hasKey?

[christopher at baus.net]

> It seems to make sense to add a hasKey method.
>
> For a lot of operations I just want to do quick existence checks and get
back a boolean yes or no.   We're doing a LARGE amount of queries and
doing a get() and getting back the data just doesn't make sense.
>
> Also... if the objects you are storing are large it also make sense even
if you're not doing to many of them.
>
> I realize that memcached is fast but for a lot of situations this could
offload the network and the CPU on the client.
>
> Kevin
>

For the application I am working on it would be useful to query the keys
in the cache and perform set operations on them as well.  For instance:
delete the keys not in the intersection of the current keys and the new
set.  I've been looking through the server code and it seems like the
protocol is pretty straight forward.  It might not be that bad to add
these types of operations.