Benchmark of the libfly JSON parser against a couple of popular C++ JSON libraries:
All results below are the median of 11 iterations of the indicated JSON file. Obviously, libfly could use some work :)
| Parser | Duration (ms) | Speed (MB/s) |
|---|---|---|
| libfly | 141.364 | 52.074 |
| boost | 30.795 | 239.044 |
| nlohmann | 80.322 | 91.648 |
| Parser | Duration (ms) | Speed (MB/s) |
|---|---|---|
| libfly | 36.768 | 58.386 |
| boost | 4.725 | 454.373 |
| nlohmann | 22.047 | 97.373 |
A profile of parsing the all_unicode.json file indicates most time is spent in the fly::Json move
constructor.
Each sample counts as 0.01 seconds.
% cumulative self self total
time seconds seconds calls ms/call ms/call name
37.32 0.53 0.53 35301398 0.00 0.00 fly::Json::Json(fly::Json&&)
11.97 0.70 0.17 12232704 0.00 0.00 fly::parser::JsonParser::parse_quoted_string[abi:cxx11]()
9.86 0.84 0.14 70602796 0.00 0.00 std::__detail::__variant::_Variant_storage<false, decltype(nullptr), std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::map<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, fly::Json, std::less<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > >, std::allocator<std::pair<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const, fly::Json> > >, std::vector<fly::Json, std::allocator<fly::Json> >, bool, long, unsigned long, long double>::_M_reset()
7.04 0.94 0.10 12234321 0.00 0.00 unsigned int fly::detail::BasicUnicode<char>::codepoint_from_string<char const*>(char const*&, char const* const&)
5.63 1.02 0.08 36698134 0.00 0.00 fly::parser::JsonParser::consume_whitespace_and_comments()
5.63 1.10 0.08 12232704 0.00 0.00 fly::Json::validate_string(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >&&)
4.93 1.17 0.07 61163531 0.00 0.00 fly::parser::JsonParser::consume_whitespace()
3.52 1.22 0.05 24465397 0.00 0.00 fly::parser::JsonParser::consume_token(fly::parser::JsonParser::Token)
3.52 1.27 0.05 12232693 0.00 0.00 fly::parser::JsonParser::consume_comma(fly::parser::JsonParser::Token)
2.11 1.30 0.03 12232715 0.00 0.00 fly::parser::JsonParser::parse_json()
2.11 1.33 0.03 12232704 0.00 0.00 std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > fly::Json::convert_to_string<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > >(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >)
2.11 1.36 0.03 12232704 0.00 0.00 fly::Json::push_back(fly::Json&&)
1.41 1.38 0.02 24465408 0.00 0.00 fly::parser::JsonParser::state_for_object_or_array(fly::parser::JsonParser::Token)
0.70 1.41 0.01 61163542 0.00 0.00 fly::parser::JsonParser::is_whitespace(fly::parser::JsonParser::Token) const
0.70 1.42 0.01 11 0.00 0.08 fly::parser::JsonParser::parse_array()
0.00 1.42 0.00 385 0.00 0.00 fly::Json::read_escaped_character(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >&, __gnu_cxx::__normal_iterator<char*, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > >&)
The move constructor is about as simple as it gets:
Json::Json(Json &&json) noexcept : m_value(std::move(json.m_value))
{
json.m_value = nullptr;
}Maybe there is a more efficient way to move std::variant? I did not see much of an improvement by
swapping the std::variant with a plain union. Alternatively, maybe the parser could hold off on
actually creating fly::Json objects as long as possible.