view mercurial/txnutil.py @ 51955:b8528c8bebf5

tests: disable `worker.backgroundclose` to stabilize a test on Windows

TIL that `worker.enabled=0` doesn't prevent these workers from spinning up.  At
any rate, there's already a whole lot of conditionalized output following
`cat client.log`, the placement of the "starting 4 threads for background file
closing" message seems unstable, and we don't care about those worker threads
here.  Preventing the message is better for test maintenance.

# txnutil.py - transaction related utilities
#
#  Copyright FUJIWARA Katsunori <[e-mail]> and others
#
# 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 annotations

from . import encoding


def mayhavepending(root):
    """return whether 'root' may have pending changes, which are
    visible to this process.
    """
    return root == encoding.environ.get(b'HG_PENDING')


def trypending(root, vfs, filename, **kwargs):
    """Open  file to be read according to HG_PENDING environment variable

    This opens '.pending' of specified 'filename' only when HG_PENDING
    is equal to 'root'.

    This returns '(fp, is_pending_opened)' tuple.
    """
    if mayhavepending(root):
        try:
            return (vfs(b'%s.pending' % filename, **kwargs), True)
        except FileNotFoundError:
            pass
    return (vfs(filename, **kwargs), False)