- must only be used for per-request connections; and
- is shared in a clustered environment.
In lib/google/lib.php it is used to set a class config value for the Google_Cache_File class.
At the top of that class, it states:
We should check whether we need this at all, and if we do see if we can use either one of:
- make_request_directory; or
- make_localcache_directory; or