Implement a multiplex facility (WIP)

Allow an arbitrary number of HTTP requests using a
small pool of connections, as is likely in a
common web browser.

confluent_server/confluent/httpapi.py

@@ -25,6 +25,7 @@ import confluent.exceptions as exc
 import confluent.log as log
 import confluent.messages
 import confluent.core as pluginapi
+import confluent.requestmultiplexer
 import confluent.shellserver as shellserver
 import confluent.tlvdata
 import confluent.util as util
@@ -352,7 +353,9 @@ def resourcehandler_backend(env, start_response):
         ("Set-Cookie", m.OutputString())
         for m in authorized['cookie'].values())
     cfgmgr = authorized['cfgmgr']
-    if (operation == 'create' and ('/console/session' in env['PATH_INFO'] or
+    if (operation == 'create') and env['PATH_INFO'] == '/multiplexer':
+        confluent.multiplexer.handle_http(env, querydict)
+    elif (operation == 'create' and ('/console/session' in env['PATH_INFO'] or
             '/shell/sessions/' in env['PATH_INFO'])):
         #hard bake JSON into this path, do not support other incarnations
         if '/console/session' in env['PATH_INFO']:

confluent_server/confluent/messages.py

@@ -1,7 +1,7 @@
 # vim: tabstop=4 shiftwidth=4 softtabstop=4
 
 # Copyright 2014 IBM Corporation
-# Copyright 2015 Lenovo
+# Copyright 2015-2016 Lenovo
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.

confluent_server/confluent/multiplexer.py

@@ -0,0 +1,80 @@
+# vim: tabstop=4 shiftwidth=4 softtabstop=4
+
+# Copyright 2016 Lenovo
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# This module handles the task of multplexing console and any watchers.
+# For example, 3 console windows may share a single http long poller
+# It can additionally add watchers for certain messages
+# messages.py will then check in for any watchers for the relevant resource
+# and trigger notifications on watchers.
+# This will allow a request to watch each individual nodes power state ond/or
+# health results will async come
+# over the watcher.  A client may only request to monitor a resource
+# if it would normally be allowed to actually request it.  Tho monitoring
+# continues, meaning any request, related or not, will send a notification
+# to a watching client
+# This enables, for example, for a web page to react on the fly to anyone
+# noticing the health, power state, add, or delete of a node (any message
+# suitably instrumented in messages.py).
+
+# This is broken out so that messages and httpapi can both import it.
+# This could be added to the socket api as well, but for now the focus shall
+# be on httpapi to enable dynamic web behavior.
+
+import confluent.util as util
+import eventlet
+import time
+
+_multiplexers = {}
+_cleanthread = None
+
+
+def _assaign_multiplexid(multiplexer):
+    sessid = util.randomstring(32)
+    while sessid in _multiplexers:
+        sessid = util.randomstring(32)
+    _multiplexers[sessid] = {'multiplexer': multiplexer,
+                               'expiry': time.time() + 60}
+    return sessid
+
+
+def _expire_multiplexers():
+    global _cleanthread
+    while multiplexers:
+        currtime = time.time()
+        for session in _multiplexers:
+            if _multiplexers[session]['expiry'] < currtime:
+                del _multiplexers[session]
+    if multiplexers:
+        _cleanthread = eventlet.spawn_after(15, _expire_multiplexers)
+    else:
+        _cleanthread = None
+
+
+class Multiplexer(object):
+    def __init__(self):
+        _assign_multiplexid(self)
+
+
+def handle_http(env, querydict):
+    global _cleanthread
+    if _cleanthread is None:
+        _cleanthread = eventlet.spawn_after(60, _expire_multiplexers)
+    if 'multiplexid' not in querydict or not querydict['multiplexid']:
+        # This is a new request, create a new multiplexer
+        multiplexer = Multiplexer()
+    else:
+        multiplexer = _multiplexers['multiplexid']['multiplexer']
+