Is it possible to make first class callables faster?

[adataxtra]

Description

First class callables feel like the right way to do callbacks since you get propper completion from from your IDE/editor but the performance hit is rather bad. I'm sadly not very familiar with C or PHP internals but would it be possible for opcache to get performance parity with the "string" version of the callbacks? Maybe not for userland functions but at least for internal functions.

<?php

$a = ['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j'];

$s = microtime(true);

for ($i = 0; $i < 100_000; $i++) {
    $u = array_map(strtoupper(...), $a);
}

echo (microtime(true) - $s) . PHP_EOL;

$s = microtime(true);

for ($i = 0; $i < 100_000; $i++) {
    $u = array_map('strtoupper', $a);
}

echo (microtime(true) - $s) . PHP_EOL;

$s = microtime(true);

for ($i = 0; $i < 100_000; $i++) {
    $u = array_map(fn($v) => strtoupper($v), $a);
}

echo (microtime(true) - $s) . PHP_EOL;

3v4l.org with PHP 8.3.13

0.061099052429199
0.026753902435303
0.043981075286865

3v4l.org with git.master

0.051828861236572
0.030702114105225
0.04832911491394

[nielsdos]

Part of the reason of this is definitely the fact you're recreating a callable object over and over in the loop. If you bring strtoupper(...) out of the loop and assign it a variable, it gets pretty close to the string case.

[adataxtra]

Oh yeah, I didn't think about that. It helped a bit but it is still a lot slower.

<?php

$a = ['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j'];

$s = microtime(true);

$f = strtoupper(...);

for($i = 0; $i < 100_000; $i++) {
    $u = array_map($f, $a);
}

echo (microtime(true) - $s) . PHP_EOL;

$s = microtime(true);

for($i = 0; $i < 100_000; $i++) {
    $u = array_map('strtoupper', $a);
}

echo (microtime(true) - $s) . PHP_EOL;

$s = microtime(true);

$f = fn($v) => strtoupper($v);

for($i = 0; $i < 100_000; $i++) {
    $u = array_map($f, $a);
}

echo (microtime(true) - $s) . PHP_EOL;

0.055514097213745
0.027177095413208
0.038023948669434

[nielsdos]

I get very different results on a release compile of 8.4-dev:

0.04678201675415
0.043025016784668
0.056145906448364

FWIW I tried this on 8.3 too:

0.045254945755005
0.043359041213989
0.054478883743286

So pretty much the same.
Are you only testing on 3v4l or also locally? Any noise in the background that may influence the results? Also try changing the order of the loops to rule out noise.

[adataxtra]

I just updated to PHP 8.3.13 locally and yes it is much closer now. I guess I'll close the issue :)

Defined outside of the loop:

0.023478984832764
0.020103931427002
0.032291889190674

Defined in the loop:

0.028333187103271
0.020879030227661
0.033040046691895