manifestmerge: use dicthelpers.diff and join
This patch improves manifestmerge performance significantly.
In a repository with 170,000 files, the following results were observed on a
clean working directory. Revision '.' adds one file.
hg perfmergecalculate -r .
- before: 0.41 seconds
- after: 0.13 seconds
hg perfmergecalculate -r .^
- before: 0.53 seconds
- after: 0.24 seconds
Comparing against '.' is much faster than comparing against '.^' because with
'.', the wctx and p2 manifest strings have the same identity, so comparisons
are simply pointer equality. With '.^', the strings have different identities
so we need to perform memcmps.
Any operation that uses manifestmerge benefits.
- hg update . goes from 2.04 seconds to 1.75
- hg update .^ goes from 2.52 seconds to 2.25
- hg rebase -r . -d .~6 (involves 4 merges) goes from 11.8 seconds to 10.8
$ "$TESTDIR/hghave" unix-permissions || exit 80
$ hg init t
$ cd t
$ echo foo > a
$ hg add a
$ hg commit -m "1"
$ hg verify
checking changesets
checking manifests
crosschecking files in changesets and manifests
checking files
1 files, 1 changesets, 1 total revisions
$ chmod -r .hg/store/data/a.i
$ hg verify
checking changesets
checking manifests
crosschecking files in changesets and manifests
checking files
abort: Permission denied: $TESTTMP/t/.hg/store/data/a.i
[255]
$ chmod +r .hg/store/data/a.i
$ hg verify
checking changesets
checking manifests
crosschecking files in changesets and manifests
checking files
1 files, 1 changesets, 1 total revisions
$ chmod -w .hg/store/data/a.i
$ echo barber > a
$ hg commit -m "2"
trouble committing a!
abort: Permission denied: $TESTTMP/t/.hg/store/data/a.i
[255]
$ chmod -w .
$ hg diff --nodates
diff -r 2a18120dc1c9 a
--- a/a
+++ b/a
@@ -1,1 +1,1 @@
-foo
+barber
$ chmod +w .
$ chmod +w .hg/store/data/a.i
$ mkdir dir
$ touch dir/a
$ hg status
M a
? dir/a
$ chmod -rx dir
$ hg status
dir: Permission denied
M a
Reenable perm to allow deletion:
$ chmod +rx dir
$ cd ..