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.
5 #ifndef BASE_PREFS_JSON_PREF_STORE_H_
6 #define BASE_PREFS_JSON_PREF_STORE_H_
11 #include "base/basictypes.h"
12 #include "base/callback_forward.h"
13 #include "base/compiler_specific.h"
14 #include "base/files/file_path.h"
15 #include "base/files/important_file_writer.h"
16 #include "base/memory/scoped_ptr.h"
17 #include "base/memory/weak_ptr.h"
18 #include "base/message_loop/message_loop_proxy.h"
19 #include "base/observer_list.h"
20 #include "base/prefs/base_prefs_export.h"
21 #include "base/prefs/persistent_pref_store.h"
26 class DictionaryValue;
28 class SequencedTaskRunner;
29 class SequencedWorkerPool;
34 // A writable PrefStore implementation that is used for user preferences.
35 class BASE_PREFS_EXPORT JsonPrefStore
36 : public PersistentPrefStore,
37 public base::ImportantFileWriter::DataSerializer,
38 public base::SupportsWeakPtr<JsonPrefStore> {
40 // Returns instance of SequencedTaskRunner which guarantees that file
41 // operations on the same file will be executed in sequenced order.
42 static scoped_refptr<base::SequencedTaskRunner> GetTaskRunnerForFile(
43 const base::FilePath& pref_filename,
44 base::SequencedWorkerPool* worker_pool);
46 // |sequenced_task_runner| is must be a shutdown-blocking task runner, ideally
47 // created by GetTaskRunnerForFile() method above.
48 JsonPrefStore(const base::FilePath& pref_filename,
49 base::SequencedTaskRunner* sequenced_task_runner,
50 scoped_ptr<PrefFilter> pref_filter);
52 // PrefStore overrides:
53 virtual bool GetValue(const std::string& key,
54 const base::Value** result) const OVERRIDE;
55 virtual void AddObserver(PrefStore::Observer* observer) OVERRIDE;
56 virtual void RemoveObserver(PrefStore::Observer* observer) OVERRIDE;
57 virtual bool HasObservers() const OVERRIDE;
58 virtual bool IsInitializationComplete() const OVERRIDE;
60 // PersistentPrefStore overrides:
61 virtual bool GetMutableValue(const std::string& key,
62 base::Value** result) OVERRIDE;
63 virtual void SetValue(const std::string& key, base::Value* value) OVERRIDE;
64 virtual void SetValueSilently(const std::string& key,
65 base::Value* value) OVERRIDE;
66 virtual void RemoveValue(const std::string& key) OVERRIDE;
67 virtual bool ReadOnly() const OVERRIDE;
68 virtual PrefReadError GetReadError() const OVERRIDE;
69 // Note this method may be asynchronous if this instance has a |pref_filter_|
70 // in which case it will return PREF_READ_ERROR_ASYNCHRONOUS_TASK_INCOMPLETE.
71 // See details in pref_filter.h.
72 virtual PrefReadError ReadPrefs() OVERRIDE;
73 virtual void ReadPrefsAsync(ReadErrorDelegate* error_delegate) OVERRIDE;
74 virtual void CommitPendingWrite() OVERRIDE;
75 virtual void ReportValueChanged(const std::string& key) OVERRIDE;
77 // Just like RemoveValue(), but doesn't notify observers. Used when doing some
78 // cleanup that shouldn't otherwise alert observers.
79 void RemoveValueSilently(const std::string& key);
81 // Registers |on_next_successful_write| to be called once, on the next
82 // successful write event of |writer_|.
83 void RegisterOnNextSuccessfulWriteCallback(
84 const base::Closure& on_next_successful_write);
86 // This method is called after the JSON file has been read. It then hands
87 // |value| (or an empty dictionary in some read error cases) to the
88 // |pref_filter| if one is set. It also gives a callback pointing at
89 // FinalizeFileRead() to that |pref_filter_| which is then responsible for
90 // invoking it when done. If there is no |pref_filter_|, FinalizeFileRead()
91 // is invoked directly.
92 // Note, this method is used with asynchronous file reading, so this class
93 // exposes it only for the internal needs (read: do not call it manually).
94 // TODO(gab): Move this method to the private section and hand a callback to
95 // it to FileThreadDeserializer rather than exposing this public method and
96 // giving a JsonPrefStore* to FileThreadDeserializer.
97 void OnFileRead(scoped_ptr<base::Value> value,
102 virtual ~JsonPrefStore();
104 // ImportantFileWriter::DataSerializer overrides:
105 virtual bool SerializeData(std::string* output) OVERRIDE;
107 // This method is called after the JSON file has been read and the result has
108 // potentially been intercepted and modified by |pref_filter_|.
109 // |initialization_successful| is pre-determined by OnFileRead() and should
110 // be used when reporting OnInitializationCompleted().
111 // |schedule_write| indicates whether a write should be immediately scheduled
112 // (typically because the |pref_filter_| has already altered the |prefs|) --
113 // this will be ignored if this store is read-only.
114 void FinalizeFileRead(bool initialization_successful,
115 scoped_ptr<base::DictionaryValue> prefs,
116 bool schedule_write);
118 base::FilePath path_;
119 const scoped_refptr<base::SequencedTaskRunner> sequenced_task_runner_;
121 scoped_ptr<base::DictionaryValue> prefs_;
125 // Helper for safely writing pref data.
126 base::ImportantFileWriter writer_;
128 scoped_ptr<PrefFilter> pref_filter_;
129 ObserverList<PrefStore::Observer, true> observers_;
131 scoped_ptr<ReadErrorDelegate> error_delegate_;
134 bool filtering_in_progress_;
135 PrefReadError read_error_;
137 std::set<std::string> keys_need_empty_value_;
139 DISALLOW_COPY_AND_ASSIGN(JsonPrefStore);
142 #endif // BASE_PREFS_JSON_PREF_STORE_H_