include/CLI/Timer.hpp

0001 // Copyright (c) 2017-2024, University of Cincinnati, developed by Henry Schreiner
0002 // under NSF AWARD 1414736 and by the respective contributors.
0003 // All rights reserved.
0004 //
0005 // SPDX-License-Identifier: BSD-3-Clause
0006
0007 #pragma once
0008
0009 // IWYU pragma: private, include "CLI/CLI.hpp"
0010
0011 // On GCC < 4.8, the following define is often missing. Due to the
0012 // fact that this library only uses sleep_for, this should be safe
0013 #if defined(__GNUC__) && !defined(__clang__) && __GNUC__ < 5 && __GNUC_MINOR__ < 8
0014 #define _GLIBCXX_USE_NANOSLEEP
0015 #endif
0016
0017 #include <cmath>
0018
0019 #include <array>
0020 #include <chrono>
0021 #include <functional>
0022 #include <iostream>
0023 #include <string>
0024 #include <utility>
0025
0026 namespace CLI {
0027
0028 /// This is a simple timer with pretty printing. Creating the timer starts counting.
0029 class Timer {
0030   protected:
0031     /// This is a typedef to make clocks easier to use
0032     using clock = std::chrono::steady_clock;
0033
0034     /// This typedef is for points in time
0035     using time_point = std::chrono::time_point<clock>;
0036
0037     /// This is the type of a printing function, you can make your own
0038     using time_print_t = std::function<std::string(std::string, std::string)>;
0039
0040     /// This is the title of the timer
0041     std::string title_;
0042
0043     /// This is the function that is used to format most of the timing message
0044     time_print_t time_print_;
0045
0046     /// This is the starting point (when the timer was created)
0047     time_point start_;
0048
0049     /// This is the number of times cycles (print divides by this number)
0050     std::size_t cycles{1};
0051
0052   public:
0053     /// Standard print function, this one is set by default
0054     static std::string Simple(std::string title, std::string time) { return title + ": " + time; }
0055
0056     /// This is a fancy print function with --- headers
0057     static std::string Big(std::string title, std::string time) {
0058         return std::string("-----------------------------------------\n") + "| " + title + " | Time = " + time + "\n" +
0059                "-----------------------------------------";
0060     }
0061
0062   public:
0063     /// Standard constructor, can set title and print function
0064     explicit Timer(std::string title = "Timer", time_print_t time_print = Simple)
0065         : title_(std::move(title)), time_print_(std::move(time_print)), start_(clock::now()) {}
0066
0067     /// Time a function by running it multiple times. Target time is the len to target.
0068     std::string time_it(std::function<void()> f, double target_time = 1) {
0069         time_point start = start_;
0070         double total_time = NAN;
0071
0072         start_ = clock::now();
0073         std::size_t n = 0;
0074         do {
0075             f();
0076             std::chrono::duration<double> elapsed = clock::now() - start_;
0077             total_time = elapsed.count();
0078         } while(n++ < 100u && total_time < target_time);
0079
0080         std::string out = make_time_str(total_time / static_cast<double>(n)) + " for " + std::to_string(n) + " tries";
0081         start_ = start;
0082         return out;
0083     }
0084
0085     /// This formats the numerical value for the time string
0086     std::string make_time_str() const {  // NOLINT(modernize-use-nodiscard)
0087         time_point stop = clock::now();
0088         std::chrono::duration<double> elapsed = stop - start_;
0089         double time = elapsed.count() / static_cast<double>(cycles);
0090         return make_time_str(time);
0091     }
0092
0093     // LCOV_EXCL_START
0094     /// This prints out a time string from a time
0095     std::string make_time_str(double time) const {  // NOLINT(modernize-use-nodiscard)
0096         auto print_it = [](double x, std::string unit) {
0097             const unsigned int buffer_length = 50;
0098             std::array<char, buffer_length> buffer;
0099             std::snprintf(buffer.data(), buffer_length, "%.5g", x);
0100             return buffer.data() + std::string(" ") + unit;
0101         };
0102
0103         if(time < .000001)
0104             return print_it(time * 1000000000, "ns");
0105         if(time < .001)
0106             return print_it(time * 1000000, "us");
0107         if(time < 1)
0108             return print_it(time * 1000, "ms");
0109         return print_it(time, "s");
0110     }
0111     // LCOV_EXCL_STOP
0112
0113     /// This is the main function, it creates a string
0114     std::string to_string() const { return time_print_(title_, make_time_str()); }  // NOLINT(modernize-use-nodiscard)
0115
0116     /// Division sets the number of cycles to divide by (no graphical change)
0117     Timer &operator/(std::size_t val) {
0118         cycles = val;
0119         return *this;
0120     }
0121 };
0122
0123 /// This class prints out the time upon destruction
0124 class AutoTimer : public Timer {
0125   public:
0126     /// Reimplementing the constructor is required in GCC 4.7
0127     explicit AutoTimer(std::string title = "Timer", time_print_t time_print = Simple) : Timer(title, time_print) {}
0128     // GCC 4.7 does not support using inheriting constructors.
0129
0130     /// This destructor prints the string
0131     ~AutoTimer() { std::cout << to_string() << '\n'; }
0132 };
0133
0134 }  // namespace CLI
0135
0136 /// This prints out the time if shifted into a std::cout like stream.
0137 inline std::ostream &operator<<(std::ostream &in, const CLI::Timer &timer) { return in << timer.to_string(); }