Faster deref of inline atoms#277
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nicoburns
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Jul 17, 2024
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@nicoburns Thanks for reviewing. Are you a maintainer of this project and able to merge? |
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I am, but I'm new to working with this crate, so I'm going to seek feedback before I go ahead and merge. I will look to push this forwards though :) See: https://servo.zulipchat.com/#narrow/stream/263398-general/topic/The.20.60string_cache.60.20crate |
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@nicoburns Amazing! Would be really great if this crate received some attention, and really appreciate it that you're willing to do so. |
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Thanks very much for merging! |
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Deref of an atom (e.g.
atom.to_string()) which stores the string inline performs slicing with&src[..len].lenis guaranteed to be within bounds, as an inline atom is always 7 bytes or less, so this can be substituted withsrc.get_unchecked(..len).Removing this bounds check improves performance of deref-ing an inline atom by approx 30%.
There's a lot of noise in the benchmarks, but it also seems to slightly improve performance of deref-ing static and dynamic atoms too, presumably because it reduces the size of the
deref()function.NB There's no gain to making the same change in
From<Cow<'a, str>> for Atom<Static>because the compiler already deduces no bounds check is required due to theif len <= MAX_INLINE_LENconditional.