ext/spl: Optimize php_spl_object_hash performance

[arshidkv12]

Optimize php_spl_object_hash performance

• Replace strpprintf() with manual hex conversion
• Avoid printf formatting overhead
• Use lookup-table-based hex encoding
• Reduce runtime from ~412ms to ~244ms in benchmark
• Achieve ~1.68x speed improvement

hyperfine --warmup 5 \                                                                                         
'./sapi/cli/php_old -dopcache.enable_cli=0 bench.php' \
'./sapi/cli/php -dopcache.enable_cli=0 bench.php'

Output:

Benchmark 1: ./sapi/cli/php_old -dopcache.enable_cli=0 bench.php
  Time (mean ± σ):     411.7 ms ±   2.3 ms    [User: 407.7 ms, System: 2.8 ms]
  Range (min … max):   407.7 ms … 416.5 ms    10 runs
 
Benchmark 2: ./sapi/cli/php -dopcache.enable_cli=0 bench.php
  Time (mean ± σ):     246.0 ms ±   1.6 ms    [User: 243.0 ms, System: 2.1 ms]
  Range (min … max):   243.9 ms … 249.0 ms    12 runs
 
Summary
  ./sapi/cli/php -dopcache.enable_cli=0 bench.php ran
    1.67 ± 0.01 times faster than ./sapi/cli/php_old -dopcache.enable_cli=0 bench.php

<?php
//bench.php
for ($i = 0; $i < 1000000; $i++) {
    spl_object_hash(new stdClass);
}

[Girgias]

Is this really a hot path in "normal" code? It might be because people use spl_object_hash() (or whatever the function is called) but does it actually make an impact in a non-synthetic benchmark?

[arshidkv12]

I think, this improves WordPress hook performance.
https://i.ibb.co/jP56JpVs/wp.png
https://github.com/WordPress/WordPress/blob/master/wp-includes/plugin.php#L1014

[staabm]

could WP use spl_object_id which is the more modern/faster alternative to spl_object_hash?

[arshidkv12]

• spl_object_id() exists only in PHP 7.2+
• WordPress still supports older PHP versions

[staabm]

• WordPress still supports older PHP versions

I think thats no longer true. lately they recommend PHP 8.3+
(and report compatibility with php 7.2+ for legacy)

see https://wordpress.org/about/requirements/

[kitrio]

Guzzle use this function

https://github.com/guzzle/guzzle/blob/b777df1776c667e287664dda75b0298ad8ae3a14/src/HandlerStack.php#L272

    private function debugCallable($fn): string
    {
        if (\is_string($fn)) {
            return "callable({$fn})";
        }

        if (\is_array($fn)) {
            return \is_string($fn[0])
                ? "callable({$fn[0]}::{$fn[1]})"
                : "callable(['".\get_class($fn[0])."', '{$fn[1]}'])";
        }

        /** @var object $fn */
        return 'callable('.\spl_object_hash($fn).')';
    }

[mvorisek]

IMO php_spl_object_hash should be deprecated as it has no advantage over faster spl_object_id.