mdiff: speed up showfunc for large diffs
This addresses the following issues with showfunc:
- Silly usage of regular expressions.
- Doing str.rstrip() needlessly in an inner loop.
- Doing catastrophic backtracking when trying to find a function line.
Finding function text is now at worst O(n lines in the old file), and
at best close to O(n hunks).
Given a diff like this[1]:
src/main/antlr3/uk/ac/cam/ch/wwmm/pregenerated/ChemicalChunker.g | 4 +-
src/main/java/uk/ac/cam/ch/wwmm/pregenerated/ChemicalChunkerLexer.java | 2 +-
src/main/java/uk/ac/cam/ch/wwmm/pregenerated/ChemicalChunkerParser.java | 29189 +++++----
3 files changed, 14741 insertions(+), 14454 deletions(-)
[1]: https://bitbucket.org/wwmm/chemicaltagger/changeset/d2bfbaecd4fc/raw
Without this change, hg log --stat --config diff.showfunc=1 takes an
absurdly long time to complete:
CallCount Recursive Total(ms) Inline(ms) module:lineno(function)
32813 0 80.3546 40.6086 mercurial.mdiff:160(yieldhunk)
+65062746 0 25.7227 25.7227 +<method 'match' of '_sre.SRE_Pattern' objects>
+65062746 0 14.0221 14.0221 +<method 'rstrip' of 'str' objects>
+1809 0 0.0009 0.0009 +mercurial.mdiff:148(contextend)
+1809 0 0.0003 0.0003 +<len>
65062746 0 25.7227 25.7227 <method 'match' of '_sre.SRE_Pattern' objects>
65062763 0 14.0221 14.0221 <method 'rstrip' of 'str' objects>
543 0 0.1631 0.1631 <zlib.decompress>
3 0 0.0505 0.0505 <mercurial.bdiff.blocks>
31007 0 80.4564 0.0477 mercurial.mdiff:147(_unidiff)
+32813 0 80.3546 40.6086 +mercurial.mdiff:160(yieldhunk)
+3 0 0.0505 0.0505 +<mercurial.bdiff.blocks>
+3618 0 0.0022 0.0022 +mercurial.mdiff:154(contextstart)
+5427 0 0.0013 0.0013 +<len>
+3 0 0.0001 0.0000 +re:188(compile)
1 0 80.8381 0.0322 mercurial.patch:1777(diffstatdata)
+107499 0 0.0235 0.0235 +<method 'startswith' of 'str' objects>
+31014 0 80.7820 0.0071 +mercurial.util:1284(iterlines)
+3 0 0.0000 0.0000 +<method 'search' of '_sre.SRE_Pattern' objects>
+4 0 0.0000 0.0000 +mercurial.patch:1783(addresult)
+3 0 0.0000 0.0000 +<method 'group' of '_sre.SRE_Match' objects>
6 0 0.0444 0.0283 mercurial.mdiff:12(splitnewlines)
+6 0 0.0160 0.0160 +<method 'split' of 'str' objects>
32 0 0.0246 0.0246 <method 'update' of '_hashlib.HASH' objects>
11 0 0.0236 0.0236 <method 'read' of 'file' objects>
Time: real 80.880 secs (user 80.200+0.000 sys 0.380+0.000)
With this change, it's almost as fast as not using showfunc at all:
CallCount Recursive Total(ms) Inline(ms) module:lineno(function)
543 0 0.1699 0.1699 <zlib.decompress>
3 0 0.0501 0.0501 <mercurial.bdiff.blocks>
32813 0 0.0415 0.0348 mercurial.mdiff:161(yieldhunk)
+70837 0 0.0058 0.0058 +<method 'isalnum' of 'str' objects>
+1809 0 0.0006 0.0006 +mercurial.mdiff:148(contextend)
+1809 0 0.0002 0.0002 +<len>
1 0 0.4879 0.0310 mercurial.patch:1777(diffstatdata)
+107499 0 0.0230 0.0230 +<method 'startswith' of 'str' objects>
+31014 0 0.4335 0.0065 +mercurial.util:1284(iterlines)
+3 0 0.0000 0.0000 +<method 'search' of '_sre.SRE_Pattern' objects>
+4 0 0.0000 0.0000 +mercurial.patch:1783(addresult)
+1 0 0.0004 0.0000 +re:188(compile)
