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
Make sure that the internal merge tools (internal:fail, internal:local,
internal:union and internal:other) are used when matched by a
merge-pattern in hgrc
Make sure HGMERGE doesn't interfere with the test:
$ unset HGMERGE
$ hg init
Initial file contents:
$ echo "line 1" > f
$ echo "line 2" >> f
$ echo "line 3" >> f
$ hg ci -Am "revision 0"
adding f
$ cat f
line 1
line 2
line 3
Branch 1: editing line 1:
$ sed 's/line 1/first line/' f > f.new
$ mv f.new f
$ hg ci -Am "edited first line"
Branch 2: editing line 3:
$ hg update 0
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ sed 's/line 3/third line/' f > f.new
$ mv f.new f
$ hg ci -Am "edited third line"
created new head
Merge using internal:fail tool:
$ echo "[merge-patterns]" > .hg/hgrc
$ echo "* = internal:fail" >> .hg/hgrc
$ hg merge
0 files updated, 0 files merged, 0 files removed, 1 files unresolved
use 'hg resolve' to retry unresolved file merges or 'hg merge --abort' to abandon
[1]
$ cat f
line 1
line 2
third line
$ hg stat
M f
Merge using internal:local tool:
$ hg update -C 2
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ sed 's/internal:fail/internal:local/' .hg/hgrc > .hg/hgrc.new
$ mv .hg/hgrc.new .hg/hgrc
$ hg merge
0 files updated, 1 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)
$ cat f
line 1
line 2
third line
$ hg stat
M f
Merge using internal:other tool:
$ hg update -C 2
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ sed 's/internal:local/internal:other/' .hg/hgrc > .hg/hgrc.new
$ mv .hg/hgrc.new .hg/hgrc
$ hg merge
0 files updated, 1 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)
$ cat f
first line
line 2
line 3
$ hg stat
M f
Merge using default tool:
$ hg update -C 2
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ rm .hg/hgrc
$ hg merge
merging f
0 files updated, 1 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)
$ cat f
first line
line 2
third line
$ hg stat
M f
Merge using internal:union tool:
$ hg update -C 2
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ echo "line 4a" >>f
$ hg ci -Am "Adding fourth line (commit 4)"
$ hg update 2
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ echo "line 4b" >>f
$ hg ci -Am "Adding fourth line v2 (commit 5)"
created new head
$ echo "[merge-patterns]" > .hg/hgrc
$ echo "* = internal:union" >> .hg/hgrc
$ hg merge 3
merging f
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)
$ cat f
line 1
line 2
third line
line 4b
line 4a