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NickNasomhdawson
NickNaso
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mhdawson
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Add additional examples
Porting asynchronous example from NAN repo. The original example is hosted here: https://github.com/nodejs/nan/tree/master/examples/async_pi_estimate. Rewrite all the logic using **node-addon-api** See the following issue https://github.com/nodejs/abi-stable-node-addon-examples/issues/10 Added examples for event emitter See: nodejs/node-addon-api#110
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‎async_pi_estimate/nan/README.md

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In this directory run `node-gyp rebuild` and then `node ./addon.js`

‎async_pi_estimate/nan/addon.cc

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#include <nan.h>
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#include "sync.h" // NOLINT(build/include)
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#include "async.h" // NOLINT(build/include)
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using v8::FunctionTemplate;
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using v8::Handle;
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using v8::Object;
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using v8::String;
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using Nan::GetFunction;
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using Nan::New;
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using Nan::Set;
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// Expose synchronous and asynchronous access to our
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// Estimate() function
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NAN_MODULE_INIT(InitAll) {
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Set(target, New<String>("calculateSync").ToLocalChecked(),
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GetFunction(New<FunctionTemplate>(CalculateSync)).ToLocalChecked());
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Set(target, New<String>("calculateAsync").ToLocalChecked(),
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GetFunction(New<FunctionTemplate>(CalculateAsync)).ToLocalChecked());
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}
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NODE_MODULE(addon, InitAll)

‎async_pi_estimate/nan/addon.js

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var addon = require('./build/Release/addon');
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var calculations = process.argv[2] || 100000000;
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function printResult(type, pi, ms) {
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console.log(type, 'method:');
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console.log('\tπ ≈ ' + pi +
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' (' + Math.abs(pi - Math.PI) + ' away from actual)');
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console.log('\tTook ' + ms + 'ms');
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console.log();
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}
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function runSync() {
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var start = Date.now();
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// Estimate() will execute in the current thread,
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// the next line won't return until it is finished
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var result = addon.calculateSync(calculations);
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printResult('Sync', result, Date.now() - start);
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}
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function runAsync() {
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// how many batches should we split the work in to?
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var batches = process.argv[3] || 16;
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var ended = 0;
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var total = 0;
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var start = Date.now();
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function done (err, result) {
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total += result;
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// have all the batches finished executing?
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if (++ended === batches) {
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printResult('Async', total / batches, Date.now() - start);
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}
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}
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// for each batch of work, request an async Estimate() for
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// a portion of the total number of calculations
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for (var i = 0; i < batches; i++) {
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addon.calculateAsync(calculations / batches, done);
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}
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}
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runSync();
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runAsync();

‎async_pi_estimate/nan/async.cc

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#include <nan.h>
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#include "pi_est.h" // NOLINT(build/include)
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#include "async.h" // NOLINT(build/include)
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using v8::Function;
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using v8::Local;
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using v8::Number;
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using v8::Value;
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using Nan::AsyncQueueWorker;
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using Nan::AsyncWorker;
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using Nan::Callback;
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using Nan::HandleScope;
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using Nan::New;
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using Nan::Null;
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using Nan::To;
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class PiWorker : public AsyncWorker {
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public:
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PiWorker(Callback *callback, int points)
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: AsyncWorker(callback), points(points), estimate(0) {}
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~PiWorker() {}
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// Executed inside the worker-thread.
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// It is not safe to access V8, or V8 data structures
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// here, so everything we need for input and output
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// should go on `this`.
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void Execute () {
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estimate = Estimate(points);
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}
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// Executed when the async work is complete
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// this function will be run inside the main event loop
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// so it is safe to use V8 again
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void HandleOKCallback () {
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HandleScope scope;
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Local<Value> argv[] = {
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Null()
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, New<Number>(estimate)
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};
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callback->Call(2, argv, async_resource);
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}
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private:
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int points;
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double estimate;
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};
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// Asynchronous access to the `Estimate()` function
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NAN_METHOD(CalculateAsync) {
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int points = To<int>(info[0]).FromJust();
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Callback *callback = new Callback(To<Function>(info[1]).ToLocalChecked());
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AsyncQueueWorker(new PiWorker(callback, points));
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}

