view mercurial/url.py @ 49658:523cacdfd324

delta-find: set the default candidate chunk size to 10 I ran performance and storage tests on repositories of various sizes and shapes for the following values of the config : 5, 10, 20, 50, 100, no-chunking The performance tests do not show any statistical impact on computation times for large pushes and pulls. For searching for an individual delta, this can provide a significant performance improvement with a minor degradation of space-quality on the result. (see data at the end of the commit). For overall store size, the change : - does not have any impact on many small repositories, - has an observable, but very negligible impact on most larger repositories. - One private repository we use for testing sees a small increase in size (1%) in the narrower version. We will try to get more numbers on a larger version of that repository to make sure nothing pathological happens. We pick "10" as the limit as "5" seems a bit more risky. There are room to improve the current code, by using more aggressive filtering and better (i.e any) sorting of the candidates. However this is already a large improvement for pathological cases, with little impact in the common situations. The initial motivation for this change is to fix performance of delta computation for a file where the previous code ended up testing 20 000 possible candidate-bases in one go, which is… slow. This affected about ½ of the file revisions leading to atrocious performance, especially during some push/pull operations. Details about individual delta finding timing: ---------------------------------------------- The vast majority of benchmark cases are unchanged but the three below. The first two do not see any impact on the final delta. The last one sees a change in delta-size that is negligible compared to the full text size. ### data-env-vars.name = mozilla-try-2019-02-18-zstd-sparse-revlog # benchmark.name = perf-delta-find # benchmark.variants.rev = manifest-snapshot-many-tries-a (revision 756096) ∞: 5.844783 5: 4.473523 (-23.46%) 10: 4.970053 (-14.97%) 20: 5.770386 (-1.27%) 50 5.821358 100: 5.834887 MANIFESTLOG: rev = 756096: (no-limit) delta-base = 301840 search-rounds = 6 try-count = 60 delta-type = snapshot snap-depth = 7 delta-size = 179 MANIFESTLOG: rev=756096: (limit = 10) delta-base=301840 search-rounds=9 try-count=51 delta-type=snapshot snap-depth=7 delta-size=179 ### data-env-vars.name = mozilla-try-2019-02-18-zstd-sparse-revlog # benchmark.name = perf-delta-find # benchmark.variants.rev = manifest-snapshot-many-tries-d (revision 754060) ∞: 5.017663 5: 3.655931 (-27.14%) 10: 4.095436 (-18.38%) 20: 4.828949 (-3.76%) 50 4.987574 100: 4.994889 MANIFESTLOG: rev=754060: (no limit) delta-base=301840 search-rounds=5 try-count=53 delta-type=snapshot snap-depth=7 delta-size = 179 MANIFESTLOG: rev=754060: (limite = 10) delta-base=301840 search-rounds=8 try-count=45 delta-type=snapshot snap-depth=7 delta-size = 179 ### data-env-vars.name = mozilla-try-2019-02-18-zstd-sparse-revlog # benchmark.name = perf-delta-find # bin-env-vars.hg.flavor = rust # benchmark.variants.rev = manifest-snapshot-many-tries-e (revision 693368) ∞: 4.869282 5: 2.039732 (-58.11%) 10: 2.413537 (-50.43%) 20: 4.449639 (-8.62%) 50 4.865863 100: 4.882649 MANIFESTLOG: rev=693368: delta-base=693336 search-rounds=6 try-count=53 delta-type=snapshot snap-depth=6 full-test-size=131065 delta-size=199 MANIFESTLOG: rev=693368: delta-base=278023 search-rounds=5 try-count=21 delta-type=snapshot snap-depth=4 full-test-size=131065 delta-size=278 Raw data for store size (in bytes) for various chunk size value below: ---------------------------------------------------------------------- 440 134 384 5 pypy/.hg/store/ 440 134 384 10 pypy/.hg/store/ 440 134 384 20 pypy/.hg/store/ 440 134 384 50 pypy/.hg/store/ 440 134 384 100 pypy/.hg/store/ 440 134 384 ... pypy/.hg/store/ 666 987 471 5 netbsd-xsrc-2022-11-15/.hg/store/ 666 987 471 10 netbsd-xsrc-2022-11-15/.hg/store/ 666 987 471 20 netbsd-xsrc-2022-11-15/.hg/store/ 666 987 471 50 netbsd-xsrc-2022-11-15/.hg/store/ 666 987 471 100 netbsd-xsrc-2022-11-15/.hg/store/ 666 987 471 ... netbsd-xsrc-2022-11-15/.hg/store/ 852 844 884 5 netbsd-pkgsrc-2022-11-15/.hg/store/ 852 844 884 10 netbsd-pkgsrc-2022-11-15/.hg/store/ 852 844 884 20 netbsd-pkgsrc-2022-11-15/.hg/store/ 852 844 884 50 netbsd-pkgsrc-2022-11-15/.hg/store/ 852 844 884 100 netbsd-pkgsrc-2022-11-15/.hg/store/ 852 844 884 ... netbsd-pkgsrc-2022-11-15/.hg/store/ 1 504 227 981 5 netbeans-2018-08-01-sparse-zstd/.hg/store/ 1 504 227 871 10 netbeans-2018-08-01-sparse-zstd/.hg/store/ 1 504 227 813 20 netbeans-2018-08-01-sparse-zstd/.hg/store/ 1 504 227 813 50 netbeans-2018-08-01-sparse-zstd/.hg/store/ 1 504 227 813 100 netbeans-2018-08-01-sparse-zstd/.hg/store/ 1 504 227 813 ... netbeans-2018-08-01-sparse-zstd/.hg/store/ 3 875 801 068 5 netbsd-src-2022-11-15/.hg/store/ 3 875 696 767 10 netbsd-src-2022-11-15/.hg/store/ 3 875 696 757 20 netbsd-src-2022-11-15/.hg/store/ 3 875 696 653 50 netbsd-src-2022-11-15/.hg/store/ 3 875 696 653 100 netbsd-src-2022-11-15/.hg/store/ 3 875 696 653 ... netbsd-src-2022-11-15/.hg/store/ 4 531 441 314 5 mozilla-central/.hg/store/ 4 531 435 157 10 mozilla-central/.hg/store/ 4 531 432 045 20 mozilla-central/.hg/store/ 4 531 429 119 50 mozilla-central/.hg/store/ 4 531 429 119 100 mozilla-central/.hg/store/ 4 531 429 119 ... mozilla-central/.hg/store/ 4 875 861 390 5 mozilla-unified/.hg/store/ 4 875 855 155 10 mozilla-unified/.hg/store/ 4 875 852 027 20 mozilla-unified/.hg/store/ 4 875 848 851 50 mozilla-unified/.hg/store/ 4 875 848 851 100 mozilla-unified/.hg/store/ 4 875 848 851 ... mozilla-unified/.hg/store/ 11 498 764 601 5 mozilla-try/.hg/store/ 11 497 968 858 10 mozilla-try/.hg/store/ 11 497 958 730 20 mozilla-try/.hg/store/ 11 497 927 156 50 mozilla-try/.hg/store/ 11 497 925 963 100 mozilla-try/.hg/store/ 11 497 923 428 ... mozilla-try/.hg/store/ 10 047 914 031 5 private-repo 9 969 132 101 10 private-repo 9 944 745 015 20 private-repo 9 939 756 703 50 private-repo 9 939 833 016 100 private-repo 9 939 822 035 ... private-repo
author Pierre-Yves David <pierre-yves.david@octobus.net>
date Wed, 23 Nov 2022 19:08:27 +0100
parents 9f3edb305261
children 3bb7c56e8fe6
line wrap: on
line source

