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)
Issue835: qpush fails immediately when patching a missing file, but
remaining added files are still created empty which will trick a
future qrefresh.
$ cat > writelines.py <<EOF
> import sys
> path = sys.argv[1]
> args = sys.argv[2:]
> assert (len(args) % 2) == 0
>
> f = file(path, 'wb')
> for i in xrange(len(args)/2):
> count, s = args[2*i:2*i+2]
> count = int(count)
> s = s.decode('string_escape')
> f.write(s*count)
> f.close()
> EOF
$ echo "[extensions]" >> $HGRCPATH
$ echo "mq=" >> $HGRCPATH
$ hg init normal
$ cd normal
$ python ../writelines.py b 10 'a\n'
$ hg ci -Am addb
adding b
$ echo a > a
$ python ../writelines.py b 2 'b\n' 10 'a\n' 2 'c\n'
$ echo c > c
$ hg add a c
$ hg qnew -f changeb
$ hg qpop
popping changeb
patch queue now empty
$ hg rm b
$ hg ci -Am rmb
Push patch with missing target:
$ hg qpush
applying changeb
unable to find 'b' for patching
2 out of 2 hunks FAILED -- saving rejects to file b.rej
patch failed, unable to continue (try -v)
patch failed, rejects left in working dir
errors during apply, please fix and refresh changeb
[2]
Display added files:
$ cat a
a
$ cat c
c
Display rejections:
$ cat b.rej
--- b
+++ b
@@ -1,3 +1,5 @@
+b
+b
a
a
a
@@ -8,3 +10,5 @@
a
a
a
+c
+c
$ cd ..
$ echo "[diff]" >> $HGRCPATH
$ echo "git=1" >> $HGRCPATH
$ hg init git
$ cd git
$ python ../writelines.py b 1 '\x00'
$ hg ci -Am addb
adding b
$ echo a > a
$ python ../writelines.py b 1 '\x01' 1 '\x00'
$ echo c > c
$ hg add a c
$ hg qnew -f changeb
$ hg qpop
popping changeb
patch queue now empty
$ hg rm b
$ hg ci -Am rmb
Push git patch with missing target:
$ hg qpush
applying changeb
unable to find 'b' for patching
1 out of 1 hunks FAILED -- saving rejects to file b.rej
patch failed, unable to continue (try -v)
patch failed, rejects left in working dir
errors during apply, please fix and refresh changeb
[2]
$ hg st
? b.rej
Display added files:
$ cat a
a
$ cat c
c
Display rejections:
$ cat b.rej
--- b
+++ b
GIT binary patch
literal 2
Jc${No0000400IC2
$ cd ..
Test push creating directory during git copy or rename:
$ hg init missingdir
$ cd missingdir
$ echo a > a
$ hg ci -Am adda
adding a
$ mkdir d
$ hg copy a d/a2
$ hg mv a d/a
$ hg qnew -g -f patch
$ hg qpop
popping patch
patch queue now empty
$ hg qpush
applying patch
now at: patch
$ cd ..