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| 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/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/gtest_prod_util.h" | |
| 17 #include "base/memory/scoped_ptr.h" | |
| 18 #include "base/memory/scoped_vector.h" | |
| 19 #include "base/memory/weak_ptr.h" | |
| 20 #include "base/observer_list.h" | |
| 21 #include "base/prefs/base_prefs_export.h" | |
| 22 #include "base/prefs/persistent_pref_store.h" | |
| 23 #include "base/threading/non_thread_safe.h" | |
| 24 | |
| 25 class PrefFilter; | |
| 26 | |
| 27 namespace base { | |
| 28 class Clock; | |
| 29 class DictionaryValue; | |
| 30 class FilePath; | |
| 31 class HistogramBase; | |
| 32 class JsonPrefStoreLossyWriteTest; | |
| 33 class SequencedTaskRunner; | |
| 34 class SequencedWorkerPool; | |
| 35 class Value; | |
| 36 FORWARD_DECLARE_TEST(JsonPrefStoreTest, WriteCountHistogramTestBasic); | |
| 37 FORWARD_DECLARE_TEST(JsonPrefStoreTest, WriteCountHistogramTestSinglePeriod); | |
| 38 FORWARD_DECLARE_TEST(JsonPrefStoreTest, WriteCountHistogramTestMultiplePeriods); | |
| 39 FORWARD_DECLARE_TEST(JsonPrefStoreTest, WriteCountHistogramTestPeriodWithGaps); | |
| 40 } | |
| 41 | |
| 42 // A writable PrefStore implementation that is used for user preferences. | |
| 43 class BASE_PREFS_EXPORT JsonPrefStore | |
| 44 : public PersistentPrefStore, | |
| 45 public base::ImportantFileWriter::DataSerializer, | |
| 46 public base::SupportsWeakPtr<JsonPrefStore>, | |
| 47 public base::NonThreadSafe { | |
| 48 public: | |
| 49 struct ReadResult; | |
| 50 | |
| 51 // Returns instance of SequencedTaskRunner which guarantees that file | |
| 52 // operations on the same file will be executed in sequenced order. | |
| 53 static scoped_refptr<base::SequencedTaskRunner> GetTaskRunnerForFile( | |
| 54 const base::FilePath& pref_filename, | |
| 55 base::SequencedWorkerPool* worker_pool); | |
| 56 | |
| 57 // Same as the constructor below with no alternate filename. | |
| 58 JsonPrefStore( | |
| 59 const base::FilePath& pref_filename, | |
| 60 const scoped_refptr<base::SequencedTaskRunner>& sequenced_task_runner, | |
| 61 scoped_ptr<PrefFilter> pref_filter); | |
| 62 | |
| 63 // |sequenced_task_runner| must be a shutdown-blocking task runner, ideally | |
| 64 // created by the GetTaskRunnerForFile() method above. | |
| 65 // |pref_filename| is the path to the file to read prefs from. | |
| 66 // |pref_alternate_filename| is the path to an alternate file which the | |
| 67 // desired prefs may have previously been written to. If |pref_filename| | |
| 68 // doesn't exist and |pref_alternate_filename| does, |pref_alternate_filename| | |
| 69 // will be moved to |pref_filename| before the read occurs. | |
| 70 JsonPrefStore( | |
| 71 const base::FilePath& pref_filename, | |
| 72 const base::FilePath& pref_alternate_filename, | |
| 73 const scoped_refptr<base::SequencedTaskRunner>& sequenced_task_runner, | |
| 74 scoped_ptr<PrefFilter> pref_filter); | |
| 75 | |
| 76 // PrefStore overrides: | |
| 77 bool GetValue(const std::string& key, | |
| 78 const base::Value** result) const override; | |
| 79 void AddObserver(PrefStore::Observer* observer) override; | |
| 80 void RemoveObserver(PrefStore::Observer* observer) override; | |
| 81 bool HasObservers() const override; | |
| 82 bool IsInitializationComplete() const override; | |
