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 a
1 files updated, 0 files merged, 1 files removed, 0 files unresolved
warning: detected divergent renames of a to:
a2
a1
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
adding a
b
b: searching for copy revision for a
b: copy a:b80de5d138758541c5f05265ad144ab9fa86d1db
committed changeset 5:89e8e4be0de296fa3d6dd7825ccc44d7dc0f1f3b
checking changesets
checking manifests
crosschecking files in changesets and manifests
checking files
4 files, 6 changesets, 4 total revisions
# HG changeset patch
# User test
# Date 0 0
# Node ID 89e8e4be0de296fa3d6dd7825ccc44d7dc0f1f3b
# Parent 7fc86ba705e717a721dbc361bf8c9bc05a18ca2f
5
diff --git a/b b/b
new file mode 100644