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
$ hg init
$ echo foo > bar
$ hg commit -Am default
adding bar
$ hg up -r null
0 files updated, 0 files merged, 1 files removed, 0 files unresolved
$ hg branch mine
marked working directory as branch mine
(branches are permanent and global, did you want a bookmark?)
$ echo hello > world
$ hg commit -Am hello
adding world
$ hg up -r null
0 files updated, 0 files merged, 1 files removed, 0 files unresolved
$ hg branch other
marked working directory as branch other
$ echo good > bye
$ hg commit -Am other
adding bye
$ hg up -r mine
1 files updated, 0 files merged, 1 files removed, 0 files unresolved
$ hg clone -U -u . .#other ../b -r 0 -r 1 -r 2 -b other
abort: cannot specify both --noupdate and --updaterev
[255]
$ hg clone -U .#other ../b -r 0 -r 1 -r 2 -b other
adding changesets
adding manifests
adding file changes
added 3 changesets with 3 changes to 3 files (+2 heads)
new changesets 8c68ee086fd0:fcc393352796
$ rm -rf ../b
$ hg clone -u . .#other ../b -r 0 -r 1 -r 2 -b other
adding changesets
adding manifests
adding file changes
added 3 changesets with 3 changes to 3 files (+2 heads)
new changesets 8c68ee086fd0:fcc393352796
updating to branch mine
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ rm -rf ../b
$ hg clone -u 0 .#other ../b -r 0 -r 1 -r 2 -b other
adding changesets
adding manifests
adding file changes
added 3 changesets with 3 changes to 3 files (+2 heads)
new changesets 8c68ee086fd0:fcc393352796
updating to branch default
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ rm -rf ../b
$ hg clone -u 1 .#other ../b -r 0 -r 1 -r 2 -b other
adding changesets
adding manifests
adding file changes
added 3 changesets with 3 changes to 3 files (+2 heads)
new changesets 8c68ee086fd0:fcc393352796
updating to branch mine
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ rm -rf ../b
$ hg clone -u 2 .#other ../b -r 0 -r 1 -r 2 -b other
adding changesets
adding manifests
adding file changes
added 3 changesets with 3 changes to 3 files (+2 heads)
new changesets 8c68ee086fd0:fcc393352796
updating to branch other
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ rm -rf ../b
Test -r mine ... mine is ignored:
$ hg clone -u 2 .#other ../b -r mine -r 0 -r 1 -r 2 -b other
adding changesets
adding manifests
adding file changes
added 3 changesets with 3 changes to 3 files (+2 heads)
new changesets 8c68ee086fd0:fcc393352796
updating to branch other
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ rm -rf ../b
$ hg clone .#other ../b -b default -b mine
adding changesets
adding manifests
adding file changes
added 3 changesets with 3 changes to 3 files (+2 heads)
new changesets 8c68ee086fd0:fcc393352796
updating to branch default
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ rm -rf ../b
$ hg clone .#other ../b
adding changesets
adding manifests
adding file changes
added 1 changesets with 1 changes to 1 files
new changesets fcc393352796
updating to branch other
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ rm -rf ../b
$ hg clone -U . ../c -r 1 -r 2 > /dev/null
$ hg clone ../c ../b
updating to branch other
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ rm -rf ../b ../c