Remove stream feature handlers on session_start.

Based on profiling, using around 35 stream handlers quarters the number
of basic message stanzas that can be processed in a second, in
comparison to only using the bare minimum of four handlers.

To help, we can drop handlers for stream features once the session
has started. So that we can re-enable these handlers when a stream
must restart, the 'stream_start' event has been added which fires
whenever a stream header is received.

The 'stream_start' event is a more generic replacement for the
existing start_stream_handler() method.

sleekxmpp/clientxmpp.py

@@ -98,13 +98,11 @@ class ClientXMPP(BaseXMPP):
 
         self.add_event_handler('connected', self._handle_connected)
         self.add_event_handler('session_bind', self._handle_session_bind)
+        self.add_event_handler('stream_start', self._handle_stream_start)
+        self.add_event_handler('session_start', self._handle_session_start)
 
         self.register_stanza(StreamFeatures)
 
-        self.register_handler(
-                Callback('Stream Features',
-                         MatchXPath('{%s}features' % self.stream_ns),
-                         self._handle_stream_features))
         self.register_handler(
                 Callback('Roster Update',
                          MatchXPath('{%s}iq/{%s}query' % (
@@ -119,6 +117,15 @@ class ClientXMPP(BaseXMPP):
         self.register_plugin('feature_mechanisms',
                 pconfig={'use_mech': sasl_mech} if sasl_mech else None)
 
+    def _handle_stream_start(self, root):
+        self.register_handler(
+                Callback('Stream Features',
+                         MatchXPath('{%s}features' % self.stream_ns),
+                         self._handle_stream_features))
+
+    def _handle_session_start(self, e):
+        self.remove_handler('Stream Features')
+
     def connect(self, address=tuple(), reattempt=True,
                 use_tls=True, use_ssl=False):
         """Connect to the XMPP server.

sleekxmpp/features/feature_mechanisms/mechanisms.py

@@ -63,6 +63,17 @@ class feature_mechanisms(base_plugin):
         self.xmpp.register_stanza(stanza.Challenge)
         self.xmpp.register_stanza(stanza.Response)
 
+        self.xmpp.add_event_handler('stream_start',
+                self._handle_stream_start)
+        self.xmpp.add_event_handler('session_start',
+                self._handle_session_start)
+
+        self.xmpp.register_feature('mechanisms',
+                self._handle_sasl_auth,
+                restart=True,
+                order=self.config.get('order', 100))
+
+    def _handle_stream_start(self, root):
         self.xmpp.register_handler(
                 Callback('SASL Success',
                          MatchXPath(stanza.Success.tag_name()),
@@ -80,10 +91,10 @@ class feature_mechanisms(base_plugin):
                          MatchXPath(stanza.Challenge.tag_name()),
                          self._handle_challenge))
 
-        self.xmpp.register_feature('mechanisms',
-                self._handle_sasl_auth,
-                restart=True,
-                order=self.config.get('order', 100))
+    def _handle_session_start(self, e):
+        self.xmpp.remove_handler('SASL Success')
+        self.xmpp.remove_handler('SASL Failure')
+        self.xmpp.remove_handler('SASL Challenge')
 
     def _handle_sasl_auth(self, features):
         """

sleekxmpp/features/feature_starttls/starttls.py

@@ -27,20 +27,30 @@ class feature_starttls(base_plugin):
         self.description = "STARTTLS Stream Feature"
         self.stanza = stanza
 
-        self.xmpp.register_handler(
-                Callback('STARTTLS Proceed',
-                        MatchXPath(stanza.Proceed.tag_name()),
-                        self._handle_starttls_proceed,
-                        instream=True))
         self.xmpp.register_feature('starttls',
                 self._handle_starttls,
                 restart=True,
                 order=self.config.get('order', 0))
 
+        self.xmpp.add_event_handler('stream_start',
+                self._handle_stream_start)
+        self.xmpp.add_event_handler('session_start',
+                self._handle_session_start)
+
         self.xmpp.register_stanza(stanza.Proceed)
         self.xmpp.register_stanza(stanza.Failure)
         register_stanza_plugin(StreamFeatures, stanza.STARTTLS)
 
+    def _handle_stream_start(self, root):
+        self.xmpp.register_handler(
+                Callback('STARTTLS Proceed',
+                        MatchXPath(stanza.Proceed.tag_name()),
+                        self._handle_starttls_proceed,
+                        instream=True))
+
+    def _handle_session_start(self, e):
+        self.xmpp.remove_handler('STARTTLS Proceed')
+
     def _handle_starttls(self, features):
         """
         Handle notification that the server supports TLS.

sleekxmpp/test/sleektest.py

@@ -367,6 +367,7 @@ class SleekTest(unittest.TestCase):
         if skip:
             if socket != 'live':
                 # Mark send queue as usable
+                self.xmpp.event('session_start')
                 self.xmpp.session_started_event.set()
                 # Clear startup stanzas
                 self.xmpp.socket.next_sent(timeout=1)

sleekxmpp/xmlstream/xmlstream.py

@@ -1223,6 +1223,7 @@ class XMLStream(object):
                     # as handshakes.
                     self.stream_end_event.clear()
                     self.start_stream_handler(root)
+                    self.event('stream_start', root, direct=True)
                 depth += 1
             if event == b'end':
                 depth -= 1