hgext/git/gitutil.py

revlog: use a "radix" to address revlog

Instead of pointing to the index directly and to derive the other file from
that, we directly provide the radix and let the revlog determine the associated
file path internally. This is more robust and will give us more flexibility for
picking this file name in the future.

Differential Revision: https://phab.mercurial-scm.org/D10576

"""utilities to assist in working with pygit2"""
from __future__ import absolute_import

from mercurial.node import bin, hex, sha1nodeconstants

from mercurial import pycompat

pygit2_module = None


def get_pygit2():
    global pygit2_module
    if pygit2_module is None:
        try:
            import pygit2 as pygit2_module

            pygit2_module.InvalidSpecError
        except (ImportError, AttributeError):
            pass
    return pygit2_module


def pygit2_version():
    mod = get_pygit2()
    v = "N/A"

    if mod:
        try:
            v = mod.__version__
        except AttributeError:
            pass

    return b"(pygit2 %s)" % v.encode("utf-8")


def togitnode(n):
    """Wrapper to convert a Mercurial binary node to a unicode hexlified node.

    pygit2 and sqlite both need nodes as strings, not bytes.
    """
    assert len(n) == 20
    return pycompat.sysstr(hex(n))


def fromgitnode(n):
    """Opposite of togitnode."""
    assert len(n) == 40
    if pycompat.ispy3:
        return bin(n.encode('ascii'))
    return bin(n)


nullgit = togitnode(sha1nodeconstants.nullid)