From d82ea5b0d01d289a53c73b475930925ee2a2992e Mon Sep 17 00:00:00 2001
From: Mike McNeil <michael.r.mcneil@gmail.com>
Date: Sun, 7 May 2017 17:09:17 -0500
Subject: [PATCH] Implement more implementorland spinlocks and timeouts -- and
 fixed an issue where the timeout wasn't being unbound in the case where the
 custom logic threw an unhandled exception.

---
 lib/private/Deferred.js | 59 ++++++++++++++++++++++++++++++++++-------
 1 file changed, 49 insertions(+), 10 deletions(-)

diff --git a/lib/private/Deferred.js b/lib/private/Deferred.js
index ad099a0..008d98e 100644
--- a/lib/private/Deferred.js
+++ b/lib/private/Deferred.js
@@ -228,16 +228,6 @@ Deferred.prototype.exec = function(_cb, handleUncaughtException){
   try {
     self._handleExec(function (err, result) {
 
-      // If the deferred has already timed out, then there's no need to warn
-      // (This was _bound_ to happen beings as how we timed out.)
-      // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-      // FUTURE: Maybe keep track to make sure this if/then statement doesn't check
-      // doesn't come back as true more than once (because that would definitely still
-      // be unexpected-- and really hard to anticipate / debug if it were to happen to you)
-      // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-      if (self._hasTimedOut) {
-        return;
-      }
 
       // Implementorland spinlock
       if (self._hasFinishedExecuting) {
@@ -252,11 +242,24 @@ Deferred.prototype.exec = function(_cb, handleUncaughtException){
           '```\n'+
           (new Error()).stack+'\n'+
           '```\n'+
+          '\n'+
+          'For more help, visit https://sailsjs.com/support\n'+
           '- - - - - - - - - - - - - - - - - - - - - - - - - - - - - -'
         );
         return;
       }
 
+      // If the deferred has already timed out, then there's no need to warn
+      // (This was _bound_ to happen beings as how we timed out.)
+      //
+      // > Note that we still set a flag to track that this happened.  This is to make sure
+      // > this if/then statement can't possibly be true more than once (because that would
+      // > definitely still be unexpected-- and really hard to anticipate / debug if it were
+      // > to happen to you)
+      if (self._hasTimedOut) {
+        self._hasFinishedExecuting = true;
+        return;
+      }
 
       // Clear timeout, if relevant.
       if (timeoutAlarm) {
@@ -295,8 +298,44 @@ Deferred.prototype.exec = function(_cb, handleUncaughtException){
       }
 
     });//</self._handleExec>
+
+  // Handle errors thrown synchronously by the `_handleExec` implementation:
   } catch (e) {
 
+    // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+    // NOTE: The following code is ALMOST exactly the same as the code above.
+    // It's duplicated in place rather than extrapolating purely for performance,
+    // and since the error messages vary a bit:
+    // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+    if (self._hasFinishedExecuting) {
+      console.warn(
+        '- - - - - - - - - - - - - - - - - - - - - - - - - - - - - -\n'+
+        'WARNING: Something seems to be wrong with this function.\n'+
+        'It threw an unhandled error during the first tick of its\n'+
+        'execution... but before doing so, it somehow managed to\n'+
+        'have already resolved/rejected once.\n'+
+        '(silently ignoring this...)\n'+
+        '\n'+
+        'To assist you in hunting this down, here is a stack trace:\n'+
+        '```\n'+
+        (new Error()).stack+'\n'+
+        '```\n'+
+        '\n'+
+        'For more help, visit https://sailsjs.com/support\n'+
+        '- - - - - - - - - - - - - - - - - - - - - - - - - - - - - -'
+      );
+      return;
+    }//-•
+
+    if (self._hasTimedOut) {
+      self._hasFinishedExecuting = true;
+      return;
+    }//-•
+
+    if (timeoutAlarm) {
+      clearTimeout(timeoutAlarm);
+    }//>-
+
     var err;
     if (_.isError(e)) { err = e; }
     else if (_.isString(e)) { err = new Error(e); }