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 >> $i; done
hg --time addremove -s75 --dry-run
before: real 264.560 secs (user 215.130+0.000 sys 49.410+0.000)
after: real 218.710 secs (user 172.790+0.000 sys 45.870+0.000)
adding b
popping changeb
patch queue now empty
% push patch with missing target
applying changeb
unable to find 'b' for patching
2 out of 2 hunks FAILED -- saving rejects to file b.rej
patch failed, unable to continue (try -v)
patch failed, rejects left in working dir
errors during apply, please fix and refresh changeb
% display added files
a
c
% display rejections
--- b
+++ b
@@ -1,3 +1,5 @@
+b
+b
a
a
a
@@ -8,3 +10,5 @@
a
a
a
+c
+c
adding b
popping changeb
patch queue now empty
% push git patch with missing target
applying changeb
unable to find 'b' for patching
1 out of 1 hunks FAILED -- saving rejects to file b.rej
patch failed, unable to continue (try -v)
b: No such file or directory
patch failed, rejects left in working dir
errors during apply, please fix and refresh changeb
? b.rej
% display added files
a
c
% display rejections
--- b
+++ b
GIT binary patch
literal 2
Jc${No0000400IC2
% test push creating directory during git copy or rename
adding a
popping patch
patch queue now empty
applying patch
now at: patch