| 83 | |
| 84 // PersistentPrefStore overrides: | |
| 85 bool GetMutableValue(const std::string& key, base::Value** result) override; | |
| 86 void SetValue(const std::string& key, | |
| 87 scoped_ptr<base::Value> value, | |
| 88 uint32 flags) override; | |
| 89 void SetValueSilently(const std::string& key, | |
| 90 scoped_ptr<base::Value> value, | |
| 91 uint32 flags) override; | |
| 92 void RemoveValue(const std::string& key, uint32 flags) override; | |
| 93 bool ReadOnly() const override; | |
| 94 PrefReadError GetReadError() const override; | |
| 95 // Note this method may be asynchronous if this instance has a |pref_filter_| | |
| 96 // in which case it will return PREF_READ_ERROR_ASYNCHRONOUS_TASK_INCOMPLETE. | |
| 97 // See details in pref_filter.h. | |
| 98 PrefReadError ReadPrefs() override; | |
| 99 void ReadPrefsAsync(ReadErrorDelegate* error_delegate) override; | |
| 100 void CommitPendingWrite() override; | |
| 101 void SchedulePendingLossyWrites() override; | |
| 102 void ReportValueChanged(const std::string& key, uint32 flags) override; | |
| 103 | |
| 104 // Just like RemoveValue(), but doesn't notify observers. Used when doing some | |
| 105 // cleanup that shouldn't otherwise alert observers. | |
| 106 void RemoveValueSilently(const std::string& key, uint32 flags); | |
| 107 | |
| 108 // Registers |on_next_successful_write| to be called once, on the next | |
| 109 // successful write event of |writer_|. | |
| 110 void RegisterOnNextSuccessfulWriteCallback( | |
| 111 const base::Closure& on_next_successful_write); | |
| 112 | |
| 113 private: | |
| 114 // Represents a histogram for recording the number of writes to the pref file | |
| 115 // that occur every kHistogramWriteReportIntervalInMins minutes. | |
| 116 class BASE_PREFS_EXPORT WriteCountHistogram { | |
| 117 public: | |
| 118 static const int32_t kHistogramWriteReportIntervalMins; | |
| 119 | |
| 120 WriteCountHistogram(const base::TimeDelta& commit_interval, | |
| 121 const base::FilePath& path); | |
| 122 // Constructor for testing. |clock| is a test Clock that is used to retrieve | |
| 123 // the time. | |
| 124 WriteCountHistogram(const base::TimeDelta& commit_interval, | |
| 125 const base::FilePath& path, | |
| 126 scoped_ptr<base::Clock> clock); | |
| 127 ~WriteCountHistogram(); | |
| 128 | |
| 129 // Record that a write has occured. | |
| 130 void RecordWriteOccured(); | |
| 131 | |
| 132 // Reports writes (that have not yet been reported) in all of the recorded | |
| 133 // intervals that have elapsed up until current time. | |
| 134 void ReportOutstandingWrites(); | |
| 135 | |
| 136 base::HistogramBase* GetHistogram(); | |
| 137 | |
| 138 private: | |
| 139 // The minimum interval at which writes can occur. | |
| 140 const base::TimeDelta commit_interval_; | |
| 141 | |
| 142 // The path to the file. | |
| 143 const base::FilePath path_; | |
| 144 | |
| 145 // Clock which is used to retrieve the current time. | |
| 146 scoped_ptr<base::Clock> clock_; | |
| 147 | |
| 148 // The interval at which to report write counts. | |
| 149 const base::TimeDelta report_interval_; | |
| 150 | |
| 151 // The time at which the last histogram value was reported for the number | |
| 152 // of write counts. | |
| 153 base::Time last_report_time_; | |
| 154 | |
