patch: support diff data loss detection and upgrade
In worst case, generating diff in upgrade mode can be two times more expensive
than generating it in git mode directly: we may have to regenerate the whole
diff again whenever a git feature is detected. Also, the first diff attempt is
completely buffered instead of being streamed. That said, even without having
profiled it yet, I am convinced we can fast-path the upgrade mode if necessary
were it to be used in regular diff commands, and not only in mq where avoiding
data loss is worth the price.
#!/bin/sh
echo '[extensions]' >> $HGRCPATH
echo 'graphlog =' >> $HGRCPATH
echo 'convert =' >> $HGRCPATH
glog()
{
hg -R "$1" glog --template '{rev} "{desc}" files: {files}\n'
}
hg init source
cd source
echo a > a
echo b > b
hg ci -d '0 0' -qAm '0: add a b'
echo c > c
hg ci -d '1 0' -qAm '1: add c'
hg copy a e
echo b >> b
hg ci -d '2 0' -qAm '2: copy e from a, change b'
hg up -C 0
echo a >> a
hg ci -d '3 0' -qAm '3: change a'
hg merge
hg copy b d
hg ci -d '4 0' -qAm '4: merge 2 and 3, copy d from b'
echo a >> a
hg ci -d '5 0' -qAm '5: change a'
cd ..
echo % convert from null revision
hg convert --config convert.hg.startrev=null source empty
glog empty
echo % convert from zero revision
hg convert --config convert.hg.startrev=0 source full
glog full
echo % convert from merge parent
hg convert --config convert.hg.startrev=1 source conv1
glog conv1
cd conv1
echo % check copy preservation
hg log --follow --copies e
echo % check copy removal on missing parent
hg log --follow --copies d
hg cat -r tip a b
hg -q verify
cd ..
echo % convert from merge
hg convert --config convert.hg.startrev=4 source conv4
glog conv4
cd conv4
hg up -C
hg cat -r tip a b
hg -q verify
cd ..