revlog: move censor logic into main revlog class
Previously, the revlog class implemented dummy methods for
various censor-related functionality. Revision censoring was
(and will continue to be) only possible on filelog instances.
So filelog implemented these methods to perform something
reasonable.
A problem with implementing censoring on filelog is that
it assumes filelog is a revlog. Upcoming work to formalize
the filelog interface will make this not true.
Furthermore, the censoring logic is security-sensitive. I
think action-at-a-distance with custom implementation of core
revlog APIs in derived classes is a bit dangerous. I think at
a minimum the censor logic should live in revlog.py.
I was tempted to created a "censored revlog" class that
basically pulled these methods out of filelog. But, I wasn't
a huge fan of overriding core methods in child classes. A
reason to do that would be performance. However, the censoring
code only comes into play when:
* hash verification fails
* delta generation
* applying deltas from changegroups
The new code is conditional on an instance attribute. So the
overhead for running the censored code when the revlog isn't
censorable is an attribute lookup. All of these operations are
at least a magnitude slower than a Python attribute lookup. So
there shouldn't be a performance concern.
Differential Revision: https://phab.mercurial-scm.org/D3151
#require hardlink
$ echo "[extensions]" >> $HGRCPATH
$ echo "relink=" >> $HGRCPATH
$ fix_path() {
> tr '\\' /
> }
$ cat > arelinked.py <<EOF
> from __future__ import absolute_import, print_function
> import os
> import sys
> from mercurial import util
> path1, path2 = sys.argv[1:3]
> if util.samefile(path1, path2):
> print('%s == %s' % (path1, path2))
> else:
> print('%s != %s' % (path1, path2))
> EOF
create source repository
$ hg init repo
$ cd repo
$ echo a > a
$ echo b > b
$ hg ci -Am addfile
adding a
adding b
$ cat "$TESTDIR/binfile.bin" >> a
$ cat "$TESTDIR/binfile.bin" >> b
$ hg ci -Am changefiles
make another commit to create files larger than 1 KB to test
formatting of final byte count
$ cat "$TESTDIR/binfile.bin" >> a
$ cat "$TESTDIR/binfile.bin" >> b
$ hg ci -m anotherchange
don't sit forever trying to double-lock the source repo
$ hg relink .
relinking $TESTTMP/repo/.hg/store to $TESTTMP/repo/.hg/store
there is nothing to relink
Test files are read in binary mode
$ $PYTHON -c "open('.hg/store/data/dummy.i', 'wb').write(b'a\r\nb\n')"
$ cd ..
clone and pull to break links
$ hg clone --pull -r0 repo clone
adding changesets
adding manifests
adding file changes
added 1 changesets with 2 changes to 2 files
new changesets 008c0c271c47
updating to branch default
2 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ cd clone
$ hg pull -q
$ echo b >> b
$ hg ci -m changeb
created new head
$ $PYTHON -c "open('.hg/store/data/dummy.i', 'wb').write(b'a\nb\r\n')"
relink
#if no-reposimplestore
$ hg relink --debug --config progress.debug=true | fix_path
relinking $TESTTMP/repo/.hg/store to $TESTTMP/clone/.hg/store
tip has 2 files, estimated total number of files: 3
collecting: 00changelog.i 1/3 files (33.33%)
collecting: 00manifest.i 2/3 files (66.67%)
collecting: a.i 3/3 files (100.00%)
collecting: b.i 4/3 files (133.33%)
collecting: dummy.i 5/3 files (166.67%)
collected 5 candidate storage files
not linkable: 00changelog.i
not linkable: 00manifest.i
pruning: data/a.i 3/5 files (60.00%)
not linkable: data/b.i
pruning: data/dummy.i 5/5 files (100.00%)
pruned down to 2 probably relinkable files
relinking: data/a.i 1/2 files (50.00%)
not linkable: data/dummy.i
relinked 1 files (1.36 KB reclaimed)
$ cd ..
check hardlinks
$ $PYTHON arelinked.py repo/.hg/store/data/a.i clone/.hg/store/data/a.i
repo/.hg/store/data/a.i == clone/.hg/store/data/a.i
$ $PYTHON arelinked.py repo/.hg/store/data/b.i clone/.hg/store/data/b.i
repo/.hg/store/data/b.i != clone/.hg/store/data/b.i
#endif