revlog: skeleton support for version 2 revlogs
There are a number of improvements we want to make to revlogs
that will require a new version - version 2. It is unclear what the
full set of improvements will be or when we'll be done with them.
What I do know is that the process will likely take longer than a
single release, will require input from various stakeholders to
evaluate changes, and will have many contentious debates and
bikeshedding.
It is unrealistic to develop revlog version 2 up front: there
are just too many uncertainties that we won't know until things
are implemented and experiments are run. Some changes will also
be invasive and prone to bit rot, so sitting on dozens of patches
is not practical.
This commit introduces skeleton support for version 2 revlogs in
a way that is flexible and not bound by backwards compatibility
concerns.
An experimental repo requirement for denoting revlog v2 has been
added. The requirement string has a sub-version component to it.
This will allow us to declare multiple requirements in the course
of developing revlog v2. Whenever we change the in-development
revlog v2 format, we can tweak the string, creating a new
requirement and locking out old clients. This will allow us to
make as many backwards incompatible changes and experiments to
revlog v2 as we want. In other words, we can land code and make
meaningful progress towards revlog v2 while still maintaining
extreme format flexibility up until the point we freeze the
format and remove the experimental labels.
To enable the new repo requirement, you must supply an experimental
and undocumented config option. But not just any boolean flag
will do: you need to explicitly use a value that no sane person
should ever type. This is an additional guard against enabling
revlog v2 on an installation it shouldn't be enabled on. The
specific scenario I'm trying to prevent is say a user with a
4.4 client with a frozen format enabling the option but then
downgrading to 4.3 and accidentally creating repos with an
outdated and unsupported repo format. Requiring a "challenge"
string should prevent this.
Because the format is not yet finalized and I don't want to take
any chances, revlog v2's version is currently 0xDEAD. I figure
squatting on a value we're likely never to use as an actual revlog
version to mean "internal testing only" is acceptable. And
"dead" is easily recognized as something meaningful.
There is a bunch of cleanup that is needed before work on revlog
v2 begins in earnest. I plan on doing that work once this patch
is accepted and we're comfortable with the idea of starting down
this path.
#require symlink execbit
$ tellmeabout() {
> if [ -h $1 ]; then
> echo $1 is a symlink:
> $TESTDIR/readlink.py $1
> elif [ -x $1 ]; then
> echo $1 is an executable file with content:
> cat $1
> else
> echo $1 is a plain file with content:
> cat $1
> fi
> }
$ hg init test1
$ cd test1
$ echo a > a
$ hg ci -Aqmadd
$ chmod +x a
$ hg ci -mexecutable
$ hg up -q 0
$ rm a
$ ln -s symlink a
$ hg ci -msymlink
created new head
Symlink is local parent, executable is other:
$ hg merge --debug
searching for copies back to rev 1
resolving manifests
branchmerge: True, force: False, partial: False
ancestor: c334dc3be0da, local: 521a1e40188f+, remote: 3574f3e69b1c
preserving a for resolve of a
a: versions differ -> m (premerge)
picked tool ':merge' for a (binary False symlink True changedelete False)
merging a
my a@521a1e40188f+ other a@3574f3e69b1c ancestor a@c334dc3be0da
warning: internal :merge cannot merge symlinks for a
warning: conflicts while merging a! (edit, then use 'hg resolve --mark')
0 files updated, 0 files merged, 0 files removed, 1 files unresolved
use 'hg resolve' to retry unresolved file merges or 'hg update -C .' to abandon
[1]
$ tellmeabout a
a is a symlink:
a -> symlink
$ hg resolve a --tool internal:other
(no more unresolved files)
$ tellmeabout a
a is an executable file with content:
a
$ hg st
M a
? a.orig
Symlink is other parent, executable is local:
$ hg update -C 1
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ hg merge --debug --tool :union
searching for copies back to rev 1
resolving manifests
branchmerge: True, force: False, partial: False
