percentile_format_json.hpp

#pragma once
 
#include <initializer_list>
 
#include <userver/formats/json/value_builder.hpp>
#include <userver/utils/assert.hpp>
#include <userver/utils/meta_light.hpp>
#include <userver/utils/statistics/metadata.hpp>
#include <userver/utils/statistics/percentile.hpp>
 
USERVER_NAMESPACE_BEGIN
 
namespace utils::statistics {
 
namespace impl {
 
template <typename T>
using HasGetPercentileResult = decltype(std::declval<const T&>().GetPercentile(0.0));
 
}  // namespace impl
 
std::string GetPercentileFieldName(double perc);
 
template <typename T>
formats::json::ValueBuilder PercentileToJson(const T& perc, std::initializer_list<double> percents) {
    static_assert(
        meta::kIsDetected<impl::HasGetPercentileResult, T>,
        "T must specify T::GetPercentile(double) returning "
        "json-serializable value"
    );
    formats::json::ValueBuilder result;
    for (double percent : percents) {
        result[GetPercentileFieldName(percent)] = perc.GetPercentile(percent);
    }
    utils::statistics::SolomonChildrenAreLabelValues(result, "percentile");
    return result;
}
 
template <typename T>
formats::json::ValueBuilder PercentileToJson(const T& perc) {
    return PercentileToJson(perc, {0, 50, 90, 95, 98, 99, 99.6, 99.9, 100});
}
 
}  // namespace utils::statistics
 
USERVER_NAMESPACE_END