# url.py - HTTP handling for mercurial
#
# Copyright 2005, 2006, 2007, 2008 Olivia Mackall <olivia@selenic.com>
# Copyright 2006, 2007 Alexis S. L. Carvalho <alexis@cecm.usp.br>
# Copyright 2006 Vadim Gelfer <vadim.gelfer@gmail.com>
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.


import base64
import socket

from .i18n import _
from . import (
    encoding,
    error,
    httpconnection as httpconnectionmod,
    keepalive,
    pycompat,
    sslutil,
    urllibcompat,
    util,
)
from .utils import (
    stringutil,
    urlutil,
)

httplib = util.httplib
stringio = util.stringio
urlerr = util.urlerr
urlreq = util.urlreq


def escape(s, quote=None):
    """Replace special characters "&", "<" and ">" to HTML-safe sequences.
    If the optional flag quote is true, the quotation mark character (")
    is also translated.

    This is the same as cgi.escape in Python, but always operates on
    bytes, whereas cgi.escape in Python 3 only works on unicodes.
    """
    s = s.replace(b"&", b"&amp;")
    s = s.replace(b"<", b"&lt;")
    s = s.replace(b">", b"&gt;")
    if quote:
        s = s.replace(b'"', b"&quot;")
    return s


class passwordmgr:
    def __init__(self, ui, passwddb):
        self.ui = ui
        self.passwddb = passwddb

    def add_password(self, realm, uri, user, passwd):
        return self.passwddb.add_password(realm, uri, user, passwd)

    def find_user_password(self, realm, authuri):
        assert isinstance(realm, (type(None), str))
        assert isinstance(authuri, str)
        authinfo = self.passwddb.find_user_password(realm, authuri)
        user, passwd = authinfo
        user, passwd = pycompat.bytesurl(user), pycompat.bytesurl(passwd)
        if user and passwd:
            self._writedebug(user, passwd)
            return (pycompat.strurl(user), pycompat.strurl(passwd))

        if not user or not passwd:
            res = httpconnectionmod.readauthforuri(self.ui, authuri, user)
            if res:
                group, auth = res
                user, passwd = auth.get(b'username'), auth.get(b'password')
                self.ui.debug(b"using auth.%s.* for authentication\n" % group)
        if not user or not passwd:
            u = urlutil.url(pycompat.bytesurl(authuri))
            u.query = None
            if not self.ui.interactive():
                raise error.Abort(
                    _(b'http authorization required for %s')
                    % urlutil.hidepassword(bytes(u))
                )

            self.ui.write(
                _(b"http authorization required for %s\n")
                % urlutil.hidepassword(bytes(u))
            )
            self.ui.write(_(b"realm: %s\n") % pycompat.bytesurl(realm))
            if user:
                self.ui.write(_(b"user: %s\n") % user)
            else:
                user = self.ui.prompt(_(b"user:"), default=None)

            if not passwd:
                passwd = self.ui.getpass()

        # As of Python 3.8, the default implementation of
        # AbstractBasicAuthHandler.retry_http_basic_auth() assumes the user
        # is set if pw is not None. This means (None, str) is not a valid
        # return type of find_user_password().
        if user is None:
            return None, None

        self.passwddb.add_password(realm, authuri, user, passwd)
        self._writedebug(user, passwd)
        return (pycompat.strurl(user), pycompat.strurl(passwd))

    def _writedebug(self, user, passwd):
        msg = _(b'http auth: user %s, password %s\n')
        self.ui.debug(msg % (user, passwd and b'*' * len(passwd) or b'not set'))

    def find_stored_password(self, authuri):
        return self.passwddb.find_user_password(None, authuri)


class proxyhandler(urlreq.proxyhandler):
    def __init__(self, ui):
        proxyurl = ui.config(b"http_proxy", b"host") or encoding.environ.get(
            b'http_proxy'
        )
        # XXX proxyauthinfo = None

        if proxyurl:
            # proxy can be proper url or host[:port]
            if not (
                proxyurl.startswith(b'http:') or proxyurl.startswith(b'https:')
            ):
                proxyurl = b'http://' + proxyurl + b'/'
            proxy = urlutil.url(proxyurl)
            if not proxy.user:
                proxy.user = ui.config(b"http_proxy", b"user")
                proxy.passwd = ui.config(b"http_proxy", b"passwd")

            # see if we should use a proxy for this url
            no_list = [b"localhost", b"127.0.0.1"]
            no_list.extend(
                [p.lower() for p in ui.configlist(b"http_proxy", b"no")]
            )
            no_list.extend(
                [
                    p.strip().lower()
                    for p in encoding.environ.get(b"no_proxy", b'').split(b',')
                    if p.strip()
                ]
            )
            # "http_proxy.always" config is for running tests on localhost
            if ui.configbool(b"http_proxy", b"always"):
                self.no_list = []
            else:
                self.no_list = no_list

