squash! properly enter microtask queue

nodejs · devsnek · Sep 5, 2018 · Sep 7, 2018 · Sep 7, 2018 · Sep 7, 2018
commit 1626f5998c4647e22a72b6807fafa4b537d9d3a3
diff --git a/lib/internal/process/next_tick.js b/lib/internal/process/next_tick.js
@@ -25,7 +25,8 @@ function setupNextTick(_setupNextTick, _setupPromises) {
   // runMicrotasks is used to run V8's micro task queue.
   const [
     tickInfo,
-    runMicrotasks
+    runMicrotasks,
+    enqueueMicrotask,
   ] = _setupNextTick(_tickCallback);
 
   // *Must* match Environment::TickInfo::Fields in src/env.h.
@@ -91,6 +92,23 @@ function setupNextTick(_setupNextTick, _setupPromises) {
     }
   }
 
+  // Internal method to enter the true microtask queue, ensuring that
+  // the callback isn't called out of order with promise jobs.
+  function queueMicrotask(callback) {
+    if (typeof callback !== 'function')
+      throw new ERR_INVALID_CALLBACK();
+
+    enqueueMicrotask(() => {
+      try {
+        callback();
+      } catch (e) {
+        process.emit('error', e);
+      }
+    });
+  }
+
+  exports.queueMicrotask = queueMicrotask;
+
   // `nextTick()` will not enqueue any callback when the process is about to
   // exit since the callback would not have a chance to be executed.
   function nextTick(callback) {

diff --git a/lib/internal/worker.js b/lib/internal/worker.js
@@ -19,6 +19,7 @@ const locks = internalBinding('locks');
 const { clearAsyncIdStack } = require('internal/async_hooks');
 const { serializeError, deserializeError } = require('internal/error-serdes');
 const DOMException = require('internal/domexception');
+const nextTickUtil = require('internal/process/next_tick');
 
 util.inherits(MessagePort, EventEmitter);
 
@@ -588,7 +589,7 @@ class LockManager {
       // promise, the current agent, environment's id, origin, callback, name,
       // options' mode dictionary member, options' ifAvailable dictionary
       // member, and option's steal dictionary member.
-      process.nextTick(() => {
+      nextTickUtil.queueMicrotask(() => {
         locks.request(
           promise,
           (name, mode, waitingPromise, release) => {
@@ -635,7 +636,7 @@ class LockManager {
   // https://wicg.github.io/web-locks/#api-lock-manager-query
   query() {
     return new Promise((resolve) => {
-      process.nextTick(() => {
+      nextTickUtil.queueMicrotask(() => {
         const snapshot = locks.snapshot();
         resolve(snapshot);
       });

diff --git a/src/bootstrapper.cc b/src/bootstrapper.cc
@@ -31,6 +31,11 @@ void RunMicrotasks(const FunctionCallbackInfo<Value>& args) {
   args.GetIsolate()->RunMicrotasks();
 }
 
+void EnqueueMicrotask(const FunctionCallbackInfo<Value>& args) {
+  CHECK(args[0]->IsFunction());
+  args.GetIsolate()->EnqueueMicrotask(args[0].As<Function>());
+}
+
 void SetupTraceCategoryState(const FunctionCallbackInfo<Value>& args) {
   Environment* env = Environment::GetCurrent(args);
   CHECK(args[0]->IsFunction());
@@ -51,9 +56,16 @@ void SetupNextTick(const FunctionCallbackInfo<Value>& args) {
           .ToLocalChecked();
   run_microtasks_fn->SetName(FIXED_ONE_BYTE_STRING(isolate, "runMicrotasks"));
 
+  Local<Function> enqueue_microtasks_fn =
+    env->NewFunctionTemplate(EnqueueMicrotask)->GetFunction(context)
+        .ToLocalChecked();
+  enqueue_microtasks_fn->SetName(
+      FIXED_ONE_BYTE_STRING(isolate, "EnqueueMicrotask"));
+
   Local<Array> ret = Array::New(isolate, 2);
   ret->Set(context, 0, env->tick_info()->fields().GetJSArray()).FromJust();
   ret->Set(context, 1, run_microtasks_fn).FromJust();
+  ret->Set(context, 2, enqueue_microtasks_fn).FromJust();
 
   args.GetReturnValue().Set(ret);
 }