view tests/flagprocessorext.py @ 38139:a0e4d654bceb

state: write the version number in plain text on top of state files

We will soon be using CBOR format to write the data in state files. But we
should not write the version number of the state files in CBOR format and we
should rather write it in plain text because in future we can change the format
of state files and we should be able to parse the version number of state file
without requiring to understand a certain format.

This will help us in making sure we have a good compatibility story with other
versions of state files.

Differential Revision: https://phab.mercurial-scm.org/D3579

# coding=UTF-8

from __future__ import absolute_import

import base64
import zlib

from mercurial import (
    changegroup,
    exchange,
    extensions,
    revlog,
    util,
)

# 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 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=revlog.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]
    revlog.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]["cg.version"] = "03"

    # Register flag processors for each extension
    revlog.addflagprocessor(
        REVIDX_NOOP,
        (
            noopdonothing,
            noopdonothing,
            validatehash,
        )
    )
    revlog.addflagprocessor(
        REVIDX_BASE64,
        (
            b64decode,
            b64encode,
            bypass,
        ),
    )
    revlog.addflagprocessor(
        REVIDX_GZIP,
        (
            gzipdecompress,
            gzipcompress,
            bypass
        )
    )