revlog: skip over empty revision when looking for delta base
There is no point in keeping an empty revision in the middle of a chain since
they won't contribute any data. So we filter them out when looking for a valid
base delta.
--- a/mercurial/revlog.py Sat Jul 28 14:14:59 2018 +0200
+++ b/mercurial/revlog.py Fri Jul 27 19:09:41 2018 +0200
@@ -743,10 +743,20 @@
p2 = revinfo.p2
revlog = self.revlog
+ deltalength = self.revlog.length
+ deltaparent = self.revlog.deltaparent
+
deltainfo = None
for candidaterevs in self._getcandidaterevs(p1, p2, cachedelta):
nominateddeltas = []
for candidaterev in candidaterevs:
+ # skip over empty delta (no need to include them in a chain)
+ while candidaterev != nullrev and not deltalength(candidaterev):
+ candidaterev = deltaparent(candidaterev)
+ # no need to try a delta against nullid, this will be handled
+ # by fulltext later.
+ if candidaterev == nullrev:
+ continue
# no delta for rawtext-changing revs (see "candelta" for why)
if revlog.flags(candidaterev) & REVIDX_RAWTEXT_CHANGING_FLAGS:
continue
--- a/tests/test-generaldelta.t Sat Jul 28 14:14:59 2018 +0200
+++ b/tests/test-generaldelta.t Fri Jul 27 19:09:41 2018 +0200
@@ -267,7 +267,7 @@
51 4 3 50 prev 356 594 611 1.02862 611 0 0.00000
52 4 4 51 p1 58 640 669 1.04531 669 0 0.00000
53 5 1 -1 base 0 0 0 0.00000 0 0 0.00000
- 54 5 2 53 p1 376 640 376 0.58750 376 0 0.00000
+ 54 6 1 -1 base 369 640 369 0.57656 369 0 0.00000
$ hg clone --pull source-repo --config experimental.maxdeltachainspan=2800 relax-chain --config format.generaldelta=yes
requesting all changes
adding changesets
@@ -333,7 +333,7 @@
51 2 13 17 p1 58 594 739 1.24411 2781 2042 2.76319
52 5 1 -1 base 369 640 369 0.57656 369 0 0.00000
53 6 1 -1 base 0 0 0 0.00000 0 0 0.00000
- 54 6 2 53 p1 376 640 376 0.58750 376 0 0.00000
+ 54 7 1 -1 base 369 640 369 0.57656 369 0 0.00000
$ hg clone --pull source-repo --config experimental.maxdeltachainspan=0 noconst-chain --config format.generaldelta=yes
requesting all changes
adding changesets
@@ -399,4 +399,4 @@
51 2 13 17 p1 58 594 739 1.24411 2642 1903 2.57510
52 2 14 51 p1 58 640 797 1.24531 2700 1903 2.38770
53 4 1 -1 base 0 0 0 0.00000 0 0 0.00000
- 54 4 2 53 p1 376 640 376 0.58750 376 0 0.00000
+ 54 5 1 -1 base 369 640 369 0.57656 369 0 0.00000