Result Cache busted when creating a new file

[gries]

Hi,
I'm scanning a rather large legacy project with about 15k files and I have noticed a weird behavior concerning the cache.

If I scan the project twice it is super fast due to the result cache.

If I make a small change within one of the existing files, the scan is still very fast depending on the file and the dependencies obviously.

But If I add a single empty php file that is not used anywhere it looks like about 20% of the cache is busted. So it rescans about 3k of the files and it takes a while.

Is this expected behavior?

I tried diffing the result cache in between runs and as expected the diff of the cache only includes the new file.

~/tmp/cache-compare » diff resultCache.php resultCache-newfile.php                                         
2810a2811,2817
>   '/home/me/app/newfile.php' => 
>   array (
>     'fileHash' => 'da39a3ee5e6b4b0d3255bfef95601890afd80709',
>     'dependentFiles' => 
>     array (
>     ),
>   ),

I have a fairly basic config

    // ...
    level: 5
    checkFunctionArgumentTypes: true
    checkNullables: true
    checkDynamicProperties: true
    checkUnionTypes: true
    customRulesetUsed: true

[ondrejmirtes]

This is expected behaviour. Adding a new file might fix any of the reported errors, so PHPStan reanalyses all files with errors.

[gries]

hi thanks for the quick answer, does this include ignored errors?

[ondrejmirtes]

Yes, result cache includes all of them. That's why regenerating the baseline or modifying ignoreErrors does not invalidate the result cache. They're filtered afterwards.

[gries]

thanks that saved me a lot of headache 👍

last question for my understanding, changing an existing file does not trigger a rescan of the errors because it is an existing file so phpstan knows about the dependencies and only scans those right?

[ondrejmirtes]

Yes.

A note: the behaviour could be improved. We should reanalyse files with errors when a new symbol appears (like a class or a function), not when a new file appears. I need to run some tests but it's possible this is currently buggy.

[gries]

thanks you for your time 🥇 that helps out a lot