INDY-1199: Improve logic of inconsistency watcher

Signed-off-by: Sergey Khoroshavin <[email protected]>

Author: Sergey Khoroshavin

plenum/server/inconsistency_watchers.py

@@ -4,18 +4,21 @@
 
 class NetworkInconsistencyWatcher:
     def __init__(self, cb: Callable):
-        self._nodes = set()
-        self.connected = set()
         self.callback = cb
-        self.quorums = Quorums(0)
+        self._nodes = set()
+        self._connected = set()
+        self._quorums = Quorums(0)
+        self._reached_consensus = False
 
     def connect(self, name: str):
-        self.connected.add(name)
+        self._connected.add(name)
+        if self._quorums.strong.is_reached(len(self._connected)):
+            self._reached_consensus = True
 
     def disconnect(self, name: str):
-        had_consensus = self._has_consensus()
-        self.connected.discard(name)
-        if had_consensus and not self._has_consensus():
+        self._connected.discard(name)
+        if self._reached_consensus and not self._quorums.weak.is_reached(len(self._connected)):
+            self._reached_consensus = False
             self.callback()
 
     @property
@@ -24,7 +27,7 @@ def nodes(self):
 
     def set_nodes(self, nodes: Iterable[str]):
         self._nodes = set(nodes)
-        self.quorums = Quorums(len(self._nodes))
+        self._quorums = Quorums(len(self._nodes))
 
     def _has_consensus(self):
-        return self.quorums.weak.is_reached(len(self.connected))
+        return self._quorums.weak.is_reached(len(self._connected))

plenum/test/restart/test_network_inconsistency_watcher.py

@@ -56,14 +56,26 @@ def test_watcher_is_not_triggered_when_just_one_node_connects_and_disconnects(wa
 def test_watcher_is_triggered_when_going_below_consensus(watcher: NetworkInconsistencyWatcher):
     watcher.connect('Alpha')
     watcher.connect('Beta')
+    watcher.connect('Gamma')
     watcher.disconnect('Beta')
+    watcher.disconnect('Gamma')
 
     assert watcher.callback.call_count == 1
 
 
+def test_watcher_is_not_triggered_when_going_below_consensus_without_going_above_strong_quorum(watcher: NetworkInconsistencyWatcher):
+    watcher.connect('Alpha')
+    watcher.connect('Beta')
+    watcher.disconnect('Beta')
+
+    assert watcher.callback.call_count == 0
+
+
 def test_watcher_is_not_triggered_when_adding_nodes_while_on_edge_of_consensus(watcher: NetworkInconsistencyWatcher):
     watcher.connect('Alpha')
     watcher.connect('Beta')
+    watcher.connect('Gamma')
+    watcher.disconnect('Gamma')
     _add_node(watcher, 'Epsilon')
     _add_node(watcher, 'Zeta')
     _add_node(watcher, 'Eta')
@@ -84,18 +96,24 @@ def test_watcher_is_not_triggered_when_removing_nodes_below_minimum_count(watche
 def test_watcher_is_not_triggered_when_removing_nodes_and_going_below_consensus(watcher: NetworkInconsistencyWatcher):
     _add_node(watcher, 'Theta')
     watcher.connect('Alpha')
+    watcher.connect('Beta')
+    watcher.connect('Gamma')
     watcher.connect('Theta')
+    watcher.disconnect('Beta')
+    watcher.disconnect('Gamma')
     _remove_node(watcher, 'Theta')
 
     assert watcher.callback.call_count == 0
 
 
-def test_watcher_is_not_triggered_when_just_two_nodes_connect_and_disconnect_in_7_node_pool(
+def test_watcher_is_not_triggered_when_just_three_nodes_connect_and_disconnect_in_7_node_pool(
         watcher: NetworkInconsistencyWatcher):
     watcher.set_nodes(['Alpha', 'Beta', 'Gamma', 'Delta', 'Epsilon', 'Zeta', 'Eta'])
     watcher.connect('Alpha')
     watcher.connect('Beta')
+    watcher.connect('Gamma')
     watcher.disconnect('Alpha')
     watcher.disconnect('Beta')
+    watcher.disconnect('Gamma')
 
     assert watcher.callback.call_count == 0