posix: give checkexec a fast path; keep the check files and test read only
Before, Mercurial would create a new temporary file every time, stat it, change
its exec mode, stat it again, and delete it. Most of this dance was done to
handle the rare and not-so-essential case of VFAT mounts on unix. The cost of
that was paid by the much more common and important case of using normal file
systems.
Instead, try to create and preserve .hg/cache/checkisexec and
.hg/cache/checknoexec with and without exec flag set. If the files exist and
have correct exec flags set, we can conclude that that file system supports the
exec flag. Best case, the whole exec check can thus be done with two stat
calls. Worst case, we delete the wrong files and check as usual. That will be
because temporary loss of exec bit or on file systems without support for the
exec bit. In that case we check as we did before, with the additional overhead
of one extra stat call.
It is possible that this different test algorithm in some cases on odd file
systems will give different behaviour. Again, I think it will be rare and
special cases and I think it is worth the risk.
test-clone.t happens to show the situation where checkisexec is left behind
from the old style check, while checknoexec only will be created next time a
exec check will be performed.
#require hardlink
$ cat > nlinks.py <<EOF
> import sys
> from mercurial import util
> for f in sorted(sys.stdin.readlines()):
> f = f[:-1]
> print util.nlinks(f), f
> EOF
$ nlinksdir()
> {
> find $1 -type f | python $TESTTMP/nlinks.py
> }
Some implementations of cp can't create hardlinks (replaces 'cp -al' on Linux):
$ cat > linkcp.py <<EOF
> from mercurial import util
> import sys
> util.copyfiles(sys.argv[1], sys.argv[2], hardlink=True)
> EOF
$ linkcp()
> {
> python $TESTTMP/linkcp.py $1 $2
> }
Prepare repo r1:
$ hg init r1
$ cd r1
$ echo c1 > f1
$ hg add f1
$ hg ci -m0
$ mkdir d1
$ cd d1
$ echo c2 > f2
$ hg add f2
$ hg ci -m1
$ cd ../..
$ nlinksdir r1/.hg/store
1 r1/.hg/store/00changelog.i
1 r1/.hg/store/00manifest.i
1 r1/.hg/store/data/d1/f2.i
1 r1/.hg/store/data/f1.i
1 r1/.hg/store/fncache
1 r1/.hg/store/phaseroots
1 r1/.hg/store/undo
1 r1/.hg/store/undo.backup.fncache
1 r1/.hg/store/undo.backupfiles
1 r1/.hg/store/undo.phaseroots
Create hardlinked clone r2:
$ hg clone -U --debug r1 r2 --config progress.debug=true
linking: 1
linking: 2
linking: 3
linking: 4
linking: 5
linking: 6
linking: 7
linked 7 files
Create non-hardlinked clone r3:
$ hg clone --pull r1 r3
requesting all changes
adding changesets
adding manifests
adding file changes
added 2 changesets with 2 changes to 2 files
updating to branch default
2 files updated, 0 files merged, 0 files removed, 0 files unresolved
Repos r1 and r2 should now contain hardlinked files:
$ nlinksdir r1/.hg/store
2 r1/.hg/store/00changelog.i
2 r1/.hg/store/00manifest.i
2 r1/.hg/store/data/d1/f2.i
2 r1/.hg/store/data/f1.i
2 r1/.hg/store/fncache
1 r1/.hg/store/phaseroots
1 r1/.hg/store/undo
1 r1/.hg/store/undo.backup.fncache
1 r1/.hg/store/undo.backupfiles
1 r1/.hg/store/undo.phaseroots
$ nlinksdir r2/.hg/store
2 r2/.hg/store/00changelog.i
2 r2/.hg/store/00manifest.i
2 r2/.hg/store/data/d1/f2.i
2 r2/.hg/store/data/f1.i
2 r2/.hg/store/fncache
Repo r3 should not be hardlinked:
$ nlinksdir r3/.hg/store
1 r3/.hg/store/00changelog.i
1 r3/.hg/store/00manifest.i
1 r3/.hg/store/data/d1/f2.i
1 r3/.hg/store/data/f1.i
1 r3/.hg/store/fncache
1 r3/.hg/store/phaseroots
1 r3/.hg/store/undo
1 r3/.hg/store/undo.backupfiles
1 r3/.hg/store/undo.phaseroots
Create a non-inlined filelog in r3:
$ cd r3/d1
>>> f = open('data1', 'wb')
>>> for x in range(10000):
... f.write("%s\n" % str(x))
>>> f.close()
$ for j in 0 1 2 3 4 5 6 7 8 9; do
> cat data1 >> f2
> hg commit -m$j
> done
$ cd ../..
