http server: support persistent connections. only "hg serve" affected yet. http server running cgi script will not use persistent connections. support for fastcgi will help that. clients that support keepalive can use one tcp connection for all commands during clone and pull. this makes latency of binary search during pull much lower over wan. if server does not know content-length, it will force connection to close at end. right fix is to use chunked transfer-encoding but this is easier and does not hurt performance. only command that is affected is "changegroup" which is always last command during a pull.

"""
node.py - basic nodeid manipulation for mercurial

Copyright 2005 Matt Mackall <mpm@selenic.com>

This software may be used and distributed according to the terms
of the GNU General Public License, incorporated herein by reference.
"""

import binascii

nullid = "\0" * 20

def hex(node):
    return binascii.hexlify(node)

def bin(node):
    return binascii.unhexlify(node)

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