Mercurial > hg
view tests/test-excessive-merge.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 | 4c94b6d0fb1c |
children | ec5886db9dc6 |
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$ hg init $ echo foo > a $ echo foo > b $ hg add a b $ hg ci -m "test" $ echo blah > a $ hg ci -m "branch a" $ hg co 0 1 files updated, 0 files merged, 0 files removed, 0 files unresolved $ echo blah > b $ hg ci -m "branch b" created new head $ HGMERGE=true hg merge 1 1 files updated, 0 files merged, 0 files removed, 0 files unresolved (branch merge, don't forget to commit) $ hg ci -m "merge b/a -> blah" $ hg co 1 1 files updated, 0 files merged, 0 files removed, 0 files unresolved $ HGMERGE=true hg merge 2 1 files updated, 0 files merged, 0 files removed, 0 files unresolved (branch merge, don't forget to commit) $ hg ci -m "merge a/b -> blah" created new head $ hg log changeset: 4:2ee31f665a86 tag: tip parent: 1:96155394af80 parent: 2:92cc4c306b19 user: test date: Thu Jan 01 00:00:00 1970 +0000 summary: merge a/b -> blah changeset: 3:e16a66a37edd parent: 2:92cc4c306b19 parent: 1:96155394af80 user: test date: Thu Jan 01 00:00:00 1970 +0000 summary: merge b/a -> blah changeset: 2:92cc4c306b19 parent: 0:5e0375449e74 user: test date: Thu Jan 01 00:00:00 1970 +0000 summary: branch b changeset: 1:96155394af80 user: test date: Thu Jan 01 00:00:00 1970 +0000 summary: branch a changeset: 0:5e0375449e74 user: test date: Thu Jan 01 00:00:00 1970 +0000 summary: test $ hg debugindex .hg/store/00changelog.i rev offset length base linkrev nodeid p1 p2 0 0 60 0 0 5e0375449e74 000000000000 000000000000 1 60 62 1 1 96155394af80 5e0375449e74 000000000000 2 122 62 2 2 92cc4c306b19 5e0375449e74 000000000000 3 184 69 3 3 e16a66a37edd 92cc4c306b19 96155394af80 4 253 29 3 4 2ee31f665a86 96155394af80 92cc4c306b19 revision 1 $ hg manifest --debug 1 79d7492df40aa0fa093ec4209be78043c181f094 644 a 2ed2a3912a0b24502043eae84ee4b279c18b90dd 644 b revision 2 $ hg manifest --debug 2 2ed2a3912a0b24502043eae84ee4b279c18b90dd 644 a 79d7492df40aa0fa093ec4209be78043c181f094 644 b revision 3 $ hg manifest --debug 3 79d7492df40aa0fa093ec4209be78043c181f094 644 a 79d7492df40aa0fa093ec4209be78043c181f094 644 b revision 4 $ hg manifest --debug 4 79d7492df40aa0fa093ec4209be78043c181f094 644 a 79d7492df40aa0fa093ec4209be78043c181f094 644 b $ hg debugindex .hg/store/data/a.i rev offset length base linkrev nodeid p1 p2 0 0 5 0 0 2ed2a3912a0b 000000000000 000000000000 1 5 6 1 1 79d7492df40a 2ed2a3912a0b 000000000000 $ hg verify checking changesets checking manifests crosschecking files in changesets and manifests checking files 2 files, 5 changesets, 4 total revisions