| 155 // The number of writes that have occured since the last write count was | |
| 156 // reported. | |
| 157 uint32_t writes_since_last_report_; | |
| 158 | |
| 159 DISALLOW_COPY_AND_ASSIGN(WriteCountHistogram); | |
| 160 }; | |
| 161 | |
| 162 FRIEND_TEST_ALL_PREFIXES(base::JsonPrefStoreTest, | |
| 163 WriteCountHistogramTestBasic); | |
| 164 FRIEND_TEST_ALL_PREFIXES(base::JsonPrefStoreTest, | |
| 165 WriteCountHistogramTestSinglePeriod); | |
| 166 FRIEND_TEST_ALL_PREFIXES(base::JsonPrefStoreTest, | |
| 167 WriteCountHistogramTestMultiplePeriods); | |
| 168 FRIEND_TEST_ALL_PREFIXES(base::JsonPrefStoreTest, | |
| 169 WriteCountHistogramTestPeriodWithGaps); | |
| 170 friend class base::JsonPrefStoreLossyWriteTest; | |
| 171 | |
| 172 ~JsonPrefStore() override; | |
| 173 | |
| 174 // This method is called after the JSON file has been read. It then hands | |
| 175 // |value| (or an empty dictionary in some read error cases) to the | |
| 176 // |pref_filter| if one is set. It also gives a callback pointing at | |
| 177 // FinalizeFileRead() to that |pref_filter_| which is then responsible for | |
| 178 // invoking it when done. If there is no |pref_filter_|, FinalizeFileRead() | |
| 179 // is invoked directly. | |
| 180 void OnFileRead(scoped_ptr<ReadResult> read_result); | |
| 181 | |
| 182 // ImportantFileWriter::DataSerializer overrides: | |
| 183 bool SerializeData(std::string* output) override; | |
| 184 | |
| 185 // This method is called after the JSON file has been read and the result has | |
| 186 // potentially been intercepted and modified by |pref_filter_|. | |
| 187 // |initialization_successful| is pre-determined by OnFileRead() and should | |
| 188 // be used when reporting OnInitializationCompleted(). | |
| 189 // |schedule_write| indicates whether a write should be immediately scheduled | |
| 190 // (typically because the |pref_filter_| has already altered the |prefs|) -- | |
| 191 // this will be ignored if this store is read-only. | |
| 192 void FinalizeFileRead(bool initialization_successful, | |
| 193 scoped_ptr<base::DictionaryValue> prefs, | |
| 194 bool schedule_write); | |
| 195 | |
| 196 // Schedule a write with the file writer as long as |flags| doesn't contain | |
| 197 // WriteablePrefStore::LOSSY_PREF_WRITE_FLAG. | |
| 198 void ScheduleWrite(uint32 flags); | |
| 199 | |
| 200 const base::FilePath path_; | |
| 201 const base::FilePath alternate_path_; | |
| 202 const scoped_refptr<base::SequencedTaskRunner> sequenced_task_runner_; | |
| 203 | |
| 204 scoped_ptr<base::DictionaryValue> prefs_; | |
| 205 | |
| 206 bool read_only_; | |
| 207 | |
| 208 // Helper for safely writing pref data. | |
| 209 base::ImportantFileWriter writer_; | |
| 210 | |
| 211 scoped_ptr<PrefFilter> pref_filter_; | |
| 212 base::ObserverList<PrefStore::Observer, true> observers_; | |
| 213 | |
| 214 scoped_ptr<ReadErrorDelegate> error_delegate_; | |
| 215 | |
| 216 bool initialized_; | |
| 217 bool filtering_in_progress_; | |
| 218 bool pending_lossy_write_; | |
| 219 PrefReadError read_error_; | |
| 220 | |
| 221 std::set<std::string> keys_need_empty_value_; | |
| 222 | |
| 223 WriteCountHistogram write_count_histogram_; | |
| 224 | |
| 225 DISALLOW_COPY_AND_ASSIGN(JsonPrefStore); | |
| 226 }; | |
| 227 | |
| 228 #endif // BASE_PREFS_JSON_PREF_STORE_H_ | |
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