bdiff: balance recursion to avoid quadratic behavior (issue4704)
For highly structured files like JSON or XML dumps with large numbers
of duplicate lines (eg braces) and isolated matching lines, bdiff
could find large numbers of equally good spans. Because it prefers
earlier matches, this would result in pathologically unbalance
recursion that resulted in quadratic performance.
This patch makes it prefer matches closer to the middle that tend to
balance recursion. This change improves the speed of a pathological
test case from 1100s to 9s.
Included is a smaller test that has a roughly 50x safety margin on the
performance it accepts. It's likely to fail on pure builds because
difflib also has a recursion-balancing problem.
#require unix-permissions
test that new files created in .hg inherit the permissions from .hg/store
$ mkdir dir
just in case somebody has a strange $TMPDIR
$ chmod g-s dir
$ cd dir
$ cat >printmodes.py <<EOF
> import os, sys
>
> allnames = []
> isdir = {}
> for root, dirs, files in os.walk(sys.argv[1]):
> for d in dirs:
> name = os.path.join(root, d)
> isdir[name] = 1
> allnames.append(name)
> for f in files:
> name = os.path.join(root, f)
> allnames.append(name)
> allnames.sort()
> for name in allnames:
> suffix = name in isdir and '/' or ''
> print '%05o %s%s' % (os.lstat(name).st_mode & 07777, name, suffix)
> EOF
$ cat >mode.py <<EOF
> import sys
> import os
> print '%05o' % os.lstat(sys.argv[1]).st_mode
> EOF
$ umask 077
$ hg init repo
$ cd repo
$ chmod 0770 .hg/store
before commit
store can be written by the group, other files cannot
store is setgid
$ python ../printmodes.py .
00700 ./.hg/
00600 ./.hg/00changelog.i
00600 ./.hg/requires
00770 ./.hg/store/
$ mkdir dir
$ touch foo dir/bar
$ hg ci -qAm 'add files'
after commit
working dir files can only be written by the owner
files created in .hg can be written by the group
(in particular, store/**, dirstate, branch cache file, undo files)
new directories are setgid
$ python ../printmodes.py .
00700 ./.hg/
00600 ./.hg/00changelog.i
00770 ./.hg/cache/
00660 ./.hg/cache/branch2-served
00660 ./.hg/cache/rbc-names-v1
00660 ./.hg/cache/rbc-revs-v1
00660 ./.hg/dirstate
00660 ./.hg/last-message.txt
00600 ./.hg/requires
00770 ./.hg/store/
00660 ./.hg/store/00changelog.i
00660 ./.hg/store/00manifest.i
00770 ./.hg/store/data/
00770 ./.hg/store/data/dir/
00660 ./.hg/store/data/dir/bar.i
00660 ./.hg/store/data/foo.i
00660 ./.hg/store/fncache
00660 ./.hg/store/phaseroots
00660 ./.hg/store/undo
00660 ./.hg/store/undo.backupfiles
00660 ./.hg/store/undo.phaseroots
00660 ./.hg/undo.backup.dirstate
00660 ./.hg/undo.bookmarks
00660 ./.hg/undo.branch
00660 ./.hg/undo.desc
00660 ./.hg/undo.dirstate
00700 ./dir/
00600 ./dir/bar
00600 ./foo
$ umask 007
$ hg init ../push
before push
group can write everything
$ python ../printmodes.py ../push
00770 ../push/.hg/
00660 ../push/.hg/00changelog.i
00660 ../push/.hg/requires
00770 ../push/.hg/store/
$ umask 077
$ hg -q push ../push
after push
group can still write everything
$ python ../printmodes.py ../push
00770 ../push/.hg/
00660 ../push/.hg/00changelog.i
00770 ../push/.hg/cache/
00660 ../push/.hg/cache/branch2-base
00660 ../push/.hg/cache/rbc-names-v1
00660 ../push/.hg/cache/rbc-revs-v1
00660 ../push/.hg/requires
00770 ../push/.hg/store/
00660 ../push/.hg/store/00changelog.i
00660 ../push/.hg/store/00manifest.i
00770 ../push/.hg/store/data/
00770 ../push/.hg/store/data/dir/
00660 ../push/.hg/store/data/dir/bar.i
00660 ../push/.hg/store/data/foo.i
00660 ../push/.hg/store/fncache
00660 ../push/.hg/store/undo
00660 ../push/.hg/store/undo.backupfiles
00660 ../push/.hg/store/undo.phaseroots
00660 ../push/.hg/undo.bookmarks
00660 ../push/.hg/undo.branch
00660 ../push/.hg/undo.desc
00660 ../push/.hg/undo.dirstate
Test that we don't lose the setgid bit when we call chmod.
Not all systems support setgid directories (e.g. HFS+), so
just check that directories have the same mode.
$ cd ..
$ hg init setgid
$ cd setgid
$ chmod g+rwx .hg/store
$ chmod g+s .hg/store 2> /dev/null || true
$ mkdir dir
$ touch dir/file
$ hg ci -qAm 'add dir/file'
$ storemode=`python ../mode.py .hg/store`
$ dirmode=`python ../mode.py .hg/store/data/dir`
$ if [ "$storemode" != "$dirmode" ]; then
> echo "$storemode != $dirmode"
> fi
$ cd ..
$ cd .. # g-s dir