perf: introduce safeattrsetter to replace direct attribute assignment
Referring not-existing attribute immediately causes failure, but
assigning a value to such attribute doesn't.
For example, perf.py has code paths below, which assign a value to
not-existing attribute. This causes incorrect performance measurement,
but these code paths are executed successfully.
- "repo._tags = None" in perftags()
recent Mercurial has tags cache information in repo._tagscache
- "branchmap.write = lambda repo: None" in perfbranchmap()
branchmap cache is written out by branchcache.write() in branchmap.py
"util.safehasattr() before assignment" can avoid this issue, but might
increase mistake at "copy & paste" attribute name or so.
To centralize (1) examining existence of, (2) assigning a value to,
and (3) restoring an old value to the attribute, this patch introduces
safeattrsetter(). This is used to replace direct attribute assignment
in subsequent patches.
Encapsulation of restoring is needed to completely remove direct
attribute assignment from perf.py, even though restoring isn't needed
so often.
#require svn svn-bindings
$ cat >> $HGRCPATH <<EOF
> [extensions]
> convert =
> EOF
$ svnadmin create svn-repo
$ svnadmin load -q svn-repo < "$TESTDIR/svn/tags.svndump"
Convert
$ hg convert --datesort svn-repo A-hg
initializing destination A-hg repository
scanning source...
sorting...
converting...
5 init projA
4 adda
3 changea
2 changea2
1 changea3
0 changea
updating tags
$ cd A-hg
$ hg log -G --template '{rev} {desc|firstline} tags: {tags}\n'
o 6 update tags tags: tip
|
o 5 changea tags: trunk.goodtag
|
o 4 changea3 tags:
|
o 3 changea2 tags: trunk.v1
|
o 2 changea tags:
|
o 1 adda tags:
|
o 0 init projA tags:
$ hg tags -q
tip
trunk.goodtag
trunk.v1
$ cd ..
Convert without tags
$ hg convert --datesort --config convert.svn.tags= svn-repo A-notags-hg
initializing destination A-notags-hg repository
scanning source...
sorting...
converting...
5 init projA
4 adda
3 changea
2 changea2
1 changea3
0 changea
$ hg -R A-notags-hg tags -q
tip