httppeer: consolidate _requestbuilder assignments and document

I collapsed multiple assignments because they don't appear to
be necessary. We don't invoke the requestbuilder in anything
called during __init__. So there's no reason to not define it
earlier AFAICT.

This seemingly useless attribute is actually an extension point.
Document it as such.

(A previous version of this patch removed the attribute because
it appeared to just be an alias.)

Differential Revision: https://phab.mercurial-scm.org/D2723

mercurial/httppeer.py

@@ -1,503 +1,504 b''
 # httppeer.py - HTTP repository proxy classes for mercurial
 #
 # Copyright 2005, 2006 Matt Mackall <[e-mail]>
 # Copyright 2006 Vadim Gelfer <[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.
 
 from __future__ import absolute_import
 
 import errno
 import io
 import os
 import socket
 import struct
 import tempfile
 
 from .i18n import _
 from . import (
     bundle2,
     error,
     httpconnection,
     pycompat,
     statichttprepo,
     url as urlmod,
     util,
     wireproto,
 )
 
 httplib = util.httplib
 urlerr = util.urlerr
 urlreq = util.urlreq
 
 def encodevalueinheaders(value, header, limit):
     """Encode a string value into multiple HTTP headers.
 
     ``value`` will be encoded into 1 or more HTTP headers with the names
     ``header-<N>`` where ``<N>`` is an integer starting at 1. Each header
     name + value will be at most ``limit`` bytes long.
 
     Returns an iterable of 2-tuples consisting of header names and
     values as native strings.
     """
     # HTTP Headers are ASCII. Python 3 requires them to be unicodes,
     # not bytes. This function always takes bytes in as arguments.
     fmt = pycompat.strurl(header) + r'-%s'
     # Note: it is *NOT* a bug that the last bit here is a bytestring
     # and not a unicode: we're just getting the encoded length anyway,
     # and using an r-string to make it portable between Python 2 and 3
     # doesn't work because then the \r is a literal backslash-r
     # instead of a carriage return.
     valuelen = limit - len(fmt % r'000') - len(': \r\n')
     result = []
 
     n = 0
     for i in xrange(0, len(value), valuelen):
         n += 1
         result.append((fmt % str(n), pycompat.strurl(value[i:i + valuelen])))
 
     return result
 
 def _wraphttpresponse(resp):
     """Wrap an HTTPResponse 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:
                     msg = _('HTTP request error (incomplete response; '
                             'expected %d bytes got %d)') % (e.expected,
                                                            len(e.partial))
                 else:
                     msg = _('HTTP request error (incomplete response)')
 
                 raise error.PeerTransportError(
                     msg,
                     hint=_('this may be an intermittent network failure; '
                            'if the error persists, consider contacting the '
                            'network or server operator'))
             except httplib.HTTPException as e:
                 raise error.PeerTransportError(
                     _('HTTP request error (%s)') % e,
                     hint=_('this may be an intermittent network failure; '
                            'if the error persists, consider contacting the '
                            'network or server operator'))
 
     resp.__class__ = readerproxy
 
 class _multifile(object):
     def __init__(self, *fileobjs):
         for f in fileobjs:
             if not util.safehasattr(f, 'length'):
                 raise ValueError(
                     '_multifile only supports file objects that '
                     'have a length but this one does not:', type(f), f)
         self._fileobjs = fileobjs
         self._index = 0
 
     @property
     def length(self):
         return sum(f.length for f in self._fileobjs)
 
     def read(self, amt=None):
         if amt <= 0:
             return ''.join(f.read() for f in self._fileobjs)
         parts = []
         while amt and self._index < len(self._fileobjs):
             parts.append(self._fileobjs[self._index].read(amt))
             got = len(parts[-1])
             if got < amt:
                 self._index += 1
             amt -= got
         return ''.join(parts)
 
     def seek(self, offset, whence=os.SEEK_SET):
         if whence != os.SEEK_SET:
             raise NotImplementedError(
                 '_multifile does not support anything other'
                 ' than os.SEEK_SET for whence on seek()')
         if offset != 0:
             raise NotImplementedError(
                 '_multifile only supports seeking to start, but that '
                 'could be fixed if you need it')
         for f in self._fileobjs:
             f.seek(0)
         self._index = 0
 
 class httppeer(wireproto.wirepeer):
     def __init__(self, ui, path):
         self._path = path
         self._caps = None
         self._urlopener = None
-        self._requestbuilder = None
+        # This is an its own attribute to facilitate extensions overriding
+        # the default type.
+        self._requestbuilder = urlreq.request
         u = util.url(path)
         if u.query or u.fragment:
             raise error.Abort(_('unsupported URL component: "%s"') %
                              (u.query or u.fragment))
 
