view mercurial/typelib.py @ 51637:3cf9e52f5e27 stable

inline-changelog: fix a critical bug in write_pending that delete data

Since a93e52f0b6ff we no longer use inline-revlog for the changelog. The goal there was to
solve the lack of testing for the two variants (inline vs split) and reduce the
complexity of the interaction with "diverted-write" on the changelog level.

However many existing repository still have inline-changelog and we
automatically move them to normal revlog as soon as we have the chances.

Unfortunately This conversion is buggy and can result in the destruction of the
changelog.i if hook triggers the "write pending" mechanism.

The bugs comes from the "revlog splitting" logic and the "write_pending" logic
stepping over each other. Ironically the change in a93e52f0b6ff aims at no
longer having this kind of problem.

This changesets fix this issue and add associated tests.

Fixing this reveal that the transaction hooks end up not seeing the pending
transaction content, because the name is not right ("changelog.i.s.a" instead of
"changelog.i.s") we fix this in the next changeset.

# typelib.py - type hint aliases and support
#
# Copyright 2022 Matt Harbison <[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.

import typing

# Note: this is slightly different from pycompat.TYPE_CHECKING, as using
# pycompat causes the BinaryIO_Proxy type to be resolved to ``object`` when
# used as the base class during a pytype run.
TYPE_CHECKING = typing.TYPE_CHECKING


# The BinaryIO class provides empty methods, which at runtime means that
# ``__getattr__`` on the proxy classes won't get called for the methods that
# should delegate to the internal object.  So to avoid runtime changes because
# of the required typing inheritance, just use BinaryIO when typechecking, and
# ``object`` otherwise.
if TYPE_CHECKING:
    from typing import (
        BinaryIO,
    )

    BinaryIO_Proxy = BinaryIO
else:
    BinaryIO_Proxy = object