Experiment: Run through esc_attr() in a single optimized pass. #5337
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The existing implementation of `esc_attr()` runs a jumble of regular expression and other search passes over its input. In this patch, if the site uses UTF-8, then an exploratory single-pass custom parser is used to escape the attribute values.
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In order to clarify the main loop of `_esc_attr_single_pass_utf8` I've moved the named character reference lookup outside of the function and into a new high-performance token set class dubbed `WP_Token_Set`. I created this class to retain the performance perks brought by the optimized data format. There are two lookup sets though because WordPress traditionally has its own custom set based on HTML4, but I would like to see us allow everything that HTML5 allows, including the common `'` so we don't have to keep writing `&WordPress#39;` (because that doesn't stand out as clearly as the name does). Performance in this change is even better than it was previously because I've removed the substitutions from the lookup table and that removes both iteration and working memory. In order to provide the reverse function, decoding these entities, it would probably be best to create two separate tables, or add a fixed byte length and offset value as a lookup into another table so that we can avoid reintroducing the double crawling scan that we had before.
dmsnell
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Mar 6, 2024
| if ( self::KEY_LENGTH < $text_length ) { | ||
| $group_key = substr( $text, $offset, self::KEY_LENGTH ); | ||
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| if ( ! isset( $this->large_words[ $group_key ] ) ) { |
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bug! if the group doesn't exist, it doesn't also imply that the short word doesn't exist. this should break but not return
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Trac ticket: Core-60841
Important note
In a test I had
esc_attr()return its given input and do no processing and could measure no impact on page runtime, at least nothing significant, so this PR is entirely exploratory and more focused now on:Benchmark on
single-page.html12 MB test document:trunkruns in 90 ms using 79.3 MB of memory.$allowedentitynamesruns in 184 ms using 73.8 MB of memory.aroundless than twice as slow but uses noticeably less memory. Since calling everything butesc_attr()consumes 41 MB we can estimate that the comparison is 39 MB against 34 MB, or that this branch uses only 86% as much astrunkBenchmark on a short string more typical of a real value:
trunkruns in 4.0 µs / 40.5 MB$allowedentitynamesruns in 3.9 µs / 40.6 MBThe existing implementation of
esc_attr()runs a jumble of regular expression and other search passes over its input.In this patch, if the site uses UTF-8, then an exploratory single-pass custom parser is used to escape the attribute values.
Trac ticket:
This Pull Request is for code review only. Please keep all other discussion in the Trac ticket. Do not merge this Pull Request. See GitHub Pull Requests for Code Review in the Core Handbook for more details.