[ccache] Testing memcached for a shared cache

[Anders Björklund]

Hi!

We are now getting ready to test the "dev/memcached" branch:
https://github.com/jrosdahl/ccache/tree/dev/memcached


It allows you to share your cache between different machines,
without having to use a shared filesystem like NFS to do it.

You have the option of using memcached in the normal fashion,
easing up the load on the "backend" (distcc rather than SQL).
Or you can use "memcached only", avoiding the disk access*.
*Currently the local filestore is still used for direct mode.

See http://memcached.org for more information about the server.
You will also need libmemcached for the client (i.e. ccache).
Then you set up your memcached(3) configuration like so:
     export CCACHE_MEMCACHED_CONF="--SERVER=<servername>"

Now the cache will be shared by all ccache clients using the
same memcached server(s), increasing your ccache hit rate!


Here are some basic instructions how to set up for testing:
https://gist.github.com/itensionanders/2bd0056027f8308d4cd8

Please add your feedback, by replying here - or in the PR:
https://github.com/jrosdahl/ccache/pull/58  ("Memcached")

/Anders