src/bench/bench.h

   1 // Copyright (c) 2015-2016 The Bitcoin Core developers
   2 // Distributed under the MIT software license, see the accompanying
   3 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
   4
   5 #ifndef BITCOIN_BENCH_BENCH_H
   6 #define BITCOIN_BENCH_BENCH_H
   7
   8 #include <functional>
   9 #include <limits>
  10 #include <map>
  11 #include <string>
  12 #include <chrono>
  13
  14 #include <boost/preprocessor/cat.hpp>
  15 #include <boost/preprocessor/stringize.hpp>
  16
  17 // Simple micro-benchmarking framework; API mostly matches a subset of the Google Benchmark
  18 // framework (see https://github.com/google/benchmark)
  19 // Why not use the Google Benchmark framework? Because adding Yet Another Dependency
  20 // (that uses cmake as its build system and has lots of features we don't need) isn't
  21 // worth it.
  22
  23 /*
  24  * Usage:
  25
  26 static void CODE_TO_TIME(benchmark::State& state)
  27 {
  28     ... do any setup needed...
  29     while (state.KeepRunning()) {
  30        ... do stuff you want to time...
  31     }
  32     ... do any cleanup needed...
  33 }
  34
  35 BENCHMARK(CODE_TO_TIME);
  36
  37  */
  38
  39 namespace benchmark {
  40     // In case high_resolution_clock is steady, prefer that, otherwise use steady_clock.
  41     struct best_clock {
  42         using hi_res_clock = std::chrono::high_resolution_clock;
  43         using steady_clock = std::chrono::steady_clock;
  44         using type = std::conditional<hi_res_clock::is_steady, hi_res_clock, steady_clock>::type;
  45     };
  46     using clock = best_clock::type;
  47     using time_point = clock::time_point;
  48     using duration = clock::duration;
  49
  50     class State {
  51         std::string name;
  52         duration maxElapsed;
  53         time_point beginTime, lastTime;
  54         duration minTime, maxTime;
  55         uint64_t count;
  56         uint64_t countMask;
  57         uint64_t beginCycles;
  58         uint64_t lastCycles;
  59         uint64_t minCycles;
  60         uint64_t maxCycles;
  61     public:
  62         State(std::string _name, duration _maxElapsed) :
  63             name(_name),
  64             maxElapsed(_maxElapsed),
  65             minTime(duration::max()),
  66             maxTime(duration::zero()),
  67             count(0),
  68             countMask(1),
  69             beginCycles(0),
  70             lastCycles(0),
  71             minCycles(std::numeric_limits<uint64_t>::max()),
  72             maxCycles(std::numeric_limits<uint64_t>::min()) {
  73         }
  74         bool KeepRunning();
  75     };
  76
  77     typedef std::function<void(State&)> BenchFunction;
  78
  79     class BenchRunner
  80     {
  81         typedef std::map<std::string, BenchFunction> BenchmarkMap;
  82         static BenchmarkMap &benchmarks();
  83
  84     public:
  85         BenchRunner(std::string name, BenchFunction func);
  86
  87         static void RunAll(duration elapsedTimeForOne = std::chrono::seconds(1));
  88     };
  89 }
  90
  91 // BENCHMARK(foo) expands to:  benchmark::BenchRunner bench_11foo("foo", foo);
  92 #define BENCHMARK(n) \
  93     benchmark::BenchRunner BOOST_PP_CAT(bench_, BOOST_PP_CAT(__LINE__, n))(BOOST_PP_STRINGIZE(n), n);
  94
  95 #endif // BITCOIN_BENCH_BENCH_H