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)
% init
% no working directory
% setup
0 files updated, 0 files merged, 2 files removed, 0 files unresolved
% hg children at revision 3 (tip)
0 files updated, 0 files merged, 1 files removed, 0 files unresolved
% hg children at nullrev (should be 0 and 3)
changeset: 0:4df8521a7374
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 0
changeset: 3:e2962852269d
tag: tip
parent: -1:000000000000
user: test
date: Thu Jan 01 00:00:03 1970 +0000
summary: 3
2 files updated, 0 files merged, 0 files removed, 0 files unresolved
% hg children at revision 1 (should be 2)
changeset: 2:8f5eea5023c2
user: test
date: Thu Jan 01 00:00:02 1970 +0000
summary: 2
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
% hg children at revision 2 (other head)
% hg children -r null
changeset: 0:4df8521a7374
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 0
changeset: 3:e2962852269d
tag: tip
parent: -1:000000000000
user: test
date: Thu Jan 01 00:00:03 1970 +0000
summary: 3
% hg children -r 0
changeset: 1:708c093edef0
user: test
date: Thu Jan 01 00:00:01 1970 +0000
summary: 1
% hg children -r 1
changeset: 2:8f5eea5023c2
user: test
date: Thu Jan 01 00:00:02 1970 +0000
summary: 2
% hg children -r 2
% hg children -r 3
% hg children -r 0 file0 (should be 2)
changeset: 2:8f5eea5023c2
user: test
date: Thu Jan 01 00:00:02 1970 +0000
summary: 2
% hg children -r 1 file0 (should be 2)
changeset: 2:8f5eea5023c2
user: test
date: Thu Jan 01 00:00:02 1970 +0000
summary: 2
1 files updated, 0 files merged, 1 files removed, 0 files unresolved
% hg children file0 at revision 0 (should be 2)
changeset: 2:8f5eea5023c2
user: test
date: Thu Jan 01 00:00:02 1970 +0000
summary: 2