bookmarks: cache reverse mapping (issue5868)
I chose a simpler implementation. If the initial cost of building reverse
mapping is significant, we'll have to move it under @propertycache.
The nodemap could be a dict of sets, but I think keeping a sorted list is
better since each node is likely to have zero/one bookmark.
Micro-benchmark with 1001 bookmarks and 1001 revisions:
$ for n in `seq 0 1000`; do touch $n; hg book book$n; hg ci -qAm$n; done
$ hg bookmarks --time > /dev/null
(orig) time: real 0.040 secs (user 0.050+0.000 sys 0.000+0.000)
(new) time: real 0.040 secs (user 0.040+0.000 sys 0.010+0.000)
$ hg log -T '{bookmarks}\n' --time > /dev/null
(orig) time: real 0.160 secs (user 0.160+0.000 sys 0.000+0.000)
(new) time: real 0.090 secs (user 0.100+0.000 sys 0.000+0.000)