本文介绍了如何提高boost :: spirit :: x3键值解析器的性能的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述 29岁程序员，3月因学历无情被辞！ 我使用 boost :: spirit :: x3 解析键值对（类似于HTTP标头）。当比较手写解析器的性能时， boost :: spirit :: x3 比那个慢10％。 我使用boost 1.61和GCC 6.1： $ g ++ -std = c ++ 14 -O3 -I / tmp / boost_1_61_0 / boost / main.cpp&&& ./a.out phrase_parse 1.97432 microseconds parseHeader 1.75742 microseconds 如何提高基于 boost :: spirit :: x3 的解析器的性能？ #include< iostream> #include< string> #include< map> #include< chrono> #include< boost / spirit / home / x3.hpp> #include< boost / fusion / adapted / std_pair.hpp> 使用header_map = std :: map< std :: string，std :: string> ;; 命名空间解析器 {命名空间x3 = boost :: spirit :: x3; using x3 :: char_; using x3 :: lexeme; x3 :: rule< class map，header_map> const map =msg; const auto key = + char _（0-9a-zA-Z-）; const auto value = +〜char _（\r\\\）; const auto header =（key>>'：'>> value>> lexeme [\r\\\]）; const auto map_def = * header>> lexeme [\r\\\]; BOOST_SPIRIT_DEFINE（map）; } template< typename it> void parseHeader（it& iter，It end，header_map& map） { std :: string key; std :: string value; it last = iter; bool inKey = true; while（iter + 1！= end） { if（inKey&& *（iter +1）=='：'） { key.assign（last，iter + 1）; iter + = 3; last = iter; inKey = false; } else if（！inKey&& *（iter + 1）=='\r'&&& *（iter + 2）=='\\\'） { value.assign（last，iter + 1）; map.insert（{std :: move（key），std :: move（value）}）; iter + = 3; last = iter; inKey = true; } else if（inKey&& *（iter）=='\r'&&& *（iter + 1）=='\\\'） { iter + = 2; break; } else { ++ iter; } } } 模板< typename F，typename ... Args> double benchmark（F func，Args& ... args） { auto start = std :: chrono :: system_clock :: now（）; constexpr auto num = 10 * 1000 * 1000; for（std :: size_t i = 0; i { func（std :: forward> args）...）; } auto end = std :: chrono :: system_clock :: now（）; auto duration = std :: chrono :: duration_cast< std :: chrono :: microseconds>（end-start）; return duration.count（）/（double）num; } int main（） { const std :: size_t headerCount = 20; std :: string str; for（std :: size_t i = 0; i { std :: string num = std :: to_string（i）; str.append（key+ num +：+value+ num +\r\\\）; } str.append（\r\\\）; double t1 = benchmark（[& str]（）{ auto iter = str.cbegin（）; auto end = str.cend（）; header_map header; phrase_parse（iter，end，parser :: map，boost :: spirit :: x3 :: ascii :: blank，header）; return header; }）; std :: cout<< phrase_parse< t1 double t2 = benchmark（[& str]（）{ auto iter = str.cbegin（）; auto end = str.cend（）; header_map header; parseHeader（iter，end，header）; return header; }）; std :: cout<< parseHeader< t2 return 0; } 统计数据为2.5μs，平均为3.5μs。 完整代码 使用 http://nonius.io 进行稳定的基准化： #include< iostream> #include< string> #include< map> #include< nonius / benchmark.h ++> #include< boost / spirit / home / x3.hpp> #include< boost / fusion / adapted / std_pair.hpp> 使用header_map = std :: map< std :: string，std :: string> ;; 命名空间解析器 {命名空间x3 = boost :: spirit :: x3; using x3 :: char_; const auto key = +〜char_（'：'）; const auto value = *（char_ - \r\\\）; const auto header = key>> '：'>>值>> \r\\\; const auto map = * header>> \r\\\; } template< typename it> void parseHeader（it& iter，It end，header_map& map） { std :: string key; std :: string value; it last = iter; bool inKey = true; while（iter + 1！= end） { if（inKey&& *（iter +1）=='：'） { key.assign（last，iter + 1）; iter + = 3; last = iter; inKey = false; } else if（！inKey&& *（iter + 1）=='\r'&&& *（iter + 2）=='\\\'） { value.assign（last，iter + 1）; map.insert（{std :: move（key），std :: move（value）}）; iter + = 3; last = iter; inKey = true; } else if（inKey&& *（iter）=='\r'&&& *（iter + 1）=='\\\'） { iter + = 2; break; } else { ++ iter; } } } static auto const str = [] { std :: string tmp; const std :: size_t headerCount = 20; for（std :: size_t i = 0; i { std :: string num = std :: to_string（i）; tmp.append（key+ num +：+value+ num +\r\\\）; } tmp.append（\r\\\）; return tmp; }（）; NONIUS_BENCHMARK（manual，[]（nonius :: chronometer cm）{ cm.measure（[]（）{ auto iter = str。 cbegin（）; auto end = str.cend（）; header_map header; parseHeader（iter，end，header）; assert （）== 20）; return header.size（）; }）; }） NONIUS_BENCHMARK（x3，[] ：chronometer cm）{ cm.measure（[] { auto iter = str.cbegin（）; auto end = str.cend（）; header_map header; parse（iter，end，parser :: map，header）; assert（header.size（）== 20）; return header.size ）; }）; }） #include< nonius / main.h ++> 我使用gcc 5.4和Boost 1.61 I am parsing key value pairs (similar to HTTP headers) using boost::spirit::x3. When comparing the performance to my handwritten parser, boost::spirit::x3 is around 10% slower than that.I am using boost 1.61 and GCC 6.1:$ g++ -std=c++14 -O3 -I/tmp/boost_1_61_0/boost/ main.cpp && ./a.outphrase_parse 1.97432 microsecondsparseHeader 1.75742 microsecondsHow can I improve the performance of the boost::spirit::x3 based parser?