Currenlty the static cache store has a flush_store() mechansim.

However it does unset(self::$staticstore); Which is not allowed in PHP. It results in a Fatal Error.

The store should be flushed before it's deleted. And this also begins to allow purging of stores to behave correctly where we ask the store to purge itself rather than expecting all of the definitions to work out what is purged and that flow down to the store level.

See MDL-49149 for the initial part of this discussion.