[ZODB-Dev] Proposing to drop some DB decoys

[Tim Peters]

The database (ZODB.DB.DB) class contains 3 related public methods I'd like
to get rid of for ZODB 3.3:

    cacheMeanAge()
    cacheMeanDeac()
    cacheMeanDeal()

There are no docs for them, no tests, and none of them does something
useful.  If you call one of them, it suppresses a pile of AttributeErrors
internally, two routines down the chain, then returns None.

cacheMeanAge() might be a handy thing to know, but (a) there's no code to
compute it; and, (b) the current version of the FileStorage cache does LRU
replacement by circular ring position, not by timestamp (i.e., the cache age
of an item may not be discoverable in a meaningful sense).

I've no idea what ...Deac and ...Deal might have been intended for.  So
maybe they *are* implementable <wink -- if you want, I'll make ...Deac()
return 'c' and ...Deal() return 'l').

Any objections to dropping these decoys?