1 // 2 // Copyright (C) 2011 The Android Open Source Project 3 // 4 // Licensed under the Apache License, Version 2.0 (the "License"); 5 // you may not use this file except in compliance with the License. 6 // You may obtain a copy of the License at 7 // 8 // http://www.apache.org/licenses/LICENSE-2.0 9 // 10 // Unless required by applicable law or agreed to in writing, software 11 // distributed under the License is distributed on an "AS IS" BASIS, 12 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 // See the License for the specific language governing permissions and 14 // limitations under the License. 15 // 16 17 #ifndef UPDATE_ENGINE_COMMON_PREFS_INTERFACE_H_ 18 #define UPDATE_ENGINE_COMMON_PREFS_INTERFACE_H_ 19 20 #include <stdint.h> 21 22 #include <string> 23 24 namespace chromeos_update_engine { 25 26 // The prefs interface allows access to a persistent preferences 27 // store. The two reasons for providing this as an interface are 28 // testing as well as easier switching to a new implementation in the 29 // future, if necessary. 30 31 class PrefsInterface { 32 public: 33 // Observer class to be notified about key value changes. 34 class ObserverInterface { 35 public: 36 virtual ~ObserverInterface() = default; 37 38 // Called when the value is set for the observed |key|. 39 virtual void OnPrefSet(const std::string& key) = 0; 40 41 // Called when the observed |key| is deleted. 42 virtual void OnPrefDeleted(const std::string& key) = 0; 43 }; 44 45 virtual ~PrefsInterface() = default; 46 47 // Gets a string |value| associated with |key|. Returns true on 48 // success, false on failure (including when the |key| is not 49 // present in the store). 50 virtual bool GetString(const std::string& key, std::string* value) const = 0; 51 52 // Associates |key| with a string |value|. Returns true on success, 53 // false otherwise. 54 virtual bool SetString(const std::string& key, const std::string& value) = 0; 55 56 // Gets an int64_t |value| associated with |key|. Returns true on 57 // success, false on failure (including when the |key| is not 58 // present in the store). 59 virtual bool GetInt64(const std::string& key, int64_t* value) const = 0; 60 61 // Associates |key| with an int64_t |value|. Returns true on success, 62 // false otherwise. 63 virtual bool SetInt64(const std::string& key, const int64_t value) = 0; 64 65 // Gets a boolean |value| associated with |key|. Returns true on 66 // success, false on failure (including when the |key| is not 67 // present in the store). 68 virtual bool GetBoolean(const std::string& key, bool* value) const = 0; 69 70 // Associates |key| with a boolean |value|. Returns true on success, 71 // false otherwise. 72 virtual bool SetBoolean(const std::string& key, const bool value) = 0; 73 74 // Returns true if the setting exists (i.e. a file with the given key 75 // exists in the prefs directory) 76 virtual bool Exists(const std::string& key) const = 0; 77 78 // Returns true if successfully deleted the file corresponding to 79 // this key. Calling with non-existent keys does nothing. 80 virtual bool Delete(const std::string& key) = 0; 81 82 // Add an observer to watch whenever the given |key| is modified. The 83 // OnPrefSet() and OnPrefDelete() methods will be called whenever any of the 84 // Set*() methods or the Delete() method are called on the given key, 85 // respectively. 86 virtual void AddObserver(const std::string& key, 87 ObserverInterface* observer) = 0; 88 89 // Remove an observer added with AddObserver(). The observer won't be called 90 // anymore for future Set*() and Delete() method calls. 91 virtual void RemoveObserver(const std::string& key, 92 ObserverInterface* observer) = 0; 93 }; 94 95 } // namespace chromeos_update_engine 96 97 #endif // UPDATE_ENGINE_COMMON_PREFS_INTERFACE_H_ 98
