Mercurial > hg
view tests/test-dumprevlog.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 | ffb5c09ba822 |
children |
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Set vars: $ CONTRIBDIR=$TESTDIR/../contrib Prepare repo-a: $ hg init repo-a $ cd repo-a $ echo this is file a > a $ hg add a $ hg commit -m first $ echo adding to file a >> a $ hg commit -m second $ echo adding more to file a >> a $ hg commit -m third $ hg verify checking changesets checking manifests crosschecking files in changesets and manifests checking files 1 files, 3 changesets, 3 total revisions Dumping revlog of file a to stdout: $ python $CONTRIBDIR/dumprevlog .hg/store/data/a.i file: .hg/store/data/a.i node: 183d2312b35066fb6b3b449b84efc370d50993d0 linkrev: 0 parents: 0000000000000000000000000000000000000000 0000000000000000000000000000000000000000 length: 15 -start- this is file a -end- node: b1047953b6e6b633c0d8197eaa5116fbdfd3095b linkrev: 1 parents: 183d2312b35066fb6b3b449b84efc370d50993d0 0000000000000000000000000000000000000000 length: 32 -start- this is file a adding to file a -end- node: 8c4fd1f7129b8cdec6c7f58bf48fb5237a4030c1 linkrev: 2 parents: b1047953b6e6b633c0d8197eaa5116fbdfd3095b 0000000000000000000000000000000000000000 length: 54 -start- this is file a adding to file a adding more to file a -end- Dump all revlogs to file repo.dump: $ find .hg/store -name "*.i" | sort | xargs python $CONTRIBDIR/dumprevlog > ../repo.dump $ cd .. Undumping into repo-b: $ hg init repo-b $ cd repo-b $ python $CONTRIBDIR/undumprevlog < ../repo.dump .hg/store/00changelog.i .hg/store/00manifest.i .hg/store/data/a.i $ cd .. Rebuild fncache with clone --pull: $ hg clone --pull -U repo-b repo-c requesting all changes adding changesets adding manifests adding file changes added 3 changesets with 3 changes to 1 files Verify: $ hg -R repo-c verify checking changesets checking manifests crosschecking files in changesets and manifests checking files 1 files, 3 changesets, 3 total revisions Compare repos: $ hg -R repo-c incoming repo-a comparing with repo-a searching for changes no changes found [1] $ hg -R repo-a incoming repo-c comparing with repo-c searching for changes no changes found [1]