local_file_sync_status.h revision 2385ea399aae016c0806a4f9ef3c9cfe3d2a39df 
1// Copyright 2013 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_FILE_SYSTEM_LOCAL_LOCAL_FILE_SYNC_STATUS_H_
6#define CHROME_BROWSER_SYNC_FILE_SYSTEM_LOCAL_LOCAL_FILE_SYNC_STATUS_H_
7
8#include <map>
9#include <set>
10
11#include "base/basictypes.h"
12#include "base/compiler_specific.h"
13#include "base/observer_list.h"
14#include "base/threading/non_thread_safe.h"
15#include "webkit/browser/fileapi/file_system_url.h"
16
17namespace fileapi {
18class FileSystemURL;
19}
20
21namespace sync_file_system {
22
23// Represents local file sync status.
24// This class is supposed to run only on IO thread.
25//
26// This class manages two important synchronization flags: writing (counter)
27// and syncing (flag).  Writing counter keeps track of which URL is in
28// writing and syncing flag indicates which URL is in syncing.
29//
30// An entry can have multiple writers but sync is exclusive and cannot overwrap
31// with any writes or syncs.
32class LocalFileSyncStatus
33    : public base::NonThreadSafe {
34 public:
35  class Observer {
36   public:
37    Observer() {}
38    virtual ~Observer() {}
39    virtual void OnSyncEnabled(const fileapi::FileSystemURL& url) = 0;
40    virtual void OnWriteEnabled(const fileapi::FileSystemURL& url) = 0;
41   private:
42    DISALLOW_COPY_AND_ASSIGN(Observer);
43  };
44
45  LocalFileSyncStatus();
46  ~LocalFileSyncStatus();
47
48  // Increment writing counter for |url|.
49  // This should not be called if the |url| is not writable.
50  void StartWriting(const fileapi::FileSystemURL& url);
51
52  // Decrement writing counter for |url|.
53  void EndWriting(const fileapi::FileSystemURL& url);
54
55  // Start syncing for |url| and disable writing.
56  // This should not be called if |url| is in syncing or in writing.
57  void StartSyncing(const fileapi::FileSystemURL& url);
58
59  // Clears the syncing flag for |url| and enable writing.
60  void EndSyncing(const fileapi::FileSystemURL& url);
61
62  // Returns true if the |url| or its parent or child is in writing.
63  bool IsWriting(const fileapi::FileSystemURL& url) const;
64
65  // Returns true if the |url| is enabled for writing (i.e. not in syncing).
66  bool IsWritable(const fileapi::FileSystemURL& url) const;
67
68  // Returns true if the |url| is enabled for syncing (i.e. neither in
69  // syncing nor writing).
70  bool IsSyncable(const fileapi::FileSystemURL& url) const;
71
72  void AddObserver(Observer* observer);
73  void RemoveObserver(Observer* observer);
74
75 private:
76  typedef std::map<fileapi::FileSystemURL,int64,
77                   fileapi::FileSystemURL::Comparator> URLCountMap;
78
79  bool IsChildOrParentWriting(const fileapi::FileSystemURL& url) const;
80  bool IsChildOrParentSyncing(const fileapi::FileSystemURL& url) const;
81
82  // If this count is non-zero positive there're ongoing write operations.
83  URLCountMap writing_;
84
85  // If this flag is set sync process is running on the file.
86  fileapi::FileSystemURLSet syncing_;
87
88  ObserverList<Observer> observer_list_;
89
90  DISALLOW_COPY_AND_ASSIGN(LocalFileSyncStatus);
91};
92
93}  // namespace sync_file_system
94
95#endif  // CHROME_BROWSER_SYNC_FILE_SYSTEM_LOCAL_LOCAL_FILE_SYNC_STATUS_H_
96