Mercurial > hg
view tests/test-empty-group.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 | b00eda50ad2b |
children | 301725c3df9a |
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# A B # # 3 4 3 # |\/| |\ # |/\| | \ # 1 2 1 2 # \ / \ / # 0 0 # # if the result of the merge of 1 and 2 # is the same in 3 and 4, no new manifest # will be created and the manifest group # will be empty during the pull # # (plus we test a failure where outgoing # wrongly reported the number of csets) $ hg init a $ cd a $ touch init $ hg ci -A -m 0 adding init $ touch x y $ hg ci -A -m 1 adding x adding y $ hg update 0 0 files updated, 0 files merged, 2 files removed, 0 files unresolved $ touch x y $ hg ci -A -m 2 adding x adding y created new head $ hg merge 1 0 files updated, 0 files merged, 0 files removed, 0 files unresolved (branch merge, don't forget to commit) $ hg ci -A -m m1 $ hg update -C 1 0 files updated, 0 files merged, 0 files removed, 0 files unresolved $ hg merge 2 0 files updated, 0 files merged, 0 files removed, 0 files unresolved (branch merge, don't forget to commit) $ hg ci -A -m m2 created new head $ cd .. $ hg clone -r 3 a b adding changesets adding manifests adding file changes added 4 changesets with 3 changes to 3 files updating to branch default 3 files updated, 0 files merged, 0 files removed, 0 files unresolved $ hg clone -r 4 a c adding changesets adding manifests adding file changes added 4 changesets with 3 changes to 3 files updating to branch default 3 files updated, 0 files merged, 0 files removed, 0 files unresolved $ hg -R a outgoing b comparing with b searching for changes changeset: 4:119caaef4ed1 tag: tip parent: 1:79f9e10cd04e parent: 2:8e1bb01c1a24 user: test date: Thu Jan 01 00:00:00 1970 +0000 summary: m2 $ hg -R a outgoing c comparing with c searching for changes changeset: 3:cbb48b367d1b parent: 2:8e1bb01c1a24 parent: 1:79f9e10cd04e user: test date: Thu Jan 01 00:00:00 1970 +0000 summary: m1 $ hg -R b outgoing c comparing with c searching for changes changeset: 3:cbb48b367d1b tag: tip parent: 2:8e1bb01c1a24 parent: 1:79f9e10cd04e user: test date: Thu Jan 01 00:00:00 1970 +0000 summary: m1 $ hg -R c outgoing b comparing with b searching for changes changeset: 3:119caaef4ed1 tag: tip parent: 1:79f9e10cd04e parent: 2:8e1bb01c1a24 user: test date: Thu Jan 01 00:00:00 1970 +0000 summary: m2 $ hg -R b pull a pulling from a searching for changes adding changesets adding manifests adding file changes added 1 changesets with 0 changes to 0 files (+1 heads) (run 'hg heads' to see heads, 'hg merge' to merge) $ hg -R c pull a pulling from a searching for changes adding changesets adding manifests adding file changes added 1 changesets with 0 changes to 0 files (+1 heads) (run 'hg heads' to see heads, 'hg merge' to merge)