[SyncFS] Refine RemoteToLocalSyncer resolver

chrome/browser/sync_file_system/drive_backend/remote_to_local_syncer.h

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CHROME_BROWSER_SYNC_FILE_SYSTEM_DRIVE_BACKEND_REMOTE_TO_LOCAL_SYNCER_H_
 #define CHROME_BROWSER_SYNC_FILE_SYSTEM_DRIVE_BACKEND_REMOTE_TO_LOCAL_SYNCER_H_
 
 #include "base/memory/weak_ptr.h"
 #include "chrome/browser/google_apis/gdata_errorcode.h"
 #include "chrome/browser/sync_file_system/drive_backend/metadata_database.pb.h"
@@ skipping 23 matching lines @@
     PRIORITY_NORMAL = 1 << 0,
     PRIORITY_LOW = 1 << 1,
   };
 
   // |priorities| must be a bitwise-or'd value of Priority.
   // Conflicting trackers will have low priority for RemoteToLocalSyncer so that
   // it should be resolved by LocatToRemoteSyncer.
   RemoteToLocalSyncer(SyncEngineContext* sync_context,
                       int priorities);
   virtual ~RemoteToLocalSyncer();
+
   virtual void Run(const SyncStatusCallback& callback) OVERRIDE;
 
  private:
-  void AnalyzeCurrentDirtyTracker();
-
+  // Dispatches remote change to handlers or to SyncCompleted() directly.
+  // This function uses information only in MetadataDatabase.
+  //
+  // If the tracker doesn't have remote metadata:
+  //   # The file is listed in a folder right before this operation.
+  //   - Dispatch to HandleMissingRemoteMetadata to fetch remote metadata.
+  // Else, if the tracker is not active or the dominating app-root is disabled:
+  //   # Assume the file has remote metadata.
+  //   - Dispatch to HandleInactiveTracker() to resolve offline solvable
+  //     dirtiness.
+  // Else, if the tracker doesn't have synced metadata:
+  //   # Assume the tracker has remote metadata and the tracker is active.
+  //   # The tracker is not yet synced ever.
+  //   - If the file is remotely deleted, do nothing to local file and dispatch
+  //     directly to SyncCompleted().
+  //   - Else, if the file is a regular file, dispatch to HandleNewFile().
+  //   - Else, if the file is a folder, dispatch to HandleNewFolder().
+  //   - Else, the file should be an unsupported active file. This should not
+  //     happen.
+  // Else, if the remote metadata is marked as deleted:
+  //   # Most of the remote metadata is missing including title, kind and md5.
+  //   - Dispatch to HandleDeletion().
+  // Else, if the tracker has different titles between its synced metadata and
+  // remote metadata:
+  //   # Assume the tracker is active and has remote metetadata and synced
+  //     metadata.
+  //   # The file is remotely renamed.
+  //   # Maybe, this can be decomposed to delete and update.
+  //   - Dispatch to HandleRemoteRename().
+  // Else, if the tracker's parent is not a parent of the remote metadata:
+  //   # The file has reorganized.
+  //   # Maybe, this can be decomposed to delete and update.
+  //   - Dispatch to HandreReorganize().
+  // Else, if the folder is a regular file and the md5 in remote metadata does
+  // not match the md5 in synced metadata:
+  //   # The file is modified remotely.
+  //   - Dispatch to HandleContentUpdate().
+  // Else, if the tracker is a folder and it has needs_folder_listing flag:
+  //   - Dispatch to HandleFolderContentListing()
+  // Else, there should be no change to sync.
+  //   - Dispatch to HandleOfflineSolvable()
   void ResolveRemoteChange(const SyncStatusCallback& callback);
 
-  void GetRemoteResource(const SyncStatusCallback& callback);
-  void DidGetRemoteResource(const SyncStatusCallback& callback,
+  // Handles missing remote metadata case.
+  // Fetches remote metadata and updates MetadataDatabase by that.  The sync
+  // operation itself will be deferred to the next sync round.
+  // Note: if the file is not found, it should be handled as if deleted.
+  void HandleMissingRemoteMetadata(const SyncStatusCallback& callback);
+  void DidGetRemoteMetadata(const SyncStatusCallback& callback,
                             int64 change_id,
                             google_apis::GDataErrorCode error,
                             scoped_ptr<google_apis::ResourceEntry> entry);
+  void DidUpdateDatabaseForRemoteMetadata(const SyncStatusCallback& callback,
+                                          SyncStatusCode status);
 
