dirstate-tree: Make `DirstateMap` borrow from a bytes buffer
… that has the contents of the `.hg/dirstate` file.
This only applies to the tree-based flavor of `DirstateMap`.
For now only the entire `&[u8]` slice is stored, so this is not useful yet.
Adding a lifetime parameter to the `DirstateMap` struct (in hg-core) makes
Python bindings non-trivial because we keep that struct in a Python object
that has a dynamic lifetime tied to Python’s reference-counting and GC.
As long as we keep the `PyBytes` that owns the borrowed bytes buffer next to
the borrowing struct, the buffer will live long enough for the borrows to stay
valid. However this relationship cannot be expressed in safe Rust code in a
way that would statisfy they borrow-checker. We use `unsafe` code to erase
that lifetime parameter, and encapsulate it in a safe abstraction similar to
the owning-ref crate: https://docs.rs/owning_ref/
Differential Revision: https://phab.mercurial-scm.org/D10557
# coding=UTF-8
from __future__ import absolute_import
import base64
import zlib
from mercurial import (
bundlecaches,
changegroup,
extensions,
revlog,
util,
)
from mercurial.revlogutils import flagutil
# 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)
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)
)