Files.app: Fix flakiness in chaining directory

I'm about to commit a patch to improve of filelist draw. But it makes some tests flaky because the currently directory changes faster than before. This patch makes the logic of directory changing more robust.

BUG=367123
TEST=browser_test passes

Review URL: https://codereview.chromium.org/312493002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@275418 0039d316-1c4b-4281-b951-d872f2087c98

ui/file_manager/file_manager/foreground/js/directory_model.js

@@ -32,6 +32,8 @@ function DirectoryModel(singleSelection, fileFilter, fileWatcher,
   this.scanFailures_ = 0;
   this.changeDirectorySequence_ = 0;
 
+  this.directoryChangeQueue_ = new AsyncUtil.Queue();
+
   this.fileFilter_ = fileFilter;
   this.fileFilter_.addEventListener('changed',
                                     this.onFilterChanged_.bind(this));
@@ -278,8 +280,14 @@ DirectoryModel.prototype.scheduleRescan = function(delay) {
     clearTimeout(this.rescanTimeoutId_);
   }
 
+  var sequence = this.changeDirectorySequence_;
+
   this.rescanTime_ = Date.now() + delay;
-  this.rescanTimeoutId_ = setTimeout(this.rescan.bind(this), delay);
+  this.rescanTimeoutId_ = setTimeout(function() {
+    this.rescanTimeoutId_ = null;
+    if (sequence === this.changeDirectorySequence_)
+      this.rescan();
+  }.bind(this), delay);
 };
 
 /**
@@ -312,9 +320,13 @@ DirectoryModel.prototype.rescan = function() {
   var dirContents = this.currentDirContents_.clone();
   dirContents.setFileList([]);
 
+  var sequence = this.changeDirectorySequence_;
+
   var successCallback = (function() {
-    this.replaceDirectoryContents_(dirContents);
-    cr.dispatchSimpleEvent(this, 'rescan-completed');
+    if (sequence === this.changeDirectorySequence_) {
+      this.replaceDirectoryContents_(dirContents);
+      cr.dispatchSimpleEvent(this, 'rescan-completed');
+    }
   }).bind(this);
 
   this.scan_(dirContents,
@@ -329,11 +341,12 @@ DirectoryModel.prototype.rescan = function() {
  *
  * @param {DirectoryContentes} newDirContents New DirectoryContents instance to
  *     replace currentDirContents_.
- * @param {function()=} opt_callback Called on success.
+ * @param {function(boolean)} callback Callback with result. True if the scan
+ *     is completed successfully, false if the scan is failed.
  * @private
  */
 DirectoryModel.prototype.clearAndScan_ = function(newDirContents,
-                                                  opt_callback) {
+                                                  callback) {
   if (this.currentDirContents_.isScanning())
     this.currentDirContents_.cancelScan();
   this.currentDirContents_ = newDirContents;
@@ -348,22 +361,46 @@ DirectoryModel.prototype.clearAndScan_ = function(newDirContents,
     this.runningScan_ = null;
   }
 
+  var sequence = this.changeDirectorySequence_;
+  var cancelled = false;
+
   var onDone = function() {
+    if (cancelled)
+      return;
+
     cr.dispatchSimpleEvent(this, 'scan-completed');
-    if (opt_callback)
-      opt_callback();
+    callback(true);
   }.bind(this);
 
   var onFailed = function() {
+    if (cancelled)
+      return;
+
     cr.dispatchSimpleEvent(this, 'scan-failed');
+    callback(false);
   }.bind(this);
 
   var onUpdated = function() {
+    if (cancelled)
+      return;
+
+    if (this.changeDirectorySequence_ !== sequence) {
+      cancelled = true;
+      cr.dispatchSimpleEvent(this, 'scan-cancelled');
+      callback(false);
+      return;
+    }
+
     cr.dispatchSimpleEvent(this, 'scan-updated');
   }.bind(this);
 
   var onCancelled = function() {
+    if (cancelled)
+      return;
+
+    cancelled = true;
     cr.dispatchSimpleEvent(this, 'scan-cancelled');
+    callback(false);
   }.bind(this);
 
   // Clear the table, and start scanning.
@@ -602,8 +639,7 @@ DirectoryModel.prototype.createDirectory = function(name,
     return;
   }
 
