Ensure watches are notified when connection state is lost

- This behaviour matches the reference implementation in Zookeeper
- New EventType added: NONE
- Path defaults to None as in reference implementation

Author: michiel-asana

kazoo/client.py

@@ -44,8 +44,11 @@
     Sync,
     Transaction
 )
+from kazoo.protocol.states import Callback
+from kazoo.protocol.states import EventType
 from kazoo.protocol.states import KazooState
 from kazoo.protocol.states import KeeperState
+from kazoo.protocol.states import WatchedEvent
 from kazoo.retry import KazooRetry
 from kazoo.security import ACL
 from kazoo.security import OPEN_ACL_UNSAFE
@@ -305,9 +308,20 @@ def _reset(self):
         self._protocol_version = None
 
     def _reset_watchers(self):
+        watchers = []
+        for child_watchers in six.itervalues(self._child_watchers):
+            watchers.extend(child_watchers)
+
+        for data_watchers in six.itervalues(self._data_watchers):
+            watchers.extend(data_watchers)
+
         self._child_watchers = defaultdict(set)
         self._data_watchers = defaultdict(set)
 
+        ev = WatchedEvent(EventType.NONE, self._state, None)
+        for watch in watchers:
+            self.handler.dispatch_callback(Callback("watch", watch, (ev,)))
+
     def _reset_session(self):
         self._session_id = None
         self._session_passwd = b'\x00' * 16

kazoo/protocol/states.py

@@ -93,13 +93,19 @@ class EventType(object):
         removed). This event does not indicate the data for a child
         node has changed, which must have its own watch established.
 
+    .. attribute:: NONE
+
+        The connection state has been altered.
+
     """
     CREATED = 'CREATED'
     DELETED = 'DELETED'
     CHANGED = 'CHANGED'
     CHILD = 'CHILD'
+    NONE = 'NONE'
 
 EVENT_TYPE_MAP = {
+    -1:EventType.NONE,
     1: EventType.CREATED,
     2: EventType.DELETED,
     3: EventType.CHANGED,