node-gypを使ってnative addonを作成する (2) - 非同期関数をとりあえず作ってみる ref: http://qiita.com/taizo/items/44bf02878f5fc0842703

async.cc

#include <node.h>
#include <v8.h>

using namespace v8;

typedef struct asyncData {
  Persistent<Function> callback;
  const char *result;
} AsyncData;

void AsyncWork(uv_work_t *req) {
  AsyncData *asyncData = (AsyncData *)req->data;
  asyncData->result = "Hello World!";
}

void AsyncAfter(uv_work_t *req) {
  HandleScope scope;

  AsyncData *asyncData = (AsyncData *)req->data;

  Handle<Value> argv[] = {
    Null(),
    String::New(asyncData->result)
  };

  // surround in a try/catch for safety
  TryCatch try_catch;
  // execute the callback function
  asyncData->callback->Call(Context::GetCurrent()->Global(), 2, argv);

  if (try_catch.HasCaught()) {
    node::FatalException(try_catch);
  }

  delete asyncData;
  delete req;
}

Handle<Value> Async(const Arguments& args) {
  HandleScope scope;

  if (args.Length() < 1) {
    ThrowException(Exception::TypeError(String::New("1 arguments expected")));
    return scope.Close(Undefined());
  }
  if (!args[0]->IsFunction()) {
    ThrowException(Exception::TypeError(String::New("Wrong arguments")));
    return scope.Close(Undefined());
  }

  Local<Function> callback = Local<Function>::Cast(args[0]);

  uv_loop_t *loop = uv_default_loop();

  uv_work_t *req = new uv_work_t;
  AsyncData *asyncData = new AsyncData;
  asyncData->callback = Persistent<Function>::New(callback);

  req->data = asyncData;

  uv_queue_work(
      loop,
      req,
      AsyncWork,
      (uv_after_work_cb)AsyncAfter
      );

  return scope.Close(Undefined());
}

void init(Handle<Object> exports) {
  exports->Set(String::NewSymbol("async"),
      FunctionTemplate::New(Async)->GetFunction());
}

NODE_MODULE(addon, init)

async.js

var addon = require('./build/Release/addon');

addon.async(function(err, res) {
  console.log('err', err); // null
  console.log('res', res); // Hello World
});

addon.async(3); // TypeError: Wrong arguments

binding.gyp

{
  "targets": [{
    "target_name": "addon",
    "sources": [
      "async.cc"
    ]
  }]
}

file3.cpp

  uv_loop_t *loop = uv_default_loop();

  uv_work_t *req = new uv_work_t;
  AsyncData *asyncData = new AsyncData;
  asyncData->callback = Persistent<Function>::New(callback);

  req->data = asyncData; // 引き回すデータを入れる

  uv_queue_work(
      loop,
      req,
      AsyncWork, // 実際の処理
      (uv_after_work_cb)AsyncAfter // 実行後の処理
      );