In-process key/value (session) store option. . .?

[David Dabbs]

Hi. I'm looking for a module (or likely a combination of modules) that will
allow me to do the following:

  * Search an in-process hashtable using a value from a request parameter or
header. (think session cache with expiry)
  * If the key is not found, then call out to some distributed cache backend
(e.g. Memcached, Redis, Tokyo) to get the value.
  * Add a new request header with the fetched value.
  * Proxy forward the request upstream.

Basically, I'm looking for simple in-process session state. If the available
modules that interface to cache backends are fast enough to obviate the need
for the in-process L1 session cache, then that's great. I've looked at the
supplied & third-party modules/extensions and I can't seem to find what I'm
looking for. Well, I found cache interfaces, but these seem to be focused on
response content caching.

Any pointers would be greatly appreciated.

Thank you,

david