comparison mercurial/revlogutils/flagutil.py @ 46709:3d740058b467

sidedata: move to new sidedata storage in revlogv2

The current (experimental) sidedata system uses flagprocessors to signify the
presence and store/retrieve sidedata from the raw revlog data. This proved to be
quite fragile from an exchange perspective and a lot more complex than simply
having a dedicated space in the new revlog format.

This change does not handle exchange (ironically), so the test for amend - that
uses a bundle - is broken. This functionality is split into the next patches.

Differential Revision: https://phab.mercurial-scm.org/D9993

46708:358737abeeef

        msg = _(b"cannot register multiple processors on flag '%#x'.") % flag
        raise error.Abort(msg)
    flagprocessors[flag] = processor


def processflagswrite(revlog, text, flags, sidedata):
    """Inspect revision data flags and applies write transformations defined
    by registered flag processors.

    ``text`` - the revision data to process
    ``flags`` - the revision flags

    Returns a 2-tuple of ``(text, validatehash)`` where ``text`` is the
    processed text and ``validatehash`` is a bool indicating whether the
    returned text should be checked for hash integrity.
    """
    return _processflagsfunc(revlog, text, flags, b'write', sidedata=sidedata)[
        :2
    ]


def processflagsread(revlog, text, flags):
    """Inspect revision data flags and applies read transformations defined
    by registered flag processors.

    returned text should be checked for hash integrity.
    """
    return _processflagsfunc(revlog, text, flags, b'raw')[1]


def _processflagsfunc(revlog, text, flags, operation, sidedata=None):
    """internal function to process flag on a revlog

    This function is private to this module, code should never needs to call it
    directly."""
    # fast path: no flag processors will run
    if flags == 0:
        return text, True, {}
    if operation not in (b'read', b'write', b'raw'):
        raise error.ProgrammingError(_(b"invalid '%s' operation") % operation)
    # Check all flags are known.
    if flags & ~REVIDX_KNOWN_FLAGS:
        raise revlog._flagserrorclass(

    # reversed due to non-commutative transforms.
    orderedflags = REVIDX_FLAGS_ORDER
    if operation == b'write':
        orderedflags = reversed(orderedflags)

    outsidedata = {}
    for flag in orderedflags:
        # If a flagprocessor has been registered for a known flag, apply the
        # related operation transform and update result tuple.
        if flag & flags:
            vhash = True

                readtransform, writetransform, rawtransform = processor

                if operation == b'raw':
                    vhash = rawtransform(revlog, text)
                elif operation == b'read':
                    text, vhash, s = readtransform(revlog, text)
                    outsidedata.update(s)
                else:  # write operation
                    text, vhash = writetransform(revlog, text, sidedata)
            validatehash = validatehash and vhash

    return text, validatehash, outsidedata

46709:3d740058b467

        msg = _(b"cannot register multiple processors on flag '%#x'.") % flag
        raise error.Abort(msg)
    flagprocessors[flag] = processor


def processflagswrite(revlog, text, flags):
    """Inspect revision data flags and applies write transformations defined
    by registered flag processors.

    ``text`` - the revision data to process
    ``flags`` - the revision flags

    Returns a 2-tuple of ``(text, validatehash)`` where ``text`` is the
    processed text and ``validatehash`` is a bool indicating whether the
    returned text should be checked for hash integrity.
    """
    return _processflagsfunc(
        revlog,
        text,
        flags,
        b'write',
    )[:2]


def processflagsread(revlog, text, flags):
    """Inspect revision data flags and applies read transformations defined
    by registered flag processors.

    returned text should be checked for hash integrity.
    """
    return _processflagsfunc(revlog, text, flags, b'raw')[1]


def _processflagsfunc(revlog, text, flags, operation):
    """internal function to process flag on a revlog

    This function is private to this module, code should never needs to call it
    directly."""
    # fast path: no flag processors will run
    if flags == 0:
        return text, True
    if operation not in (b'read', b'write', b'raw'):
        raise error.ProgrammingError(_(b"invalid '%s' operation") % operation)
    # Check all flags are known.
    if flags & ~REVIDX_KNOWN_FLAGS:
        raise revlog._flagserrorclass(

    # reversed due to non-commutative transforms.
    orderedflags = REVIDX_FLAGS_ORDER
    if operation == b'write':
        orderedflags = reversed(orderedflags)

    for flag in orderedflags:
        # If a flagprocessor has been registered for a known flag, apply the
        # related operation transform and update result tuple.
        if flag & flags:
            vhash = True

                readtransform, writetransform, rawtransform = processor

                if operation == b'raw':
                    vhash = rawtransform(revlog, text)
                elif operation == b'read':
                    text, vhash = readtransform(revlog, text)
                else:  # write operation
                    text, vhash = writetransform(revlog, text)
            validatehash = validatehash and vhash

    return text, validatehash