lib: run microtasks before ticks

This resolve multiple timing issues related to promises
and nextTick. As well as resolving zaldo in promise only
code, i.e. our current best practice of using process.nextTick
will always apply and work.

Refs: nodejs#51156
Refs: nodejs#51156 (comment)
Refs: nodejs#51114
Refs: nodejs#51070
Refs: nodejs#51156

PR-URL: nodejs#51267

doc/api/cli.md

@@ -863,6 +863,20 @@ Use this flag to generate a blob that can be injected into the Node.js
 binary to produce a [single executable application][]. See the documentation
 about [this configuration][`--experimental-sea-config`] for details.
 
+
+### `--experimental-task-ordering`
+
+<!-- YAML
+added: REPLACEME
+-->
+
+> Stability: 1 - Experimental
+
+Enable experimental task ordering. Always drain micro task queue
+before running `process.nextTick` to avoid unintuitive behavior
+and unexpected logical deadlocks when mixing async callback and
+event API's with `Promise`, `async`/`await`` and `queueMicroTask`.
+
 ### `--experimental-shadow-realm`
 
 <!-- YAML

lib/internal/process/task_queues.js

@@ -41,6 +41,7 @@ const {
 
 const { AsyncResource } = require('async_hooks');
 
+let experimentalTaskOrdering;
 // *Must* match Environment::TickInfo::Fields in src/env.h.
 const kHasTickScheduled = 0;
 
@@ -55,16 +56,26 @@ function setHasTickScheduled(value) {
 const queue = new FixedQueue();
 
 // Should be in sync with RunNextTicksNative in node_task_queue.cc
-function runNextTicks() {
+function runNextTicksNew() {
   if (!hasTickScheduled() && !hasRejectionToWarn())
     runMicrotasks();
   if (!hasTickScheduled() && !hasRejectionToWarn())
     return;
 
-  processTicksAndRejections();
+  processTicksAndRejectionsNew();
 }
 
-function processTicksAndRejections() {
+// Should be in sync with RunNextTicksNative in node_task_queue.cc
+function runNextTicksOld() {
+  if (!hasTickScheduled() && !hasRejectionToWarn())
+    runMicrotasks();
+  if (!hasTickScheduled() && !hasRejectionToWarn())
+    return;
+
+  processTicksAndRejectionsOld();
+}
+
+function processTicksAndRejectionsOld() {
   let tock;
   do {
     while ((tock = queue.shift()) !== null) {
@@ -98,6 +109,40 @@ function processTicksAndRejections() {
   setHasRejectionToWarn(false);
 }
 
+function processTicksAndRejectionsNew() {
+  let tock;
+  do {
+    runMicrotasks();
+    while ((tock = queue.shift()) !== null) {
+      const asyncId = tock[async_id_symbol];
+      emitBefore(asyncId, tock[trigger_async_id_symbol], tock);
+
+      try {
+        const callback = tock.callback;
+        if (tock.args === undefined) {
+          callback();
+        } else {
+          const args = tock.args;
+          switch (args.length) {
+            case 1: callback(args[0]); break;
+            case 2: callback(args[0], args[1]); break;
+            case 3: callback(args[0], args[1], args[2]); break;
+            case 4: callback(args[0], args[1], args[2], args[3]); break;
+            default: callback(...args);
+          }
+        }
+      } finally {
+        if (destroyHooksExist())
+          emitDestroy(asyncId);
+      }
+
+      emitAfter(asyncId);
+    }
+  } while (!queue.isEmpty() || processPromiseRejections());
+  setHasTickScheduled(false);
+  setHasRejectionToWarn(false);
+}
+
 // `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) {
@@ -160,13 +205,23 @@ function queueMicrotask(callback) {
 
 module.exports = {
   setupTaskQueue() {
+    if (experimentalTaskOrdering === undefined) {
+      const { getOptionValue } = require('internal/options');
+      experimentalTaskOrdering = getOptionValue('--experimental-task-ordering');
+    }
+
     // Sets the per-isolate promise rejection callback
     listenForRejections();
     // Sets the callback to be run in every tick.
-    setTickCallback(processTicksAndRejections);
+    setTickCallback(experimentalTaskOrdering
+      ? processTicksAndRejectionsNew
+      : processTicksAndRejectionsOld
+    );
     return {
       nextTick,
-      runNextTicks,
+      runNextTicks: experimentalTaskOrdering
+        ? runNextTicksNew
+        : runNextTicksOld,
     };
   },
   queueMicrotask,