncWorker *worker = new DataProcessingAsyncWorker(data, cb);
+    worker->Queue();
+}
+
+Object Init(Env env, Object exports) {
+    exports.Set(String::New(env, "processData"),
+                Function::New(env, ProcessData));
+    return exports;
+}
+
+NODE_API_MODULE(NODE_GYP_MODULE_NAME, Init)

asynchronous-c++-addons-for-nodejs-with-napi/DataProcessingAsyncWorker.cc

@@ -0,0 +1,25 @@
+#include <DataProcessingAsyncWorker.h>
+
+DataProcessingAsyncWorker::DataProcessingAsyncWorker(Buffer<uint8_t> &data,
+                                                     Function &callback) : AsyncWorker(callback),
+                                                                           dataRef(ObjectReference::New(data, 1)),
+                                                                           dataPtr(data.Data()),
+                                                                           dataLength(data.Length())
+{
+}
+
+void DataProcessingAsyncWorker::Execute()
+{
+    for (size_t i = 0; i < dataLength; i++)
+    {
+        uint8_t value = *(dataPtr + i);
+        *(dataPtr + i) = value * 2;
+    }
+}
+
+void DataProcessingAsyncWorker::OnOK()
+{
+    Callback().Call({});
+
+    dataRef.Unref();
+}

asynchronous-c++-addons-for-nodejs-with-napi/DataProcessingAsyncWorker.h

@@ -0,0 +1,19 @@
+#include <napi.h>
+
+using namespace Napi;
+
+class DataProcessingAsyncWorker : public AsyncWorker
+{
+    public:
+        DataProcessingAsyncWorker(Buffer<uint8_t> &data,
+                                  Function &callback);
+
+        void Execute();
+
+        void OnOK();
+
+    private:
+        ObjectReference dataRef;
+        uint8_t *dataPtr;
+        size_t dataLength;
+};

asynchronous-c++-addons-for-nodejs-with-napi/binding.gyp

@@ -0,0 +1,11 @@
+{
+  'targets': [
+    {
+      'target_name': 'addon',
+      'sources': [ 'Addon.cc', 'DataProcessingAsyncWorker.cc' ],
+      'include_dirs': ["<!@(node -p \"require('node-addon-api').include\")", "./"],
+      'dependencies': ["<!(node -p \"require('node-addon-api').gyp\")"],
+      'defines': [ 'NAPI_DISABLE_CPP_EXCEPTIONS' ]
+    }
+  ]
+}

asynchronous-c++-addons-for-nodejs-with-napi/main.js

@@ -0,0 +1 @@
+module.exports = require('bindings')('addon.node');

asynchronous-c++-addons-for-nodejs-with-napi/native-addon-app.js

@@ -0,0 +1,20 @@
+console.time('Program runtime');
+
+const fs = require('fs');
+
+const addon = require('./main');
+
+const buf = fs.readFileSync('test-data');
+
+console.time('Time spent in addon on main event loop thread');
+console.time('Data manipulation');
+
+addon.processData(buf, () => {
+    console.timeEnd('Data manipulation');
+
+    fs.writeFileSync('test-data-modified', buf);
+
+    console.timeEnd('Program runtime');
+});
+
+console.timeEnd('Time spent in addon on main event loop thread');

asynchronous-c++-addons-for-nodejs-with-napi/package.json

@@ -0,0 +1,15 @@
+{
+  "name": "addon",
+  "version": "1.0.0",
+  "description": "",
+  "main": "main.js",
+  "scripts": {
+  },
+  "author": "Codemerx",
+  "license": "MIT",
+  "gypfile": true,
+  "dependencies": {
+    "bindings": "^1.5.0",
+    "node-addon-api": "^1.6.2"
+  }
+}

asynchronous-c++-addons-for-nodejs-with-napi/plain-javascript-app.js

@@ -0,0 +1,15 @@
+console.time('Program runtime');
+
+const fs = require('fs');
+
+const buf = fs.readFileSync('test-data');
+
+console.time('Data manipulation');
+for (let i = 0; i < buf.length; i++) {
+    buf[i] *= 2;
+}
+console.timeEnd('Data manipulation');
+
+fs.writeFileSync('test-data-modified', buf);
+
+console.timeEnd('Program runtime');