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