[Monotone-devel] Re: next release

[graydon hoare]

Richard Levitte - VMS Whacker wrote:
> In message <address@hidden> on Mon, 27 Dec 2004 14:15:37 -0500, graydon hoare 
> <address@hidden> said:
>
> graydon>    - make a "rechangesetify" command (suggestions for a nicer
> graydon>      name welcome) which rebuilds the rev graph from the
> graydon>      underlying manifests, with predictable rename lossage
>
> Uhmmmm...  I probably missed something.  Why do we need to
> changesetify *again*?

yes. there was a bug in the changeset merging code which produced (and 
saved, published, shared all around) some completely bogus changesets. 
like, they make no sense. you can read them, they are structurally sound 
-- they can parse and print -- but logically nuts. they describe 
combinations of additions and patches which don't have any sensible 
interpretation, and shouldn't occur there anyways. they don't describe 
the differences between the manifests on either side.

the presence of these "bad" revisions is something we can detect, and 
fault on. unfortunately every bad revision has a hash code, and this 
code is used as the ancestor for revisions which follow it. so 
everything "after" a bad revision is essentially tainted with some badness.

the badness is only so bad: you won't encounter it unless you want to do 
a merge which traverses one of the bad edges, during a propagate or 
common-ancestor search. the rest of the time it's just "crazy history". 
but we discussed this a bit on IRC and largely came to the conclusion 
that it's better to remove the badness now by rebuilding the graph than 
it is to let it fester there for years.

-graydon