Mercurial > hg
view tests/test-relink.t @ 14007:d764463b433e
atomictempfile: avoid infinite recursion in __del__().
The problem is that a programmer using atomictempfile directly can
make an innocent everyday mistake -- not enough args to the
constructor -- which escalates badly. You would expect a simple
TypeError crash in that case, but you actually get an infinite
recursion that is surprisingly difficult to kill: it happens between
__del__() and __getattr__(), and Python does not handle infinite
recursion from __del__() well.
The fix is to not implement __getattr__(), but instead assign instance
attributes for the methods we wish to delegate to the builtin file
type: write() and fileno(). I've audited mercurial.* and hgext.* and
found no users of atomictempfile using methods other than write() and
rename(). I audited third-party extensions and found one (snap)
passing an atomictempfile to util.fstat(), so I also threw in
fileno().
The last time I submitted a similar patch, Matt proposed that we make
atomictempfile a subclass of file instead of wrapping it. Rejected on
grounds of unnecessary complexity: for one thing, it would make the
Windows implementation of posixfile quite a bit more complex. It would
have to become a subclass of file rather than a simple function -- but
since it's written in C, this is non-obvious and non-trivial.
Furthermore, there's nothing wrong with wrapping objects and
delegating methods: it's a well-established pattern that works just
fine in many cases. Subclassing is not the answer to all of life's
problems.
author | Greg Ward <greg@gerg.ca> |
---|---|
date | Sun, 24 Apr 2011 19:25:10 -0400 |
parents | a73f38d8bbdb |
children | 9910f60a37ee |
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$ echo "[extensions]" >> $HGRCPATH $ echo "relink=" >> $HGRCPATH $ fix_path() { > tr '\\' / > } $ cat > arelinked.py <<EOF > import sys, os > 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 "file('.hg/store/data/dummy.i', 'wb').write('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 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 "file('.hg/store/data/dummy.i', 'wb').write('a\nb\r\n')" relink $ hg relink --debug | 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 (1.37 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