localrepo: stop doing special dirstate backup at transaction open
Since the dirstate writes are already managed by the transaction, we already do
a backup of the dirstate when necessary (and even trigger one to keep `hg
rollback` happy).
We needs some special code to deal with the initial empty checkout, but it is
not too complicated.
Managing variable filename (as dirstate-v2 uses) at the "journalfile" level, is
complex and fragile (which is consistent with the fact these files are not
journal…). If we no longer do it, our life is significantly simpler.
In some sense, we apply the xkcd-1134¹ solution to our savebackup/restorebackup
problem.
[1] https://xkcd.com/1134/
(the change to test-hardlink are expect as decreasing the number of duplicated
backup drive the hardlink count down)
Force revlog max inline value to be smaller than default
$ mkdir $TESTTMP/ext
$ cat << EOF > $TESTTMP/ext/small_inline.py
> from mercurial import revlog
> revlog._maxinline = 8
> EOF
$ cat << EOF >> $HGRCPATH
> [extensions]
> small_inline=$TESTTMP/ext/small_inline.py
> EOF
$ hg init repo
$ cd repo
Try on an empty repository
$ hg debug-revlog-stats
rev-count data-size inl type target
0 0 yes changelog
0 0 yes manifest
$ mkdir folder
$ touch a b folder/c folder/d
$ hg commit -Aqm 0
$ echo "text" > a
$ hg rm b
$ echo "longer string" > folder/d
$ hg commit -Aqm 1
Differences in data size observed with pure is due to different compression
algorithms
$ hg debug-revlog-stats
rev-count data-size inl type target
2 138 no changelog (no-pure !)
2 137 no changelog (pure !)
2 177 no manifest (no-pure !)
2 168 no manifest (pure !)
2 6 yes file a
1 0 yes file b
1 0 yes file folder/c
2 15 no file folder/d
Test 'changelog' command argument
$ hg debug-revlog-stats -c
rev-count data-size inl type target
2 138 no changelog (no-pure !)
2 137 no changelog (pure !)
Test 'manifest' command argument
$ hg debug-revlog-stats -m
rev-count data-size inl type target
2 177 no manifest (no-pure !)
2 168 no manifest (pure !)
Test 'file' command argument
$ hg debug-revlog-stats -f
rev-count data-size inl type target
2 6 yes file a
1 0 yes file b
1 0 yes file folder/c
2 15 no file folder/d
Test multiple command arguments
$ hg debug-revlog-stats -cm
rev-count data-size inl type target
2 138 no changelog (no-pure !)
2 137 no changelog (pure !)
2 177 no manifest (no-pure !)
2 168 no manifest (pure !)