         # urllib cannot handle URLs with embedded user or passwd
         self._url, authinfo = u.authinfo()
 
         self._ui = ui
         ui.debug('using %s\n' % self._url)
 
         self._urlopener = urlmod.opener(ui, authinfo)
-        self._requestbuilder = urlreq.request
 
     def __del__(self):
         urlopener = getattr(self, '_urlopener', None)
         if urlopener:
             for h in urlopener.handlers:
                 h.close()
                 getattr(h, "close_all", lambda: None)()
 
     def _openurl(self, req):
         if (self._ui.debugflag
             and self._ui.configbool('devel', 'debug.peer-request')):
             dbg = self._ui.debug
             line = 'devel-peer-request: %s\n'
             dbg(line % '%s %s' % (req.get_method(), req.get_full_url()))
             hgargssize = None
 
             for header, value in sorted(req.header_items()):
                 if header.startswith('X-hgarg-'):
                     if hgargssize is None:
                         hgargssize = 0
                     hgargssize += len(value)
                 else:
                     dbg(line % '  %s %s' % (header, value))
 
             if hgargssize is not None:
                 dbg(line % '  %d bytes of commands arguments in headers'
                     % hgargssize)
 
             if req.has_data():
                 data = req.get_data()
                 length = getattr(data, 'length', None)
                 if length is None:
                     length = len(data)
                 dbg(line % '  %d bytes of data' % length)
 
             start = util.timer()
 
         ret = self._urlopener.open(req)
         if self._ui.configbool('devel', 'debug.peer-request'):
             dbg(line % '  finished in %.4f seconds (%s)'
                 % (util.timer() - start, ret.code))
         return ret
 
     # Begin of _basepeer interface.
 
     @util.propertycache
     def ui(self):
         return self._ui
 
     def url(self):
         return self._path
 
     def local(self):
         return None
 
     def peer(self):
         return self
 
     def canpush(self):
         return True
 
     def close(self):
         pass
 
     # End of _basepeer interface.
 
     # Begin of _basewirepeer interface.
 
     def capabilities(self):
         # self._fetchcaps() should have been called as part of peer
         # handshake. So self._caps should always be set.
         assert self._caps is not None
         return self._caps
 
     # End of _basewirepeer interface.
 
     # look up capabilities only when needed
 
     def _fetchcaps(self):
         self._caps = set(self._call('capabilities').split())
 
     def _callstream(self, cmd, _compressible=False, **args):
         args = pycompat.byteskwargs(args)
         if cmd == 'pushkey':
             args['data'] = ''
         data = args.pop('data', None)
         headers = args.pop('headers', {})
 
         self.ui.debug("sending %s command\n" % cmd)
         q = [('cmd', cmd)]
         headersize = 0
         varyheaders = []
         # Important: don't use self.capable() here or else you end up
         # with infinite recursion when trying to look up capabilities
         # for the first time.
         postargsok = self._caps is not None and 'httppostargs' in self._caps
 
         # Send arguments via POST.
         if postargsok and args:
             strargs = urlreq.urlencode(sorted(args.items()))
             if not data:
                 data = strargs
             else:
                 if isinstance(data, bytes):
                     i = io.BytesIO(data)
                     i.length = len(data)
                     data = i
                 argsio = io.BytesIO(strargs)
                 argsio.length = len(strargs)
                 data = _multifile(argsio, data)
             headers[r'X-HgArgs-Post'] = len(strargs)
         elif args:
             # Calling self.capable() can infinite loop if we are calling
             # "capabilities". But that command should never accept wire
             # protocol arguments. So this should never happen.
             assert cmd != 'capabilities'
             httpheader = self.capable('httpheader')
             if httpheader:
                 headersize = int(httpheader.split(',', 1)[0])
 
