DevTools: Fix race condition in TextPrompt completions

third_party/WebKit/Source/devtools/front_end/ui/TextPrompt.js

 /*
  * Copyright (C) 2008 Apple Inc.  All rights reserved.
  * Copyright (C) 2011 Google Inc.  All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
@@ skipping 27 matching lines @@
 {
     /**
      * @type {!Element|undefined}
      */
     this._proxyElement;
     this._proxyElementDisplay = "inline-block";
     this._loadCompletions = completions;
     this._completionStopCharacters = stopCharacters || " =:[({;,!+-*/&|^<>.";
     this._autocompletionTimeout = WebInspector.TextPrompt.DefaultAutocompletionTimeout;
     this._title = "";
+    this._completionsCounter = 0;

[lushnikov, 2016/09/08 14:45:50]

let's name it _completionRequestId 

[einbinder, 2016/09/08 17:49:16]

Done.

 }
 
 WebInspector.TextPrompt.DefaultAutocompletionTimeout = 250;
 
 /** @enum {symbol} */
 WebInspector.TextPrompt.Events = {
     ItemApplied: Symbol("text-prompt-item-applied"),
     ItemAccepted: Symbol("text-prompt-item-accepted")
 };
 
@@ skipping 315 matching lines @@
 
     clearAutoComplete: function()
     {
         if (this.isSuggestBoxVisible())
             this._suggestBox.hide();
 
         if (this._completeTimeout) {
             clearTimeout(this._completeTimeout);
             delete this._completeTimeout;
         }
-        delete this._waitingForCompletions;
 
         if (!this.autoCompleteElement)
             return;
 
         this.autoCompleteElement.remove();
         delete this.autoCompleteElement;
         delete this._userEnteredRange;
         delete this._userEnteredText;
     },
 
@@ skipping 30 matching lines @@
             var wordSuffixRange = selectionRange.startContainer.rangeOfWord(selectionRange.endOffset, this._completionStopCharacters, this._element, "forward");
             if (wordSuffixRange.toString().length)
                 shouldExit = true;
         }
         if (shouldExit) {
             this.clearAutoComplete();
             return;
         }
 
         var wordPrefixRange = selectionRange.startContainer.rangeOfWord(selectionRange.startOffset, this._completionStopCharacters, this._element, "backward");
-        this._waitingForCompletions = true;
-        this._loadCompletions(/** @type {!Element} */ (this._proxyElement), wordPrefixRange, force || false, this._completionsReady.bind(this, selection, wordPrefixRange, !!reverse, !!force));
+        this._loadCompletions(/** @type {!Element} */ (this._proxyElement), wordPrefixRange, force || false, this._completionsReady.bind(this, selection, wordPrefixRange, !!reverse, !!force, ++this._completionsCounter));
     },
 
     disableDefaultSuggestionForEmptyInput: function()
     {
         this._disableDefaultSuggestionForEmptyInput = true;
     },
 
     /**
      * @param {!Selection} selection
      * @param {!Range} textRange
@@ skipping 47 matching lines @@
     additionalCompletions: function(prefix)
     {
         return [];
     },
 
     /**
      * @param {!Selection} selection
      * @param {!Range} originalWordPrefixRange
      * @param {boolean} reverse
      * @param {boolean} force
+     * @param {number} completionsCounter

[lushnikov, 2016/09/08 14:45:50]

let's make it the very first one and name it completionRequestId

[einbinder, 2016/09/08 17:49:16]

Done.

      * @param {!Array.<string>} completions
      * @param {number=} selectedIndex
      */
-    _completionsReady: function(selection, originalWordPrefixRange, reverse, force, completions, selectedIndex)
+    _completionsReady: function(selection, originalWordPrefixRange, reverse, force, completionsCounter, completions, selectedIndex)
     {
         var prefix = originalWordPrefixRange.toString();
 
         // Filter out dupes.
         var store = new Set();
         completions = completions.filter(item => !store.has(item) && !!store.add(item));
         var annotatedCompletions = completions.map(item => ({title: item}));
 
         if (prefix || force) {
             if (prefix)
                 annotatedCompletions = annotatedCompletions.concat(this.additionalCompletions(prefix));
             else
                 annotatedCompletions = this.additionalCompletions(prefix).concat(annotatedCompletions);
         }
 
-        if (!this._waitingForCompletions || !annotatedCompletions.length) {
+        if (this._completionsCounter !== completionsCounter || !annotatedCompletions.length) {

[lushnikov, 2016/09/08 14:45:50]

let's bail out in the very beginning of the callback - we should not do anything
in case requestId has changed.

[einbinder, 2016/09/08 17:49:16]

Done.

             this.clearAutoComplete();
             return;
         }
 
-        delete this._waitingForCompletions;
-
         var selectionRange = selection.getRangeAt(0);
 
         var fullWordRange = this._createRange();
         fullWordRange.setStart(originalWordPrefixRange.startContainer, originalWordPrefixRange.startOffset);
         fullWordRange.setEnd(selectionRange.endContainer, selectionRange.endOffset);
 
         if (prefix + selectionRange.toString() !== fullWordRange.toString())
             return;
 
         selectedIndex = (this._disableDefaultSuggestionForEmptyInput && !this.text()) ? -1 : (selectedIndex || 0);
@@ skipping 479 matching lines @@
     },
 
     /**
      * @return {string|undefined}
      */
     _currentHistoryItem: function()
     {
         return this._data[this._data.length - this._historyOffset];
     }
 };