ancestor: c334dc3be0da, local: 3574f3e69b1c+, remote: 521a1e40188f
preserving a for resolve of a
a: versions differ -> m (premerge)
picked tool ':union' for a (binary False symlink True changedelete False)
merging a
my a@3574f3e69b1c+ other a@521a1e40188f ancestor a@c334dc3be0da
warning: internal :union cannot merge symlinks for a
warning: conflicts while merging a! (edit, then use 'hg resolve --mark')
0 files updated, 0 files merged, 0 files removed, 1 files unresolved
use 'hg resolve' to retry unresolved file merges or 'hg update -C .' to abandon
[1]
$ tellmeabout a
a is an executable file with content:
a
$ hg update -C 1
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ hg merge --debug --tool :merge3
searching for copies back to rev 1
resolving manifests
branchmerge: True, force: False, partial: False
ancestor: c334dc3be0da, local: 3574f3e69b1c+, remote: 521a1e40188f
preserving a for resolve of a
a: versions differ -> m (premerge)
picked tool ':merge3' for a (binary False symlink True changedelete False)
merging a
my a@3574f3e69b1c+ other a@521a1e40188f ancestor a@c334dc3be0da
warning: internal :merge3 cannot merge symlinks for a
warning: conflicts while merging a! (edit, then use 'hg resolve --mark')
0 files updated, 0 files merged, 0 files removed, 1 files unresolved
use 'hg resolve' to retry unresolved file merges or 'hg update -C .' to abandon
[1]
$ tellmeabout a
a is an executable file with content:
a
$ hg update -C 1
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ hg merge --debug --tool :merge-local
searching for copies back to rev 1
resolving manifests
branchmerge: True, force: False, partial: False
ancestor: c334dc3be0da, local: 3574f3e69b1c+, remote: 521a1e40188f
preserving a for resolve of a
a: versions differ -> m (premerge)
picked tool ':merge-local' for a (binary False symlink True changedelete False)
merging a
my a@3574f3e69b1c+ other a@521a1e40188f ancestor a@c334dc3be0da
warning: internal :merge-local cannot merge symlinks for a
0 files updated, 0 files merged, 0 files removed, 1 files unresolved
use 'hg resolve' to retry unresolved file merges or 'hg update -C .' to abandon
[1]
$ tellmeabout a
a is an executable file with content:
a
$ hg update -C 1
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ hg merge --debug --tool :merge-other
searching for copies back to rev 1
resolving manifests
branchmerge: True, force: False, partial: False
ancestor: c334dc3be0da, local: 3574f3e69b1c+, remote: 521a1e40188f
preserving a for resolve of a
a: versions differ -> m (premerge)
picked tool ':merge-other' for a (binary False symlink True changedelete False)
merging a
my a@3574f3e69b1c+ other a@521a1e40188f ancestor a@c334dc3be0da
warning: internal :merge-other cannot merge symlinks for a
0 files updated, 0 files merged, 0 files removed, 1 files unresolved
use 'hg resolve' to retry unresolved file merges or 'hg update -C .' to abandon
[1]
$ tellmeabout a
a is an executable file with content:
a
Update to link without local change should get us a symlink (issue3316):
$ hg up -C 0
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ hg up
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
1 other heads for branch "default"
$ hg st
? a.orig
Update to link with local change should cause a merge prompt (issue3200):
$ hg up -Cq 0
$ echo data > a
$ HGMERGE= hg up -y --debug
searching for copies back to rev 2
resolving manifests
branchmerge: False, force: False, partial: False
ancestor: c334dc3be0da, local: c334dc3be0da+, remote: 521a1e40188f
preserving a for resolve of a
a: versions differ -> m (premerge)
(couldn't find merge tool hgmerge|tool hgmerge can't handle symlinks) (re)
no tool found to merge a
picked tool ':prompt' for a (binary False symlink True changedelete False)
keep (l)ocal [working copy], take (o)ther [destination], or leave (u)nresolved for a? u
0 files updated, 0 files merged, 0 files removed, 1 files unresolved
use 'hg resolve' to retry unresolved file merges
1 other heads for branch "default"
[1]
$ hg diff --git
diff --git a/a b/a
old mode 120000
new mode 100644
--- a/a
+++ b/a
@@ -1,1 +1,1 @@
-symlink
\ No newline at end of file
+data
Test only 'l' change - happens rarely, except when recovering from situations
where that was what happened.
