/
with_state_management_for_cumulative_metrics.h
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/
with_state_management_for_cumulative_metrics.h
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/**
* Copyright (C) 2023-present MongoDB, Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the Server Side Public License, version 1,
* as published by MongoDB, Inc.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* Server Side Public License for more details.
*
* You should have received a copy of the Server Side Public License
* along with this program. If not, see
* <http://www.mongodb.com/licensing/server-side-public-license>.
*
* As a special exception, the copyright holders give permission to link the
* code of portions of this program with the OpenSSL library under certain
* conditions as described in each individual source file and distribute
* linked combinations including the program with the OpenSSL library. You
* must comply with the Server Side Public License in all respects for
* all of the code used other than as permitted herein. If you modify file(s)
* with this exception, you may extend this exception to your version of the
* file(s), but you are not obligated to do so. If you do not wish to do so,
* delete this exception statement from your version. If you delete this
* exception statement from all source files in the program, then also delete
* it in the license file.
*/
#pragma once
#include "mongo/bson/bsonobjbuilder.h"
#include "mongo/db/s/cumulative_metrics_state_holder.h"
namespace mongo {
namespace detail {
template <typename StateEnum, template <typename> typename SizeHelper>
using StateEnumToHolderType =
CumulativeMetricsStateHolder<StateEnum, SizeHelper<StateEnum>::getSize()>;
}
template <typename Base, template <typename> typename SizeHelper, typename... StateEnums>
class WithStateManagementForCumulativeMetrics : public Base {
public:
using AnyState = std::variant<StateEnums...>;
using StateFieldNameMap = stdx::unordered_map<AnyState, StringData>;
template <typename... Args>
WithStateManagementForCumulativeMetrics(Args&&... args) : Base{std::forward<Args>(args)...} {}
template <typename T>
void onStateTransition(boost::optional<T> before, boost::optional<T> after) {
getHolderFor<T>().onStateTransition(before, after);
}
protected:
template <typename T>
int64_t getCountInState(T state) const {
return getHolderFor<T>().getStateCounter(state)->load();
}
void reportCountsForAllStates(const StateFieldNameMap& names, BSONObjBuilder* bob) const {
(reportCountsForStatesIn<StateEnums>(names, bob), ...);
}
template <typename State>
static boost::optional<StringData> getNameFor(State state, const StateFieldNameMap& names) {
auto it = names.find(state);
if (it == names.end()) {
return boost::none;
}
return it->second;
}
private:
template <typename StateEnum>
auto& getHolderFor() const {
return std::get<detail::StateEnumToHolderType<StateEnum, SizeHelper>>(_holders);
}
template <typename StateEnum>
auto& getHolderFor() {
return std::get<detail::StateEnumToHolderType<StateEnum, SizeHelper>>(_holders);
}
template <typename StateEnum>
void reportCountsForStatesIn(const StateFieldNameMap& names, BSONObjBuilder* bob) const {
using IntType = std::underlying_type_t<StateEnum>;
for (IntType i = 0; i < static_cast<IntType>(SizeHelper<StateEnum>::getSize()); i++) {
StateEnum state{i};
if (auto name = getNameFor(state, names); name.has_value()) {
bob->append(*name, getCountInState(state));
}
}
}
std::tuple<detail::StateEnumToHolderType<StateEnums, SizeHelper>...> _holders;
};
} // namespace mongo