view mercurial/node.py @ 29201:a109bf7e0dc2

util: make atomictempfile avoid ambiguity of file stat if needed

Ambiguity check is executed at close(), only if:

  - atomictempfile is created with checkambig=True, and
  - target file exists before renaming

This restriction avoids performance decrement by needless examination
of file stat (for example, filelog doesn't need exact cache
validation, even though it uses atomictempfile to write changes out).

See description of filestat class for detail about why the logic in
this patch works as expected.

This patch is a part of preparation for "Exact Cache Validation Plan":

    https://www.mercurial-scm.org/wiki/ExactCacheValidationPlan

# node.py - basic nodeid manipulation for mercurial
#
# Copyright 2005, 2006 Matt Mackall <[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.

from __future__ import absolute_import

import binascii

# This ugly style has a noticeable effect in manifest parsing
hex = binascii.hexlify
bin = binascii.unhexlify

nullrev = -1
nullid = b"\0" * 20
nullhex = hex(nullid)

# pseudo identifiers for working directory
# (they are experimental, so don't add too many dependencies on them)
wdirrev = 0x7fffffff
wdirid = b"\xff" * 20

def short(node):
    return hex(node[:6])