view mercurial/revlogutils/revlogv0.py @ 47072:4c041c71ec01

revlog: introduce an explicit tracking of what the revlog is about

Since the dawn of time, people have been forced to rely to lossy introspection
of the index filename to determine what the purpose and role of the revlog they
encounter is. This is hacky, error prone, inflexible, abstraction-leaky,
<insert-your-own-complaints-here>.

In f63299ee7e4d Raphaël introduced a new attribute to track this information:
`revlog_kind`. However it is initialized in an odd place and various instances
end up not having it set. In addition is only tracking some of the information
we end up having to introspect in various pieces of code.

So we add a new attribute that holds more data and is more strictly enforced.
This work is done in collaboration with Raphaël.

The `revlog_kind` one will be removed/adapted in the next changeset. We expect
to be able to clean up various existing piece of code and to simplify coming
work around the newer revlog format.

Differential Revision: https://phab.mercurial-scm.org/D10352

# revlogv0 - code related to revlog format "V0"
#
# Copyright 2005-2007 Olivia Mackall <[e-mail]>
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.
from __future__ import absolute_import


from ..node import sha1nodeconstants
from .constants import (
    INDEX_ENTRY_V0,
)
from ..i18n import _

from .. import (
    error,
    node,
    pycompat,
    util,
)

from . import (
    flagutil,
    nodemap as nodemaputil,
)


def getoffset(q):
    return int(q >> 16)


def gettype(q):
    return int(q & 0xFFFF)


def offset_type(offset, type):
    if (type & ~flagutil.REVIDX_KNOWN_FLAGS) != 0:
        raise ValueError(b'unknown revlog index flags')
    return int(int(offset) << 16 | type)


class revlogoldindex(list):
    entry_size = INDEX_ENTRY_V0.size

    @property
    def nodemap(self):
        msg = b"index.nodemap is deprecated, use index.[has_node|rev|get_rev]"
        util.nouideprecwarn(msg, b'5.3', stacklevel=2)
        return self._nodemap

    @util.propertycache
    def _nodemap(self):
        nodemap = nodemaputil.NodeMap({sha1nodeconstants.nullid: node.nullrev})
        for r in range(0, len(self)):
            n = self[r][7]
            nodemap[n] = r
        return nodemap

    def has_node(self, node):
        """return True if the node exist in the index"""
        return node in self._nodemap

    def rev(self, node):
        """return a revision for a node

        If the node is unknown, raise a RevlogError"""
        return self._nodemap[node]

    def get_rev(self, node):
        """return a revision for a node

        If the node is unknown, return None"""
        return self._nodemap.get(node)

    def append(self, tup):
        self._nodemap[tup[7]] = len(self)
        super(revlogoldindex, self).append(tup)

    def __delitem__(self, i):
        if not isinstance(i, slice) or not i.stop == -1 or i.step is not None:
            raise ValueError(b"deleting slices only supports a:-1 with step 1")
        for r in pycompat.xrange(i.start, len(self)):
            del self._nodemap[self[r][7]]
        super(revlogoldindex, self).__delitem__(i)

    def clearcaches(self):
        self.__dict__.pop('_nodemap', None)

    def __getitem__(self, i):
        if i == -1:
            return (0, 0, 0, -1, -1, -1, -1, node.nullid)
        return list.__getitem__(self, i)

    def pack_header(self, header):
        """pack header information in binary"""
        return b''

    def entry_binary(self, rev):
        """return the raw binary string representing a revision"""
        entry = self[rev]
        if gettype(entry[0]):
            raise error.RevlogError(
                _(b'index entry flags need revlog version 1')
            )
        e2 = (
            getoffset(entry[0]),
            entry[1],
            entry[3],
            entry[4],
            self[entry[5]][7],
            self[entry[6]][7],
            entry[7],
        )
        return INDEX_ENTRY_V0.pack(*e2)


def parse_index_v0(data, inline):
    s = INDEX_ENTRY_V0.size
    index = []
    nodemap = nodemaputil.NodeMap({node.nullid: node.nullrev})
    n = off = 0
    l = len(data)
    while off + s <= l:
        cur = data[off : off + s]
        off += s
        e = INDEX_ENTRY_V0.unpack(cur)
        # transform to revlogv1 format
        e2 = (
            offset_type(e[0], 0),
            e[1],
            -1,
            e[2],
            e[3],
            nodemap.get(e[4], node.nullrev),
            nodemap.get(e[5], node.nullrev),
            e[6],
        )
        index.append(e2)
        nodemap[e[6]] = n
        n += 1

    index = revlogoldindex(index)
    return index, None