chrome/browser/sync_file_system/local/local_file_sync_status.h

   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
  17 namespace fileapi {
  18 class FileSystemURL;
  19 }
  20
  21 namespace 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.
  32 class 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_