HTML API: Optimize low-level parsing details.

[dmsnell]

Trac ticket: Core-61545

Status

• passes all tests, code audit looks right
• performs more efficiently in almost all cases, but worse in only a few minor cases. the expected speedup is around 3.5% - 7.5% for the cost of parsing the tags in realistic HTML documents.

Summary

Measured change in parsing time to count tags in HTML5 spec:

• from 1050ms to 930ms
• roughly 13% faster in the HTML spec single-page.html
• much less speedup in small documents with a higher text-to-syntax ratio

Benchmarking

Based on the top100 set of URLs from https://github.com/ada-url/url-various-datasets I ran a script count the number of tags in each document, having previously downloaded all URLs.

Of these, not all downloaded successfully and not all were HTML files.

82,406 HTML files were analyzed, representing pages from the top 100 most popular websites.

When counting all tags, trunk took between 310 seconds and 313 seconds across multiple test runs, measured from microtime() within the process parsing the HTML, and only measuring around the next_token() loop.

On this branch, the counting took between 293 seconds and 300 seconds, representing around a 5% real-world improvement in token parsing speed.

For the top100 dataset, this histogram represents the relative parsing speed in MB/s for the branch against trunk.

[dmsnell]

thanks @adamziel for pointing out to me that strspn() and strcspn() have the $length parameter!

[github-actions]

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[github-actions]

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[dmsnell]

Merged in [58613]
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