mirror of
https://github.com/tfussell/xlnt.git
synced 2024-03-22 13:11:17 +08:00
fix dumb bug in input randomiser, add basic double->string benchmarks
* input randomiser was feeding a constant value previously, now actually randomising * start to_string with the current method (sstream), an faster more correct version (sstream_cached), snprintf, and std::to_chars ** NOTE: only std::to_chars and sstream_cached are correct in the face of locales Run on (4 X 3500 MHz CPU s) CPU Caches: L1 Data 32K (x4) L1 Instruction 32K (x4) L2 Unified 262K (x4) L3 Unified 6291K (x1) ------------------------------------------------------------------------------------------------------------- Benchmark Time CPU Iterations ------------------------------------------------------------------------------------------------------------- RandFloatStrs/double_from_string_sstream 1012 ns 1001 ns 640000 RandFloatStrs/double_from_string_strtod 276 ns 276 ns 2488889 RandFloatStrs/double_from_string_strtod_fixed 312 ns 308 ns 2133333 RandFloatStrs/double_from_string_strtod_fixed_const_ref 307 ns 300 ns 2240000 RandFloatStrs/double_from_string_std_from_chars 194 ns 188 ns 3733333 RandFloatCommaStrs/double_from_string_strtod_fixed_comma_ref 315 ns 314 ns 2240000 RandFloatCommaStrs/double_from_string_strtod_fixed_comma_const_ref 306 ns 305 ns 2357895 RandFloats/string_from_double_sstream 1372 ns 1381 ns 497778 RandFloats/string_from_double_sstream_cached 1136 ns 1123 ns 640000 RandFloats/string_from_double_snprintf 536 ns 516 ns 1000000 RandFloats/string_from_double_std_to_chars 116 ns 115 ns 6400000
This commit is contained in:
JCrawfy
parent
0adb8a69b1
commit
7ba36b5e73
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@ -1,2 +1,151 @@
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#include "benchmark/benchmark.h"
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// A core part of the xlsx serialisation routine is taking doubles from memory and stringifying them
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// this has a few requirements
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// - expect strings in the form 1234.56 (i.e. no thousands seperator, '.' used for the decimal seperator)
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// - outputs up to 15 significant figures (excel only serialises numbers up to 15sf)
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#include "benchmark/benchmark.h"
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#include <locale>
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#include <random>
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#include <sstream>
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namespace {
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// setup a large quantity of random doubles as strings
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template <bool Decimal_Locale = true>
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class RandomFloats : public benchmark::Fixture
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{
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static constexpr size_t Number_of_Elements = 1 << 20;
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static_assert(Number_of_Elements > 1'000'000, "ensure a decent set of random values is generated");
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std::vector<double> inputs;
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size_t index = 0;
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const char *locale_str = nullptr;
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public:
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void SetUp(const ::benchmark::State &state)
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{
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if (Decimal_Locale)
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{
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locale_str = setlocale(LC_ALL, "C");
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}
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else
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{
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locale_str = setlocale(LC_ALL, "de-DE");
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}
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std::random_device rd; // obtain a seed for the random number engine
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std::mt19937 gen(rd());
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// doing full range is stupid (<double>::min/max()...), it just ends up generating very large numbers
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// uniform is probably not the best distribution to use here, but it will do for now
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std::uniform_real_distribution<double> dis(-1'000, 1'000);
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// generate a large quantity of doubles to deserialise
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inputs.reserve(Number_of_Elements);
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for (int i = 0; i < Number_of_Elements; ++i)
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{
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double d = dis(gen);
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inputs.push_back(d);
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}
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}
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void TearDown(const ::benchmark::State &state)
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{
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// restore locale
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setlocale(LC_ALL, locale_str);
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// gbench is keeping the fixtures alive somewhere, need to clear the data after use
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inputs = std::vector<double>{};
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}
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double &get_rand()
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{
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return inputs[++index & (Number_of_Elements - 1)];
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}
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};
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/// Takes in a double and outputs a string form of that number which will
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/// serialise and deserialise without loss of precision
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std::string serialize_number_to_string(double num)
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{
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// more digits and excel won't match
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constexpr int Excel_Digit_Precision = 15; //sf
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std::stringstream ss;
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ss.precision(Excel_Digit_Precision);
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ss << num;
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return ss.str();
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}
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class number_serialiser
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{
