branchcache: add a "pure topological head" fast path
In a narrow but actually quick common case, all topological heads are all on
the same branch and all open. In this case, computing the branch map is very
simple. We can quickly detect situation where this situation will not change.
So we update the V3 format to be able to express this situation and upgrade the
update code to detect we remains in that mode.
The branch cache is populated with the actual value when the branch map is
accessed, but the update_disk method can do the update without needing to
populate it.
$ . "$TESTDIR/histedit-helpers.sh"
$ cat >> $HGRCPATH <<EOF
> [extensions]
> histedit=
> EOF
$ hg init r
$ cd r
$ for x in a b c d e f ; do
> echo $x > $x
> hg add $x
> hg ci -m $x
> done
$ hg book -r 1 will-move-backwards
$ hg book -r 2 two
$ hg book -r 2 also-two
$ hg book -r 3 three
$ hg book -r 4 four
$ hg book -r tip five
$ hg log --graph
@ changeset: 5:652413bf663e
| bookmark: five
| tag: tip
| user: test
| date: Thu Jan 01 00:00:00 1970 +0000
| summary: f
|
o changeset: 4:e860deea161a
| bookmark: four
| user: test
| date: Thu Jan 01 00:00:00 1970 +0000
| summary: e
|
o changeset: 3:055a42cdd887
| bookmark: three
| user: test
| date: Thu Jan 01 00:00:00 1970 +0000
| summary: d
|
o changeset: 2:177f92b77385
| bookmark: also-two
| bookmark: two
| user: test
| date: Thu Jan 01 00:00:00 1970 +0000
| summary: c
|
o changeset: 1:d2ae7f538514
| bookmark: will-move-backwards
| user: test
| date: Thu Jan 01 00:00:00 1970 +0000
| summary: b
|
o changeset: 0:cb9a9f314b8b
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: a
$ HGEDITOR=cat hg histedit 1
pick d2ae7f538514 1 b
pick 177f92b77385 2 c
pick 055a42cdd887 3 d
pick e860deea161a 4 e
pick 652413bf663e 5 f
# Edit history between d2ae7f538514 and 652413bf663e
#
# Commits are listed from least to most recent
#
# You can reorder changesets by reordering the lines
#
# Commands:
#
# e, edit = use commit, but allow edits before making new commit
# m, mess = edit commit message without changing commit content
# p, pick = use commit
# b, base = checkout changeset and apply further changesets from there
# d, drop = remove commit from history
# f, fold = use commit, but combine it with the one above
# r, roll = like fold, but discard this commit's description and date
#
$ hg histedit 1 --commands - --verbose << EOF | grep histedit
> pick 177f92b77385 2 c
> drop d2ae7f538514 1 b
> pick 055a42cdd887 3 d
> fold e860deea161a 4 e
> pick 652413bf663e 5 f
> EOF
saved backup bundle to $TESTTMP/r/.hg/strip-backup/96e494a2d553-45c027ab-histedit.hg
$ hg log --graph
@ changeset: 3:cacdfd884a93
| bookmark: five
| tag: tip
| user: test
| date: Thu Jan 01 00:00:00 1970 +0000
| summary: f
|
o changeset: 2:59d9f330561f
| bookmark: four
| bookmark: three
| user: test
| date: Thu Jan 01 00:00:00 1970 +0000
| summary: d
|
o changeset: 1:b346ab9a313d
| bookmark: also-two
| bookmark: two
| user: test
| date: Thu Jan 01 00:00:00 1970 +0000
| summary: c
|
o changeset: 0:cb9a9f314b8b
bookmark: will-move-backwards
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: a
$ HGEDITOR=cat hg histedit 1
pick b346ab9a313d 1 c
pick 59d9f330561f 2 d
pick cacdfd884a93 3 f
# Edit history between b346ab9a313d and cacdfd884a93
#
# Commits are listed from least to most recent
#
# You can reorder changesets by reordering the lines
#
# Commands:
#
# e, edit = use commit, but allow edits before making new commit
# m, mess = edit commit message without changing commit content
# p, pick = use commit
# b, base = checkout changeset and apply further changesets from there
# d, drop = remove commit from history
# f, fold = use commit, but combine it with the one above
# r, roll = like fold, but discard this commit's description and date
#
$ hg histedit 1 --commands - --verbose << EOF | grep histedit
> pick b346ab9a313d 1 c
> pick cacdfd884a93 3 f
> pick 59d9f330561f 2 d
> EOF
saved backup bundle to $TESTTMP/r/.hg/strip-backup/59d9f330561f-073008af-histedit.hg
We expect 'five' to stay at tip, since the tipmost bookmark is most
likely the useful signal.
$ hg log --graph
@ changeset: 3:c04e50810e4b
| bookmark: five
| bookmark: four
| bookmark: three
| tag: tip
| user: test
| date: Thu Jan 01 00:00:00 1970 +0000
| summary: d
|
o changeset: 2:c13eb81022ca
| user: test
| date: Thu Jan 01 00:00:00 1970 +0000
| summary: f
|
o changeset: 1:b346ab9a313d
| bookmark: also-two
| bookmark: two
| user: test
| date: Thu Jan 01 00:00:00 1970 +0000
| summary: c
|
o changeset: 0:cb9a9f314b8b
bookmark: will-move-backwards
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: a