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/**
* @brief Export DBus property to scalar MIB value
*
* This file is part of sila-snmp project.
*
* Copyright (c) 2022 SILA
*
* 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 "sdbusplus/helper.hpp"
#include <memory>
namespace phosphor
{
namespace snmp
{
namespace data
{
template <typename T> class Scalar
{
public:
using value_t = std::variant<T>;
/* Define all of the basic class operations:
* Not allowed:
* - Default constructor to avoid nullptrs.
* - Copy operations due to internal unique_ptr.
* Allowed:
* - Move operations.
* - Destructor.
*/
Scalar() = delete;
Scalar(const Scalar&) = delete;
Scalar& operator=(const Scalar&) = delete;
Scalar(Scalar&&) = default;
Scalar& operator=(Scalar&&) = default;
~Scalar() = default;
/**
* @brief Object constructor
*/
Scalar(const std::string& path, const std::string& iface,
const std::string& prop, const T& initValue) :
_value(initValue),
_path(path), _iface(iface), _prop(prop),
_onChangedMatch(sdbusplus::helper::helper::getBus(),
sdbusplus::bus::match::rules::propertiesChanged(
path.c_str(), iface.c_str()),
std::bind(&Scalar<T>::onPropertyChanged, this,
std::placeholders::_1))
{
}
/**
* @brief Sent request to DBus object and store new value of property
*/
void update()
{
try
{
auto service = sdbusplus::helper::helper::getService(_path, _iface);
auto r = sdbusplus::helper::helper::callMethod(
service, _path, sdbusplus::helper::PROPERTIES_IFACE, "Get",
_iface, _prop);
value_t var;
r.read(var);
setValue(var);
}
catch (const sdbusplus::exception::SdBusError&)
{
// Corresponding service is not started yet.
// When service is started, we'll receive data with
// `propertiesChanged` signal.
// So, this catch block is just for silencing the exception.
}
}
const T& getValue() const
{
return _value;
}
const std::string& getPath() const
{
return _path;
}
const std::string& getInterface() const
{
return _iface;
}
const std::string& getProperty() const
{
return _prop;
}
protected:
/**
* @brief DBus signal `PropertiesChanged` handler
*/
void onPropertyChanged(sdbusplus::message::message& m)
{
std::string iface;
std::map<std::string, value_t> data;
std::vector<std::string> v;
m.read(iface, data, v);
if (data.find(_prop) != data.end())
{
setValue(data[_prop]);
}
}
/**
* @brief Setter for actual value
*/
virtual void setValue(value_t& var)
{
auto newValue = std::get<T>(var);
std::swap(_value, newValue);
}
private:
T _value;
std::string _path;
std::string _iface;
std::string _prop;
sdbusplus::bus::match::match _onChangedMatch;
};
} // namespace data
} // namespace snmp
} // namespace phosphor
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