            # Keys and values need to be str because the standard library
            # expects them to be.
            proxyurl = str(proxy)
            proxies = {'http': proxyurl, 'https': proxyurl}
            ui.debug(
                b'proxying through %s\n' % urlutil.hidepassword(bytes(proxy))
            )
        else:
            proxies = {}

        urlreq.proxyhandler.__init__(self, proxies)
        self.ui = ui

    def proxy_open(self, req, proxy, type_):
        host = pycompat.bytesurl(urllibcompat.gethost(req)).split(b':')[0]
        for e in self.no_list:
            if host == e:
                return None
            if e.startswith(b'*.') and host.endswith(e[2:]):
                return None
            if e.startswith(b'.') and host.endswith(e[1:]):
                return None

        return urlreq.proxyhandler.proxy_open(self, req, proxy, type_)


def _gen_sendfile(orgsend):
    def _sendfile(self, data):
        # send a file
        if isinstance(data, httpconnectionmod.httpsendfile):
            # if auth required, some data sent twice, so rewind here
            data.seek(0)
            for chunk in util.filechunkiter(data):
                orgsend(self, chunk)
        else:
            orgsend(self, data)

    return _sendfile


has_https = util.safehasattr(urlreq, b'httpshandler')


class httpconnection(keepalive.HTTPConnection):
    # must be able to send big bundle as stream.
    send = _gen_sendfile(keepalive.HTTPConnection.send)


# Large parts of this function have their origin from before Python 2.6
# and could potentially be removed.
def _generic_start_transaction(handler, h, req):
    tunnel_host = req._tunnel_host
    if tunnel_host:
        if tunnel_host[:7] not in ['http://', 'https:/']:
            tunnel_host = 'https://' + tunnel_host
        new_tunnel = True
    else:
        tunnel_host = urllibcompat.getselector(req)
        new_tunnel = False

    if new_tunnel or tunnel_host == urllibcompat.getfullurl(req):  # has proxy
        u = urlutil.url(pycompat.bytesurl(tunnel_host))
        if new_tunnel or u.scheme == b'https':  # only use CONNECT for HTTPS
            h.realhostport = b':'.join([u.host, (u.port or b'443')])
            h.headers = req.headers.copy()
            h.headers.update(handler.parent.addheaders)
            return

    h.realhostport = None
    h.headers = None


def _generic_proxytunnel(self: "httpsconnection"):
    headers = self.headers  # pytype: disable=attribute-error
    proxyheaders = {
        pycompat.bytestr(x): pycompat.bytestr(headers[x])
        for x in headers
        if x.lower().startswith('proxy-')
    }
    realhostport = self.realhostport  # pytype: disable=attribute-error
    self.send(b'CONNECT %s HTTP/1.0\r\n' % realhostport)

    for header in proxyheaders.items():
        self.send(b'%s: %s\r\n' % header)
    self.send(b'\r\n')

    # majority of the following code is duplicated from
    # httplib.HTTPConnection as there are no adequate places to
    # override functions to provide the needed functionality.

    # pytype: disable=attribute-error
    res = self.response_class(self.sock, method=self._method)
    # pytype: enable=attribute-error

    while True:
        # pytype: disable=attribute-error
        version, status, reason = res._read_status()
        # pytype: enable=attribute-error
        if status != httplib.CONTINUE:
            break
        # skip lines that are all whitespace
        list(iter(lambda: res.fp.readline().strip(), b''))

    if status == 200:
        # skip lines until we find a blank line
        list(iter(res.fp.readline, b'\r\n'))
    else:
        self.close()
        raise socket.error(
            "Tunnel connection failed: %d %s" % (status, reason.strip())
        )


class httphandler(keepalive.HTTPHandler):
    def http_open(self, req):
        return self.do_open(httpconnection, req)

    def _start_transaction(self, h, req):
        _generic_start_transaction(self, h, req)
        return keepalive.HTTPHandler._start_transaction(self, h, req)


class logginghttpconnection(keepalive.HTTPConnection):
    def __init__(self, createconn, *args, **kwargs):
        keepalive.HTTPConnection.__init__(self, *args, **kwargs)
        self._create_connection = createconn


class logginghttphandler(httphandler):
    """HTTP handler that logs socket I/O."""

