view tests/test-convert-p4.out @ 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.

% create p4 depot
% start the p4 server
% create a client spec
Client hg-p4-import saved.
% populate the depot
//depot/test-mercurial-import/a#1 - opened for add
//depot/test-mercurial-import/b/c#1 - opened for add
Submitting change 1.
Locking 2 files ...
add //depot/test-mercurial-import/a#1
add //depot/test-mercurial-import/b/c#1
Change 1 submitted.
% change some files
//depot/test-mercurial-import/a#1 - opened for edit
Submitting change 2.
Locking 1 files ...
edit //depot/test-mercurial-import/a#2
Change 2 submitted.
//depot/test-mercurial-import/b/c#1 - opened for edit
Submitting change 3.
Locking 1 files ...
edit //depot/test-mercurial-import/b/c#2
Change 3 submitted.
% convert
initializing destination dst repository
reading p4 views
collecting p4 changelists
1 initial
2 change a
3 change b/c
scanning source...
sorting...
converting...
2 initial
1 change a
0 change b/c
rev=2 desc="change b/c" tags="tip" files="b/c"
rev=1 desc="change a" tags="" files="a"
rev=0 desc="initial" tags="" files="a b/c"
% change some files
//depot/test-mercurial-import/a#2 - opened for edit
//depot/test-mercurial-import/b/c#2 - opened for edit
Submitting change 4.
Locking 2 files ...
edit //depot/test-mercurial-import/a#3
edit //depot/test-mercurial-import/b/c#3
Change 4 submitted.
% convert again
reading p4 views
collecting p4 changelists
1 initial
2 change a
3 change b/c
4 change a b/c
scanning source...
sorting...
converting...
0 change a b/c
rev=3 desc="change a b/c" tags="tip" files="a b/c"
rev=2 desc="change b/c" tags="" files="b/c"
rev=1 desc="change a" tags="" files="a"
rev=0 desc="initial" tags="" files="a b/c"
% interesting names
//depot/test-mercurial-import/d d#1 - opened for add
//depot/test-mercurial-import/ e/ f#1 - opened for add
Submitting change 5.
Locking 2 files ...
add //depot/test-mercurial-import/ e/ f#1
add //depot/test-mercurial-import/d d#1
Change 5 submitted.
% convert again
reading p4 views
collecting p4 changelists
1 initial
2 change a
3 change b/c
4 change a b/c
5 add d e f
scanning source...
sorting...
converting...
0 add d e f
rev=4 desc="add d e f" tags="tip" files=" e/ f d d"
rev=3 desc="change a b/c" tags="" files="a b/c"
rev=2 desc="change b/c" tags="" files="b/c"
rev=1 desc="change a" tags="" files="a"
rev=0 desc="initial" tags="" files="a b/c"
% stop the p4 server