branchcache: add a "pure topological head" fast path
In a narrow but actually quick common case, all topological heads are all on
the same branch and all open. In this case, computing the branch map is very
simple. We can quickly detect situation where this situation will not change.
So we update the V3 format to be able to express this situation and upgrade the
update code to detect we remains in that mode.
The branch cache is populated with the actual value when the branch map is
accessed, but the update_disk method can do the update without needing to
populate it.
# mercurial.revlogutils -- basic utilities for revlog
#
# Copyright 2019 Pierre-Yves David <pierre-yves.david@octobus.net>
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.
from ..thirdparty import attr
from ..interfaces import repository
# See mercurial.revlogutils.constants for doc
COMP_MODE_INLINE = 2
RANK_UNKNOWN = -1
def offset_type(offset, type):
if (type & ~repository.REVISION_FLAGS_KNOWN) != 0:
raise ValueError(b'unknown revlog index flags: %d' % type)
return int(int(offset) << 16 | type)
def entry(
data_offset,
data_compressed_length,
data_delta_base,
link_rev,
parent_rev_1,
parent_rev_2,
node_id,
flags=0,
data_uncompressed_length=-1,
data_compression_mode=COMP_MODE_INLINE,
sidedata_offset=0,
sidedata_compressed_length=0,
sidedata_compression_mode=COMP_MODE_INLINE,
rank=RANK_UNKNOWN,
):
"""Build one entry from symbolic name
This is useful to abstract the actual detail of how we build the entry
tuple for caller who don't care about it.
This should always be called using keyword arguments. Some arguments have
default value, this match the value used by index version that does not store such data.
"""
return (
offset_type(data_offset, flags),
data_compressed_length,
data_uncompressed_length,
data_delta_base,
link_rev,
parent_rev_1,
parent_rev_2,
node_id,
sidedata_offset,
sidedata_compressed_length,
data_compression_mode,
sidedata_compression_mode,
rank,
)
@attr.s(slots=True, frozen=True)
class revisioninfo:
"""Information about a revision that allows building its fulltext
node: expected hash of the revision
p1, p2: parent revs of the revision (as node)
btext: built text cache consisting of a one-element list
cachedelta: (baserev, uncompressed_delta, usage_mode) or None
flags: flags associated to the revision storage
One of btext[0] or cachedelta must be set.
"""
node = attr.ib()
p1 = attr.ib()
p2 = attr.ib()
btext = attr.ib()
textlen = attr.ib()
cachedelta = attr.ib()
flags = attr.ib()