PHP misreporting existence of directory or files

Recently I was working with a WordPress site where I was deleting a network. When the network was deleted, the root site was also deleted (or vice versa). And when the root site deleted, it deleted its own media directory and the parent network’s media directory as well. This worked out OK in most cases (because the root site and root network are one-in-the-same in a multisite network). However in some of my workplace’s custom code, we hooked into both network and site deletion. We tried to delete some extra folders attached with the network and site. Some folders were shared, so once they were deleted, they should’ve shown up as missing. However the folders were showing up as existing on second try and when deleting were giving out errors. So…

PHP has something called stat cache to make file operations faster. It caches information anytime you make a call to functions like “stat(), lstat(), file_exists(), is_writable(), is_readable(), is_executable(), is_file(), is_dir(), is_link(), filectime(), fileatime(), filemtime(), fileinode(), filegroup(), fileowner(), filesize(), filetype(), and fileperms().” Coincidentally, PHP was misreporting the existence of files and folders when they were clearly deleted and glob() would be confirming that fact. In the end, we had to add calls to clearstatcache() to avoid this trap.

I wish there was a way to disable the stat caching for a session, because calling this function every time gets to be a pain.

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