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)
#!/bin/sh
echo "% setup"
# create a little extension that has 3 side-effects:
# 1) ensure changelog data is not inlined
# 2) make revlog to use lazyparser
# 3) test that repo.lookup() works
# 1 and 2 are preconditions for the bug; 3 is the bug.
cat > commitwrapper.py <<EOF
from mercurial import extensions, node, revlog
def reposetup(ui, repo):
def wrapcommit(orig, *args, **kwargs):
result = orig(*args, **kwargs)
tip1 = node.short(repo.changelog.tip())
tip2 = node.short(repo.lookup(tip1))
assert tip1 == tip2
ui.write('new tip: %s\n' % tip1)
return result
extensions.wrapfunction(repo, 'commit', wrapcommit)
def extsetup(ui):
revlog._maxinline = 8 # split out 00changelog.d early
revlog._prereadsize = 8 # use revlog.lazyparser
EOF
cat >> $HGRCPATH <<EOF
[extensions]
commitwrapper = $PWD/commitwrapper.py
EOF
hg init repo1
cd repo1
echo a > a
hg commit -A -m'add a with a long commit message to make the changelog a bit bigger'
echo ""
echo "% test that new changesets are visible to repo.lookup()"
echo a >> a
hg commit -m'one more commit to demonstrate the bug'
hg tip