localrepo: stop doing special dirstate backup at transaction open
Since the dirstate writes are already managed by the transaction, we already do
a backup of the dirstate when necessary (and even trigger one to keep `hg
rollback` happy).
We needs some special code to deal with the initial empty checkout, but it is
not too complicated.
Managing variable filename (as dirstate-v2 uses) at the "journalfile" level, is
complex and fragile (which is consistent with the fact these files are not
journal…). If we no longer do it, our life is significantly simpler.
In some sense, we apply the xkcd-1134¹ solution to our savebackup/restorebackup
problem.
[1] https://xkcd.com/1134/
(the change to test-hardlink are expect as decreasing the number of duplicated
backup drive the hardlink count down)
# coding=UTF-8
import base64
import zlib
from mercurial import (
bundlecaches,
changegroup,
extensions,
revlog,
util,
)
from mercurial.revlogutils import flagutil
from mercurial.interfaces import repository
# Test only: These flags are defined here only in the context of testing the
# behavior of the flag processor. The canonical way to add flags is to get in
# touch with the community and make them known in revlog.
REVIDX_NOOP = 1 << 3
REVIDX_BASE64 = 1 << 2
REVIDX_GZIP = 1 << 1
REVIDX_FAIL = 1
def validatehash(self, text):
return True
def bypass(self, text):
return False
def noopdonothing(self, text):
return (text, True)
def noopdonothingread(self, text):
return (text, True)
def b64encode(self, text):
return (base64.b64encode(text), False)
def b64decode(self, text):
return (base64.b64decode(text), True)
def gzipcompress(self, text):
return (zlib.compress(text), False)
def gzipdecompress(self, text):
return (zlib.decompress(text), True)
def supportedoutgoingversions(orig, repo):
versions = orig(repo)
versions.discard(b'01')
versions.discard(b'02')
versions.add(b'03')
return versions
def allsupportedversions(orig, ui):
versions = orig(ui)
versions.add(b'03')
return versions
def makewrappedfile(obj):
class wrappedfile(obj.__class__):
def addrevision(
self,
text,
transaction,
link,
p1,
p2,
cachedelta=None,
node=None,
flags=flagutil.REVIDX_DEFAULT_FLAGS,
):
if b'[NOOP]' in text:
flags |= REVIDX_NOOP
if b'[BASE64]' in text:
flags |= REVIDX_BASE64
if b'[GZIP]' in text:
flags |= REVIDX_GZIP
# This addrevision wrapper is meant to add a flag we will not have
# transforms registered for, ensuring we handle this error case.
if b'[FAIL]' in text:
flags |= REVIDX_FAIL
return super(wrappedfile, self).addrevision(
text,
transaction,
link,
p1,
p2,
cachedelta=cachedelta,
node=node,
flags=flags,
)
obj.__class__ = wrappedfile
def reposetup(ui, repo):
class wrappingflagprocessorrepo(repo.__class__):
def file(self, f):
orig = super(wrappingflagprocessorrepo, self).file(f)
makewrappedfile(orig)
return orig
repo.__class__ = wrappingflagprocessorrepo
def extsetup(ui):
# Enable changegroup3 for flags to be sent over the wire
wrapfunction = extensions.wrapfunction
wrapfunction(
changegroup, 'supportedoutgoingversions', supportedoutgoingversions
)
wrapfunction(changegroup, 'allsupportedversions', allsupportedversions)
# Teach revlog about our test flags
flags = [REVIDX_NOOP, REVIDX_BASE64, REVIDX_GZIP, REVIDX_FAIL]
flagutil.REVIDX_KNOWN_FLAGS |= util.bitsfrom(flags)
repository.REVISION_FLAGS_KNOWN |= util.bitsfrom(flags)
revlog.REVIDX_FLAGS_ORDER.extend(flags)
# Teach exchange to use changegroup 3
for k in bundlecaches._bundlespeccontentopts.keys():
bundlecaches._bundlespeccontentopts[k][b"cg.version"] = b"03"
# Register flag processors for each extension
flagutil.addflagprocessor(
REVIDX_NOOP,
(
noopdonothingread,
noopdonothing,
validatehash,
),
)
flagutil.addflagprocessor(
REVIDX_BASE64,
(
b64decode,
b64encode,
bypass,
),
)
flagutil.addflagprocessor(
REVIDX_GZIP, (gzipdecompress, gzipcompress, bypass)
)