             # Send arguments via HTTP headers.
             if headersize > 0:
                 # The headers can typically carry more data than the URL.
                 encargs = urlreq.urlencode(sorted(args.items()))
                 for header, value in encodevalueinheaders(encargs, 'X-HgArg',
                                                           headersize):
                     headers[header] = value
                     varyheaders.append(header)
             # Send arguments via query string (Mercurial <1.9).
             else:
                 q += sorted(args.items())
 
         qs = '?%s' % urlreq.urlencode(q)
         cu = "%s%s" % (self._url, qs)
         size = 0
         if util.safehasattr(data, 'length'):
             size = data.length
         elif data is not None:
             size = len(data)
         if data is not None and r'Content-Type' not in headers:
             headers[r'Content-Type'] = r'application/mercurial-0.1'
 
         # Tell the server we accept application/mercurial-0.2 and multiple
         # compression formats if the server is capable of emitting those
         # payloads.
         protoparams = []
 
         mediatypes = set()
         if self._caps is not None:
             mt = self.capable('httpmediatype')
             if mt:
                 protoparams.append('0.1')
                 mediatypes = set(mt.split(','))
 
         if '0.2tx' in mediatypes:
             protoparams.append('0.2')
 
         if '0.2tx' in mediatypes and self.capable('compression'):
             # We /could/ compare supported compression formats and prune
             # non-mutually supported or error if nothing is mutually supported.
             # For now, send the full list to the server and have it error.
             comps = [e.wireprotosupport().name for e in
                      util.compengines.supportedwireengines(util.CLIENTROLE)]
             protoparams.append('comp=%s' % ','.join(comps))
 
         if protoparams:
             protoheaders = encodevalueinheaders(' '.join(protoparams),
                                                 'X-HgProto',
                                                 headersize or 1024)
             for header, value in protoheaders:
                 headers[header] = value
                 varyheaders.append(header)
 
         if varyheaders:
             headers[r'Vary'] = r','.join(varyheaders)
 
         req = self._requestbuilder(pycompat.strurl(cu), data, headers)
 
         if data is not None:
             self.ui.debug("sending %d bytes\n" % size)
             req.add_unredirected_header(r'Content-Length', r'%d' % size)
         try:
             resp = self._openurl(req)
         except urlerr.httperror as inst:
             if inst.code == 401:
                 raise error.Abort(_('authorization failed'))
             raise
         except httplib.HTTPException as inst:
             self.ui.debug('http error while sending %s command\n' % cmd)
             self.ui.traceback()
             raise IOError(None, inst)
 
         # Insert error handlers for common I/O failures.
         _wraphttpresponse(resp)
 
         # record the url we got redirected to
         resp_url = pycompat.bytesurl(resp.geturl())
         if resp_url.endswith(qs):
             resp_url = resp_url[:-len(qs)]
         if self._url.rstrip('/') != resp_url.rstrip('/'):
             if not self.ui.quiet:
                 self.ui.warn(_('real URL is %s\n') % resp_url)
         self._url = resp_url
         try:
             proto = pycompat.bytesurl(resp.getheader(r'content-type', r''))
         except AttributeError:
             proto = pycompat.bytesurl(resp.headers.get(r'content-type', r''))
 
         safeurl = util.hidepassword(self._url)
         if proto.startswith('application/hg-error'):
             raise error.OutOfBandError(resp.read())
         # accept old "text/plain" and "application/hg-changegroup" for now
         if not (proto.startswith('application/mercurial-') or
                 (proto.startswith('text/plain')
                  and not resp.headers.get('content-length')) or
                 proto.startswith('application/hg-changegroup')):
             self.ui.debug("requested URL: '%s'\n" % util.hidepassword(cu))
             raise error.RepoError(
                 _("'%s' does not appear to be an hg repository:\n"
                   "---%%<--- (%s)\n%s\n---%%<---\n")
                 % (safeurl, proto or 'no content-type', resp.read(1024)))
 
         if proto.startswith('application/mercurial-'):
             try:
                 version = proto.split('-', 1)[1]
                 version_info = tuple([int(n) for n in version.split('.')])
             except ValueError:
                 raise error.RepoError(_("'%s' sent a broken Content-Type "
                                         "header (%s)") % (safeurl, proto))
 