+  // Handles modification to inactive or disabled-app tracker.
+  // TODO(tzik): Write details and implement this.
+  void HandleInactiveTracker(const SyncStatusCallback& callback);
+
+  // Handles remotely added file.  Needs Prepare() call.
+  // TODO(tzik): Write details and implement this.
+  void HandleNewFile(const SyncStatusCallback& callback);
+  void DidPrepareForNewFile(const SyncStatusCallback& callback,
+                            SyncStatusCode status);
+
+  // Handles remotely added folder.  Needs Prepare() call.
+  // TODO(tzik): Write details and implement this.
+  void HandleNewFolder(const SyncStatusCallback& callback);
+
+  // Handles deleted remote file.  Needs Prepare() call.
+  // If the deleted tracker is the sync-root:
+  //  - TODO(tzik): Needs special handling.
+  // Else, if the deleted tracker is a app-root:
+  //  - TODO(tzik): Needs special handling.
+  // Else, if the local file is already deleted:
+  //  - Do nothing anymore to the local, call SyncCompleted().
+  // Else, if the local file is modified:
+  //  - Do nothing to the local file, call SyncCompleted().
+  // Else, if the local file is not modified:
+  //  - Delete local file.
+  //  # Note: if the local file is a folder, delete recursively.
   void HandleDeletion(const SyncStatusCallback& callback);
   void DidPrepareForDeletion(const SyncStatusCallback& callback,
                              SyncStatusCode status);
 
-  void HandleNewFile(const SyncStatusCallback& callback);
-  void DidPrepareForNewFile(const SyncStatusCallback& callback,
-                            SyncStatusCode status);
+  // TODO(tzik): Write details and implement this.
+  void HandleRename(const SyncStatusCallback& callback);
 
+  // TODO(tzik): Write details and implement this.
+  void HandleReorganize(const SyncStatusCallback& callback);
+
+  // Handles new file.  Needs Prepare() call.
   void HandleContentUpdate(const SyncStatusCallback& callback);
   void DidPrepareForContentUpdate(const SyncStatusCallback& callback,
                                   SyncStatusCode status);
 
-  void ListFolderContent(const SyncStatusCallback& callback);
+  void HandleFolderContentListing(const SyncStatusCallback& callback);
   void DidPrepareForFolderListing(const SyncStatusCallback& callback,
                                   SyncStatusCode status);
 
-  void HandleRename(const SyncStatusCallback& callback);
-  void HandleReorganize(const SyncStatusCallback& callback);
   void HandleOfflineSolvable(const SyncStatusCallback& callback);
 
   void SyncCompleted(const SyncStatusCallback& callback);
 
   void Prepare(const SyncStatusCallback& callback);
   void DidPrepare(const SyncStatusCallback& callback,
                   SyncStatusCode status,
                   const SyncFileMetadata& metadata,
                   const FileChangeList& changes);
 
   void DeleteLocalFile(const SyncStatusCallback& callback);
   void DidDeleteLocalFile(const SyncStatusCallback& callback,
                           SyncStatusCode status);
 
   drive::DriveServiceInterface* drive_service();
   MetadataDatabase* metadata_database();
   RemoteChangeProcessor* remote_change_processor();
 
   SyncEngineContext* sync_context_;  // Not owned.
 
   int priorities_;
-  FileTracker dirty_tracker_;
-  FileTracker parent_tracker_;
-  FileMetadata remote_metadata_;
-
-  bool missing_remote_details_;
-  bool missing_synced_details_;
-  bool deleted_remote_details_;
-  bool deleted_synced_details_;
-  bool title_changed_;
-  bool content_changed_;
-  bool needs_folder_listing_;
-  bool missing_parent_;
-
-  bool sync_root_modification_;
+  scoped_ptr<FileTracker> dirty_tracker_;
+  scoped_ptr<FileMetadata> remote_metadata_;
 
   fileapi::FileSystemURL url_;
 
   SyncFileMetadata local_metadata_;
   FileChangeList local_changes_;
 
   base::WeakPtrFactory<RemoteToLocalSyncer> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(RemoteToLocalSyncer);
 };
 
 }  // namespace drive_backend
 }  // namespace sync_file_system
 
 #endif  // CHROME_BROWSER_SYNC_FILE_SYSTEM_DRIVE_BACKEND_REMOTE_TO_LOCAL_SYNCER_H_