opcache: fix revalidation in long running CLI scripts

[Sannis]

It looks like opcache was initially designed with short-lived requests in mind, so when checking if the file should be re-validated, the code uses 'request time' instead of 'now', where request time is calculated once on the script startup. Which basically means that in CLI this check will never succeed.

This PR containing the patch to fix this issue covered with a test that passes in this branch but not in PHP-8.3.
The issue itself is older, but I rebased the patch to PHP-8.3 as mentioned in CONTRIBUTING doc.

Not sure if I must fill the issue separately, but will be happy to do if needed.

[mvorisek]

https://www.php.net/manual/en/function.php-sapi-name.php - maybe there is a better way to detect cli /wo extra property.

Also the time getter can be probably deduplicated to something like microtime(true).

[Sannis]

Thanks for the suggestion.

We considered using php_sapi_name() for detecting the environment at runtime, but opted to precompute this value once during initialization and store it in a cli_mode flag for performance reasons.

The motivation is that validate_timestamp_and_record() is invoked on every include or require, not just on actual cache invalidations. Using strcmp() or a similar runtime check each time would introduce measurable overhead. By storing this as a precomputed boolean, we ensure this logic has minimal runtime cost.

[Sannis]

Regarding microtime(true), I believe there may be some confusion here. The microtime() function referenced is a userland PHP function and not directly available within the engine context.

The implementation I used is based on the internal php_time() logic, with slight adjustments to return a double for better precision.

I also avoided using microtime() as-is because it's not available consistently across all platforms.

If there’s a preferred helper or abstraction for obtaining a double-precision current time in the engine, I’m happy to switch to that but I wanted to avoid introducing inconsistencies across platforms.

[Sannis]

Anyway, it looks like this part of PR may be weak, and I'm happy for any suggestions to it. Maybe I can drop double precision logic and switch to php_time() here.