| // Copyright 2012 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 SYNC_ENGINE_MODEL_CHANGING_SYNCER_COMMAND_H_ |
| #define SYNC_ENGINE_MODEL_CHANGING_SYNCER_COMMAND_H_ |
| |
| #include "base/compiler_specific.h" |
| #include "sync/base/sync_export.h" |
| #include "sync/engine/syncer_command.h" |
| #include "sync/internal_api/public/engine/model_safe_worker.h" |
| |
| namespace syncer { |
| namespace sessions { |
| class SyncSession; |
| } |
| |
| // An abstract SyncerCommand which dispatches its Execute step to the |
| // model-safe worker thread. Classes derived from ModelChangingSyncerCommand |
| // instead of SyncerCommand must implement ModelChangingExecuteImpl instead of |
| // ExecuteImpl, but otherwise, the contract is the same. |
| // |
| // A command should derive from ModelChangingSyncerCommand instead of |
| // SyncerCommand whenever the operation might change any client-visible |
| // fields on any syncable::Entry. If the operation involves creating a |
| // WriteTransaction, this is a sign that ModelChangingSyncerCommand is likely |
| // necessary. |
| class SYNC_EXPORT_PRIVATE ModelChangingSyncerCommand : public SyncerCommand { |
| public: |
| ModelChangingSyncerCommand() : work_session_(NULL) { } |
| virtual ~ModelChangingSyncerCommand() { } |
| |
| // SyncerCommand implementation. Sets work_session to session. |
| virtual SyncerError ExecuteImpl(sessions::SyncSession* session) OVERRIDE; |
| |
| // Wrapper so implementations don't worry about storing work_session. |
| SyncerError StartChangingModel() { |
| return ModelChangingExecuteImpl(work_session_); |
| } |
| |
| std::set<ModelSafeGroup> GetGroupsToChangeForTest( |
| const sessions::SyncSession& session) const { |
| return GetGroupsToChange(session); |
| } |
| |
| protected: |
| // This should return the set of groups in |session| that need to be |
| // changed. The returned set should be a subset of |
| // session.GetEnabledGroups(). Subclasses can guarantee this either |
| // by calling one of the session.GetEnabledGroups*() functions and |
| // filtering that, or using GetGroupForModelType() (which handles |
| // top-level/unspecified nodes) to project from model types to |
| // groups. |
| virtual std::set<ModelSafeGroup> GetGroupsToChange( |
| const sessions::SyncSession& session) const = 0; |
| |
| // Abstract method to be implemented by subclasses to handle logic that |
| // operates on the model. This is invoked with a SyncSession ModelSafeGroup |
| // restriction in place so that bits of state belonging to data types |
| // running on an unsafe thread are siloed away. |
| virtual SyncerError ModelChangingExecuteImpl( |
| sessions::SyncSession* session) = 0; |
| |
| private: |
| // ExecuteImpl is expected to be run by SyncerCommand to set work_session. |
| // StartChangingModel is called to start this command running. |
| // Implementations will implement ModelChangingExecuteImpl and not |
| // worry about storing the session or setting it. They are given work_session. |
| sessions::SyncSession* work_session_; |
| |
| DISALLOW_COPY_AND_ASSIGN(ModelChangingSyncerCommand); |
| }; |
| |
| } // namespace syncer |
| |
| #endif // SYNC_ENGINE_MODEL_CHANGING_SYNCER_COMMAND_H_ |