Re: [RFC] Lazy Objects

From: Date: Fri, 05 Jul 2024 19:58:41 +0000
Subject: Re: [RFC] Lazy Objects
References: 1 2 3 4 5  Groups: php.internals 
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Hi

On 7/2/24 17:49, Arnaud Le Blanc wrote:

I'm curious, how did the implementation look like? Is there a proof of
concept commit or patch available somewhere? As the author of the first
internal enum (Random\IntervalBoundary) I had the pleasure of finding
out that there was no trivial way to efficiently match the various enum
cases. See the PR review here:
https://github.com/php/php-src/pull/9679#discussion_r1045943444


I've benchmarked this implementation:
https://github.com/arnaud-lb/php-src/commit/f5f87d8a7abeba2f406407606949e5c6e512baab.
Using a backed enum to have a more direct way to map enum cases to
integers didn't make a significant difference.
Here is the benchmark:
https://gist.github.com/arnaud-lb/76f77b5d7409a9e4deea995c179c6e96.
Caching the options array between calls had a less dramatic slowdown
(around 10%): https://gist.github.com/arnaud-lb/87e7f58cc11463dd3aa098218eb95a90.


Your Gists don't seem to include the actual numbers, so the second link is not particularly useful.

However you said that using a backed enum does not improve the situation, so there probably really is not much that can be done.

For completeness I want to note, though: You might be able to improve the type checking performance by directly checking the CE instead of going through instanceof_function(), because you know that inheritance is not a thing for enums. Not sure if this makes much of a difference, given the fact that instanceof_function() already does this and is force-inlined, but it might remove the branch with the call to instanceof_function_slow().

Best regards
Tim Düsterhus

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