branchmap: Save changectx creation during update
The newly introduced `branchmap` function allows us to skip the
creation of changectx objects. This speeds up the construction of
the branchmap.
On the mozilla repository (117293 changesets, 15490 mutable)
Before:
! impactable 19.9
! mutable 0.576
! unserved 3.16
After:
! impactable 7.03 (2.8x faster)
! mutable 0.352 (1.6x)
! unserved 1.15 (2.7x)
On the cpython repository (81418 changesets, 6418 mutable)
Before:
! impactable 15.9
! mutable 0.451
! unserved 0.861
After:
! impactable 6.55 (2.4x faster)
! mutable 0.170 (2.6x faster)
! unserved 0.289 (2.9x faster)
On the pypy repository (58852 changesets)
Before:
! impactable 13.6
After:
! impactable 6.17 (2.2x faster)
On my Mercurial repository (18295 changesets, 2210 mutable)
Before:
! impactable 23.9
! mutable 0.368
! unserved 0.057
After:
! impactable 1.31 (18x faster)
! mutable 0.042 (8.7x)
! unserved 0.025 (2.2x)
Create a repository:
$ hg init t
$ cd t
Make a changeset:
$ echo a > a
$ hg add a
$ hg commit -m test
This command is ancient:
$ hg history
changeset: 0:acb14030fe0a
tag: tip
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: test
Verify that updating to revision 0 via commands.update() works properly
$ cat <<EOF > update_to_rev0.py
> from mercurial import ui, hg, commands
> myui = ui.ui()
> repo = hg.repository(myui, path='.')
> commands.update(myui, repo, rev=0)
> EOF
$ hg up null
0 files updated, 0 files merged, 1 files removed, 0 files unresolved
$ python ./update_to_rev0.py
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ hg identify -n
0
Poke around at hashes:
$ hg manifest --debug
b789fdd96dc2f3bd229c1dd8eedf0fc60e2b68e3 644 a
$ hg cat a
a
Verify should succeed:
$ hg verify
checking changesets
checking manifests
crosschecking files in changesets and manifests
checking files
1 files, 1 changesets, 1 total revisions
At the end...
$ cd ..