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)
% bundle w/o type option
adding file.txt
summary: a
searching for changes
1 changesets found
pulling from ../b1
requesting all changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 1 changes to 1 files
(run 'hg update' to get a working copy)
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
summary: a
% test bundle type None
searching for changes
1 changesets found
HG10UN
pulling from ../bNone
requesting all changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 1 changes to 1 files
(run 'hg update' to get a working copy)
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
summary: a
% test bundle type bzip2
searching for changes
1 changesets found
HG10BZ
pulling from ../bbzip2
requesting all changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 1 changes to 1 files
(run 'hg update' to get a working copy)
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
summary: a
% test bundle type gzip
searching for changes
1 changesets found
HG10GZ
pulling from ../bgzip
requesting all changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 1 changes to 1 files
(run 'hg update' to get a working copy)
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
summary: a
% test garbage file
abort: ../bgarbage: not a Mercurial bundle file
% test invalid bundle type
1 changesets found
abort: unknown bundle type specified with --type