1// Copyright (c) 2006-2009 The Chromium Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5#ifndef CHROME_BROWSER_SYNC_GLUE_CHANGE_PROCESSOR_H_
6#define CHROME_BROWSER_SYNC_GLUE_CHANGE_PROCESSOR_H_
7#pragma once
8
9#include "chrome/browser/sync/engine/syncapi.h"
10#include "chrome/browser/sync/glue/sync_backend_host.h"
11
12class Profile;
13
14namespace browser_sync {
15
16class ModelAssociator;
17class UnrecoverableErrorHandler;
18
19// An interface used to apply changes from the sync model to the browser's
20// native model.  This does not currently distinguish between model data types.
21class ChangeProcessor {
22 public:
23  explicit ChangeProcessor(UnrecoverableErrorHandler* error_handler)
24      : running_(false), error_handler_(error_handler), share_handle_(NULL) {}
25  virtual ~ChangeProcessor();
26
27  // Call when the processor should accept changes from either provided model
28  // and apply them to the other.  Both the chrome model and sync_api are
29  // expected to be initialized and loaded.  You must have set a valid
30  // ModelAssociator and UnrecoverableErrorHandler before using this method,
31  // and the two models should be associated w.r.t the ModelAssociator provided.
32  // It is safe to call Start again after previously Stop()ing the processor.
33  // Subclasses can extract their associated chrome model from |profile| in
34  // |StartImpl|.
35  void Start(Profile* profile, sync_api::UserShare* share_handle);
36  void Stop();
37  virtual bool IsRunning() const;
38
39  // Changes have been applied to the backend model and are ready to be
40  // applied to the frontend model. See syncapi.h for detailed instructions on
41  // how to interpret and process |changes|.
42  virtual void ApplyChangesFromSyncModel(
43      const sync_api::BaseTransaction* trans,
44      const sync_api::SyncManager::ChangeRecord* changes,
45      int change_count) = 0;
46
47  // The changes found in ApplyChangesFromSyncModel may be too slow to be
48  // performed while holding a [Read/Write]Transaction lock. This function
49  // is called once the lock is released and performs any slow I/O operations
50  // without unnecessarily slowing the UI. Note that not all datatypes need
51  // this, so we provide an empty default version.
52  virtual void CommitChangesFromSyncModel() { }
53
54 protected:
55  // These methods are invoked by Start() and Stop() to do
56  // implementation-specific work.
57  virtual void StartImpl(Profile* profile) = 0;
58  virtual void StopImpl() = 0;
59
60  bool running() { return running_; }
61  UnrecoverableErrorHandler* error_handler() { return error_handler_; }
62  sync_api::UserShare* share_handle() { return share_handle_; }
63
64 private:
65  bool running_;  // True if we have been told it is safe to process changes.
66  UnrecoverableErrorHandler* error_handler_;  // Guaranteed to outlive us.
67
68  // The sync model we are processing changes from. Non-NULL when |running_| is
69  // true.
70  sync_api::UserShare* share_handle_;
71
72  DISALLOW_COPY_AND_ASSIGN(ChangeProcessor);
73};
74
75}  // namespace browser_sync
76
77#endif  // CHROME_BROWSER_SYNC_GLUE_CHANGE_PROCESSOR_H_
78