Cut call time of add_prefix() by 99.8%
#69
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Fix: #68
Previously on perf hunting: we had stumbled across a method in the wild that seemed harmless enough, but upon getting closer it turned to attack and we saw that it was in fact O(2n^2) in disguise!!
On this episode: we propose a function-neutral change that looks the same to an external observer (eg. someone that calls and of the public methods
combine(),prefixes(), ornamespaces()methods directly) but internally within theadd_prefixmethod we avoid set comprehensions that become very expensive as thenamespacesorprefixessets become large.For
Run on thelinkmltests--with-slow` enabled, no tests fail and...Current version: 156s (cumulative), 0.00580s per call
This PR: 0.2s (cumulative), 7.75e-06s per call
Change: -155.2s, 99.8% decrease