dirstate-tree: Make `DirstateMap` borrow from a bytes buffer
… that has the contents of the `.hg/dirstate` file.
This only applies to the tree-based flavor of `DirstateMap`.
For now only the entire `&[u8]` slice is stored, so this is not useful yet.
Adding a lifetime parameter to the `DirstateMap` struct (in hg-core) makes
Python bindings non-trivial because we keep that struct in a Python object
that has a dynamic lifetime tied to Python’s reference-counting and GC.
As long as we keep the `PyBytes` that owns the borrowed bytes buffer next to
the borrowing struct, the buffer will live long enough for the borrows to stay
valid. However this relationship cannot be expressed in safe Rust code in a
way that would statisfy they borrow-checker. We use `unsafe` code to erase
that lifetime parameter, and encapsulate it in a safe abstraction similar to
the owning-ref crate: https://docs.rs/owning_ref/
Differential Revision: https://phab.mercurial-scm.org/D10557
#require no-reposimplestore
Test unionrepo functionality
Create one repository
$ hg init repo1
$ cd repo1
$ touch repo1-0
$ echo repo1-0 > f
$ hg ci -Aqmrepo1-0
$ touch repo1-1
$ echo repo1-1 >> f
$ hg ci -Aqmrepo1-1
$ touch repo1-2
$ echo repo1-2 >> f
$ hg ci -Aqmrepo1-2
$ hg log --template '{rev}:{node|short} {desc|firstline}\n'
2:68c0685446a3 repo1-2
1:8a58db72e69d repo1-1
0:f093fec0529b repo1-0
$ tip1=`hg id -q`
$ cd ..
- and a clone with a not-completely-trivial history
$ hg clone -q repo1 --rev 0 repo2
$ cd repo2
$ touch repo2-1
$ sed '1i\
> repo2-1 at top
> ' f > f.tmp
$ mv f.tmp f
$ hg ci -Aqmrepo2-1
$ touch repo2-2
$ hg pull -q ../repo1 -r 1
$ hg merge -q
$ hg ci -Aqmrepo2-2-merge
$ touch repo2-3
$ echo repo2-3 >> f
$ hg ci -mrepo2-3
$ hg log --template '{rev}:{node|short} {desc|firstline}\n'
4:2f0d178c469c repo2-3
3:9e6fb3e0b9da repo2-2-merge
2:8a58db72e69d repo1-1
1:c337dba826e7 repo2-1
0:f093fec0529b repo1-0
$ cd ..
revisions from repo2 appear as appended / pulled to repo1
$ hg -R union:repo1+repo2 log --template '{rev}:{node|short} {desc|firstline}\n'
5:2f0d178c469c repo2-3
4:9e6fb3e0b9da repo2-2-merge
3:c337dba826e7 repo2-1
2:68c0685446a3 repo1-2
1:8a58db72e69d repo1-1
0:f093fec0529b repo1-0
manifest can be retrieved for revisions in both repos
$ hg -R union:repo1+repo2 mani -r $tip1
f
repo1-0
repo1-1
repo1-2
$ hg -R union:repo1+repo2 mani -r 4
f
repo1-0
repo1-1
repo2-1
repo2-2
files can be retrieved form both repos
$ hg -R repo1 cat repo1/f -r2
repo1-0
repo1-1
repo1-2
$ hg -R union:repo1+repo2 cat -r$tip1 repo1/f
repo1-0
repo1-1
repo1-2
$ hg -R union:repo1+repo2 cat -r4 $TESTTMP/repo1/f
repo2-1 at top
repo1-0
repo1-1
files can be compared across repos
$ hg -R union:repo1+repo2 diff -r$tip1 -rtip
diff -r 68c0685446a3 -r 2f0d178c469c f
--- a/f Thu Jan 01 00:00:00 1970 +0000
+++ b/f Thu Jan 01 00:00:00 1970 +0000
@@ -1,3 +1,4 @@
+repo2-1 at top
repo1-0
repo1-1
-repo1-2
+repo2-3
heads from both repos are found correctly
$ hg -R union:repo1+repo2 heads --template '{rev}:{node|short} {desc|firstline}\n'
5:2f0d178c469c repo2-3
2:68c0685446a3 repo1-2
revsets works across repos
$ hg -R union:repo1+repo2 id -r "ancestor($tip1, 5)"
8a58db72e69d
annotate works - an indication that linkrevs works
$ hg --cwd repo1 -Runion:../repo2 annotate $TESTTMP/repo1/f -r tip
3: repo2-1 at top
0: repo1-0
1: repo1-1
5: repo2-3
union repos can be cloned ... and clones works correctly
$ hg clone -U union:repo1+repo2 repo3
requesting all changes
adding changesets
adding manifests
adding file changes
added 6 changesets with 11 changes to 6 files (+1 heads)
new changesets f093fec0529b:2f0d178c469c (6 drafts)
$ hg -R repo3 paths
default = union:repo1+repo2
$ hg -R repo3 verify
checking changesets
checking manifests
crosschecking files in changesets and manifests
checking files
checked 6 changesets with 11 changes to 6 files
$ hg -R repo3 heads --template '{rev}:{node|short} {desc|firstline}\n'
5:2f0d178c469c repo2-3
2:68c0685446a3 repo1-2
$ hg -R repo3 log --template '{rev}:{node|short} {desc|firstline}\n'
5:2f0d178c469c repo2-3
4:9e6fb3e0b9da repo2-2-merge
3:c337dba826e7 repo2-1
2:68c0685446a3 repo1-2
1:8a58db72e69d repo1-1
0:f093fec0529b repo1-0
union repos should use the correct rev number (issue5024)
$ hg init a
$ cd a
$ echo a0 >> f
$ hg ci -Aqm a0
$ cd ..
$ hg init b
$ cd b
$ echo b0 >> f
$ hg ci -Aqm b0
$ echo b1 >> f
$ hg ci -qm b1
$ cd ..
"hg files -v" to call fctx.size() -> fctx.iscensored()
$ hg files -R union:b+a -r2 -v
3 b/f