Profiler for C++ tracks time consumption in scope {}

ProfiledScope.hpp

#pragma once

#include <iostream>
#include <vector>
#include <map>
#include <string>
#include <chrono>
#include <cstdio>
#include <unistd.h>

#include <fmt/chrono.h>
#include "fmt_eprint.hpp"


// *INDENT-OFF*
struct separate_thousands : std::numpunct<char> {
    char_type do_thousands_sep() const override { return '\''; }  // separate with commas
    string_type do_grouping() const override { return "\3"; } // groups of 3 digit
};
template<typename T> struct scoped_locale_change {
    std::locale prev_locale;
    scoped_locale_change(){
        // prev_locale = std::cout.getloc();
        // std::cout.imbue( std::locale( std::cout.getloc(), thousands.release() ) );
        auto thousands = std::make_unique<separate_thousands>();
        prev_locale = std::locale::global( std::locale( std::cout.getloc(), thousands.release() ) );
    }
    ~scoped_locale_change(){
        std::locale::global( prev_locale );
    }
};
// *INDENT-ON*


struct ProfiledScope
{
    std::string name{"unnamed"};
    std::chrono::steady_clock::time_point timepoint_begin = std::chrono::steady_clock::now();
    ~ProfiledScope()
    {
        scoped_locale_change<separate_thousands> slc;
        fmt::eprint( "-- ProfiledScope {} elapsed {:L}ns\n", name, ( std::chrono::steady_clock::now() - timepoint_begin ).count() );
    }
};
struct ProfiledScope2
{
    private:
        std::chrono::steady_clock::time_point timepoint_begin = std::chrono::steady_clock::now();
        std::string name{"unnamed"};
    public:
        ProfiledScope2( std::string &&name ) : name( name ) {} 
        ~ProfiledScope2()
        {
            auto const elapsed = std::chrono::steady_clock::now() - timepoint_begin;
            auto &info = ProfiledScope2::the_map[name];
            info.elapsed += elapsed;
            info.calls_count += 1;
        }
        struct ElapsedCount
        {
            std::chrono::steady_clock::duration elapsed{0};
            size_t calls_count{0};
        };
    private: //static
        static std::map<std::string, ElapsedCount> the_map;
    public: // static
        static void report()
        {
            scoped_locale_change<separate_thousands> slc;

            for( auto const &each : ProfiledScope2::the_map )
            {
                auto const &name = each.first;
                auto const &elapsed = each.second.elapsed;
                auto const &calls_count = each.second.calls_count;
                auto const avg = elapsed / calls_count;
                fmt::eprint( "-- ProfiledScope2 {} totally elapsed {:L}ns during n:{} calls avg:{:L}ns todoMAX:_ todoMAXatIDX:_ \n",
                             name, elapsed.count(), calls_count, ( unsigned long long )avg.count() );
            }
        }
};
// /*static*/ std::map<std::string, ProfiledScope2::ElapsedCount> ProfiledScope2::the_map;  //ToDo not required in C++17