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Differential D10889

revlog: factor the logic to determine the delta compression out
ClosedPublic

Authored by marmoute on Jun 21 2021, 9:10 AM.

Details

Reviewers
indygreg
Alphare
Group Reviewers
hg-reviewers
Commits
rHGc6844912c327: revlog: factor the logic to determine the delta compression out
Summary

This make the logic clearly isolated and documented and it will help use to
reuse it during censors/strip.

Diff Detail

Repository
rHG Mercurial
Lint
Automatic diff as part of commit; lint not applicable.
Unit
Automatic diff as part of commit; unit tests not applicable.

Event Timeline

marmoute created this revision.Jun 21 2021, 9:10 AM
Alphare accepted this revision.Jun 21 2021, 10:24 AM
Alphare added a subscriber: Alphare.

Not a big fan of one-letter variables, but this is strictly better.

This revision is now accepted and ready to land.Jun 21 2021, 10:24 AM
marmoute added a comment.Jun 21 2021, 10:42 AM
In D10889#166551, @Alphare wrote:

Not a big fan of one-letter variables, but this is strictly better.

I am just moving code around !

(okay, okay, I wrote the initial code)

I can expand this in a follow up. I would rather keep the change along side the movement minimal.

Revision Contents
Changeset List

PathPackages
Mmercurial/revlog.py (18 lines)
Mmercurial/revlogutils/deltas.py (28 lines)

Diff 28660

mercurial/revlog.py

cachedelta, cachedelta,
flags, flags,
) )
deltainfo = deltacomputer.finddeltainfo(revinfo, fh) deltainfo = deltacomputer.finddeltainfo(revinfo, fh)
compression_mode = COMP_MODE_INLINE compression_mode = COMP_MODE_INLINE
if self._docket is not None: if self._docket is not None:
h, d = deltainfo.data default_comp = self._docket.default_compression_header
if not h and not d: r = deltautil.delta_compression(default_comp, deltainfo)
# not data to store at all... declare them uncompressed compression_mode, deltainfo = r
compression_mode = COMP_MODE_PLAIN
elif not h:
t = d[0:1]
if t == b'\0':
compression_mode = COMP_MODE_PLAIN
elif t == self._docket.default_compression_header:
compression_mode = COMP_MODE_DEFAULT
elif h == b'u':
# we have a more efficient way to declare uncompressed
h = b''
compression_mode = COMP_MODE_PLAIN
deltainfo = deltautil.drop_u_compression(deltainfo)
sidedata_compression_mode = COMP_MODE_INLINE sidedata_compression_mode = COMP_MODE_INLINE
if sidedata and self.hassidedata: if sidedata and self.hassidedata:
sidedata_compression_mode = COMP_MODE_PLAIN sidedata_compression_mode = COMP_MODE_PLAIN
serialized_sidedata = sidedatautil.serialize_sidedata(sidedata) serialized_sidedata = sidedatautil.serialize_sidedata(sidedata)
sidedata_offset = self._docket.sidedata_end sidedata_offset = self._docket.sidedata_end
h, comp_sidedata = self.compress(serialized_sidedata) h, comp_sidedata = self.compress(serialized_sidedata)
if ( if (

mercurial/revlogutils/deltas.py

import struct import struct
# import stuff from node for others to import from revlog # import stuff from node for others to import from revlog
from ..node import nullrev from ..node import nullrev
from ..i18n import _ from ..i18n import _
from ..pycompat import getattr from ..pycompat import getattr
from .constants import ( from .constants import (
COMP_MODE_DEFAULT,
COMP_MODE_INLINE,
COMP_MODE_PLAIN,
REVIDX_ISCENSORED, REVIDX_ISCENSORED,
REVIDX_RAWTEXT_CHANGING_FLAGS, REVIDX_RAWTEXT_CHANGING_FLAGS,
) )
from ..thirdparty import attr from ..thirdparty import attr
from .. import ( from .. import (
error, error,
if deltainfo is not None: if deltainfo is not None:
candidaterevs = groups.send(deltainfo.base) candidaterevs = groups.send(deltainfo.base)
else: else:
candidaterevs = next(groups) candidaterevs = next(groups)
if deltainfo is None: if deltainfo is None:
deltainfo = self._fullsnapshotinfo(fh, revinfo) deltainfo = self._fullsnapshotinfo(fh, revinfo)
return deltainfo return deltainfo
def delta_compression(default_compression_header, deltainfo):
"""return (COMPRESSION_MODE, deltainfo)
used by revlog v2+ format to dispatch between PLAIN and DEFAULT
compression.
"""
h, d = deltainfo.data
compression_mode = COMP_MODE_INLINE
if not h and not d:
# not data to store at all... declare them uncompressed
compression_mode = COMP_MODE_PLAIN
elif not h:
t = d[0:1]
if t == b'\0':
compression_mode = COMP_MODE_PLAIN
elif t == default_compression_header:
compression_mode = COMP_MODE_DEFAULT
elif h == b'u':
# we have a more efficient way to declare uncompressed
h = b''
compression_mode = COMP_MODE_PLAIN
deltainfo = drop_u_compression(deltainfo)
return compression_mode, deltainfo