    def __init__(self, logfh, name, observeropts, timeout=None):
        super(logginghttphandler, self).__init__(timeout=timeout)

        self._logfh = logfh
        self._logname = name
        self._observeropts = observeropts

    # do_open() calls the passed class to instantiate an HTTPConnection. We
    # pass in a callable method that creates a custom HTTPConnection instance
    # whose callback to create the socket knows how to proxy the socket.
    def http_open(self, req):
        return self.do_open(self._makeconnection, req)

    def _makeconnection(self, *args, **kwargs):
        def createconnection(*args, **kwargs):
            sock = socket.create_connection(*args, **kwargs)
            return util.makeloggingsocket(
                self._logfh, sock, self._logname, **self._observeropts
            )

        return logginghttpconnection(createconnection, *args, **kwargs)


if has_https:

    class httpsconnection(keepalive.HTTPConnection):
        response_class = keepalive.HTTPResponse
        default_port = httplib.HTTPS_PORT
        # must be able to send big bundle as stream.
        send = _gen_sendfile(keepalive.safesend)
        getresponse = keepalive.wrapgetresponse(httplib.HTTPConnection)

        def __init__(
            self,
            host,
            port=None,
            key_file=None,
            cert_file=None,
            *args,
            **kwargs
        ):
            keepalive.HTTPConnection.__init__(self, host, port, *args, **kwargs)
            self.key_file = key_file
            self.cert_file = cert_file

        def connect(self):
            self.sock = socket.create_connection((self.host, self.port))

            host = self.host
            realhostport = self.realhostport  # pytype: disable=attribute-error
            if realhostport:  # use CONNECT proxy
                _generic_proxytunnel(self)
                host = realhostport.rsplit(b':', 1)[0]
            self.sock = sslutil.wrapsocket(
                self.sock,
                self.key_file,
                self.cert_file,
                ui=self.ui,  # pytype: disable=attribute-error
                serverhostname=host,
            )
            sslutil.validatesocket(self.sock)

    class httpshandler(keepalive.KeepAliveHandler, urlreq.httpshandler):
        def __init__(self, ui, timeout=None):
            keepalive.KeepAliveHandler.__init__(self, timeout=timeout)
            urlreq.httpshandler.__init__(self)
            self.ui = ui
            self.pwmgr = passwordmgr(self.ui, self.ui.httppasswordmgrdb)

        def _start_transaction(self, h, req):
            _generic_start_transaction(self, h, req)
            return keepalive.KeepAliveHandler._start_transaction(self, h, req)

        def https_open(self, req):
            # urllibcompat.getfullurl() does not contain credentials
            # and we may need them to match the certificates.
            url = urllibcompat.getfullurl(req)
            user, password = self.pwmgr.find_stored_password(url)
            res = httpconnectionmod.readauthforuri(self.ui, url, user)
            if res:
                group, auth = res
                self.auth = auth
                self.ui.debug(b"using auth.%s.* for authentication\n" % group)
            else:
                self.auth = None
            return self.do_open(self._makeconnection, req)

        def _makeconnection(self, host, port=None, *args, **kwargs):
            keyfile = None
            certfile = None

            if len(args) >= 1:  # key_file
                keyfile = args[0]
            if len(args) >= 2:  # cert_file
                certfile = args[1]
            args = args[2:]