32 0 0.0293 0.0293 <method 'update' of '_hashlib.HASH' objects>
6 0 0.0427 0.0279 mercurial.mdiff:12(splitnewlines)
+6 0 0.0147 0.0147 +<method 'split' of 'str' objects>
31007 0 0.1169 0.0235 mercurial.mdiff:147(_unidiff)
+3 0 0.0501 0.0501 +<mercurial.bdiff.blocks>
+32813 0 0.0415 0.0348 +mercurial.mdiff:161(yieldhunk)
+3618 0 0.0012 0.0012 +mercurial.mdiff:154(contextstart)
+5427 0 0.0006 0.0006 +<len>
107597 0 0.0230 0.0230 <method 'startswith' of 'str' objects>
16 0 0.0213 0.0213 <mercurial.mpatch.patches>
194 0 0.0149 0.0149 <method 'split' of 'str' objects>
Time: real 0.530 secs (user 0.450+0.000 sys 0.070+0.000)
$ echo "[extensions]" >> $HGRCPATH
$ echo "mq=" >> $HGRCPATH
$ hg init foo
$ cd foo
$ echo a > a
$ hg ci -qAm a
Default queue:
$ hg qqueue
patches (active)
$ echo b > a
$ hg qnew -fgDU somestuff
Applied patches in default queue:
$ hg qap
somestuff
Try to change patch (create succeeds, switch fails):
$ hg qqueue foo --create
abort: patches applied - cannot set new queue active
[255]
$ hg qqueue
foo
patches (active)
Empty default queue:
$ hg qpop
popping somestuff
patch queue now empty
Switch queue:
$ hg qqueue foo
$ hg qqueue
foo (active)
patches
List queues, quiet:
$ hg qqueue --quiet
foo
patches
Fail creating queue with already existing name:
$ hg qqueue --create foo
abort: queue "foo" already exists
[255]
$ hg qqueue
foo (active)
patches
Create new queue for rename:
$ hg qqueue --create bar
$ hg qqueue
bar (active)
foo
patches
Rename queue, same name:
$ hg qqueue --rename bar
abort: can't rename "bar" to its current name
[255]
Rename queue to existing:
$ hg qqueue --rename foo
abort: queue "foo" already exists
[255]
Rename queue:
$ hg qqueue --rename buz
$ hg qqueue
buz (active)
foo
patches
Switch back to previous queue:
$ hg qqueue foo
$ hg qqueue --delete buz
$ hg qqueue
foo (active)
patches
Create queue for purge:
$ hg qqueue --create purge-me
$ hg qqueue
foo
patches
purge-me (active)
Create patch for purge:
$ hg qnew patch-purge-me
$ ls -1d .hg/patches-purge-me 2>/dev/null || true
.hg/patches-purge-me
$ hg qpop -a
popping patch-purge-me
patch queue now empty
Purge queue:
$ hg qqueue foo
$ hg qqueue --purge purge-me
$ hg qqueue
foo (active)
patches
$ ls -1d .hg/patches-purge-me 2>/dev/null || true
Unapplied patches:
$ hg qun
$ echo c > a
$ hg qnew -fgDU otherstuff
Fail switching back:
$ hg qqueue patches
abort: patches applied - cannot set new queue active
[255]
Fail deleting current:
$ hg qqueue foo --delete
abort: cannot delete currently active queue
[255]
Switch back and delete foo:
$ hg qpop -a
popping otherstuff
patch queue now empty
$ hg qqueue patches
$ hg qqueue foo --delete
$ hg qqueue
patches (active)
Tricky cases:
$ hg qqueue store --create
$ hg qnew journal
$ hg qqueue
patches
store (active)
$ hg qpop -a
popping journal
patch queue now empty
$ hg qqueue patches
$ hg qun
somestuff
Invalid names:
$ hg qqueue test/../../bar --create
abort: invalid queue name, may not contain the characters ":\/."
[255]
$ hg qqueue . --create
abort: invalid queue name, may not contain the characters ":\/."
[255]
$ cd ..