rank: naive rank property computation and retrieval
This stores the rank (size of the ancestor set of a revision, including itself)
in a changelog field and allows this property to be retrieved.
This new property is used as part of stable-range computations, which will be
introduced later on.
The value is computed in a naive way from the definition of the rank. This will
be replaced by a more efficient version subsequently.
Differential Revision: https://phab.mercurial-scm.org/D12139
--- a/mercurial/revlog.py Mon Feb 07 22:54:38 2022 -0800
+++ b/mercurial/revlog.py Fri Jan 28 11:33:01 2022 +0100
@@ -40,11 +40,13 @@
COMP_MODE_DEFAULT,
COMP_MODE_INLINE,
COMP_MODE_PLAIN,
+ ENTRY_RANK,
FEATURES_BY_VERSION,
FLAG_GENERALDELTA,
FLAG_INLINE_DATA,
INDEX_HEADER,
KIND_CHANGELOG,
+ RANK_UNKNOWN,
REVLOGV0,
REVLOGV1,
REVLOGV1_FLAGS,
@@ -857,6 +859,22 @@
return len(self.revision(rev))
+ def fast_rank(self, rev):
+ """Return the rank of a revision if already known, or None otherwise.
+
+ The rank of a revision is the size of the sub-graph it defines as a
+ head. Equivalently, the rank of a revision `r` is the size of the set
+ `ancestors(r)`, `r` included.
+
+ This method returns the rank retrieved from the revlog in constant
+ time. It makes no attempt at computing unknown values for versions of
+ the revlog which do not persist the rank.
+ """
+ rank = self.index[rev][ENTRY_RANK]
+ if rank == RANK_UNKNOWN:
+ return None
+ return rank
+
def chainbase(self, rev):
base = self._chainbasecache.get(rev)
if base is not None:
@@ -2444,6 +2462,10 @@
# than ones we manually add.
sidedata_offset = 0
+ rank = RANK_UNKNOWN
+ if self._format_version == CHANGELOGV2:
+ rank = len(list(self.ancestors([p1r, p2r], inclusive=True))) + 1
+
e = revlogutils.entry(
flags=flags,
data_offset=offset,
@@ -2458,6 +2480,7 @@
sidedata_offset=sidedata_offset,
sidedata_compressed_length=len(serialized_sidedata),
sidedata_compression_mode=sidedata_compression_mode,
+ rank=rank,
)
self.index.append(e)