node: support v8 microtask queue

When V8 started supporting Promises natively it also introduced a
microtack queue. This feature operates similar to process.nextTick(),
and created an issue where neither knew when the other had run. This
patch has nextTick() call the microtask queue runner at the end of
processing callbacks in the nextTickQueue.

Fixes: #7714
Reviewed-by: Trevor Norris <trev.norris@gmail.com>

src/node.cc

@@ -967,13 +967,18 @@ void SetupDomainUse(const FunctionCallbackInfo<Value>& args) {
       FIXED_ONE_BYTE_STRING(args.GetIsolate(), "_setupDomainUse"));
 }
 
+void RunMicrotasks(const FunctionCallbackInfo<Value>& args) {
+  args.GetIsolate()->RunMicrotasks();
+}
+
 
 void SetupNextTick(const FunctionCallbackInfo<Value>& args) {
   HandleScope handle_scope(args.GetIsolate());
   Environment* env = Environment::GetCurrent(args.GetIsolate());
 
   assert(args[0]->IsObject());
   assert(args[1]->IsFunction());
+  assert(args[2]->IsObject());
 
   // Values use to cross communicate with processNextTick.
   Local<Object> tick_info_obj = args[0].As<Object>();
@@ -984,6 +989,8 @@ void SetupNextTick(const FunctionCallbackInfo<Value>& args) {
 
   env->set_tick_callback_function(args[1].As<Function>());
 
+  NODE_SET_METHOD(args[2].As<Object>(), "runMicrotasks", RunMicrotasks);
+
   // Do a little housekeeping.
   env->process_object()->Delete(
       FIXED_ONE_BYTE_STRING(args.GetIsolate(), "_setupNextTick"));

src/node.js

@@ -294,6 +294,10 @@
     var _runAsyncQueue = tracing._runAsyncQueue;
     var _loadAsyncQueue = tracing._loadAsyncQueue;
     var _unloadAsyncQueue = tracing._unloadAsyncQueue;
+    var microtasksScheduled = false;
+
+    // Used to run V8's micro task queue.
+    var _runMicrotasks = {};
 
     // This tickInfo thing is used so that the C++ code in src/node.cc
     // can have easy accesss to our nextTick state, and avoid unnecessary
@@ -312,7 +316,9 @@
     process._tickCallback = _tickCallback;
     process._tickDomainCallback = _tickDomainCallback;
 
-    process._setupNextTick(tickInfo, _tickCallback);
+    process._setupNextTick(tickInfo, _tickCallback, _runMicrotasks);
+
+    _runMicrotasks = _runMicrotasks.runMicrotasks;
 
     function tickDone() {
       if (tickInfo[kLength] !== 0) {
@@ -327,11 +333,34 @@
       tickInfo[kIndex] = 0;
     }
 
+    function scheduleMicrotasks() {
+      if (microtasksScheduled)
+        return;
+
+      nextTickQueue.push({
+        callback: runMicrotasksCallback,
+        domain: null
+      });
+
+      tickInfo[kLength]++;
+      microtasksScheduled = true;
+    }
+
+    function runMicrotasksCallback() {
+      microtasksScheduled = false;
+      _runMicrotasks();
+
+      if (tickInfo[kIndex] < tickInfo[kLength])
+        scheduleMicrotasks();
+    }
+
     // Run callbacks that have no domain.
     // Using domains will cause this to be overridden.
     function _tickCallback() {
       var callback, hasQueue, threw, tock;
 
+      scheduleMicrotasks();
+
       while (tickInfo[kIndex] < tickInfo[kLength]) {
         tock = nextTickQueue[tickInfo[kIndex]++];
         callback = tock.callback;
@@ -358,6 +387,8 @@
     function _tickDomainCallback() {
       var callback, domain, hasQueue, threw, tock;
 
+      scheduleMicrotasks();
+
       while (tickInfo[kIndex] < tickInfo[kLength]) {
         tock = nextTickQueue[tickInfo[kIndex]++];
         callback = tock.callback;

test/simple/test-microtask-queue-integration-domain.js

@@ -0,0 +1,70 @@
+// Copyright Joyent, Inc. and other Node contributors.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a
+// copy of this software and associated documentation files (the
+// "Software"), to deal in the Software without restriction, including
+// without limitation the rights to use, copy, modify, merge, publish,
+// distribute, sublicense, and/or sell copies of the Software, and to permit
+// persons to whom the Software is furnished to do so, subject to the
+// following conditions:
+//
+// The above copyright notice and this permission notice shall be included
+// in all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN
+// NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
+// DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
+// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
+// USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+var common = require('../common');
+var assert = require('assert');
+var domain = require('domain');
+
+var implementations = [
+  function (fn) {
+    Promise.resolve().then(fn);
+  },
+  function (fn) {
+    var obj = {};
+
+    Object.observe(obj, fn);
+
+    obj.a = 1;
+  }
+];
+
+var expected = 0;
+var done = 0;
+
+process.on('exit', function () {
+  assert.equal(done, expected);
+});
+
+function test (scheduleMicrotask) {
+  var nextTickCalled = false;
+  expected++;
+
+  scheduleMicrotask(function () {
+    process.nextTick(function () {
+      nextTickCalled = true;
+    });
+
+    setTimeout(function () {
+      assert(nextTickCalled);
+      done++;
+    }, 0);
+  });
+}
+
+// first tick case
+implementations.forEach(test);
+
+// tick callback case
+setTimeout(function () {
+  implementations.forEach(function (impl) {
+    process.nextTick(test.bind(null, impl));
+  });
+}, 0);

test/simple/test-microtask-queue-integration.js

@@ -0,0 +1,69 @@
+// Copyright Joyent, Inc. and other Node contributors.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a
+// copy of this software and associated documentation files (the
+// "Software"), to deal in the Software without restriction, including
+// without limitation the rights to use, copy, modify, merge, publish,
+// distribute, sublicense, and/or sell copies of the Software, and to permit
+// persons to whom the Software is furnished to do so, subject to the
+// following conditions:
+//
+// The above copyright notice and this permission notice shall be included
+// in all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN
+// NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
+// DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
+// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
+// USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+var common = require('../common');
+var assert = require('assert');
+
+var implementations = [
+  function (fn) {
+    Promise.resolve().then(fn);
+  },
+  function (fn) {
+    var obj = {};
+
+    Object.observe(obj, fn);
+
+    obj.a = 1;
+  }
+];
+
+var expected = 0;
+var done = 0;
+
+process.on('exit', function () {
+  assert.equal(done, expected);
+});
+
+function test (scheduleMicrotask) {
+  var nextTickCalled = false;
+  expected++;
+
+  scheduleMicrotask(function () {
+    process.nextTick(function () {
+      nextTickCalled = true;
+    });
+
+    setTimeout(function () {
+      assert(nextTickCalled);
+      done++;
+    }, 0);
+  });
+}
+
+// first tick case
+implementations.forEach(test);
+
+// tick callback case
+setTimeout(function () {
+  implementations.forEach(function (impl) {
+    process.nextTick(test.bind(null, impl));
+  });
+}, 0);