‎async_pi_estimate/nan/async.h

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#ifndef EXAMPLES_ASYNC_PI_ESTIMATE_ASYNC_H_
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#define EXAMPLES_ASYNC_PI_ESTIMATE_ASYNC_H_
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#include <nan.h>
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NAN_METHOD(CalculateAsync);
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#endif // EXAMPLES_ASYNC_PI_ESTIMATE_ASYNC_H_

‎async_pi_estimate/nan/binding.gyp

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{
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"targets": [
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{
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"target_name": "addon",
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"sources": [
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"addon.cc",
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"pi_est.cc",
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"sync.cc",
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"async.cc"
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],
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"include_dirs": ["<!(node -e \"require('nan')\")"]
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}
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]
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}

‎async_pi_estimate/nan/package.json

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{
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"name": "async_work",
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"version": "0.0.0",
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"description": "Node.js Addons Example #9",
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"main": "addon.js",
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"private": true,
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"gypfile": true,
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"dependencies": {
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"nan": "*"
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}
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}

‎async_pi_estimate/nan/pi_est.cc

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#include <cstdlib>
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#include "pi_est.h" // NOLINT(build/include)
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/*
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Estimate the value of π by using a Monte Carlo method.
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Take `points` samples of random x and y values on a
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[0,1][0,1] plane. Calculating the length of the diagonal
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tells us whether the point lies inside, or outside a
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quarter circle running from 0,1 to 1,0. The ratio of the
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number of points inside to outside gives us an
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approximation of π/4.
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See https://en.wikipedia.org/wiki/File:Pi_30K.gif
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for a visualization of how this works.
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*/
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inline int randall(unsigned int *p_seed) {
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// windows has thread safe rand()
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#ifdef _WIN32
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return rand(); // NOLINT(runtime/threadsafe_fn)
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#else
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return rand_r(p_seed);
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#endif
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}
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double Estimate (int points) {
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int i = points;
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int inside = 0;
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unsigned int randseed = 1;
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#ifdef _WIN32
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srand(randseed);
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#endif
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// unique seed for each run, for threaded use
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unsigned int seed = randall(&randseed);
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#ifdef _WIN32
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srand(seed);
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#endif
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while (i-- > 0) {
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double x = randall(&seed) / static_cast<double>(RAND_MAX);
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double y = randall(&seed) / static_cast<double>(RAND_MAX);
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// x & y and now values between 0 and 1
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// now do a pythagorean diagonal calculation
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// `1` represents our 1/4 circle
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if ((x * x) + (y * y) <= 1)
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inside++;
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}
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// calculate ratio and multiply by 4 for π
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return (inside / static_cast<double>(points)) * 4;
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}

‎async_pi_estimate/nan/pi_est.h

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#ifndef EXAMPLES_ASYNC_PI_ESTIMATE_PI_EST_H_
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#define EXAMPLES_ASYNC_PI_ESTIMATE_PI_EST_H_
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double Estimate(int points);
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#endif // EXAMPLES_ASYNC_PI_ESTIMATE_PI_EST_H_

‎async_pi_estimate/nan/sync.cc

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#include <nan.h>
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#include "pi_est.h" // NOLINT(build/include)
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#include "sync.h" // NOLINT(build/include)
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// Simple synchronous access to the `Estimate()` function
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NAN_METHOD(CalculateSync) {
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// expect a number as the first argument
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int points = info[0]->Uint32Value();
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double est = Estimate(points);
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info.GetReturnValue().Set(est);
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}

‎async_pi_estimate/nan/sync.h

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#ifndef EXAMPLES_ASYNC_PI_ESTIMATE_SYNC_H_
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#define EXAMPLES_ASYNC_PI_ESTIMATE_SYNC_H_
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#include <nan.h>
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NAN_METHOD(CalculateSync);
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#endif // EXAMPLES_ASYNC_PI_ESTIMATE_SYNC_H_

‎async_pi_estimate/node-addon-api/README.md

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In this directory run `node-gyp rebuild` and then `node ./addon.js`

‎async_pi_estimate/node-addon-api/addon.cc

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#include <napi.h>
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#include "sync.h" // NOLINT(build/include)
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#include "async.h" // NOLINT(build/include)
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// Expose synchronous and asynchronous access to our
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// Estimate() function
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Napi::Object Init(Napi::Env env, Napi::Object exports) {
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exports.Set(Napi::String::New(env, "calculateSync"), Napi::Function::New(env, CalculateSync));
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exports.Set(Napi::String::New(env, "calculateAsync"), Napi::Function::New(env, CalculateAsync));
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return exports;
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}
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NODE_API_MODULE(NODE_GYP_MODULE_NAME, Init)

