documentation: add some internals documentation about bid merge
This is an important algorithm that was only documented on the wiki so far.
Some update to the algorithm (and associated doc) is to expected in the future
since the bid merge algorithm is bug-ridden when it comes to file deletion comes
to play.
Differential Revision: https://phab.mercurial-scm.org/D8711
#!/usr/bin/env python
#
# Based on python's Tools/scripts/md5sum.py
#
# This software may be used and distributed according to the terms
# of the PYTHON SOFTWARE FOUNDATION LICENSE VERSION 2, which is
# GPL-compatible.
from __future__ import absolute_import
import hashlib
import os
import sys
try:
import msvcrt
msvcrt.setmode(sys.stdout.fileno(), os.O_BINARY)
msvcrt.setmode(sys.stderr.fileno(), os.O_BINARY)
except ImportError:
pass
for filename in sys.argv[1:]:
try:
fp = open(filename, 'rb')
except IOError as msg:
sys.stderr.write('%s: Can\'t open: %s\n' % (filename, msg))
sys.exit(1)
m = hashlib.md5()
try:
for data in iter(lambda: fp.read(8192), b''):
m.update(data)
except IOError as msg:
sys.stderr.write('%s: I/O error: %s\n' % (filename, msg))
sys.exit(1)
sys.stdout.write('%s %s\n' % (m.hexdigest(), filename))
sys.exit(0)