revlog: increase I/O bound to 4x the amount of data consumed
This doesn't affect normal clones since they'd be bound by the CPU bound below
anyway -- it does, however, improve generaldelta clones significantly.
This also results in better deltaing for generaldelta clones -- in generaldelta
clones, we calculate deltas with respect to the closest base if it has a higher
revision number than either parent. If the base is on a significantly different
branch, this can result in pointlessly massive deltas. This reduces the number
of bases and hence the number of bad deltas.
Empirically, for a highly branchy repository, this resulted in an improvement
of around 15% to manifest size.
$ hg init t
$ cd t
$ echo 1 > foo
$ hg ci -Am m
adding foo
$ cd ..
$ hg clone t tt
updating to branch default
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ cd tt
$ echo 1.1 > foo
$ hg ci -Am m
$ cd ../t
$ echo 1.2 > foo
$ hg ci -Am m
Should not update:
$ hg pull -u ../tt
pulling from ../tt
searching for changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 1 changes to 1 files (+1 heads)
not updating: not a linear update
(merge or update --check to force update)
$ cd ../tt
Should not update:
$ hg pull -u ../t
pulling from ../t
searching for changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 1 changes to 1 files (+1 heads)
not updating: not a linear update
(merge or update --check to force update)
$ HGMERGE=true hg merge
merging foo
0 files updated, 1 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)
$ hg ci -mm
$ cd ../t
Should work:
$ hg pull -u ../tt
pulling from ../tt
searching for changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 1 changes to 1 files (-1 heads)
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ cd ..