phases: large rewrite on retract boundary
The new code is still pure Python, so we still have room to going significantly
faster. However its complexity of the complex part is `O(|[min_new_draft, tip]|)` instead of
`O(|[min_draft, tip]|` which should help tremendously one repository with old
draft (like mercurial-devel or mozilla-try).
This is especially useful as the most common "retract boundary" operation
happens when we commit/rewrite new drafts or when we push new draft to a
non-publishing server. In this case, the smallest new_revs is very close to the
tip and there is very few work to do.
A few smaller optimisation could be done for these cases and will be introduced in
later changesets.
We still have iterate over large sets of roots, but this is already a great
improvement for a very small amount of work. We gather information on the
affected changeset as we go as we can put it to use in the next changesets.
This extra data collection might slowdown the `register_new` case a bit, however
for register_new, it should not really matters. The set of new nodes is either
small, so the impact is negligible, or the set of new nodes is large, and the
amount of work to do to had them will dominate the overhead the collecting
information in `changed_revs`.
As this new code compute the changes on the fly, it unlock other interesting
improvement to be done in later changeset.
$ echo "[extensions]" >> $HGRCPATH
$ echo "mq=" >> $HGRCPATH
$ hg init
$ echo qqq>qqq.txt
rollback dry run without rollback information
$ hg rollback
no rollback information available
[1]
add file
$ hg add
adding qqq.txt
commit first revision
$ hg ci -m 1
set bookmark
$ hg book test
$ echo www>>qqq.txt
commit second revision
$ hg ci -m 2
set bookmark
$ hg book test2
update to -2 (deactivates the active bookmark)
$ hg update -r -2
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
(leaving bookmark test2)
$ echo eee>>qqq.txt
commit new head
$ hg ci -m 3
created new head
bookmarks updated?
$ hg book
test 1:25e1ee7a0081
test2 1:25e1ee7a0081
strip to revision 1
$ hg strip 1
saved backup bundle to $TESTTMP/.hg/strip-backup/*-backup.hg (glob)
list bookmarks
$ hg book
test 0:5c9ad3787638
test2 0:5c9ad3787638