localrepo: create new function for instantiating a local repo object
Today, there is a single local repository class - localrepository. Its
__init__ is responsible for loading the .hg/requires file and taking
different actions depending on what is present.
In addition, extensions may define a "reposetup" function that
monkeypatches constructed repository instances, often by implementing
a derived type and changing the __class__ of the repo instance.
Work around alternate storage backends and partial clone has made it
clear to me that shoehorning all this logic into __init__ and operating
on an existing instance is too convoluted. For example, localrepository
assumes revlog storage and swapping in non-revlog storage requires
overriding e.g. file() to return something that isn't a revlog. I've
authored various patches that either:
a) teach various methods (like file()) about different states and
taking the appropriate code path at run-time
b) create methods/attributes/callables used for instantiating things
and populating these in __init__
"a" incurs run-time performance penalties and makes code more
complicated since various functions have a bunch of "if storage is X"
branches.
"b" makes localrepository quickly explode in complexity.
My plan for tackling this problem is to make the local repository type
more dynamic. Instead of a static localrepository class/type that
supports all of the local repository configurations (revlogs vs other,
revlogs with ellipsis, revlog v1 versus revlog v2, etc), we'll
dynamically construct a type providing the implementations that are
needed for the repository on disk, derived from the .hg/requires file
and configuration options. The constructed repository type will be
specialized and methods won't need to be taught about different
implementations nor overloaded.
We may also leverage this functionality for building types that don't
implement all attributes. For example, the "intents" feature allows
commands to declare that they are read only. By dynamically
constructing a repository type, we could return a repository instance
with no attributes related to mutating the repository. This could
include things like a "changelog" property implementation that doesn't
check whether it needs to invalidate the hidden revisions set on every
access.
This commit establishes a function for building a local repository
instance. Future commits will start moving functionality from
localrepository.__init__ to this function. Then we'll start dynamically
changing the returned type depending on options that are present.
This change may seem radical. But it should be fully compatible with
the reposetup() model - at least for now.
Differential Revision: https://phab.mercurial-scm.org/D4563
test branch selection options
$ hg init branch
$ cd branch
$ hg branch a
marked working directory as branch a
(branches are permanent and global, did you want a bookmark?)
$ echo a > foo
$ hg ci -d '0 0' -Ama
adding foo
$ echo a2 > foo
$ hg ci -d '0 0' -ma2
$ hg up 0
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ hg branch c
marked working directory as branch c
$ echo c > foo
$ hg ci -d '0 0' -mc
$ hg tag -l z
$ cd ..
$ hg clone -r 0 branch branch2
adding changesets
adding manifests
adding file changes
added 1 changesets with 1 changes to 1 files
new changesets 5b65ba7c951d
updating to branch a
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ cd branch2
$ hg up 0
0 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ hg branch b
marked working directory as branch b
$ echo b > foo
$ hg ci -d '0 0' -mb
$ hg up 0
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ hg --encoding utf-8 branch æ
marked working directory as branch \xc3\xa6 (esc)
$ echo ae1 > foo
$ hg ci -d '0 0' -mae1
$ hg up 0
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ hg --encoding utf-8 branch -f æ
marked working directory as branch \xc3\xa6 (esc)
$ echo ae2 > foo
$ hg ci -d '0 0' -mae2
created new head
$ hg up 0
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ hg branch -f b
marked working directory as branch b
$ echo b2 > foo
$ hg ci -d '0 0' -mb2
created new head
unknown branch and fallback
$ hg in -qbz
abort: unknown branch 'z'!
[255]
$ hg in -q ../branch#z
2:f25d57ab0566
$ hg out -qbz
abort: unknown branch 'z'!
[255]
in rev c branch a
$ hg in -qr c ../branch#a
1:dd6e60a716c6
2:f25d57ab0566
$ hg in -qr c -b a
1:dd6e60a716c6
2:f25d57ab0566
out branch .
$ hg out -q ../branch#.
1:b84708d77ab7
4:65511d0e2b55
$ hg out -q -b .
1:b84708d77ab7
4:65511d0e2b55
out branch . non-ascii
$ hg --encoding utf-8 up æ
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ hg --encoding latin1 out -q ../branch#.
2:df5a44224d4e
3:4f4a5125ca10
$ hg --encoding latin1 out -q -b .
2:df5a44224d4e
3:4f4a5125ca10
clone branch b
$ cd ..
$ hg clone branch2#b branch3
adding changesets
adding manifests
adding file changes
added 3 changesets with 3 changes to 1 files (+1 heads)
new changesets 5b65ba7c951d:65511d0e2b55
updating to branch b
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ hg -q -R branch3 heads b
2:65511d0e2b55
1:b84708d77ab7
$ hg -q -R branch3 parents
2:65511d0e2b55
$ rm -rf branch3
clone rev a branch b
$ hg clone -r a branch2#b branch3
adding changesets
adding manifests
adding file changes
added 3 changesets with 3 changes to 1 files (+1 heads)
new changesets 5b65ba7c951d:65511d0e2b55
updating to branch a
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ hg -q -R branch3 heads b
2:65511d0e2b55
1:b84708d77ab7
$ hg -q -R branch3 parents
0:5b65ba7c951d
$ rm -rf branch3