view mercurial/node.py @ 18604:a1141f04e368

manifest: use a size 3 LRU cache to store parsed manifests

Previously, the manifest cache would store the last manifest parsed. We could
run into situations with operations like update where we would try parsing the
manifest for a revision r1, then r2, then r1 again. This increases the cache
size to 3 to avoid that bit of performance fragility.

# 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.

import binascii

nullrev = -1
nullid = "\0" * 20

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

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