wireprotoserver: make abstractserverproto a proper abstract base class

Plug in the abc module so we can have run-time validation of type
conformance.

Differential Revision: https://phab.mercurial-scm.org/D1990

mercurial/wireprotoserver.py

@@ -1,344 +1,347
 # Copyright 21 May 2005 - (c) 2005 Jake Edge <[e-mail]>
 # Copyright 2005-2007 Matt Mackall <[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 abc
 import cgi
 import struct
 import sys
 
 from .i18n import _
 from . import (
     encoding,
     error,
     hook,
     pycompat,
     util,
     wireproto,
 )
 
 stringio = util.stringio
 
 urlerr = util.urlerr
 urlreq = util.urlreq
 
 HTTP_OK = 200
 
 HGTYPE = 'application/mercurial-0.1'
 HGTYPE2 = 'application/mercurial-0.2'
 HGERRTYPE = 'application/hg-error'
 
 class abstractserverproto(object):
     """abstract class that summarizes the protocol API
 
     Used as reference and documentation.
     """
 
+    __metaclass__ = abc.ABCMeta
+
+    @abc.abstractmethod
     def getargs(self, args):
         """return the value for arguments in <args>
 
         returns a list of values (same order as <args>)"""
-        raise NotImplementedError()
 
+    @abc.abstractmethod
     def getfile(self, fp):
         """write the whole content of a file into a file like object
 
         The file is in the form::
 
             (<chunk-size>\n<chunk>)+0\n
 
         chunk size is the ascii version of the int.
         """
-        raise NotImplementedError()
 
+    @abc.abstractmethod
     def redirect(self):
         """may setup interception for stdout and stderr
 
         See also the `restore` method."""
-        raise NotImplementedError()
 
     # If the `redirect` function does install interception, the `restore`
     # function MUST be defined. If interception is not used, this function
     # MUST NOT be defined.
     #
     # left commented here on purpose
     #
     #def restore(self):
     #    """reinstall previous stdout and stderr and return intercepted stdout
     #    """
     #    raise NotImplementedError()
 
 def decodevaluefromheaders(req, headerprefix):
     """Decode a long value from multiple HTTP request headers.
 
     Returns the value as a bytes, not a str.
     """
     chunks = []
     i = 1
     prefix = headerprefix.upper().replace(r'-', r'_')
     while True:
         v = req.env.get(r'HTTP_%s_%d' % (prefix, i))
         if v is None:
             break
         chunks.append(pycompat.bytesurl(v))
         i += 1
 
     return ''.join(chunks)
 
 class webproto(abstractserverproto):
     def __init__(self, req, ui):
         self._req = req
         self._ui = ui
         self.name = 'http'
 
     def getargs(self, args):
         knownargs = self._args()
         data = {}
         keys = args.split()
         for k in keys:
             if k == '*':
                 star = {}
                 for key in knownargs.keys():
                     if key != 'cmd' and key not in keys:
                         star[key] = knownargs[key][0]
                 data['*'] = star
             else:
                 data[k] = knownargs[k][0]
         return [data[k] for k in keys]
 
     def _args(self):
         args = self._req.form.copy()
         if pycompat.ispy3:
             args = {k.encode('ascii'): [v.encode('ascii') for v in vs]
                     for k, vs in args.items()}
         postlen = int(self._req.env.get(r'HTTP_X_HGARGS_POST', 0))
         if postlen:
             args.update(cgi.parse_qs(
                 self._req.read(postlen), keep_blank_values=True))
             return args
 
         argvalue = decodevaluefromheaders(self._req, r'X-HgArg')
         args.update(cgi.parse_qs(argvalue, keep_blank_values=True))
         return args
 
     def getfile(self, fp):
         length = int(self._req.env[r'CONTENT_LENGTH'])
         # If httppostargs is used, we need to read Content-Length
         # minus the amount that was consumed by args.
         length -= int(self._req.env.get(r'HTTP_X_HGARGS_POST', 0))
         for s in util.filechunkiter(self._req, limit=length):
             fp.write(s)
 
     def redirect(self):
         self._oldio = self._ui.fout, self._ui.ferr
         self._ui.ferr = self._ui.fout = stringio()
 
     def restore(self):
         val = self._ui.fout.getvalue()
         self._ui.ferr, self._ui.fout = self._oldio
         return val
 
     def _client(self):
         return 'remote:%s:%s:%s' % (
             self._req.env.get('wsgi.url_scheme') or 'http',
             urlreq.quote(self._req.env.get('REMOTE_HOST', '')),
             urlreq.quote(self._req.env.get('REMOTE_USER', '')))
 
     def responsetype(self, prefer_uncompressed):
         """Determine the appropriate response type and compression settings.
 