$ hg init test2
$ cd test2
$ printf base > f
$ hg ci -Aqm0
$ echo file > f
$ echo content >> f
$ hg ci -qm1
$ hg up -qr0
$ rm f
$ ln -s base f
$ hg ci -qm2
$ hg merge
merging f
warning: internal :merge cannot merge symlinks for f
warning: conflicts while merging f! (edit, then use 'hg resolve --mark')
0 files updated, 0 files merged, 0 files removed, 1 files unresolved
use 'hg resolve' to retry unresolved file merges or 'hg update -C .' to abandon
[1]
$ tellmeabout f
f is a symlink:
f -> base
$ hg up -Cqr1
$ hg merge
merging f
warning: internal :merge cannot merge symlinks for f
warning: conflicts while merging f! (edit, then use 'hg resolve --mark')
0 files updated, 0 files merged, 0 files removed, 1 files unresolved
use 'hg resolve' to retry unresolved file merges or 'hg update -C .' to abandon
[1]
$ tellmeabout f
f is a plain file with content:
file
content
$ cd ..
Test removed 'x' flag merged with change to symlink
$ hg init test3
$ cd test3
$ echo f > f
$ chmod +x f
$ hg ci -Aqm0
$ chmod -x f
$ hg ci -qm1
$ hg up -qr0
$ rm f
$ ln -s dangling f
$ hg ci -qm2
$ hg merge
merging f
warning: internal :merge cannot merge symlinks for f
warning: conflicts while merging f! (edit, then use 'hg resolve --mark')
0 files updated, 0 files merged, 0 files removed, 1 files unresolved
use 'hg resolve' to retry unresolved file merges or 'hg update -C .' to abandon
[1]
$ tellmeabout f
f is a symlink:
f -> dangling
$ hg up -Cqr1
$ hg merge
merging f
warning: internal :merge cannot merge symlinks for f
warning: conflicts while merging f! (edit, then use 'hg resolve --mark')
0 files updated, 0 files merged, 0 files removed, 1 files unresolved
use 'hg resolve' to retry unresolved file merges or 'hg update -C .' to abandon
[1]
$ tellmeabout f
f is a plain file with content:
f
Test removed 'x' flag merged with content change - both ways
$ hg up -Cqr0
$ echo change > f
$ hg ci -qm3
$ hg merge -r1
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)
$ tellmeabout f
f is a plain file with content:
change
$ hg up -qCr1
$ hg merge -r3
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)
$ tellmeabout f
f is a plain file with content:
change
$ cd ..
Test merge with no common ancestor:
a: just different
b: x vs -, different (cannot calculate x, cannot ask merge tool)
c: x vs -, same (cannot calculate x, merge tool is no good)
d: x vs l, different
e: x vs l, same
f: - vs l, different
g: - vs l, same
h: l vs l, different
(where same means the filelog entry is shared and there thus is an ancestor!)
