by over 50 times.
Looking at the usage, toHTTPDateStream is not called anywhere (except
internally by toHTTPDateString), and toHTTPDateString is called only
once outside of lldate.cpp, by LLStringUtil::formatDatetime. Also, the
method is most commonly called with a single two-character token, such
as "%Y" or "%A".
I therefore removed toHTTPDateStream and optimized toHTTPDateString.
Setting the locale was the most expensive operation, so I looked into
caching that, both in terms of std::ostream and strftime. The timings
for those implementations (averaged over 10 calls) is:
toHTTPDateString timings:
- with ostream (current) -> 0.314156 ms
- with ostream and std::locale caching -> 0.033999 ms
- with strftime and setlocale() caching -> 0.005985 ms
I therefore went with the standard C library strftime solution.
I also wrote a few unit tests to make sure that I didn't break any
existing functionality, and tested this under Windows and Linux.
Reviewed by steve.
f7231263d4