Fixup for #1085 -- only check for changed metadata on disconnected nodes

Author: dpkp

kafka/client_async.py

@@ -325,31 +325,37 @@ def _conn_state_change(self, node_id, conn):
     def _maybe_connect(self, node_id):
         """Idempotent non-blocking connection attempt to the given node id."""
         broker = self.cluster.broker_metadata(node_id)
+        conn = self._conns.get(node_id)
 
-        # If broker metadata indicates that a node's host/port has changed, remove it
-        if node_id in self._conns and broker is not None:
-            conn = self._conns[node_id]
-            host, _, __ = get_ip_port_afi(broker.host)
-            if conn.host != host or conn.port != broker.port:
-                log.debug("Closing connection to decommissioned node %s at %s:%s",
-                          node_id, conn.host, conn.port)
-                conn.close()
-                self._conns.pop(node_id)
-
-        if node_id not in self._conns:
+        if conn is None:
             assert broker, 'Broker id %s not in current metadata' % node_id
 
             log.debug("Initiating connection to node %s at %s:%s",
                       node_id, broker.host, broker.port)
             host, port, afi = get_ip_port_afi(broker.host)
             cb = functools.partial(self._conn_state_change, node_id)
-            self._conns[node_id] = BrokerConnection(host, broker.port, afi,
-                                                    state_change_callback=cb,
-                                                    node_id=node_id,
-                                                    **self.config)
-        conn = self._conns[node_id]
-        if conn.connected():
+            conn = BrokerConnection(host, broker.port, afi,
+                                    state_change_callback=cb,
+                                    node_id=node_id,
+                                    **self.config)
+            self._conns[node_id] = conn
+
+        # Check if existing connection should be recreated because host/port changed
+        elif conn.disconnected() and broker is not None:
+            host, _, __ = get_ip_port_afi(broker.host)
+            if conn.host != host or conn.port != broker.port:
+                log.info("Broker metadata change detected for node %s"
+                         " from %s:%s to %s:%s", node_id, conn.host, conn.port,
+                         broker.host, broker.port)
+
+                # Drop old connection object.
+                # It will be recreated on next _maybe_connect
+                self._conns.pop(node_id)
+                return False
+
+        elif conn.connected():
             return True
+
         conn.connect()
         return conn.connected()