#include <chrono>
#include <iostream>
#include <string>

using namespace std::chrono;

class LogDuration {
public:
	explicit LogDuration(const string& msg = "")
			: message(msg + ": ")
			, start(steady_clock::now())
	{
	}

	~LogDuration() {
		auto finish = steady_clock::now();
		auto dur = finish - start;
		cerr << message
			 << duration_cast<microseconds>(dur).count()
			 << " microseconds" << endl;
	}
private:
	string message;
	steady_clock::time_point start;
};

#define UNIQ_ID_IMPL(lineno) _a_local_var_##lineno
#define UNIQ_ID(lineno) UNIQ_ID_IMPL(lineno)

#define LOG_DURATION(message) \
LogDuration UNIQ_ID(__LINE__){message};