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static constexpr int Excel_Digit_Precision = 15; //sf
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std::ostringstream ss;
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public:
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explicit number_serialiser()
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{
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ss.precision(Excel_Digit_Precision);
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ss.imbue(std::locale("C"));
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}
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std::string serialise(double d)
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{
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ss.str(""); // reset string buffer
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ss.clear(); // reset any error flags
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ss << d;
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return ss.str();
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}
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};
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using RandFloats = RandomFloats<true>;
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} // namespace
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BENCHMARK_F(RandFloats, string_from_double_sstream)
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(benchmark::State &state)
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{
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while (state.KeepRunning())
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{
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benchmark::DoNotOptimize(
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serialize_number_to_string(get_rand()));
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}
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}
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BENCHMARK_F(RandFloats, string_from_double_sstream_cached)
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(benchmark::State &state)
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{
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number_serialiser ser;
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while (state.KeepRunning())
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{
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benchmark::DoNotOptimize(
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ser.serialise(get_rand()));
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}
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}
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BENCHMARK_F(RandFloats, string_from_double_snprintf)
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(benchmark::State &state)
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{
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while (state.KeepRunning())
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{
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char buf[16];
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int len = snprintf(buf, sizeof(buf), "%16f", get_rand());
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benchmark::DoNotOptimize(
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std::string(buf, len));
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}
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}
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// locale names are different between OS's, and std::from_chars is only complete in MSVC
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#ifdef _MSC_VER
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#include <charconv>
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BENCHMARK_F(RandFloats, string_from_double_std_to_chars)
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(benchmark::State &state)
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{
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while (state.KeepRunning())
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{
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char buf[16];
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std::to_chars_result result = std::to_chars(buf, buf + std::size(buf), get_rand());
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benchmark::DoNotOptimize(
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std::string(buf, result.ptr));
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}
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}
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#endif
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@ -1,15 +1,18 @@
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// A core part of the xlsx parsing routine is taking strings from the xml parser and parsing these to a double
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// this has a few requirements
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// - expect numbers in the form 1234.56 (i.e. no thousands seperator, '.' used for the decimal seperator)
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// - expect strings in the form 1234.56 (i.e. no thousands seperator, '.' used for the decimal seperator)
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// - handles atleast 15 significant figures (excel only serialises numbers up to 15sf)
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#include <benchmark/benchmark.h>
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#include <locale>
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#include <random>
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#include <sstream>
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namespace {
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// setup a large quantity of random doubles as strings
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template <bool Decimal_Locale = true>
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class RandomFloats : public benchmark::Fixture
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class RandomFloatStrs : public benchmark::Fixture
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{
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static constexpr size_t Number_of_Elements = 1 << 20;
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static_assert(Number_of_Elements > 1'000'000, "ensure a decent set of random values is generated");
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@ -17,7 +20,7 @@ class RandomFloats : public benchmark::Fixture
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std::vector<std::string> inputs;
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size_t index = 0;
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const char *locale_str;
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const char *locale_str = nullptr;
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public:
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void SetUp(const ::benchmark::State &state)
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@ -50,19 +53,18 @@ public:
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{
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// restore locale
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setlocale(LC_ALL, locale_str);
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// gbench is keeping the fixtures alive somewhere, need to clear the data...
