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)
% basic
% unknown
alias 'unknown' resolves to unknown command 'bargle'
alias 'unknown' resolves to unknown command 'bargle'
% ambiguous
alias 'ambiguous' resolves to ambiguous command 's'
alias 'ambiguous' resolves to ambiguous command 's'
% recursive
alias 'recursive' resolves to unknown command 'recursive'
alias 'recursive' resolves to unknown command 'recursive'
% no definition
no definition for alias 'nodefinition'
no definition for alias 'nodefinition'
% no usage
no rollback information available
adding foo
% with opts
C foo
% with opts and whitespace
0 e63c23eaa88a | 1970-01-01 00:00 +0000
% interaction with defaults
0:e63c23eaa88a
-1:000000000000
% properly recursive
changeset: -1:0000000000000000000000000000000000000000
parent: -1:0000000000000000000000000000000000000000
parent: -1:0000000000000000000000000000000000000000
manifest: -1:0000000000000000000000000000000000000000
user:
date: Thu Jan 01 00:00:00 1970 +0000
extra: branch=default
% path expanding
# HG changeset patch
# User test
# Date 0 0
# Node ID e63c23eaa88ae77967edcf4ea194d31167c478b0
# Parent 0000000000000000000000000000000000000000
foo
diff -r 000000000000 -r e63c23eaa88a foo
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/foo Thu Jan 01 00:00:00 1970 +0000
@@ -0,0 +1,1 @@
+foo