            # if the user has specified different key/cert files in
            # hgrc, we prefer these
            if self.auth and b'key' in self.auth and b'cert' in self.auth:
                keyfile = self.auth[b'key']
                certfile = self.auth[b'cert']

            conn = httpsconnection(
                host, port, keyfile, certfile, *args, **kwargs
            )
            conn.ui = self.ui
            return conn


class httpdigestauthhandler(urlreq.httpdigestauthhandler):
    def __init__(self, *args, **kwargs):
        urlreq.httpdigestauthhandler.__init__(self, *args, **kwargs)
        self.retried_req = None

    def reset_retry_count(self):
        # Python 2.6.5 will call this on 401 or 407 errors and thus loop
        # forever. We disable reset_retry_count completely and reset in
        # http_error_auth_reqed instead.
        pass

    def http_error_auth_reqed(self, auth_header, host, req, headers):
        # Reset the retry counter once for each request.
        if req is not self.retried_req:
            self.retried_req = req
            self.retried = 0
        return urlreq.httpdigestauthhandler.http_error_auth_reqed(
            self, auth_header, host, req, headers
        )


class httpbasicauthhandler(urlreq.httpbasicauthhandler):
    def __init__(self, *args, **kwargs):
        self.auth = None
        urlreq.httpbasicauthhandler.__init__(self, *args, **kwargs)
        self.retried_req = None

    def http_request(self, request):
        if self.auth:
            request.add_unredirected_header(self.auth_header, self.auth)

        return request

    def https_request(self, request):
        if self.auth:
            request.add_unredirected_header(self.auth_header, self.auth)

        return request

    def reset_retry_count(self):
        # Python 2.6.5 will call this on 401 or 407 errors and thus loop
        # forever. We disable reset_retry_count completely and reset in
        # http_error_auth_reqed instead.
        pass

    def http_error_auth_reqed(self, auth_header, host, req, headers):
        # Reset the retry counter once for each request.
        if req is not self.retried_req:
            self.retried_req = req
            self.retried = 0
        return urlreq.httpbasicauthhandler.http_error_auth_reqed(
            self, auth_header, host, req, headers
        )

    def retry_http_basic_auth(self, host, req, realm):
        user, pw = self.passwd.find_user_password(
            realm, urllibcompat.getfullurl(req)
        )
        if pw is not None:
            raw = b"%s:%s" % (pycompat.bytesurl(user), pycompat.bytesurl(pw))
            auth = 'Basic %s' % pycompat.strurl(base64.b64encode(raw).strip())
            if req.get_header(self.auth_header, None) == auth:
                return None
            self.auth = auth
            req.add_unredirected_header(self.auth_header, auth)
            return self.parent.open(req)
        else:
            return None


class cookiehandler(urlreq.basehandler):
    def __init__(self, ui):
        self.cookiejar = None

        cookiefile = ui.config(b'auth', b'cookiefile')
        if not cookiefile:
            return

        cookiefile = util.expandpath(cookiefile)
        try:
            cookiejar = util.cookielib.MozillaCookieJar(
                pycompat.fsdecode(cookiefile)
            )
            cookiejar.load()
            self.cookiejar = cookiejar
        except util.cookielib.LoadError as e:
            ui.warn(
                _(
                    b'(error loading cookie file %s: %s; continuing without '
                    b'cookies)\n'
                )
                % (cookiefile, stringutil.forcebytestr(e))
            )

    def http_request(self, request):
        if self.cookiejar:
            self.cookiejar.add_cookie_header(request)

        return request

    def https_request(self, request):
        if self.cookiejar:
            self.cookiejar.add_cookie_header(request)

        return request


handlerfuncs = []


def opener(
    ui,
    authinfo=None,
    useragent=None,
    loggingfh=None,
    loggingname=b's',
    loggingopts=None,
    sendaccept=True,
):
    """
    construct an opener suitable for urllib2
    authinfo will be added to the password manager

    The opener can be configured to log socket events if the various
    ``logging*`` arguments are specified.

    ``loggingfh`` denotes a file object to log events to.
    ``loggingname`` denotes the name of the to print when logging.
    ``loggingopts`` is a dict of keyword arguments to pass to the constructed
    ``util.socketobserver`` instance.

