Replace ipv4 inet_ntop with a handrolled function #367
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Thank you for your contribution to improving Drogon’s performance! I appreciate your work on this 🎉 |
For some reason gcc assumes that static constexpr array can be modified and does not attempt to zero init the string, reading from the array instead. Having the buffer be initialized in the function instead via a consteval seems to yield proper results. MSVC just straight up doesn't understand static initialization and attempts to initialize the static buffer on every function call. Microsoft never fails to disappoint.
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toIpis a surprisingly hot function when used in Drogon, accounting for a grand 6% of total runtime when I measured it during my stress tests.I've tried to make the new function as efficient and consistent as possible, avoiding allocations by abusing the small string optimization. The longest IPv4 address has a total of 15 characters which is just enough to fit in a small libstdc++ string.
To abuse this, I preallocated the string and performed the conversion inside of it with a helper function that does work unconditionally, which achieves really good throughput and low run to run variance.
This speeds up IP to string conversion by about 10x