dirstate: when calling rebuild(), avoid some N^2 codepaths
I had a user repo with 200k files in it. Calling `hg debugrebuilddirstate` took
tens of minutes (I didn't wait for it). In that situation,
changedfiles==allfiles, and both are lists. This meant that we had to run an
average of 100k comparisons, for each of 200k files, just to check whether a
file needed to have normallookup called (it always did), or drop.
While it's probably not a huge issue, in my very awkward synthetic benchmark I
wrote (not using a benchmark library or anything), I was seeing some slowdowns
for small-changedfiles and very-large-allfiles invocations, with an inflection
somewhere around 10 items in changedfiles (regardless of the size of allfiles);
above 10 items in changedfiles, the new code appears to always be faster. For
the case of 50k files in changedfiles and the same items in allfiles, I'm seeing
differences of 15s of just running comparisons vs. 0.003793s. I haven't bothered
to run a comparison of 200k items in changedfiles and allfiles. :)
Differential Revision: https://phab.mercurial-scm.org/D7665
A python hook for "hg fix" that prints out the number of files and revisions
that were affected, along with which fixer tools were applied. Also checks how
many times it sees a specific key generated by one of the fixer tools defined
below.
$ cat >> $TESTTMP/postfixhook.py <<EOF
> import collections
> def file(ui, repo, rev=None, path=b'', metadata=None, **kwargs):
> ui.status(b'fixed %s in revision %d using %s\n' %
> (path, rev, b', '.join(metadata.keys())))
> def summarize(ui, repo, replacements=None, wdirwritten=False,
> metadata=None, **kwargs):
> counts = collections.defaultdict(int)
> keys = 0
> for fixername, metadatalist in metadata.items():
> for metadata in metadatalist:
> if metadata is None:
> continue
> counts[fixername] += 1
> if 'key' in metadata:
> keys += 1
> ui.status(b'saw "key" %d times\n' % (keys,))
> for name, count in sorted(counts.items()):
> ui.status(b'fixed %d files with %s\n' % (count, name))
> if replacements:
> ui.status(b'fixed %d revisions\n' % (len(replacements),))
> if wdirwritten:
> ui.status(b'fixed the working copy\n')
> EOF
Some mock output for fixer tools that demonstrate what could go wrong with
expecting the metadata output format.
$ printf 'new content\n' > $TESTTMP/missing
$ printf 'not valid json\0new content\n' > $TESTTMP/invalid
$ printf '{"key": "value"}\0new content\n' > $TESTTMP/valid
Configure some fixer tools based on the output defined above, and enable the
hooks defined above. Disable parallelism to make output of the parallel file
processing phase stable.
$ cat >> $HGRCPATH <<EOF
> [extensions]
> fix =
> [fix]
> metadatafalse:command=cat $TESTTMP/missing
> metadatafalse:pattern=metadatafalse
> metadatafalse:metadata=false
> missing:command=cat $TESTTMP/missing
> missing:pattern=missing
> missing:metadata=true
> invalid:command=cat $TESTTMP/invalid
> invalid:pattern=invalid
> invalid:metadata=true
> valid:command=cat $TESTTMP/valid
> valid:pattern=valid
> valid:metadata=true
> [hooks]
> postfixfile = python:$TESTTMP/postfixhook.py:file
> postfix = python:$TESTTMP/postfixhook.py:summarize
> [worker]
> enabled=false
> EOF
See what happens when we execute each of the fixer tools. Some print warnings,
some write back to the file.
$ hg init repo
$ cd repo
$ printf "old content\n" > metadatafalse
$ printf "old content\n" > invalid
$ printf "old content\n" > missing
$ printf "old content\n" > valid
$ hg add -q
$ hg fix -w
ignored invalid output from fixer tool: invalid
fixed metadatafalse in revision 2147483647 using metadatafalse
ignored invalid output from fixer tool: missing
fixed valid in revision 2147483647 using valid
saw "key" 1 times
fixed 1 files with valid
fixed the working copy
$ cat metadatafalse
new content
$ cat missing
old content
$ cat invalid
old content
$ cat valid
new content
$ cd ..