    ``sendaccept`` allows controlling whether the ``Accept`` request header
    is sent. The header is sent by default.
    """
    timeout = ui.configwith(float, b'http', b'timeout')
    handlers = []

    if loggingfh:
        handlers.append(
            logginghttphandler(
                loggingfh, loggingname, loggingopts or {}, timeout=timeout
            )
        )
        # We don't yet support HTTPS when logging I/O. If we attempt to open
        # an HTTPS URL, we'll likely fail due to unknown protocol.

    else:
        handlers.append(httphandler(timeout=timeout))
        if has_https:
            handlers.append(httpshandler(ui, timeout=timeout))

    handlers.append(proxyhandler(ui))

    passmgr = passwordmgr(ui, ui.httppasswordmgrdb)
    if authinfo is not None:
        realm, uris, user, passwd = authinfo
        saveduser, savedpass = passmgr.find_stored_password(uris[0])
        if user != saveduser or passwd:
            passmgr.add_password(realm, uris, user, passwd)
        ui.debug(
            b'http auth: user %s, password %s\n'
            % (user, passwd and b'*' * len(passwd) or b'not set')
        )

    handlers.extend(
        (httpbasicauthhandler(passmgr), httpdigestauthhandler(passmgr))
    )
    handlers.extend([h(ui, passmgr) for h in handlerfuncs])
    handlers.append(cookiehandler(ui))
    opener = urlreq.buildopener(*handlers)

    # keepalive.py's handlers will populate these attributes if they exist.
    opener.requestscount = 0
    opener.sentbytescount = 0
    opener.receivedbytescount = 0

    # The user agent should should *NOT* be used by servers for e.g.
    # protocol detection or feature negotiation: there are other
    # facilities for that.
    #
    # "mercurial/proto-1.0" was the original user agent string and
    # exists for backwards compatibility reasons.
    #
    # The "(Mercurial %s)" string contains the distribution
    # name and version. Other client implementations should choose their
    # own distribution name. Since servers should not be using the user
    # agent string for anything, clients should be able to define whatever
    # user agent they deem appropriate.
    #
    # The custom user agent is for lfs, because unfortunately some servers
    # do look at this value.
    if not useragent:
        agent = b'mercurial/proto-1.0 (Mercurial %s)' % util.version()
        opener.addheaders = [('User-agent', pycompat.sysstr(agent))]
    else:
        opener.addheaders = [('User-agent', pycompat.sysstr(useragent))]

    # This header should only be needed by wire protocol requests. But it has
    # been sent on all requests since forever. We keep sending it for backwards
    # compatibility reasons. Modern versions of the wire protocol use
    # X-HgProto-<N> for advertising client support.
    if sendaccept:
        opener.addheaders.append(('Accept', 'application/mercurial-0.1'))

    return opener


def open(ui, url_, data=None, sendaccept=True):
    u = urlutil.url(url_)
    if u.scheme:
        u.scheme = u.scheme.lower()
        url_, authinfo = u.authinfo()
    else:
        path = util.normpath(util.abspath(url_))
        url_ = b'file://' + pycompat.bytesurl(
            urlreq.pathname2url(pycompat.fsdecode(path))
        )
        authinfo = None
    return opener(ui, authinfo, sendaccept=sendaccept).open(
        pycompat.strurl(url_), data
    )


def wrapresponse(resp):
    """Wrap a response object with common error handlers.

    This ensures that any I/O from any consumer raises the appropriate
    error and messaging.
    """
    origread = resp.read

    class readerproxy(resp.__class__):
        def read(self, size=None):
            try:
                return origread(size)
            except httplib.IncompleteRead as e:
                # e.expected is an integer if length known or None otherwise.
                if e.expected:
                    got = len(e.partial)
                    total = e.expected + got
                    msg = _(
                        b'HTTP request error (incomplete response; '
                        b'expected %d bytes got %d)'
                    ) % (total, got)
                else:
                    msg = _(b'HTTP request error (incomplete response)')

                raise error.PeerTransportError(
                    msg,
                    hint=_(
                        b'this may be an intermittent network failure; '
                        b'if the error persists, consider contacting the '
                        b'network or server operator'
                    ),
                )
            except httplib.HTTPException as e:
                raise error.PeerTransportError(
                    _(b'HTTP request error (%s)') % e,
                    hint=_(
                        b'this may be an intermittent network failure; '
                        b'if the error persists, consider contacting the '
                        b'network or server operator'
                    ),
                )

    resp.__class__ = readerproxy