[MERGE] Repository.get_revision_graph improvements

[John Arbash Meinel]

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

Robert Collins wrote:
| On Tue, 2008-02-26 at 17:30 -0600, John Arbash Meinel wrote:
|> If we instead chose a fixed hash algorithm to say 32-bit integers then
|> the combined index can have 1 single hash => (index, offset) map. So
|> when looking up revision-foo-bar you hash it 1 time, and get back the
|> possible indexes and positions right away.
|
| I think there are two problems in this proposal:
| a) the in memory hashtable becomes very big. This is a scaling problem
| itself.
| b) it will force pack-count reads to start any operations, which is also
| a scaling problem (rather than being a missed-lookup problem)
|
| That said I don't see my design prohibiting combining of hashtables as
| long as the same hash is chosen before the truncation.
|
| -Rob
|


Actually, you don't have to have it fully populated all the time. Just have it
"these are the hash entries I've seen". If you get a miss, then you go load the
next index in the list.

John
=:->
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.5 (Cygwin)
Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org

iD8DBQFHxYIFJdeBCYSNAAMRAt8uAJ9wxJ4wPw+3NRFvumE3W/cjwUrvJgCeLSoS
vg2eW64cfDJk5NhLDhXOTjE=
=Kays
-----END PGP SIGNATURE-----