Architecture of Backing Store Descriptors

[Jonathan Shapiro]

   I'm (Bill Frantz) not sure I understand the problem.  Perhaps a concrete
   example would help.

Let's see...

Suppose I wish to memory may an object, and I want a special keeper
for it.  For example, I'm doing networking coherency at the page level
by juggling the page keys.  Somebody hands me a segment key that they
allege contains the pages for the object, and I wrap this segment with
a red segment in order to place my keeper in control of it.

What happens if the segment I got handed implements its own internal
keeper logic isn't pretty. There is an ambiguity as to which keeper
(internal or mine) should be called.  In some cases I may want both
the internal keeper and my own keeper called, and I might want them
called either top-down or bottom-up in the seg tree logic.


Jonathan