blob: 2f4403570ff45954a9a967a58c775ce522e003b8 [file] [log] [blame]
/*
* Copyright (c) 2021 Project CHIP Authors
*
* 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.
*/
#pragma once
#include <app/ConcreteAttributePath.h>
#include <app/util/attribute-metadata.h>
#include <lib/support/Span.h>
namespace chip {
namespace app {
/**
* Interface for persisting attribute values.
*/
class AttributePersistenceProvider
{
public:
virtual ~AttributePersistenceProvider() = default;
AttributePersistenceProvider() = default;
/**
* Write an attribute value from the attribute store (i.e. not a struct or
* list) to non-volatile memory.
*
* @param [in] aPath the attribute path for the data being written.
* @param [in] aValue the data to write. Integers and floats are
* represented in native endianness. Strings are represented
* as Pascal-style strings, as in ZCL, with a length prefix
* whose size depends on the actual string type. The length is
* stored as little-endian.
*
* Integer and float values have a size that matches the `size`
* member of aMetadata.
*
* String values have a size that corresponds to the actual size
* of the data in the string (including the length prefix),
* which is no larger than the `size` member of aMetadata.
*/
virtual CHIP_ERROR WriteValue(const ConcreteAttributePath & aPath, const ByteSpan & aValue) = 0;
/**
* Read an attribute value from non-volatile memory.
*
* @param [in] aPath the attribute path for the data being persisted.
* @param [in] aMetadata the attribute metadata, as a convenience.
* @param [in,out] aValue where to place the data. The size of the buffer
* will be equal to `size` member of aMetadata.
*
* The data is expected to be in native endianness for
* integers and floats. For strings, see the string
* representation description in the WriteValue
* documentation.
*/
virtual CHIP_ERROR ReadValue(const ConcreteAttributePath & aPath, const EmberAfAttributeMetadata * aMetadata,
MutableByteSpan & aValue) = 0;
};
/**
* Instance getter for the global AttributePersistenceProvider.
*
* Callers have to externally synchronize usage of this function.
*
* @return The global AttributePersistenceProvider. This must never be null.
*/
AttributePersistenceProvider * GetAttributePersistenceProvider();
/**
* Instance setter for the global AttributePersistenceProvider.
*
* Callers have to externally synchronize usage of this function.
*
* If the `provider` is nullptr, the value is not changed.
*
* @param[in] aProvider the AttributePersistenceProvider implementation to use.
*/
void SetAttributePersistenceProvider(AttributePersistenceProvider * aProvider);
} // namespace app
} // namespace chip