It might be less intrusive codewise and more flexible if we left the behavior of cache expiration the same and added a parameter to each template called "Time to Refresh" (TTR). Then you set long or unlimited cache expirations, which are always in effect, but set a shorter TTR that would trigger an asynchronous refresh when the TTR expired. If the db is not available these refreshes will simply fail, but the data will remain in the cache at least until it's expired by the usual means.

This gives the solution designer the option of deciding how long a system can run disconnected while still being able to separately determine how stale the contents of the cache will get when connected. It also means that pcache itself doesn't need to switch modes based on whether it thinks it's connected to a db or not, and it fact may not need to even know if it is connected or not.

There is still room in this design for a flag that controls whether pcache should behave as if it's disconnected or connected, but I'm not sure how useful that is given the changes described above.

Cheers,

-Matt

Matthew Hardin Symas Corporation - The LDAP Guys http://www.symas.com