revset: add depth limit to descendants() (issue5374)
This is naive implementation using two-pass scanning. Tracking descendants
isn't an easy problem if both start and stop depths are specified. It's
impractical to remember all possible depths of each node while scanning from
roots to descendants because the number of depths explodes. Instead, we could
cache (min, max) depths as a good approximation and track ancestors back when
needed, but that's likely to have off-by-one bug.
Since this implementation appears not significantly slower, and is quite
straightforward, I think it's good enough for practical use cases. The time
and space complexity is O(n) ish.
revisions:
0) 1-pass scanning with (min, max)-depth cache (worst-case quadratic)
1) 2-pass scanning (this version)
repository:
mozilla-central
# descendants(0) (for reference)
*) 0.430353
# descendants(0, depth=1000)
0) 0.264889
1) 0.398289
# descendants(limit(tip:0, 1, offset=10000), depth=1000)
0) 0.025478
1) 0.029099
# descendants(0, depth=2000, startdepth=1000)
0) painfully slow (due to quadratic backtracking of ancestors)
1) 1.531138
#!/bin/bash -eu
. $(dirname $0)/dockerlib.sh
. $(dirname $0)/packagelib.sh
BUILDDIR=$(dirname $0)
export ROOTDIR=$(cd $BUILDDIR/.. > /dev/null; pwd)
checkdocker
DISTID="$1"
CODENAME="$2"
PLATFORM="$1-$2"
shift; shift # extra params are passed to build process
OUTPUTDIR=${OUTPUTDIR:=$ROOTDIR/packages/$PLATFORM}
initcontainer $PLATFORM
# debuild only appears to be able to save built debs etc to .., so we
# have to share the .. of the current directory with the docker
# container and hope it's writable. Whee.
dn=$(basename $PWD)
if [ $(uname) = "Darwin" ] ; then
$DOCKER run -u $DBUILDUSER --rm -v $PWD/..:/mnt $CONTAINER \
sh -c "cd /mnt/$dn && make clean && make local"
fi
$DOCKER run -u $DBUILDUSER --rm -v $PWD/..:/mnt $CONTAINER \
sh -c "cd /mnt/$dn && DEB_BUILD_OPTIONS='${DEB_BUILD_OPTIONS:=}' contrib/builddeb --build --distid $DISTID --codename $CODENAME $@"
contrib/builddeb --cleanup --distid $DISTID --codename $CODENAME
if [ $(uname) = "Darwin" ] ; then
$DOCKER run -u $DBUILDUSER --rm -v $PWD/..:/mnt $CONTAINER \
sh -c "cd /mnt/$dn && make clean"
fi