Re: Bindings, Locks, and MOVE

   From: ccjason@us.ibm.com

   <js/>
   I do have trouble following your description of the fixup stage, though.  I
   take it you don't think we face the awkward situation Kevin described, where
   there end up being 2 resources where there used to be only one.  But how do
   you avoid this?

   <jlc/>
   I have to agree that I couldn't quite understand what GC meant by "fixup"
   since it seemed none was necessary.
   I also don't understand what you are saying about extra resources.

<gmc/> This thread was one where Judy was concerned that our
definition of MOVE was incompatible with being "logically equivalent
to COPY/fixup/DELETE".  So although an extra resource is what you
would expect (rightly so) after a COPY, an extra resource is *not*
what you would expect after a MOVE.  In an earlier posting, I pointed
out that the "fixup step" could be used to get rid of the extra resource.
But to emphasize, defining MOVE as COPY/fixup/DELETE is *bad* (as in
"bad dog, don't mess the carpet" :-)

   <jlc/> As for the MOVE, we start with two resources and end with two.
   No surprise once again.

<gmc/> But without a "fixup", if you just do COPY/DELETE to implement
your MOVE, Judy's example would end up with three
resources following the MOVE, rather than two, thus her concern.

Cheers,
Geoff

Received on Wednesday, 15 September 1999 17:10:26 UTC