‎async_pi_estimate/node-addon-api/addon.js

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var addon = require('bindings')('addon');
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var calculations = process.argv[2] || 100000000;
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function printResult(type, pi, ms) {
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console.log(type, 'method:');
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console.log('\tπ ≈ ' + pi +
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' (' + Math.abs(pi - Math.PI) + ' away from actual)');
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console.log('\tTook ' + ms + 'ms');
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console.log();
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}
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function runSync() {
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var start = Date.now();
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// Estimate() will execute in the current thread,
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// the next line won't return until it is finished
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var result = addon.calculateSync(calculations);
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printResult('Sync', result, Date.now() - start);
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}
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function runAsync() {
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// how many batches should we split the work in to?
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var batches = process.argv[3] || 16;
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var ended = 0;
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var total = 0;
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var start = Date.now();
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function done (err, result) {
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total += result;
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// have all the batches finished executing?
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if (++ended === batches) {
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printResult('Async', total / batches, Date.now() - start);
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}
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}
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// for each batch of work, request an async Estimate() for
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// a portion of the total number of calculations
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for (var i = 0; i < batches; i++) {
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addon.calculateAsync(calculations / batches, done);
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}
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}
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runSync();
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runAsync();

‎async_pi_estimate/node-addon-api/async.cc

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#include <napi.h>
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#include "pi_est.h" // NOLINT(build/include)
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#include "async.h" // NOLINT(build/include)
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class PiWorker : public Napi::AsyncWorker {
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public:
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PiWorker(Napi::Function& callback, int points)
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: Napi::AsyncWorker(callback), points(points), estimate(0) {}
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~PiWorker() {}
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// Executed inside the worker-thread.
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// It is not safe to access JS engine data structure
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// here, so everything we need for input and output
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// should go on `this`.
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void Execute () {
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estimate = Estimate(points);
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}
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// Executed when the async work is complete
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// this function will be run inside the main event loop
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// so it is safe to use JS engine data again
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void OnOK() {
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Napi::HandleScope scope(Env());
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Callback().Call({Env().Undefined(), Napi::Number::New(Env(), estimate)});
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}
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private:
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int points;
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double estimate;
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};
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// Asynchronous access to the `Estimate()` function
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Napi::Value CalculateAsync(const Napi::CallbackInfo& info) {
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int points = info[0].As<Napi::Number>().Uint32Value();
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Napi::Function callback = info[1].As<Napi::Function>();
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PiWorker* piWorker = new PiWorker(callback, points);
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piWorker->Queue();
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return info.Env().Undefined();
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}

‎async_pi_estimate/node-addon-api/async.h

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#ifndef EXAMPLES_ASYNC_PI_ESTIMATE_ASYNC_H_
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#define EXAMPLES_ASYNC_PI_ESTIMATE_ASYNC_H_
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#include <napi.h>
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Napi::Value CalculateAsync(const Napi::CallbackInfo& info);
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#endif // EXAMPLES_ASYNC_PI_ESTIMATE_ASYNC_H_

‎async_pi_estimate/node-addon-api/binding.gyp

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{
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"targets": [
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{
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"target_name": "addon",
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"sources": [
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"addon.cc",
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"pi_est.cc",
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"sync.cc",
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"async.cc"
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],
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'cflags!': [ '-fno-exceptions' ],
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'cflags_cc!': [ '-fno-exceptions' ],
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'include_dirs': ["<!@(node -p \"require('node-addon-api').include\")"],
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'dependencies': ["<!(node -p \"require('node-addon-api').gyp\")"],
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'conditions': [
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['OS=="win"', {
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"msvs_settings": {
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"VCCLCompilerTool": {
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"ExceptionHandling": 1
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}
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}
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}],
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['OS=="mac"', {
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"xcode_settings": {
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"CLANG_CXX_LIBRARY": "libc++",
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'GCC_ENABLE_CPP_EXCEPTIONS': 'YES',
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'MACOSX_DEPLOYMENT_TARGET': '10.7'
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}
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}]
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]
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}
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]
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}

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