Fix bug #330 (Calling FileIndexManager.getFileInfoList() fails if another such call in progress)

src/project/FileIndexManager.js

@@ -280,39 +280,36 @@ define(function (require, exports, module) {
      * Used by syncFileIndex function to prevent reentrancy
      * @private
      */
-    var _syncFileIndexReentracyGuard = false;
+    var _ongoingSyncPromise = null;
 
     /**
     * Clears and rebuilds all of the fileIndexes and sets _indexListDirty to false
     * @return {$.Promise} resolved when index has been updated
     */
     function syncFileIndex() {
 
-        // TODO (issue 330) - allow multiple calls to syncFileIndex to be batched up so that this code isn't necessary
-        if (_syncFileIndexReentracyGuard) {
-            console.error("syncFileIndex cannot be called Recursively");
-            return;
+        // If we're already syncing, don't kick off a second one
+        if (_ongoingSyncPromise) {
+            return _ongoingSyncPromise;
         }
 
-        _syncFileIndexReentracyGuard = true;
-
         var rootDir = ProjectManager.getProjectRoot();
         if (_indexListDirty) {
             PerfUtils.markStart(PerfUtils.FILE_INDEX_MANAGER_SYNC);
 
             _clearIndexes();
-
-            return _scanDirectorySubTree(rootDir)
+            
+            _ongoingSyncPromise = _scanDirectorySubTree(rootDir)
                 .done(function () {
                     PerfUtils.addMeasurement(PerfUtils.FILE_INDEX_MANAGER_SYNC);
                     _indexListDirty = false;
-                    _syncFileIndexReentracyGuard = false;
+                    _ongoingSyncPromise = null;
 
                     //_logFileList(_indexList["all"].fileInfos);
                     //_logFileList(_indexList["css"].fileInfos);
                 });
+            return _ongoingSyncPromise;
         } else {
-            _syncFileIndexReentracyGuard = false;
             return $.Deferred().resolve().promise();
         }
     }

test/spec/FileIndexManager-test.js

@@ -23,7 +23,7 @@
 
 
 /*jslint vars: true, plusplus: true, devel: true, browser: true, nomen: true, indent: 4, maxerr: 50 */
-/*global define: false, describe: false, beforeEach: false, afterEach: false, it: false, runs: false, waitsFor: false, expect: false, brackets: false */
+/*global define, describe, beforeEach, afterEach, it, runs, waitsFor, waitsForDone, expect, spyOn */
 
 define(function (require, exports, module) {
     'use strict';
@@ -89,6 +89,41 @@ define(function (require, exports, module) {
 
         });
 
+        it("should handle simultaneous requests without doing extra work", function () {  // #330
+            // Open a directory
+            SpecRunnerUtils.loadProjectInTestWindow(testPath);
+
+            var projectRoot;
+            var promise1, promise2;
+            var allFiles1, allFiles2;
+            runs(function () {
+                projectRoot = ProjectManager.getProjectRoot();
+                spyOn(projectRoot, "createReader").andCallThrough();
+
+                // Kick off two index requests in parallel
+                promise1 = FileIndexManager.getFileInfoList("all")
+                    .done(function (result) {
+                        allFiles1 = result;
+                    });
+                promise2 = FileIndexManager.getFileInfoList("all")
+                    .done(function (result) {
+                        allFiles2 = result;
+                    });
+
+                waitsForDone(promise1, "First FileIndexManager.getFileInfoList()");
+                waitsForDone(promise2, "Second FileIndexManager.getFileInfoList()");
+            });
+
+            runs(function () {
+                // Correct response to both promises
+                expect(allFiles1.length).toEqual(8);
+                expect(allFiles2.length).toEqual(8);
+
+                // Didn't scan project tree twice
+                expect(projectRoot.createReader.callCount).toBe(1);
+            });
+        });
+
         it("should match a specific filename and return the correct FileInfo", function () {
             // Open a directory
             SpecRunnerUtils.loadProjectInTestWindow(testPath);