#include <iostream>#include <string>#include <map>#include <chrono>#include <boost/spirit/home/x3.hpp>#include <boost/fusion/adapted/std_pair.hpp>using header_map = std::map<std::string, std::string>;namespace parser{ namespace x3 = boost::spirit::x3; using x3::char_; using x3::lexeme; x3::rule<class map, header_map> const map = "msg"; const auto key = +char_("0-9a-zA-Z-"); const auto value = +~char_("\r\n"); const auto header =(key >> ':' >> value >> lexeme["\r\n"]); const auto map_def = *header >> lexeme["\r\n"]; BOOST_SPIRIT_DEFINE(map);}template <typename It>void parseHeader(It& iter, It end, header_map& map){ std::string key; std::string value; It last = iter; bool inKey = true; while(iter+1 != end) { if(inKey && *(iter+1)==':') { key.assign(last, iter+1); iter+=3; last = iter; inKey = false; } else if (!inKey && *(iter+1)=='\r' && *(iter+2)=='\n') { value.assign(last, iter+1); map.insert({std::move(key), std::move(value)}); iter+=3; last = iter; inKey = true; } else if (inKey && *(iter)=='\r' && *(iter+1)=='\n') { iter+=2; break; } else { ++iter; } }}template<typename F, typename ...Args>double benchmark(F func, Args&&... args){ auto start = std::chrono::system_clock::now(); constexpr auto num = 10 * 1000 * 1000; for (std::size_t i = 0; i < num; ++i) { func(std::forward<Args>(args)...); } auto end = std::chrono::system_clock::now(); auto duration = std::chrono::duration_cast<std::chrono::microseconds>(end - start); return duration.count() / (double)num;}int main(){ const std::size_t headerCount = 20; std::string str; for(std::size_t i = 0; i < headerCount; ++i) { std::string num = std::to_string(i); str.append("key" + num + ": " + "value" + num + "\r\n"); } str.append("\r\n"); double t1 = benchmark([&str]() { auto iter = str.cbegin(); auto end = str.cend(); header_map header; phrase_parse(iter, end, parser::map, boost::spirit::x3::ascii::blank, header); return header; }); std::cout << "phrase_parse " << t1 << " microseconds"<< std::endl; double t2 = benchmark([&str]() { auto iter = str.cbegin(); auto end = str.cend(); header_map header; parseHeader(iter, end, header); return header; }); std::cout << "parseHeader " << t2 << " microseconds"<< std::endl; return 0;}live example 解决方案 Here's a fixed x3 grammar that comes a lot closer to your hand rolled "parser":const auto key = +~char_(':');const auto value = *(char_ - "\r\n");const auto header = key >> ':' >> value >> "\r\n";const auto map = *header >> "\r\n";Of course, it's still more strict and more robust. Also, don't call it with a space skipper, since your hand-rolled parser doesn't do that either.Here's the performance measurements on my box:Statistics that's 2.5µs vs. 3.5µs on average.Full CodeUsing http://nonius.io for robust benchmarking:#include <iostream>#include <string>#include <map>#include <nonius/benchmark.h++>#include <boost/spirit/home/x3.hpp>#include <boost/fusion/adapted/std_pair.hpp>using header_map = std::map<std::string, std::string>;namespace parser{ namespace x3 = boost::spirit::x3; using x3::char_; const auto key = +~char_(':'); const auto value = *(char_ - "\r\n"); const auto header = key >> ':' >> value >> "\r\n"; const auto map = *header >> "\r\n";}template <typename It>void parseHeader(It& iter, It end, header_map& map){ std::string key; std::string value; It last = iter; bool inKey = true; while(iter+1 != end) { if(inKey && *(iter+1)==':') { key.assign(last, iter+1); iter+=3; last = iter; inKey = false; } else if (!inKey && *(iter+1)=='\r' && *(iter+2)=='\n') { value.assign(last, iter+1); map.insert({std::move(key), std::move(value)}); iter+=3; last = iter; inKey = true; } else if (inKey && *(iter)=='\r' && *(iter+1)=='\n') { iter+=2; break; } else { ++iter; } }}static auto const str = [] { std::string tmp; const std::size_t headerCount = 20; for(std::size_t i = 0; i < headerCount; ++i) { std::string num = std::to_string(i); tmp.append("key" + num + ": " + "value" + num + "\r\n"); } tmp.append("\r\n"); return tmp;}();NONIUS_BENCHMARK("manual", [](nonius::chronometer cm) { cm.measure([]() { auto iter = str.cbegin(); auto end = str.cend(); header_map header; parseHeader(iter, end, header); assert(header.size() == 20); return header.size(); });})NONIUS_BENCHMARK("x3", [](nonius::chronometer cm) { cm.measure([] { auto iter = str.cbegin(); auto end = str.cend(); header_map header; parse(iter, end, parser::map, header); assert(header.size() == 20); return header.size(); });})#include <nonius/main.h++>I'm using gcc 5.4 and Boost 1.61 这篇关于如何提高boost :: spirit :: x3键值解析器的性能的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！ 上岸，阿里云！
