view tests/flagprocessorext.py @ 43033:21025a4107d4

sidedata: add a new module with basic documentation

For now the storage strategy is very simple. We can augment it in the future if
needed.

Code to actually support what is described will be introduced in later
changesets.

Differential Revision: https://phab.mercurial-scm.org/D6889

# coding=UTF-8

from __future__ import absolute_import

import base64
import zlib

from mercurial import (
    changegroup,
    exchange,
    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, sidedata):
    return (text, True)

def noopdonothingread(self, text):
    return (text, True, {})

def b64encode(self, text, sidedata):
    return (base64.b64encode(text), False)

def b64decode(self, text):
    return (base64.b64decode(text), True, {})

def gzipcompress(self, text, sidedata):
    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 exchange._bundlespeccontentopts.keys():
        exchange._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
        )
    )