snapshot: use None as a stop value when looking for a good delta
Having clear stop value should help keep clear logic around the co-routine.
The alternative of using a StopIteration exception give a messier result.
This is one 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 11:17:32 2018 -0400
@@ -577,6 +577,7 @@
"""
# should we try to build a delta?
if not (len(revlog) and revlog._storedeltachains):
+ yield None
return
deltalength = revlog.length
@@ -612,6 +613,7 @@
# impacting performances. Some bounding or slicing mecanism
# would help to reduce this impact.
yield tuple(group)
+ yield None
def _findsnapshots(revlog, cache, start_rev):
"""find snapshot from start_rev to tip"""
@@ -842,7 +844,8 @@
p1r, p2r = revlog.rev(p1), revlog.rev(p2)
groups = _candidategroups(self.revlog, revinfo.textlen,
p1r, p2r, cachedelta)
- for candidaterevs in groups:
+ candidaterevs = next(groups)
+ while candidaterevs is not None:
nominateddeltas = []
for candidaterev in candidaterevs:
candidatedelta = self._builddeltainfo(revinfo, candidaterev, fh)
@@ -851,6 +854,7 @@
if nominateddeltas:
deltainfo = min(nominateddeltas, key=lambda x: x.deltalen)
break
+ candidaterevs = next(groups)
if deltainfo is None:
deltainfo = self._fullsnapshotinfo(fh, revinfo)