True memcache support

[GoogleCodeExporter]

Currently the GAE SDK stores cached data in process memory. Need to change
this to use memcached and examine performance improvements.

Original issue reported on code.google.com by shattere...@gmail.com on 1 Oct 2009 at 9:06

[GoogleCodeExporter]

Initial memcache support added. Scratch install script now installs memcached 
and
python-memcache from apt-get. Changes to GAE SDK now allow for true-memcache 
set,
get, stats, and flush-all. Other functions to come soon.

Original comment by shattere...@gmail.com on 12 Oct 2009 at 10:09

• Changed state: Started

[GoogleCodeExporter]

Done. Added support for increment, decrement, and delete (all other functions 
appear
to use these 6 total functions under the hood). Will be in next appscale 
release.

One minor caveat: the stats method reveals to the user the oldest item in the 
cache.
Since memcache does not reveal this functionality, we had no way of finding it
either, so we do what the GAE SDK does and simply report the time since the 
first
read to memcached.

Next step is to update the scratch install to use the latest memcached and
python-memcached packages instead of the significantly older ones found in 
apt-get.
Currently in progress, should be done soon.

Original comment by shattere...@gmail.com on 13 Oct 2009 at 6:24

[GoogleCodeExporter]

Done. Now installing latest memcached, but having some pythonpath problem that
prevents GAE from seeing the newest python-memcached package (although the
interpreter can see it fine).

Will return to this at a later time to see if this is worth addressing.

Original comment by shattere...@gmail.com on 14 Oct 2009 at 6:10

• Changed state: Fixed