view tests/bzr-definitions @ 17970:0b03454abae7

ancestor: faster algorithm for difference of ancestor sets

One of the major reasons rebase is slow in large repositories is
the computation of the detach set: the set of ancestors of the
changesets to rebase not in the destination parent. This is currently
done via a revset that does two walks all the way to the root of
the DAG. Instead of doing that, to find ancestors of a set <revs>
not in another set <common> we walk up the tree in reverse revision
number order, maintaining sets of nodes visited from <revs>, <common>
or both.

For the common case where the sets are close both topologically and
in revision number (relative to repository size), this has been
found to speed up rebase by around 15-20%. When the nodes are farther
apart and the DAG is highly branching, it is harder to say which
would win.

Here's how long computing the detach set takes in a linear repository
with over 400000 changesets, rebasing near tip:

Rebasing across 4 changesets
Revset method: 2.2s
New algorithm: 0.00015s

Rebasing across 250 changesets
Revset method: 2.2s
New algorithm: 0.00069s

Rebasing across 10000 changesets
Revset method: 2.4s
New algorithm: 0.019s

# this file holds the definitions that are used in various bzr tests

"$TESTDIR/hghave" bzr || exit 80

TERM=dumb; export TERM
echo '[extensions]' >> $HGRCPATH
echo 'convert = ' >> $HGRCPATH
echo 'hgext.graphlog = ' >> $HGRCPATH

glog()
{
    hg glog --template '{rev}@{branch} "{desc|firstline}" files: {files}\n' "$@"
}

manifest()
{
    echo "% manifest of $2"
    hg -R $1 manifest -v -r $2
}