tests/test-mq-strip

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 "[extensions]" >> $HGRCPATH
echo "mq=" >> $HGRCPATH

teststrip() {
    hg up -C $1
    echo % before update $1, strip $2
    hg parents
    hg strip $2 2>&1 | sed 's/\(saving bundle to \).*/\1/'
    echo % after update $1, strip $2
    hg parents
    hg unbundle -q .hg/strip-backup/*
    rm .hg/strip-backup/*
}

hg init test
cd test

echo foo > bar
hg ci -Ama

echo more >> bar
hg ci -Amb

echo blah >> bar
hg ci -Amc

hg up 1
echo blah >> bar
hg ci -Amd

echo final >> bar
hg ci -Ame

hg log

teststrip 4 4
teststrip 4 3
teststrip 1 4
teststrip 4 2
teststrip 4 1
teststrip null 4

hg log

hg up -C 2
hg merge 4
echo % before strip of merge parent
hg parents
hg strip 4 2>&1 | sed 's/\(saving bundle to \).*/\1/'
echo % after strip of merge parent
hg parents