view mercurial/revlogutils/revlogv0.py @ 47249:130c9f7ed914

revlog: add a "data compression mode" entry in the index tuple

That will make it possible to keep track of compression information in the
revlog index, opening the way to more efficient revision restoration (in native
code, but the python usage is already defeating performance work).

We start with adding a new entry to the index tuple, using a value matching the
current behavior. We will introduce storage and other value in later changesets.

Differential Revision: https://phab.mercurial-scm.org/D10646

# 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 (
    COMP_MODE_INLINE,
    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
    null_item = (
        0,
        0,
        0,
        -1,
        -1,
        -1,
        -1,
        sha1nodeconstants.nullid,
        0,
        0,
        COMP_MODE_INLINE,
    )

    @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 self.null_item
        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],
            0,  # no side data support
            0,  # no side data support
            COMP_MODE_INLINE,
        )
        index.append(e2)
        nodemap[e[6]] = n
        n += 1

    index = revlogoldindex(index)
    return index, None