bdiff: early pruning of common prefix before doing expensive computations
It seems quite common that files don't change completely. New lines are often
pretty much appended, and modifications will often only change a small section
of the file which on average will be in the middle.
There can thus be a big win by pruning a common prefix before starting the more
expensive search for longest common substrings.
Worst case, it will scan through a long sequence of similar bytes without
encountering a newline. Splitlines will then have to do the same again ...
twice for each side. If similar lines are found, splitlines will save the
double iteration and hashing of the lines ... plus there will be less lines to
find common substrings in.
This change might in some cases make the algorith pick shorter or less optimal
common substrings. We can't have the cake and eat it.
This make hg --time bundle --base null -r 4.0 go from 14.5 to 15 s - a 3%
increase.
On mozilla-unified:
perfbdiff -m 3041e4d59df2
! wall 0.053088 comb 0.060000 user 0.060000 sys 0.000000 (best of 100) to
! wall 0.024618 comb 0.020000 user 0.020000 sys 0.000000 (best of 116)
perfbdiff 0e9928989e9c --alldata --count 10
! wall 0.702075 comb 0.700000 user 0.700000 sys 0.000000 (best of 15) to
! wall 0.579235 comb 0.580000 user 0.580000 sys 0.000000 (best of 18)
# httpconnection.py - urllib2 handler for new http support
#
# Copyright 2005, 2006, 2007, 2008 Matt Mackall <mpm@selenic.com>
# Copyright 2006, 2007 Alexis S. L. Carvalho <alexis@cecm.usp.br>
# Copyright 2006 Vadim Gelfer <vadim.gelfer@gmail.com>
# Copyright 2011 Google, Inc.
#
# 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 logging
import os
import socket
from .i18n import _
from . import (
httpclient,
sslutil,
util,
)
urlerr = util.urlerr
urlreq = util.urlreq
# moved here from url.py to avoid a cycle
class httpsendfile(object):
"""This is a wrapper around the objects returned by python's "open".
Its purpose is to send file-like objects via HTTP.
It do however not define a __len__ attribute because the length
might be more than Py_ssize_t can handle.
"""
def __init__(self, ui, *args, **kwargs):
self.ui = ui
self._data = open(*args, **kwargs)
self.seek = self._data.seek
self.close = self._data.close
self.write = self._data.write
self.length = os.fstat(self._data.fileno()).st_size
self._pos = 0
self._total = self.length // 1024 * 2
def read(self, *args, **kwargs):
try:
ret = self._data.read(*args, **kwargs)
except EOFError:
self.ui.progress(_('sending'), None)
self._pos += len(ret)
# We pass double the max for total because we currently have
# to send the bundle twice in the case of a server that
# requires authentication. Since we can't know until we try
# once whether authentication will be required, just lie to
# the user and maybe the push succeeds suddenly at 50%.
self.ui.progress(_('sending'), self._pos // 1024,
unit=_('kb'), total=self._total)
return ret
def __enter__(self):
return self
def __exit__(self, exc_type, exc_val, exc_tb):
self.close()
# moved here from url.py to avoid a cycle
def readauthforuri(ui, uri, user):
# Read configuration
config = dict()
for key, val in ui.configitems('auth'):
if '.' not in key:
ui.warn(_("ignoring invalid [auth] key '%s'\n") % key)
continue
group, setting = key.rsplit('.', 1)
gdict = config.setdefault(group, dict())
if setting in ('username', 'cert', 'key'):
val = util.expandpath(val)
gdict[setting] = val
# Find the best match
scheme, hostpath = uri.split('://', 1)
bestuser = None
bestlen = 0
bestauth = None
for group, auth in config.iteritems():
if user and user != auth.get('username', user):
# If a username was set in the URI, the entry username
# must either match it or be unset
continue
prefix = auth.get('prefix')
if not prefix:
continue
p = prefix.split('://', 1)
if len(p) > 1:
schemes, prefix = [p[0]], p[1]
else:
schemes = (auth.get('schemes') or 'https').split()
if (prefix == '*' or hostpath.startswith(prefix)) and \
(len(prefix) > bestlen or (len(prefix) == bestlen and \
not bestuser and 'username' in auth)) \
and scheme in schemes:
bestlen = len(prefix)
bestauth = group, auth
bestuser = auth.get('username')
if user and not bestuser:
auth['username'] = user
return bestauth
# Mercurial (at least until we can remove the old codepath) requires
# that the http response object be sufficiently file-like, so we
# provide a close() method here.
class HTTPResponse(httpclient.HTTPResponse):
def close(self):
pass
class HTTPConnection(httpclient.HTTPConnection):
response_class = HTTPResponse
def request(self, method, uri, body=None, headers=None):
if headers is None:
headers = {}
if isinstance(body, httpsendfile):
body.seek(0)
httpclient.HTTPConnection.request(self, method, uri, body=body,
headers=headers)
_configuredlogging = False
LOGFMT = '%(levelname)s:%(name)s:%(lineno)d:%(message)s'
# Subclass BOTH of these because otherwise urllib2 "helpfully"
# reinserts them since it notices we don't include any subclasses of
# them.
class http2handler(urlreq.httphandler, urlreq.httpshandler):
def __init__(self, ui, pwmgr):
global _configuredlogging
urlreq.abstracthttphandler.__init__(self)
self.ui = ui
self.pwmgr = pwmgr
self._connections = {}
# developer config: ui.http2debuglevel
loglevel = ui.config('ui', 'http2debuglevel', default=None)
if loglevel and not _configuredlogging:
_configuredlogging = True
logger = logging.getLogger('mercurial.httpclient')
logger.setLevel(getattr(logging, loglevel.upper()))
handler = logging.StreamHandler()
handler.setFormatter(logging.Formatter(LOGFMT))
logger.addHandler(handler)
def close_all(self):
"""Close and remove all connection objects being kept for reuse."""
