findrenames: Optimise "addremove -s100" by matching files by their SHA1 hashes.
We speed up 'findrenames' for the usecase when a user specifies they
want a similarity of 100% by matching files by their exact SHA1 hash
value. This reduces the number of comparisons required to find exact
matches from O(n^2) to O(n).
While it would be nice if we could just use mercurial's pre-calculated
SHA1 hash for existing files, this hash includes the file's ancestor
information making it unsuitable for our purposes. Instead, we calculate
the hash of old content from scratch.
The following benchmarks were taken on the current head of crew:
addremove 100% similarity:
rm -rf *; hg up -C; mv tests tests.new
hg --time addremove -s100 --dry-run
before: real 176.350 secs (user 128.890+0.000 sys 47.430+0.000)
after: real 2.130 secs (user 1.890+0.000 sys 0.240+0.000)
addremove 75% similarity:
rm -rf *; hg up -C; mv tests tests.new; \
for i in tests.new/*; do echo x >> $i; done
hg --time addremove -s75 --dry-run
before: real 264.560 secs (user 215.130+0.000 sys 49.410+0.000)
after: real 218.710 secs (user 172.790+0.000 sys 45.870+0.000)
reverting foo
changeset 2:4d9e78aaceee backs out changeset 1:b515023e500e
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
searching for copies back to rev 1
unmatched files in local:
bar
resolving manifests
overwrite None partial False
ancestor bbd179dfa0a7 local 71766447bdbb+ remote 4d9e78aaceee
foo: remote is newer -> g
update: foo 1/1 files (100.00%)
getting foo
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)
n 0 -2 unset foo
M foo
c6fc755d7e68f49f880599da29f15add41f42f5a 644 foo
rev offset length base linkrev nodeid p1 p2
0 0 5 0 0 2ed2a3912a0b 000000000000 000000000000
1 5 9 1 1 6f4310b00b9a 2ed2a3912a0b 000000000000
2 14 5 2 2 c6fc755d7e68 6f4310b00b9a 000000000000