opcache.use_cwd has no effect (when used with file_cache?)

[kkmuffme]

Description

The following code:

/foo/test.php

<?php

function foo() {
    echo "hello" . PHP_EOL;
}

foo();

/bar/test.php

<?php

function foo() {
    echo "world" . PHP_EOL;
}

foo();

Run:

cd /foo
php -d opcache.enable_cli=1 -d opcache.jit=disable -d opcache.file_cache=/tmp/opcache -d opcache.use_cwd=0 test.php
cd /bar
php -d opcache.enable_cli=1 -d opcache.jit=disable -d opcache.file_cache=/tmp/opcache -d opcache.use_cwd=0 test.php

Resulted in this output:

hello
world

But I expected this output instead:

hello
hello

In fact the output makes sense, what doesn't make sense is opcache.use_cwd since the files are stored with an absolute path in /tmp/opcache anyway.

1. does "use_cwd" only have an effect for opcache in memory? If yes, why does the file_cache store everything with absolute paths but in memory not?

2. what if chdir() is called in the PHP script? When opcache.use_cwd=1 (default) is used this would mean that things that are in opcache already won't be used since cwd changed? Or does cwd only refer to the directory from which the PHP service is (re)started from? (which would have some quite funny side-effects)

Depending on the answer, this would possibly imply that opcache.use_cwd should be default 0 when used with the CLI SAPI.

Also, this matters especially when calling opcache_compile_file(...) with opcache.use_cwd=1 (default) as well as for opcache.preload

EDIT: or do opcache_compile_file() and opcache.preload only populate the memory, but not the file cache?
What if file cache exists and opcache.preload is used - will things from file cache be used or from opcache.preload?

PHP Version

8.4 (same in 8.3 and probably before)

Operating System

No response

[iluuu1994]

opcache.use_cwd is not used for file cache, it's only used for the key in the shared memory script hashmap. It's main use is performance (disabling it can avoid an allocation and construction of the key), at the cost of potential conflict. So, the conflict is not really a feature, more of a trade-off. Since file cache will be inherently slow, this trade-off doesn't make much sense.

[kkmuffme]

opcache.use_cwd is not used for file cache

Should be documented. I'll open an issue and PR it in the docs.

What about question 2?

From the docs https://www.php.net/manual/en/opcache.configuration.php

OPcache appends the current working directory to the script key, thereby eliminating possible collisions between files with the same base name

Assuming working directory is /foo and use_cwd=1 how does opcache distinguish files /foo/bar/hello.php and /foo/xyz/hello.php? If only the basename is used (hello.php) and the working directory is the same, they'd be the same in opcache? (obviously they aren't and it works correctly, I am just trying to understand what is missing in the documentation here, so I can improve it) So using use_cwd=1 (or 0) wouldn't make a difference in this case according to the docs, which is wrong?

[iluuu1994]

Should be documented. I'll open an issue and PR it in the docs.

Thanks!

Assuming working directory is /foo and use_cwd=1 how does opcache distinguish files /foo/bar/hello.php and /foo/xyz/hello.php?

If you use opcache.use_cwd=0, PHP will use the exact key passed to require for the hash map index. This does mean require __DIR__ . '/bar/hello.php'; and require 'bar/hello.php'; will actually result in different entries.

If only the basename is used (hello.php) and the working directory is the same, they'd be the same in opcache?

PHP does not use the files base name, it uses the name as provided by the user.

[iluuu1994]

Ok, I think there's no bug here. If you could create an issue & PR for the docs, that would be great! Certainly, this could be explained clearer. Thank you!