for openconns in self._connections.values():
for conn in openconns:
conn.close()
self._connections = {}
# shamelessly borrowed from urllib2.AbstractHTTPHandler
def do_open(self, http_class, req, use_ssl):
"""Return an addinfourl object for the request, using http_class.
http_class must implement the HTTPConnection API from httplib.
The addinfourl return value is a file-like object. It also
has methods and attributes including:
- info(): return a mimetools.Message object for the headers
- geturl(): return the original request URL
- code: HTTP status code
"""
# If using a proxy, the host returned by get_host() is
# actually the proxy. On Python 2.6.1, the real destination
# hostname is encoded in the URI in the urllib2 request
# object. On Python 2.6.5, it's stored in the _tunnel_host
# attribute which has no accessor.
tunhost = getattr(req, '_tunnel_host', None)
host = req.get_host()
if tunhost:
proxyhost = host
host = tunhost
elif req.has_proxy():
proxyhost = req.get_host()
host = req.get_selector().split('://', 1)[1].split('/', 1)[0]
else:
proxyhost = None
if proxyhost:
if ':' in proxyhost:
# Note: this means we'll explode if we try and use an
# IPv6 http proxy. This isn't a regression, so we
# won't worry about it for now.
proxyhost, proxyport = proxyhost.rsplit(':', 1)
else:
proxyport = 3128 # squid default
proxy = (proxyhost, proxyport)
else:
proxy = None
if not host:
raise urlerr.urlerror('no host given')
connkey = use_ssl, host, proxy
allconns = self._connections.get(connkey, [])
conns = [c for c in allconns if not c.busy()]
if conns:
h = conns[0]
else:
if allconns:
self.ui.debug('all connections for %s busy, making a new '
'one\n' % host)
timeout = None
if req.timeout is not socket._GLOBAL_DEFAULT_TIMEOUT:
timeout = req.timeout
h = http_class(host, timeout=timeout, proxy_hostport=proxy)
self._connections.setdefault(connkey, []).append(h)
headers = dict(req.headers)
headers.update(req.unredirected_hdrs)
headers = dict(
(name.title(), val) for name, val in headers.items())
try:
path = req.get_selector()
if '://' in path:
path = path.split('://', 1)[1].split('/', 1)[1]
if path[0] != '/':
path = '/' + path
h.request(req.get_method(), path, req.data, headers)
r = h.getresponse()
except socket.error as err: # XXX what error?
raise urlerr.urlerror(err)
# Pick apart the HTTPResponse object to get the addinfourl
# object initialized properly.
r.recv = r.read
resp = urlreq.addinfourl(r, r.headers, req.get_full_url())
resp.code = r.status
resp.msg = r.reason
return resp
# httplib always uses the given host/port as the socket connect
# target, and then allows full URIs in the request path, which it
# then observes and treats as a signal to do proxying instead.
def http_open(self, req):
if req.get_full_url().startswith('https'):
return self.https_open(req)
def makehttpcon(*args, **kwargs):
k2 = dict(kwargs)
k2['use_ssl'] = False
return HTTPConnection(*args, **k2)
return self.do_open(makehttpcon, req, False)
def https_open(self, req):
# req.get_full_url() does not contain credentials and we may
# need them to match the certificates.
url = req.get_full_url()
user, password = self.pwmgr.find_stored_password(url)
res = readauthforuri(self.ui, url, user)
if res:
group, auth = res
self.auth = auth
self.ui.debug("using auth.%s.* for authentication\n" % group)
else:
self.auth = None
return self.do_open(self._makesslconnection, req, True)
def _makesslconnection(self, host, port=443, *args, **kwargs):
keyfile = None
certfile = None
if args: # key_file
keyfile = args.pop(0)
if args: # cert_file
certfile = args.pop(0)
# if the user has specified different key/cert files in
# hgrc, we prefer these
if self.auth and 'key' in self.auth and 'cert' in self.auth:
keyfile = self.auth['key']
certfile = self.auth['cert']
# let host port take precedence
if ':' in host and '[' not in host or ']:' in host:
host, port = host.rsplit(':', 1)
port = int(port)
if '[' in host:
host = host[1:-1]
kwargs['keyfile'] = keyfile
kwargs['certfile'] = certfile
con = HTTPConnection(host, port, use_ssl=True,
ssl_wrap_socket=sslutil.wrapsocket,
ssl_validator=sslutil.validatesocket,
ui=self.ui,
**kwargs)
return con