snapshot: add refining logic at the findeltainfo level
Once we found a delta, we want to have the candidates logic challenge it,
searching for a better candidate.
The logic at the lower level is still missing. We'll introduce it later.
Adding small changes in individual commits make it simpler to explain the code
change.
This is another small step toward turning `_refinegroups` into a co-routine.
--- a/mercurial/revlogutils/deltas.py Fri Sep 07 11:17:32 2018 -0400
+++ b/mercurial/revlogutils/deltas.py Fri Sep 07 11:17:33 2018 -0400
@@ -582,6 +582,7 @@
deltalength = revlog.length
deltaparent = revlog.deltaparent
+ good = None
deltas_limit = textlen * LIMIT_DELTA2TEXT
@@ -612,7 +613,9 @@
# XXX: in the sparse revlog case, group can become large,
# impacting performances. Some bounding or slicing mecanism
# would help to reduce this impact.
- yield tuple(group)
+ good = yield tuple(group)
+ if good is not None:
+ break
yield None
def _findsnapshots(revlog, cache, start_rev):
@@ -847,14 +850,20 @@
candidaterevs = next(groups)
while candidaterevs is not None:
nominateddeltas = []
+ if deltainfo is not None:
+ # if we already found a good delta,
+ # challenge it against refined candidates
+ nominateddeltas.append(deltainfo)
for candidaterev in candidaterevs:
candidatedelta = self._builddeltainfo(revinfo, candidaterev, fh)
if isgooddeltainfo(self.revlog, candidatedelta, revinfo):
nominateddeltas.append(candidatedelta)
if nominateddeltas:
deltainfo = min(nominateddeltas, key=lambda x: x.deltalen)
- break
- candidaterevs = next(groups)
+ if deltainfo is not None:
+ candidaterevs = groups.send(deltainfo.base)
+ else:
+ candidaterevs = next(groups)
if deltainfo is None:
deltainfo = self._fullsnapshotinfo(fh, revinfo)