             # TODO consider switching to a decompression reader that uses
             # generators.
             if version_info == (0, 1):
                 if _compressible:
                     return util.compengines['zlib'].decompressorreader(resp)
                 return resp
             elif version_info == (0, 2):
                 # application/mercurial-0.2 always identifies the compression
                 # engine in the payload header.
                 elen = struct.unpack('B', resp.read(1))[0]
                 ename = resp.read(elen)
                 engine = util.compengines.forwiretype(ename)
                 return engine.decompressorreader(resp)
             else:
                 raise error.RepoError(_("'%s' uses newer protocol %s") %
                                       (safeurl, version))
 
         if _compressible:
             return util.compengines['zlib'].decompressorreader(resp)
 
         return resp
 
     def _call(self, cmd, **args):
         fp = self._callstream(cmd, **args)
         try:
             return fp.read()
         finally:
             # if using keepalive, allow connection to be reused
             fp.close()
 
     def _callpush(self, cmd, cg, **args):
         # have to stream bundle to a temp file because we do not have
         # http 1.1 chunked transfer.
 
         types = self.capable('unbundle')
         try:
             types = types.split(',')
         except AttributeError:
             # servers older than d1b16a746db6 will send 'unbundle' as a
             # boolean capability. They only support headerless/uncompressed
             # bundles.
             types = [""]
         for x in types:
             if x in bundle2.bundletypes:
                 type = x
                 break
 
         tempname = bundle2.writebundle(self.ui, cg, None, type)
         fp = httpconnection.httpsendfile(self.ui, tempname, "rb")
         headers = {r'Content-Type': r'application/mercurial-0.1'}
 
         try:
             r = self._call(cmd, data=fp, headers=headers, **args)
             vals = r.split('\n', 1)
             if len(vals) < 2:
                 raise error.ResponseError(_("unexpected response:"), r)
             return vals
         except urlerr.httperror:
             # Catch and re-raise these so we don't try and treat them
             # like generic socket errors. They lack any values in
             # .args on Python 3 which breaks our socket.error block.
             raise
         except socket.error as err:
             if err.args[0] in (errno.ECONNRESET, errno.EPIPE):
                 raise error.Abort(_('push failed: %s') % err.args[1])
             raise error.Abort(err.args[1])
         finally:
             fp.close()
             os.unlink(tempname)
 
     def _calltwowaystream(self, cmd, fp, **args):
         fh = None
         fp_ = None
         filename = None
         try:
             # dump bundle to disk
             fd, filename = tempfile.mkstemp(prefix="hg-bundle-", suffix=".hg")
             fh = os.fdopen(fd, r"wb")
             d = fp.read(4096)
             while d:
                 fh.write(d)
                 d = fp.read(4096)
             fh.close()
             # start http push
             fp_ = httpconnection.httpsendfile(self.ui, filename, "rb")
             headers = {r'Content-Type': r'application/mercurial-0.1'}
             return self._callstream(cmd, data=fp_, headers=headers, **args)
         finally:
             if fp_ is not None:
                 fp_.close()
             if fh is not None:
                 fh.close()
                 os.unlink(filename)
 
     def _callcompressable(self, cmd, **args):
         return self._callstream(cmd, _compressible=True, **args)
 
     def _abort(self, exception):
         raise exception
 
 def instance(ui, path, create):
     if create:
         raise error.Abort(_('cannot create new http repository'))
     try:
         if path.startswith('https:') and not urlmod.has_https:
             raise error.Abort(_('Python support for SSL and HTTPS '
                                 'is not installed'))
 
         inst = httppeer(ui, path)
         inst._fetchcaps()
 
         return inst
     except error.RepoError as httpexception:
         try:
             r = statichttprepo.instance(ui, "static-" + path, create)
             ui.note(_('(falling back to static-http)\n'))
             return r
         except error.RepoError:
             raise httpexception # use the original http RepoError instead