This PR was merged into the 3.2-dev branch.Discussion----------[Cache] Added PhpFilesAdapter| Q             | A| ------------- | ---| Branch?       | master| Bug fix?      | no| New feature?  | yes| BC breaks?    | no| Deprecations? | no| Tests pass?   | yes| Fixed tickets | -| License       | MIT| Doc PR        | -This is taking over#18832.With a warm cache I get these numbers consistently (PhpArrayAdapter being the implem in#18823 ):```Fetching randomly 5000 items 10000 times: Symfony\Component\Cache\Adapter\FilesystemAdapter: 0.1367,    2 megabytes   Symfony\Component\Cache\Adapter\PhpArrayAdapter: 0.0071,    2 megabytes   Symfony\Component\Cache\Adapter\PhpFilesAdapter: 0.0389,    2 megabytes       Symfony\Component\Cache\Adapter\ApcuAdapter: 0.0361,    2 megabytes```This means that the PhpArrayAdapter should be used first, then ApcuAdapter preferred over PhpFilesAdapter, then FilesystemAdapter. This is what AbstractAdapter does here.Also note that to get the cache working, one should stay within the limits defined by the following ini settings:- memory_limit- apc.shm_size- opcache.memory_consumption- opcache.interned_strings_buffer- opcache.max_accelerated_filesCommits-------8983e83 [Cache] Optimize & wire PhpFilesAdapter14bcd79 [Cache] Added PhpFilesAdapter

…weaverryan)This PR was merged into the 3.2 branch.Discussion----------Covering two missing Cache adapters introduced in 3.2Hi guys!These are 2 missing adapters that were introduced in 3.2!symfony/symfony#18894 andsymfony/symfony#18823Cheers!Commits-------a3e69e2 Tweaks based on feedback!1b6cb69 Covering two missing adapters introduced in 3.2