avg_timer.hpp

#include <unordered_map>

class avg_timer
{
public:
	avg_timer(const char *name, int batch = 120) : name_(name), batch_(batch) {}
	avg_timer(const scope_timer &) = delete;
	~avg_timer() noexcept
	{
		auto elapsed = std::chrono::steady_clock::now() - start_;
		auto &it = stats_[name_];
		it.microseconds += std::chrono::duration_cast<std::chrono::microseconds>(elapsed).count();
		if (++it.iterations >= batch_)
		{
			auto us = it.microseconds / it.iterations;
			if (us >= 1000000)
				printf("avg_timer(%s) = %g s\n", name_, (us / 1000) / 1000.0);
			else
				printf("avg_timer(%s) = %g ms\n", name_, us / 1000.0);
			it.iterations = 0;
			it.microseconds = 0;
		}
	}

private:
	struct stats
	{
		int iterations {0};
		std::chrono::microseconds::rep microseconds {0};
	};

	const char *name_;
	int batch_;
	std::chrono::steady_clock::time_point start_ {std::chrono::steady_clock::now()};
	static std::unordered_map<std::string, stats> stats_;
};

std::unordered_map<std::string, avg_timer::stats> avg_timer::stats_;