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[Tril]

On Thu, Jul 04, 2002 at 12:46:58PM -0700, Justin R. Hall wrote:
> > Subject: max
> >         o TODO: add backlinking for addresses contained in sets.
> >
> On Thu, Jul 04, 2002 at 11:20:09AM -0700, Tril wrote:
> > We can work on this last one together if you want.  I figured out what
> > has to be done, but there are multiple ways to implement it.
>=20
> Sounds good.=20

When?

> Also, you need to draw a very neat, organized picture on my
> white board of "backlinks" because I'm still a little shady on them.

No I don't.  It's not complicated enough :)
You understand a pointer points at one address.
Say I want to get a set of all pointers that point at a particular
address.
If I want to do that once, I can go through all pointers, and see if
they point at that address.  Works fine.

If I want to get the set of all pointers to a particular address,
repeatedly, or, if the number of pointers (that may or may not point at
this address) is enormous, then this will be time consuming.  If some of
the pointers are stored on remote machines, my goal will be expensive
for the owners of those machines. If I don't have access to look at all
the pointers, then my goal will be impossible.

To solve the problems -- I can maintain the set of pointers to a
particular address, in a data structure associated with the address. The
set can be updated anytime a pointer is changed from or to this address.