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
  13 #include <boost/preprocessor/cat.hpp>
  14 #include <boost/preprocessor/stringize.hpp>
  15
  16 // Simple micro-benchmarking framework; API mostly matches a subset of the Google Benchmark
  17 // framework (see https://github.com/google/benchmark)
  18 // Why not use the Google Benchmark framework? Because adding Yet Another Dependency
  19 // (that uses cmake as its build system and has lots of features we don't need) isn't
  20 // worth it.
  21
  22 /*
  23  * Usage:
  24
  25 static void CODE_TO_TIME(benchmark::State& state)
  26 {
  27     ... do any setup needed...
  28     while (state.KeepRunning()) {
  29        ... do stuff you want to time...
  30     }
  31     ... do any cleanup needed...
  32 }
  33
  34 BENCHMARK(CODE_TO_TIME);
  35
  36  */
  37
  38 namespace benchmark {
  39
  40     class State {
  41         std::string name;
  42         double maxElapsed;
  43         double beginTime;
  44         double lastTime, minTime, maxTime, countMaskInv;
  45         uint64_t count;
  46         uint64_t countMask;
  47         uint64_t beginCycles;
  48         uint64_t lastCycles;
  49         uint64_t minCycles;
  50         uint64_t maxCycles;
  51     public:
  52         State(std::string _name, double _maxElapsed) : name(_name), maxElapsed(_maxElapsed), count(0) {
  53             minTime = std::numeric_limits<double>::max();
  54             maxTime = std::numeric_limits<double>::min();
  55             minCycles = std::numeric_limits<uint64_t>::max();
  56             maxCycles = std::numeric_limits<uint64_t>::min();
  57             countMask = 1;
  58             countMaskInv = 1./(countMask + 1);
  59         }
  60         bool KeepRunning();
  61     };
  62
  63     typedef std::function<void(State&)> BenchFunction;
  64
  65     class BenchRunner
  66     {
  67         typedef std::map<std::string, BenchFunction> BenchmarkMap;
  68         static BenchmarkMap &benchmarks();
  69
  70     public:
  71         BenchRunner(std::string name, BenchFunction func);
  72
  73         static void RunAll(double elapsedTimeForOne=1.0);
  74     };
  75 }
  76
  77 // BENCHMARK(foo) expands to:  benchmark::BenchRunner bench_11foo("foo", foo);
  78 #define BENCHMARK(n) \
  79     benchmark::BenchRunner BOOST_PP_CAT(bench_, BOOST_PP_CAT(__LINE__, n))(BOOST_PP_STRINGIZE(n), n);
  80
  81 #endif // BITCOIN_BENCH_BENCH_H