         Returns a tuple of (mediatype, compengine, engineopts).
         """
         # Determine the response media type and compression engine based
         # on the request parameters.
         protocaps = decodevaluefromheaders(self._req, r'X-HgProto').split(' ')
 
         if '0.2' in protocaps:
             # All clients are expected to support uncompressed data.
             if prefer_uncompressed:
                 return HGTYPE2, util._noopengine(), {}
 
             # Default as defined by wire protocol spec.
             compformats = ['zlib', 'none']
             for cap in protocaps:
                 if cap.startswith('comp='):
                     compformats = cap[5:].split(',')
                     break
 
             # Now find an agreed upon compression format.
             for engine in wireproto.supportedcompengines(self._ui, self,
                                                          util.SERVERROLE):
                 if engine.wireprotosupport().name in compformats:
                     opts = {}
                     level = self._ui.configint('server',
                                               '%slevel' % engine.name())
                     if level is not None:
                         opts['level'] = level
 
                     return HGTYPE2, engine, opts
 
             # No mutually supported compression format. Fall back to the
             # legacy protocol.
 
         # Don't allow untrusted settings because disabling compression or
         # setting a very high compression level could lead to flooding
         # the server's network or CPU.
         opts = {'level': self._ui.configint('server', 'zliblevel')}
         return HGTYPE, util.compengines['zlib'], opts
 
 def iscmd(cmd):
     return cmd in wireproto.commands
 
 def callhttp(repo, req, cmd):
     proto = webproto(req, repo.ui)
 
     def genversion2(gen, engine, engineopts):
         # application/mercurial-0.2 always sends a payload header
         # identifying the compression engine.
         name = engine.wireprotosupport().name
         assert 0 < len(name) < 256
         yield struct.pack('B', len(name))
         yield name
 
         for chunk in gen:
             yield chunk
 
     rsp = wireproto.dispatch(repo, proto, cmd)
     if isinstance(rsp, bytes):
         req.respond(HTTP_OK, HGTYPE, body=rsp)
         return []
     elif isinstance(rsp, wireproto.streamres_legacy):
         gen = rsp.gen
         req.respond(HTTP_OK, HGTYPE)
         return gen
     elif isinstance(rsp, wireproto.streamres):
         gen = rsp.gen
 
         # This code for compression should not be streamres specific. It
         # is here because we only compress streamres at the moment.
         mediatype, engine, engineopts = proto.responsetype(
             rsp.prefer_uncompressed)
         gen = engine.compressstream(gen, engineopts)
 
         if mediatype == HGTYPE2:
             gen = genversion2(gen, engine, engineopts)
 
         req.respond(HTTP_OK, mediatype)
         return gen
     elif isinstance(rsp, wireproto.pushres):
         val = proto.restore()
         rsp = '%d\n%s' % (rsp.res, val)
         req.respond(HTTP_OK, HGTYPE, body=rsp)
         return []
     elif isinstance(rsp, wireproto.pusherr):
         # drain the incoming bundle
         req.drain()
         proto.restore()
         rsp = '0\n%s\n' % rsp.res
         req.respond(HTTP_OK, HGTYPE, body=rsp)
         return []
     elif isinstance(rsp, wireproto.ooberror):
         rsp = rsp.message
         req.respond(HTTP_OK, HGERRTYPE, body=rsp)
         return []
     raise error.ProgrammingError('hgweb.protocol internal failure', rsp)
 
 class sshserver(abstractserverproto):
     def __init__(self, ui, repo):
         self._ui = ui
         self._repo = repo
         self._fin = ui.fin
         self._fout = ui.fout
         self.name = 'ssh'
 
         hook.redirect(True)
         ui.fout = repo.ui.fout = ui.ferr
 
         # Prevent insertion/deletion of CRs
         util.setbinary(self._fin)
         util.setbinary(self._fout)
 
     def getargs(self, args):
         data = {}
         keys = args.split()
         for n in xrange(len(keys)):
             argline = self._fin.readline()[:-1]
             arg, l = argline.split()
             if arg not in keys:
                 raise error.Abort(_("unexpected parameter %r") % arg)
             if arg == '*':
                 star = {}
                 for k in xrange(int(l)):
                     argline = self._fin.readline()[:-1]
                     arg, l = argline.split()
                     val = self._fin.read(int(l))
                     star[arg] = val
                 data['*'] = star
             else:
                 val = self._fin.read(int(l))
                 data[arg] = val
         return [data[k] for k in keys]
 
     def getfile(self, fpout):
         self._sendresponse('')
         count = int(self._fin.readline())
         while count:
             fpout.write(self._fin.read(count))
             count = int(self._fin.readline())
 
     def redirect(self):
         pass
 
     def _sendresponse(self, v):
         self._fout.write("%d\n" % len(v))
         self._fout.write(v)
         self._fout.flush()
 
     def _sendstream(self, source):
         write = self._fout.write
         for chunk in source.gen:
             write(chunk)
         self._fout.flush()
 
     def _sendpushresponse(self, rsp):
         self._sendresponse('')
         self._sendresponse(str(rsp.res))
 
     def _sendpusherror(self, rsp):
         self._sendresponse(rsp.res)
 
     def _sendooberror(self, rsp):
         self._ui.ferr.write('%s\n-\n' % rsp.message)
         self._ui.ferr.flush()
         self._fout.write('\n')
         self._fout.flush()
 
     def serve_forever(self):
         while self.serve_one():
             pass
         sys.exit(0)
 
     _handlers = {
         str: _sendresponse,
         wireproto.streamres: _sendstream,
         wireproto.streamres_legacy: _sendstream,
         wireproto.pushres: _sendpushresponse,
         wireproto.pusherr: _sendpusherror,
         wireproto.ooberror: _sendooberror,
     }
 
     def serve_one(self):
         cmd = self._fin.readline()[:-1]
         if cmd and cmd in wireproto.commands:
             rsp = wireproto.dispatch(self._repo, self, cmd)
             self._handlers[rsp.__class__](self, rsp)
         elif cmd:
             self._sendresponse("")
         return cmd != ''
 
     def _client(self):
         client = encoding.environ.get('SSH_CLIENT', '').split(' ', 1)[0]
         return 'remote:ssh:' + client