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// gbench is keeping the fixtures alive somewhere, need to clear the data after use
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inputs = std::vector<std::string>{};
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}
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std::string &get_rand()
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{
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return inputs[++index & Number_of_Elements];
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return inputs[++index & (Number_of_Elements - 1)];
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}
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};
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// method used by xlsx_consumer.cpp in commit - ba01de47a7d430764c20ec9ac9600eec0eb38bcf
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// std::istringstream with the locale set to "C"
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#include <sstream>
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struct number_converter
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{
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number_converter()
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@ -82,32 +84,6 @@ struct number_converter
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double result;
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};
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using RandFloats = RandomFloats<true>;
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BENCHMARK_F(RandFloats, double_from_string_sstream)
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(benchmark::State &state)
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{
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number_converter converter;
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while (state.KeepRunning())
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{
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benchmark::DoNotOptimize(
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converter.stold(get_rand()));
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}
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}
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// using strotod
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// https://en.cppreference.com/w/cpp/string/byte/strtof
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// this naive usage is broken in the face of locales (fails condition 1)
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#include <cstdlib>
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BENCHMARK_F(RandFloats, double_from_string_strtod)
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(benchmark::State &state)
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{
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while (state.KeepRunning())
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{
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benchmark::DoNotOptimize(
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strtod(get_rand().c_str(), nullptr));
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}
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}
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// to resolve the locale issue with strtod, a little preprocessing of the input is required
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struct number_converter_mk2
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@ -151,7 +127,37 @@ private:
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bool should_convert_to_comma = false;
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};
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BENCHMARK_F(RandFloats, double_from_string_strtod_fixed)
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using RandFloatStrs = RandomFloatStrs<true>;
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// german locale uses ',' as the seperator
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using RandFloatCommaStrs = RandomFloatStrs<false>;
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} // namespace
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BENCHMARK_F(RandFloatStrs, double_from_string_sstream)
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(benchmark::State &state)
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{
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number_converter converter;
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while (state.KeepRunning())
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{
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benchmark::DoNotOptimize(
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converter.stold(get_rand()));
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}
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}
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// using strotod
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// https://en.cppreference.com/w/cpp/string/byte/strtof
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// this naive usage is broken in the face of locales (fails condition 1)
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#include <cstdlib>
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BENCHMARK_F(RandFloatStrs, double_from_string_strtod)
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(benchmark::State &state)
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{
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while (state.KeepRunning())
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{
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benchmark::DoNotOptimize(
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strtod(get_rand().c_str(), nullptr));
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}
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}
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BENCHMARK_F(RandFloatStrs, double_from_string_strtod_fixed)
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(benchmark::State &state)
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{
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number_converter_mk2 converter;
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@ -162,7 +168,7 @@ BENCHMARK_F(RandFloats, double_from_string_strtod_fixed)
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}
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}
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BENCHMARK_F(RandFloats, double_from_string_strtod_fixed_const_ref)
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BENCHMARK_F(RandFloatStrs, double_from_string_strtod_fixed_const_ref)
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(benchmark::State &state)
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{
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number_converter_mk2 converter;
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@ -178,7 +184,7 @@ BENCHMARK_F(RandFloats, double_from_string_strtod_fixed_const_ref)
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#ifdef _MSC_VER
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#include <charconv>
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BENCHMARK_F(RandFloats, double_from_string_std_from_chars)
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BENCHMARK_F(RandFloatStrs, double_from_string_std_from_chars)
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(benchmark::State &state)
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{
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while (state.KeepRunning())
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@ -191,9 +197,7 @@ BENCHMARK_F(RandFloats, double_from_string_std_from_chars)
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}
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// not using the standard "C" locale with '.' seperator
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// german locale uses ',' as the seperator
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using RandFloatsComma = RandomFloats<false>;
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BENCHMARK_F(RandFloatsComma, double_from_string_strtod_fixed_comma_ref)
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BENCHMARK_F(RandFloatCommaStrs, double_from_string_strtod_fixed_comma_ref)
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(benchmark::State &state)
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{
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number_converter_mk2 converter;
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@ -204,7 +208,7 @@ BENCHMARK_F(RandFloatsComma, double_from_string_strtod_fixed_comma_ref)
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}
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}
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BENCHMARK_F(RandFloatsComma, double_from_string_strtod_fixed_comma_const_ref)
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BENCHMARK_F(RandFloatCommaStrs, double_from_string_strtod_fixed_comma_const_ref)
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(benchmark::State &state)
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{
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number_converter_mk2 converter;
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