Add N-API thread-safe function round trip example

Closes: gabrielschulhof/abi-stable-node-addon-examples#1
Reviewed-By: Michael Dawson <michael_dawson@ca.ibm.com>
PR-URL: #67

Author: Gabriel Schulhof

thread_safe_function_round_trip/node-api/binding.gyp

@@ -0,0 +1,8 @@
+{
+  'targets': [
+    {
+      'target_name': 'round_trip',
+      'sources': [ 'round_trip.c' ]
+    }
+  ]
+}

thread_safe_function_round_trip/node-api/index.js

@@ -0,0 +1,13 @@
+const bindings = require('bindings')('round_trip');
+
+bindings.startThread((item, thePrime) => {
+  console.log('The prime: ' + thePrime);
+
+  // Answer the call with a 90% probability of returning true somewhere between
+  // 200 and 400 ms from now.
+  setTimeout(() => {
+    const theAnswer = (Math.random() > 0.1);
+    console.log(thePrime + ': answering with ' + theAnswer);
+    bindings.registerReturnValue(item, theAnswer);
+  }, Math.random() * 200 + 200);
+});

thread_safe_function_round_trip/node-api/package.json

@@ -0,0 +1,14 @@
+{
+  "name": "thread_safe_function_round_trip",
+  "version": "0.0.0",
+  "description": "Thread-safe Function Example With JavaScript Round Trip",
+  "main": "index.js",
+  "private": true,
+  "dependencies": {
+    "bindings": "~1.2.1"
+  },
+  "scripts": {
+    "test": "node index.js"
+  },
+  "gypfile": true
+}