combine all the broker replacement pieces

* local redis for event processing
* postgres for message broker
* redis for websockets

awx/main/dispatch/__init__.py

@@ -1,5 +1,85 @@
+import psycopg2
+import select
+import sys
+import logging
+
+from contextlib import contextmanager
+
 from django.conf import settings
 
 
+NOT_READY = ([], [], [])
+if 'run_callback_receiver' in sys.argv:
+    logger = logging.getLogger('awx.main.commands.run_callback_receiver')
+else:
+    logger = logging.getLogger('awx.main.dispatch')
+
+
 def get_local_queuename():
     return settings.CLUSTER_HOST_ID
+
+
+class PubSub(object):
+    def __init__(self, conn):
+        assert conn.autocommit, "Connection must be in autocommit mode."
+        self.conn = conn
+
+    def listen(self, channel):
+        with self.conn.cursor() as cur:
+            cur.execute('LISTEN "%s";' % channel)
+
+    def unlisten(self, channel):
+        with self.conn.cursor() as cur:
+            cur.execute('UNLISTEN "%s";' % channel)
+
+    def notify(self, channel, payload):
+        with self.conn.cursor() as cur:
+            cur.execute('SELECT pg_notify(%s, %s);', (channel, payload))
+
+    def get_event(self, select_timeout=0):
+        # poll the connection, then return one event, if we have one.  Else
+        # return None.
+        select.select([self.conn], [], [], select_timeout)
+        self.conn.poll()
+        if self.conn.notifies:
+            return self.conn.notifies.pop(0)
+
+    def get_events(self, select_timeout=0):
+        # Poll the connection and return all events, if there are any.  Else
+        # return None.
+        select.select([self.conn], [], [], select_timeout) # redundant?
+        self.conn.poll()
+        events = []
+        while self.conn.notifies:
+            events.append(self.conn.notifies.pop(0))
+        if events:
+            return events
+
+    def events(self, select_timeout=5, yield_timeouts=False):
+        while True:
+            if select.select([self.conn], [], [], select_timeout) == NOT_READY:
+                if yield_timeouts:
+                    yield None
+            else:
+                self.conn.poll()
+                while self.conn.notifies:
+                    yield self.conn.notifies.pop(0)
+
+    def close(self):
+        self.conn.close()
+
+
+@contextmanager
+def pg_bus_conn():
+    conf = settings.DATABASES['default']
+    conn = psycopg2.connect(dbname=conf['NAME'],
+			    host=conf['HOST'],
+			    user=conf['USER'],
+			    password=conf['PASSWORD'])
+    # Django connection.cursor().connection doesn't have autocommit=True on
+    conn.set_session(autocommit=True)
+    pubsub = PubSub(conn)
+    yield pubsub
+    conn.close()
+
+