$ hg init test4
$ cd test4
$ echo 0 > 0
$ hg ci -Aqm0
$ echo 1 > a
$ echo 1 > b
$ chmod +x b
$ echo 1 > bx
$ chmod +x bx
$ echo x > c
$ chmod +x c
$ echo 1 > d
$ chmod +x d
$ printf x > e
$ chmod +x e
$ echo 1 > f
$ printf x > g
$ ln -s 1 h
$ hg ci -qAm1
$ hg up -qr0
$ echo 2 > a
$ echo 2 > b
$ echo 2 > bx
$ chmod +x bx
$ echo x > c
$ ln -s 2 d
$ ln -s x e
$ ln -s 2 f
$ ln -s x g
$ ln -s 2 h
$ hg ci -Aqm2
$ hg merge
merging a
warning: cannot merge flags for b without common ancestor - keeping local flags
merging b
merging bx
warning: cannot merge flags for c without common ancestor - keeping local flags
merging d
warning: internal :merge cannot merge symlinks for d
warning: conflicts while merging d! (edit, then use 'hg resolve --mark')
merging f
warning: internal :merge cannot merge symlinks for f
warning: conflicts while merging f! (edit, then use 'hg resolve --mark')
merging h
warning: internal :merge cannot merge symlinks for h
warning: conflicts while merging h! (edit, then use 'hg resolve --mark')
warning: conflicts while merging a! (edit, then use 'hg resolve --mark')
warning: conflicts while merging b! (edit, then use 'hg resolve --mark')
warning: conflicts while merging bx! (edit, then use 'hg resolve --mark')
3 files updated, 0 files merged, 0 files removed, 6 files unresolved
use 'hg resolve' to retry unresolved file merges or 'hg update -C .' to abandon
[1]
$ hg resolve -l
U a
U b
U bx
U d
U f
U h
$ tellmeabout a
a is a plain file with content:
<<<<<<< working copy: 0c617753b41b - test: 2
2
=======
1
>>>>>>> merge rev: 2e60aa20b912 - test: 1
$ tellmeabout b
b is a plain file with content:
<<<<<<< working copy: 0c617753b41b - test: 2
2
=======
1
>>>>>>> merge rev: 2e60aa20b912 - test: 1
$ tellmeabout c
c is a plain file with content:
x
$ tellmeabout d
d is a symlink:
d -> 2
$ tellmeabout e
e is a symlink:
e -> x
$ tellmeabout f
f is a symlink:
f -> 2
$ tellmeabout g
g is a symlink:
g -> x
$ tellmeabout h
h is a symlink:
h -> 2
$ hg up -Cqr1
$ hg merge
merging a
warning: cannot merge flags for b without common ancestor - keeping local flags
merging b
merging bx
warning: cannot merge flags for c without common ancestor - keeping local flags
merging d
warning: internal :merge cannot merge symlinks for d
warning: conflicts while merging d! (edit, then use 'hg resolve --mark')
merging f
warning: internal :merge cannot merge symlinks for f
warning: conflicts while merging f! (edit, then use 'hg resolve --mark')
merging h
warning: internal :merge cannot merge symlinks for h
warning: conflicts while merging h! (edit, then use 'hg resolve --mark')
warning: conflicts while merging a! (edit, then use 'hg resolve --mark')
warning: conflicts while merging b! (edit, then use 'hg resolve --mark')
warning: conflicts while merging bx! (edit, then use 'hg resolve --mark')
3 files updated, 0 files merged, 0 files removed, 6 files unresolved
use 'hg resolve' to retry unresolved file merges or 'hg update -C .' to abandon
[1]
$ tellmeabout a
a is a plain file with content:
<<<<<<< working copy: 2e60aa20b912 - test: 1
1
=======
2
>>>>>>> merge rev: 0c617753b41b - test: 2
$ tellmeabout b
b is an executable file with content:
<<<<<<< working copy: 2e60aa20b912 - test: 1
1
=======
2
>>>>>>> merge rev: 0c617753b41b - test: 2
$ tellmeabout c
c is an executable file with content:
x
$ tellmeabout d
d is an executable file with content:
1
$ tellmeabout e
e is an executable file with content:
x (no-eol)
$ tellmeabout f
f is a plain file with content:
1
$ tellmeabout g
g is a plain file with content:
x (no-eol)
$ tellmeabout h
h is a symlink:
h -> 1
$ cd ..