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_JSON_PREF_STORE_H_ 6 #define BASE_PREFS_JSON_PREF_STORE_H_ 7 8 #include <set> 9 #include <string> 10 11 #include "base/basictypes.h" 12 #include "base/compiler_specific.h" 13 #include "base/files/file_path.h" 14 #include "base/files/important_file_writer.h" 15 #include "base/memory/scoped_ptr.h" 16 #include "base/message_loop/message_loop_proxy.h" 17 #include "base/observer_list.h" 18 #include "base/prefs/base_prefs_export.h" 19 #include "base/prefs/persistent_pref_store.h" 20 21 namespace base { 22 class DictionaryValue; 23 class FilePath; 24 class SequencedTaskRunner; 25 class SequencedWorkerPool; 26 class Value; 27 } 28 29 30 // A writable PrefStore implementation that is used for user preferences. 31 class BASE_PREFS_EXPORT JsonPrefStore 32 : public PersistentPrefStore, 33 public base::ImportantFileWriter::DataSerializer { 34 public: 35 // Returns instance of SequencedTaskRunner which guarantees that file 36 // operations on the same file will be executed in sequenced order. 37 static scoped_refptr<base::SequencedTaskRunner> GetTaskRunnerForFile( 38 const base::FilePath& pref_filename, 39 base::SequencedWorkerPool* worker_pool); 40 41 // |sequenced_task_runner| is must be a shutdown-blocking task runner, ideally 42 // created by GetTaskRunnerForFile() method above. 43 JsonPrefStore(const base::FilePath& pref_filename, 44 base::SequencedTaskRunner* sequenced_task_runner); 45 46 // PrefStore overrides: 47 virtual bool GetValue(const std::string& key, 48 const base::Value** result) const OVERRIDE; 49 virtual void AddObserver(PrefStore::Observer* observer) OVERRIDE; 50 virtual void RemoveObserver(PrefStore::Observer* observer) OVERRIDE; 51 virtual bool HasObservers() const OVERRIDE; 52 virtual bool IsInitializationComplete() const OVERRIDE; 53 54 // PersistentPrefStore overrides: 55 virtual bool GetMutableValue(const std::string& key, 56 base::Value** result) OVERRIDE; 57 virtual void SetValue(const std::string& key, base::Value* value) OVERRIDE; 58 virtual void SetValueSilently(const std::string& key, 59 base::Value* value) OVERRIDE; 60 virtual void RemoveValue(const std::string& key) OVERRIDE; 61 virtual bool ReadOnly() const OVERRIDE; 62 virtual PrefReadError GetReadError() const OVERRIDE; 63 virtual PrefReadError ReadPrefs() OVERRIDE; 64 virtual void ReadPrefsAsync(ReadErrorDelegate* error_delegate) OVERRIDE; 65 virtual void CommitPendingWrite() OVERRIDE; 66 virtual void ReportValueChanged(const std::string& key) OVERRIDE; 67 68 // This method is called after JSON file has been read. Method takes 69 // ownership of the |value| pointer. Note, this method is used with 70 // asynchronous file reading, so class exposes it only for the internal needs. 71 // (read: do not call it manually). 72 void OnFileRead(base::Value* value_owned, PrefReadError error, bool no_dir); 73 74 private: 75 virtual ~JsonPrefStore(); 76 77 // ImportantFileWriter::DataSerializer overrides: 78 virtual bool SerializeData(std::string* output) OVERRIDE; 79 80 base::FilePath path_; 81 const scoped_refptr<base::SequencedTaskRunner> sequenced_task_runner_; 82 83 scoped_ptr<base::DictionaryValue> prefs_; 84 85 bool read_only_; 86 87 // Helper for safely writing pref data. 88 base::ImportantFileWriter writer_; 89 90 ObserverList<PrefStore::Observer, true> observers_; 91 92 scoped_ptr<ReadErrorDelegate> error_delegate_; 93 94 bool initialized_; 95 PrefReadError read_error_; 96 97 std::set<std::string> keys_need_empty_value_; 98 99 DISALLOW_COPY_AND_ASSIGN(JsonPrefStore); 100 }; 101 102 #endif // BASE_PREFS_JSON_PREF_STORE_H_ 103