base/prefs/persistent_pref_store.h

   1 // Copyright (c) 2012 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 BASE_PREFS_PERSISTENT_PREF_STORE_H_
   6 #define BASE_PREFS_PERSISTENT_PREF_STORE_H_
   7
   8 #include <string>
   9
  10 #include "base/prefs/base_prefs_export.h"
  11 #include "base/prefs/writeable_pref_store.h"
  12
  13 // This interface is complementary to the PrefStore interface, declaring
  14 // additional functionality that adds support for setting values and persisting
  15 // the data to some backing store.
  16 class BASE_PREFS_EXPORT PersistentPrefStore : public WriteablePrefStore {
  17  public:
  18   // Unique integer code for each type of error so we can report them
  19   // distinctly in a histogram.
  20   // NOTE: Don't change the explicit values of the enums as it will change the
  21   // server's meaning of the histogram.
  22   enum PrefReadError {
  23     PREF_READ_ERROR_NONE = 0,
  24     PREF_READ_ERROR_JSON_PARSE = 1,
  25     PREF_READ_ERROR_JSON_TYPE = 2,
  26     PREF_READ_ERROR_ACCESS_DENIED = 3,
  27     PREF_READ_ERROR_FILE_OTHER = 4,
  28     PREF_READ_ERROR_FILE_LOCKED = 5,
  29     PREF_READ_ERROR_NO_FILE = 6,
  30     PREF_READ_ERROR_JSON_REPEAT = 7,
  31     // PREF_READ_ERROR_OTHER = 8,  // Deprecated.
  32     PREF_READ_ERROR_FILE_NOT_SPECIFIED = 9,
  33     // Indicates that ReadPrefs() couldn't complete synchronously and is waiting
  34     // for an asynchronous task to complete first.
  35     PREF_READ_ERROR_ASYNCHRONOUS_TASK_INCOMPLETE = 10,
  36     PREF_READ_ERROR_MAX_ENUM
  37   };
  38
  39   class ReadErrorDelegate {
  40    public:
  41     virtual ~ReadErrorDelegate() {}
  42
  43     virtual void OnError(PrefReadError error) = 0;
  44   };
  45
  46   // Whether the store is in a pseudo-read-only mode where changes are not
  47   // actually persisted to disk.  This happens in some cases when there are
  48   // read errors during startup.
  49   virtual bool ReadOnly() const = 0;
  50
  51   // Gets the read error. Only valid if IsInitializationComplete() returns true.
  52   virtual PrefReadError GetReadError() const = 0;
  53
  54   // Reads the preferences from disk. Notifies observers via
  55   // "PrefStore::OnInitializationCompleted" when done.
  56   virtual PrefReadError ReadPrefs() = 0;
  57
  58   // Reads the preferences from disk asynchronously. Notifies observers via
  59   // "PrefStore::OnInitializationCompleted" when done. Also it fires
  60   // |error_delegate| if it is not NULL and reading error has occurred.
  61   // Owns |error_delegate|.
  62   virtual void ReadPrefsAsync(ReadErrorDelegate* error_delegate) = 0;
  63
  64   // Lands any pending writes to disk.
  65   virtual void CommitPendingWrite() = 0;
  66
  67   // Schedule a write if there is any lossy data pending. Unlike
  68   // CommitPendingWrite() this does not immediately sync to disk, instead it
  69   // triggers an eventual write if there is lossy data pending and if there
  70   // isn't one scheduled already.
  71   virtual void SchedulePendingLossyWrites() = 0;
  72
  73  protected:
  74   ~PersistentPrefStore() override {}
  75 };
  76
  77 #endif  // BASE_PREFS_PERSISTENT_PREF_STORE_H_