Files
MaxScale/maxutils/maxbase/include/maxbase/stopwatch.hh

159 lines
4.3 KiB
C++

/*
* Copyright (c) 2018 MariaDB Corporation Ab
*
* Use of this software is governed by the Business Source License included
* in the LICENSE.TXT file and at www.mariadb.com/bsl11.
*
* Change Date: 2022-01-01
*
* On the date above, in accordance with the Business Source License, use
* of this software will be governed by version 2 or later of the General
* Public License.
*/
#pragma once
#include <maxbase/ccdefs.hh>
#include <chrono>
#include <iosfwd>
#include <string>
namespace maxbase
{
/**
* @class Clock
*
* MaxScale "standard" std::chrono clock
*/
using Clock = std::chrono::steady_clock;
/**
* @class Duration
*
* Duration behaves exactly like Clock::duration, but adds ADL and, a
* conveniece constructor and function secs() for seconds as a double.
*/
struct Duration : public Clock::duration
{
using Clock::duration::duration;
Duration() = default;
Duration(Clock::duration d)
: Clock::duration(d)
{
}
/** From seconds */
explicit Duration(double secs)
: Duration{rep(secs * period::den / period::num)}
{
}
/** To seconds */
double secs() const
{
return std::chrono::duration<double>(*this).count();
}
};
/**
* @class TimePoint
*
* A std::chrono::time_point to go with Clock and Duration.
*/
using TimePoint = std::chrono::time_point<Clock, Duration>;
/**
* @class StopWatch
*
* Simple stopwatch for measuring time.
*
* Example usage:
* auto limit = maxbase::Duration(std::chrono::milliseconds(100));
*
* maxbase::StopWatch sw;
* foo();
* auto duration = sw.split();
*
* std::cout << "foo duration " << duration << std::endl;
* if (duration > limit)
* {
* maxbase::Duration diff = duration - limit; // no auto, would become Clock::duration.
* std::cerr << "foo exceeded the limit " << limit << " by " << diff << std::endl;
* }
* Possible output:
* foo duration 100.734ms
* foo exceeded the limit 100ms by 733.636us
*/
class StopWatch
{
public:
/** Create and start the stopwatch. */
StopWatch();
/** Split time. Overall duration since creation or last restart(). */
Duration split() const;
/** Lap time. Time since last lap() call, or if lap() was not called, creation or last restart(). */
Duration lap();
/** Return split time and restart stopwatch. */
Duration restart();
private:
TimePoint m_start;
TimePoint m_lap;
};
/** IntervalTimer for accumulating intervals (i.e. durations). Do not expect many very short
* durations to accumulate properly (unless you have a superfast processor, RTLinux, etc.)
*
* Usage pattern:
* IntervalTimer timer; // created ahead of time.
* ...
* In some sort of a loop (explicit or implicit):
* timer.start_interval();
* foo();
* timer.end_interval();
* ...
* And finally:
* std::cout << timer.total() << std::endl;
*
*/
class IntervalTimer
{
public:
/** Create but do not start the intervaltimer, i.e. starting in paused mode. */
IntervalTimer();
/** Resume measuring time. Ok to call multiple times without an end_interval(). */
void start_interval();
/** Pause measuring time. Ok to call without a start_interval. */
void end_interval();
/** Total duration of intervals (thus far). */
Duration total() const;
private:
TimePoint m_last_start;
Duration m_total;
};
/** Returns the duration as a double and string adjusted to a suffix like ms for milliseconds.
* The double and suffix (unit) combination is selected to be easy to read.
* This is for output conveniece. You can always convert a duration to a specific unit:
* long ms {std::chrono::duration_cast<std::chrono::milliseconds>(dur).count()};
*/
std::pair<double, std::string> dur_to_human_readable(Duration dur);
/** Create a string using dur_to_human_readable, std::ostringstream << d.first << sep << d.second. */
std::string to_string(Duration dur, const std::string& sep = "");
/** Stream to os << d.first << d.second. Not using to_string(), which would use a default stream. */
std::ostream& operator<<(std::ostream& os, Duration dur);
/** TimePoint to string, formatted using strftime formats. */
std::string to_string(TimePoint tp, const std::string& fmt = "%F %T");
/** Stream to std::ostream using to_string(tp) */
std::ostream& operator<<(std::ostream&, TimePoint tp);
}