$ nlinksdir r3/.hg/store
1 r3/.hg/store/00changelog.i
1 r3/.hg/store/00manifest.i
1 r3/.hg/store/data/d1/f2.d
1 r3/.hg/store/data/d1/f2.i
1 r3/.hg/store/data/f1.i
1 r3/.hg/store/fncache
1 r3/.hg/store/phaseroots
1 r3/.hg/store/undo
1 r3/.hg/store/undo.backup.fncache
1 r3/.hg/store/undo.backup.phaseroots
1 r3/.hg/store/undo.backupfiles
1 r3/.hg/store/undo.phaseroots
Push to repo r1 should break up most hardlinks in r2:
$ hg -R r2 verify
checking changesets
checking manifests
crosschecking files in changesets and manifests
checking files
2 files, 2 changesets, 2 total revisions
$ cd r3
$ hg push
pushing to $TESTTMP/r1 (glob)
searching for changes
adding changesets
adding manifests
adding file changes
added 10 changesets with 10 changes to 1 files
$ cd ..
$ nlinksdir r2/.hg/store
1 r2/.hg/store/00changelog.i
1 r2/.hg/store/00manifest.i
1 r2/.hg/store/data/d1/f2.i
2 r2/.hg/store/data/f1.i
1 r2/.hg/store/fncache
$ hg -R r2 verify
checking changesets
checking manifests
crosschecking files in changesets and manifests
checking files
2 files, 2 changesets, 2 total revisions
$ cd r1
$ hg up
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
Committing a change to f1 in r1 must break up hardlink f1.i in r2:
$ echo c1c1 >> f1
$ hg ci -m00
$ cd ..
$ nlinksdir r2/.hg/store
1 r2/.hg/store/00changelog.i
1 r2/.hg/store/00manifest.i
1 r2/.hg/store/data/d1/f2.i
1 r2/.hg/store/data/f1.i
1 r2/.hg/store/fncache
$ cd r3
$ hg tip --template '{rev}:{node|short}\n'
11:a6451b6bc41f
$ echo bla > f1
$ hg ci -m1
$ cd ..
Create hardlinked copy r4 of r3 (on Linux, we would call 'cp -al'):
$ linkcp r3 r4
r4 has hardlinks in the working dir (not just inside .hg):
$ nlinksdir r4
2 r4/.hg/00changelog.i
2 r4/.hg/branch
2 r4/.hg/cache/branch2-served
2 r4/.hg/cache/checkisexec
2 r4/.hg/cache/checknoexec
2 r4/.hg/cache/rbc-names-v1
2 r4/.hg/cache/rbc-revs-v1
2 r4/.hg/dirstate
2 r4/.hg/hgrc
2 r4/.hg/last-message.txt
2 r4/.hg/requires
2 r4/.hg/store/00changelog.i
2 r4/.hg/store/00manifest.i
2 r4/.hg/store/data/d1/f2.d
2 r4/.hg/store/data/d1/f2.i
2 r4/.hg/store/data/f1.i
2 r4/.hg/store/fncache
2 r4/.hg/store/phaseroots
2 r4/.hg/store/undo
2 r4/.hg/store/undo.backup.fncache
2 r4/.hg/store/undo.backup.phaseroots
2 r4/.hg/store/undo.backupfiles
2 r4/.hg/store/undo.phaseroots
2 r4/.hg/undo.backup.dirstate
2 r4/.hg/undo.bookmarks
2 r4/.hg/undo.branch
2 r4/.hg/undo.desc
2 r4/.hg/undo.dirstate
2 r4/d1/data1
2 r4/d1/f2
2 r4/f1
Update back to revision 11 in r4 should break hardlink of file f1:
$ hg -R r4 up 11
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ nlinksdir r4
2 r4/.hg/00changelog.i
1 r4/.hg/branch
2 r4/.hg/cache/branch2-served
2 r4/.hg/cache/checkisexec
2 r4/.hg/cache/checknoexec
2 r4/.hg/cache/rbc-names-v1
2 r4/.hg/cache/rbc-revs-v1
1 r4/.hg/dirstate
2 r4/.hg/hgrc
2 r4/.hg/last-message.txt
2 r4/.hg/requires
2 r4/.hg/store/00changelog.i
2 r4/.hg/store/00manifest.i
2 r4/.hg/store/data/d1/f2.d
2 r4/.hg/store/data/d1/f2.i
2 r4/.hg/store/data/f1.i
2 r4/.hg/store/fncache
2 r4/.hg/store/phaseroots
2 r4/.hg/store/undo
2 r4/.hg/store/undo.backup.fncache
2 r4/.hg/store/undo.backup.phaseroots
2 r4/.hg/store/undo.backupfiles
2 r4/.hg/store/undo.phaseroots
2 r4/.hg/undo.backup.dirstate
2 r4/.hg/undo.bookmarks
2 r4/.hg/undo.branch
2 r4/.hg/undo.desc
2 r4/.hg/undo.dirstate
2 r4/d1/data1
2 r4/d1/f2
1 r4/f1
Test hardlinking outside hg:
$ mkdir x
$ echo foo > x/a
$ linkcp x y
$ echo bar >> y/a
No diff if hardlink:
$ diff x/a y/a
Test mq hardlinking:
$ echo "[extensions]" >> $HGRCPATH
$ echo "mq=" >> $HGRCPATH
$ hg init a
$ cd a
$ hg qimport -n foo - << EOF
> # HG changeset patch
> # Date 1 0
> diff -r 2588a8b53d66 a
> --- /dev/null Thu Jan 01 00:00:00 1970 +0000
> +++ b/a Wed Jul 23 15:54:29 2008 +0200
> @@ -0,0 +1,1 @@
> +a
> EOF
adding foo to series file
$ hg qpush
applying foo
now at: foo
$ cd ..
$ linkcp a b
$ cd b
$ hg qimport -n bar - << EOF
> # HG changeset patch
> # Date 2 0
> diff -r 2588a8b53d66 a
> --- /dev/null Thu Jan 01 00:00:00 1970 +0000
> +++ b/b Wed Jul 23 15:54:29 2008 +0200
> @@ -0,0 +1,1 @@
> +b
> EOF
adding bar to series file
$ hg qpush
applying bar
now at: bar
$ cat .hg/patches/status
430ed4828a74fa4047bc816a25500f7472ab4bfe:foo
4e7abb4840c46a910f6d7b4d3c3fc7e5209e684c:bar
$ cat .hg/patches/series
foo
bar
$ cat ../a/.hg/patches/status
430ed4828a74fa4047bc816a25500f7472ab4bfe:foo
$ cat ../a/.hg/patches/series
foo
Test tags hardlinking:
$ hg qdel -r qbase:qtip
patch foo finalized without changeset message
patch bar finalized without changeset message
$ hg tag -l lfoo
$ hg tag foo
$ cd ..
$ linkcp b c
$ cd c
$ hg tag -l -r 0 lbar
$ hg tag -r 0 bar
$ cat .hgtags
4e7abb4840c46a910f6d7b4d3c3fc7e5209e684c foo
430ed4828a74fa4047bc816a25500f7472ab4bfe bar
$ cat .hg/localtags
4e7abb4840c46a910f6d7b4d3c3fc7e5209e684c lfoo
430ed4828a74fa4047bc816a25500f7472ab4bfe lbar
$ cat ../b/.hgtags
4e7abb4840c46a910f6d7b4d3c3fc7e5209e684c foo
$ cat ../b/.hg/localtags
4e7abb4840c46a910f6d7b4d3c3fc7e5209e684c lfoo
$ cd ..