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//
// Copyright (C) 2011 The Android Open Source Project
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
#ifndef UPDATE_ENGINE_COMMON_PREFS_INTERFACE_H_
#define UPDATE_ENGINE_COMMON_PREFS_INTERFACE_H_
#include <stdint.h>
#include <string>
#include <vector>
namespace chromeos_update_engine {
// The prefs interface allows access to a persistent preferences
// store. The two reasons for providing this as an interface are
// testing as well as easier switching to a new implementation in the
// future, if necessary.
class PrefsInterface {
public:
// Observer class to be notified about key value changes.
class ObserverInterface {
public:
virtual ~ObserverInterface() = default;
// Called when the value is set for the observed |key|.
virtual void OnPrefSet(const std::string& key) = 0;
// Called when the observed |key| is deleted.
virtual void OnPrefDeleted(const std::string& key) = 0;
};
virtual ~PrefsInterface() = default;
// Gets a string |value| associated with |key|. Returns true on
// success, false on failure (including when the |key| is not
// present in the store).
virtual bool GetString(const std::string& key, std::string* value) const = 0;
// Associates |key| with a string |value|. Returns true on success,
// false otherwise.
virtual bool SetString(const std::string& key, std::string_view value) = 0;
// Gets an int64_t |value| associated with |key|. Returns true on
// success, false on failure (including when the |key| is not
// present in the store).
virtual bool GetInt64(const std::string& key, int64_t* value) const = 0;
// Associates |key| with an int64_t |value|. Returns true on success,
// false otherwise.
virtual bool SetInt64(const std::string& key, const int64_t value) = 0;
// Gets a boolean |value| associated with |key|. Returns true on
// success, false on failure (including when the |key| is not
// present in the store).
virtual bool GetBoolean(const std::string& key, bool* value) const = 0;
// Associates |key| with a boolean |value|. Returns true on success,
// false otherwise.
virtual bool SetBoolean(const std::string& key, const bool value) = 0;
// Returns true if the setting exists (i.e. a file with the given key
// exists in the prefs directory)
virtual bool Exists(const std::string& key) const = 0;
// Returns true if successfully deleted the file corresponding to
// this key. Calling with non-existent keys does nothing.
virtual bool Delete(const std::string& key) = 0;
// Deletes the pref key from platform and given namespace subdirectories.
// Keys are matched against end of pref keys in each namespace.
// Returns true if all deletes were successful.
virtual bool Delete(const std::string& pref_key,
const std::vector<std::string>& nss) = 0;
// Creates a key which is part of a sub preference.
static std::string CreateSubKey(const std::vector<std::string>& ns_with_key);
// Returns a list of keys within the namespace.
virtual bool GetSubKeys(const std::string& ns,
std::vector<std::string>* keys) const = 0;
// Add an observer to watch whenever the given |key| is modified. The
// OnPrefSet() and OnPrefDelete() methods will be called whenever any of the
// Set*() methods or the Delete() method are called on the given key,
// respectively.
virtual void AddObserver(const std::string& key,
ObserverInterface* observer) = 0;
// Remove an observer added with AddObserver(). The observer won't be called
// anymore for future Set*() and Delete() method calls.
virtual void RemoveObserver(const std::string& key,
ObserverInterface* observer) = 0;
protected:
// Key separator used to create sub key and get file names,
static const char kKeySeparator = '/';
};
} // namespace chromeos_update_engine
#endif // UPDATE_ENGINE_COMMON_PREFS_INTERFACE_H_