-  var tracker = this.createDirectoryChangeTracker();
-  tracker.start();
+  var sequence = this.changeDirectorySequence_;
 
   new Promise(entry.getDirectory.bind(
       entry, name, {create: true, exclusive: true})).
@@ -621,8 +657,7 @@ DirectoryModel.prototype.createDirectory = function(name,
       then(function(newEntry) {
         // Do not change anything or call the callback if current
         // directory changed.
-        tracker.stop();
-        if (tracker.hasChanged) {
+        if (this.changeDirectorySequence_ !== sequence) {
           abortCallback();
           return;
         }
@@ -641,7 +676,6 @@ DirectoryModel.prototype.createDirectory = function(name,
           successCallback(newEntry);
         }
       }.bind(this), function(reason) {
-        tracker.stop();
         errorCallback(reason);
       });
 };
@@ -668,26 +702,38 @@ DirectoryModel.prototype.changeDirectoryEntry = function(
   this.changeDirectorySequence_++;
   this.clearSearch_();
 
-  var promise = new Promise(
-      function(onFulfilled, onRejected) {
-        this.fileWatcher_.changeWatchedDirectory(dirEntry, onFulfilled);
-      }.bind(this)).
-
-      then(function(sequence) {
-        return new Promise(function(onFulfilled, onRejected) {
-          if (this.changeDirectorySequence_ !== sequence)
+  this.directoryChangeQueue_.run(function(sequence, queueTaskCallback) {
+    this.fileWatcher_.changeWatchedDirectory(
+        dirEntry,
+        function() {
+          if (this.changeDirectorySequence_ !== sequence) {
+            queueTaskCallback();
             return;
+          }
 
           var newDirectoryContents = this.createDirectoryContents_(
               this.currentFileListContext_, dirEntry, '');
-          if (!newDirectoryContents)
+          if (!newDirectoryContents) {
+            queueTaskCallback();
             return;
+          }
 
-          var previousDirEntry = this.currentDirContents_.getDirectoryEntry();
-          this.clearAndScan_(newDirectoryContents, opt_callback);
-
-          // For tests that open the dialog to empty directories, everything is
-          // loaded at this point.
+          var previousDirEntry =
+              this.currentDirContents_.getDirectoryEntry();
+          this.clearAndScan_(
+              newDirectoryContents,
+              function(result) {
+                // Calls the callback of the method when successful.
+                if (result && opt_callback)
+                  opt_callback();
+
+                // Notify that the current task of this.directoryChangeQueue_
+                // is completed.
+                setTimeout(queueTaskCallback);
+              });
+
+          // For tests that open the dialog to empty directories, everything
+          // is loaded at this point.
           util.testSendMessage('directory-change-complete');
 
           var event = new Event('directory-changed');
@@ -695,7 +741,7 @@ DirectoryModel.prototype.changeDirectoryEntry = function(
           event.newDirEntry = dirEntry;
           this.dispatchEvent(event);
         }.bind(this));
-      }.bind(this, this.changeDirectorySequence_));
+  }.bind(this, this.changeDirectorySequence_));
 };
 
 /**
@@ -903,25 +949,41 @@ DirectoryModel.prototype.search = function(query,
     return;
   }
 
-  if (!(query || '').trimLeft()) {
-    if (this.isSearching()) {
-      var newDirContents = this.createDirectoryContents_(
-          this.currentFileListContext_,
-          currentDirEntry);
-      this.clearAndScan_(newDirContents);
+  this.changeDirectorySequence_++;
+  this.directoryChangeQueue_.run(function(sequence, callback) {
+    if (this.changeDirectorySequence_ !== sequence) {
+      callback();
+      return;
+    }
+
+    if (!(query || '').trimLeft()) {
+      if (this.isSearching()) {
+        var newDirContents = this.createDirectoryContents_(
+            this.currentFileListContext_,
+            currentDirEntry);
+        this.clearAndScan_(newDirContents,
+                           sequence,
+                           callback);
+      } else {
+        callback();
+      }
+      return;
     }
-    return;
-  }
 
-  var newDirContents = this.createDirectoryContents_(
-      this.currentFileListContext_, currentDirEntry, query);
-  if (!newDirContents)
-    return;
+    var newDirContents = this.createDirectoryContents_(
+        this.currentFileListContext_, currentDirEntry, query);
+    if (!newDirContents) {
+      callback();
+      return;
+    }
 
-  this.onSearchCompleted_ = onSearchRescan;
-  this.onClearSearch_ = onClearSearch;
-  this.addEventListener('scan-completed', this.onSearchCompleted_);
-  this.clearAndScan_(newDirContents);
+    this.onSearchCompleted_ = onSearchRescan;
+    this.onClearSearch_ = onClearSearch;
+    this.addEventListener('scan-completed', this.onSearchCompleted_);
+    this.clearAndScan_(newDirContents,
+                       sequence,
+                       callback);
+  }.bind(this, this.changeDirectorySequence_));
 };
 
 /**