comparison mercurial/revlogutils/nodemap.py @ 47310:9a3aa54774ff

persistent-nodemap: add a way to make the picked uid predictable

This will make the test less volatile and therefore easier to maintain. I am
setting this is for the persistent nodemap docket first, but my target is to use
similar logic for the revlogv2 (and co) test.

For persisent nodemap, they are too many different in how each test variants (with rust, without rust, etc) needs new uid for this be really useful (right now). However it will be directly useful for the revlogv2 logic.

Differential Revision: https://phab.mercurial-scm.org/D10753

47309:af4d1a177548

from __future__ import absolute_import

import errno
import os
import re
import struct

from ..node import hex

from .. import (
    error,
    util,
)


class NodeMap(dict):

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

    The identifier is random and composed of ascii characters."""
    return hex(os.urandom(ID_SIZE))


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

47310:9a3aa54774ff

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

    The identifier is random and composed of ascii characters."""
    return hex(os.urandom(ID_SIZE))


# 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 * 8)
        assert ID_SIZE == 8
        p = struct.pack('>Q', 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