From d945f5f1e4e7af6743e06a54f68568df3d27d460 Mon Sep 17 00:00:00 2001
From: YellowAfterlife <yellowafterlife@hotmail.com>
Date: Thu, 29 Apr 2021 16:38:13 +0300
Subject: [PATCH] Immediate-return optimization for
 Autocomplete.updateCompletions (#4482)

---
 lib/ace/autocomplete.js | 55 +++++++++++++++++++++++++++++------------
 1 file changed, 39 insertions(+), 16 deletions(-)

diff --git a/lib/ace/autocomplete.js b/lib/ace/autocomplete.js
index 07659197954..dde0afd04ab 100644
--- a/lib/ace/autocomplete.js
+++ b/lib/ace/autocomplete.js
@@ -293,22 +293,16 @@ var Autocomplete = function() {
 
         // Save current gatherCompletions session, session is close when a match is insert
         var _id = this.gatherCompletionsId;
-        this.gatherCompletions(this.editor, function(err, results) {
-            // Only detach if result gathering is finished
-            var detachIfFinished = function() {
-                if (!results.finished) return;
-                return this.detach();
-            }.bind(this);
 
-            var prefix = results.prefix;
-            var matches = results && results.matches;
+        // Only detach if result gathering is finished
+        var detachIfFinished = function(results) {
+            if (!results.finished) return;
+            return this.detach();
+        }.bind(this);
 
-            if (!matches || !matches.length)
-                return detachIfFinished();
-
-            // Wrong prefix or wrong session -> ignore
-            if (prefix.indexOf(results.prefix) !== 0 || _id != this.gatherCompletionsId)
-                return;
+        var processResults = function(results) {
+            var prefix = results.prefix;
+            var matches = results.matches;
 
             this.completions = new FilteredList(matches);
 
@@ -320,18 +314,47 @@ var Autocomplete = function() {
 
             // No results
             if (!filtered.length)
-                return detachIfFinished();
+                return detachIfFinished(results);
 
             // One result equals to the prefix
             if (filtered.length == 1 && filtered[0].value == prefix && !filtered[0].snippet)
-                return detachIfFinished();
+                return detachIfFinished(results);
 
             // Autoinsert if one result
             if (this.autoInsert && filtered.length == 1 && results.finished)
                 return this.insertMatch(filtered[0]);
 
             this.openPopup(this.editor, prefix, keepPopupPosition);
+        }.bind(this);
+
+        var isImmediate = true;
+        var immediateResults = null;
+        this.gatherCompletions(this.editor, function(err, results) {
+            var prefix = results.prefix;
+            var matches = results && results.matches;
+
+            if (!matches || !matches.length)
+                return detachIfFinished(results);
+
+            // Wrong prefix or wrong session -> ignore
+            if (prefix.indexOf(results.prefix) !== 0 || _id != this.gatherCompletionsId)
+                return;
+
+            // If multiple completers return their results immediately, we want to process them together
+            if (isImmediate) {
+                immediateResults = results;
+                return;
+            }
+
+            processResults(results);
         }.bind(this));
+        
+        isImmediate = false;
+        if (immediateResults) {
+            var results = immediateResults;
+            immediateResults = null;
+            processResults(results);
+        }
     };
 
     this.cancelContextMenu = function() {