comparison mercurial/revlogutils/nodemap.py @ 47312:7ea39d633cf3

docket: move the uid logic in the `revlogutils.docket` module

We want to use it for revlog-v2 (& Co), it seems more logical to have the logic
lives inside the `docket` file than the `nodemap` file.

Differential Revision: https://phab.mercurial-scm.org/D10755

47311:5bc6d2fc1cfc

# GNU General Public License version 2 or any later version.

from __future__ import absolute_import

import errno
import os
import random
import re
import struct

from ..node import hex

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


class NodeMap(dict):
    def __missing__(self, x):
        raise error.RevlogError(b'unknown node: %s' % x)

ONDISK_VERSION = 1
S_VERSION = struct.Struct(">B")
S_HEADER = struct.Struct(">BQQQQ")

ID_SIZE = 8


def _make_uid():
    """return a new unique identifier.

    The identifier is random and composed of ascii characters."""
    # size we "hex" the result we need half the number of bits to have a final
    # uuid of size ID_SIZE
    return hex(os.urandom(ID_SIZE // 2))


# some special test logic to avoid anoying random output in the test
stable_docket_file = encoding.environ.get(b'HGTEST_DOCKETIDFILE')

if stable_docket_file:

    def _make_uid():
        try:
            with open(stable_docket_file, mode='rb') as f:
                seed = f.read().strip()
        except IOError as inst:
            if inst.errno != errno.ENOENT:
                raise
            seed = b'4'  # chosen by a fair dice roll. garanteed to be random
        if pycompat.ispy3:
            iter_seed = iter(seed)
        else:
            iter_seed = (ord(c) for c in seed)
        # some basic circular sum hashing on 64 bits
        int_seed = 0
        low_mask = int('1' * 35, 2)
        for i in iter_seed:
            high_part = int_seed >> 35
            low_part = (int_seed & low_mask) << 28
            int_seed = high_part + low_part + i
        r = random.Random()
        if pycompat.ispy3:
            r.seed(int_seed, version=1)
        else:
            r.seed(int_seed)
        # once we drop python 3.8 support we can simply use r.randbytes
        raw = r.getrandbits(ID_SIZE * 4)
        assert ID_SIZE == 8
        p = struct.pack('>L', raw)
        new = hex(p)
        with open(stable_docket_file, 'wb') as f:
            f.write(new)
        return new


class NodeMapDocket(object):
    """metadata associated with persistent nodemap data

    The persistent data may come from disk or be on their way to disk.
    """

    def __init__(self, uid=None):
        if uid is None:
            uid = _make_uid()
        # a unique identifier for the data file:
        #   - When new data are appended, it is preserved.
        #   - When a new data file is created, a new identifier is generated.
        self.uid = uid
        # the tipmost revision stored in the data file. This revision and all

47312:7ea39d633cf3

# GNU General Public License version 2 or any later version.

from __future__ import absolute_import

import errno
import re
import struct

from ..node import hex

from .. import (
    error,
    util,
)
from . import docket as docket_mod


class NodeMap(dict):
    def __missing__(self, x):
        raise error.RevlogError(b'unknown node: %s' % x)

ONDISK_VERSION = 1
S_VERSION = struct.Struct(">B")
S_HEADER = struct.Struct(">BQQQQ")


class NodeMapDocket(object):
    """metadata associated with persistent nodemap data

    The persistent data may come from disk or be on their way to disk.
    """

    def __init__(self, uid=None):
        if uid is None:
            uid = docket_mod.make_uid()
        # a unique identifier for the data file:
        #   - When new data are appended, it is preserved.
        #   - When a new data file is created, a new identifier is generated.
        self.uid = uid
        # the tipmost revision stored in the data file. This revision and all