Revert "libn/networkdb: stop table events from racing network leaves"

This reverts commit 270a4d41dc.

Signed-off-by: Rob Murray <rob.murray@docker.com>

libnetwork/networkdb/delegate.go

@@ -148,13 +148,8 @@ func (nDB *NetworkDB) handleTableEvent(tEvent *TableEvent, isBulkSync bool) bool
 	// Update our local clock if the received messages has newer time.
 	nDB.tableClock.Witness(tEvent.LTime)
 
-	nDB.Lock()
-	// Hold the lock until after we broadcast the event to watchers so that
-	// the new watch receives either the synthesized event or the event we
-	// broadcast, never both.
-	defer nDB.Unlock()
-
 	// Ignore the table events for networks that are in the process of going away
+	nDB.RLock()
 	networks := nDB.networks[nDB.config.NodeID]
 	network, ok := networks[tEvent.NetworkID]
 	// Check if the owner of the event is still part of the network
@@ -166,12 +161,18 @@ func (nDB *NetworkDB) handleTableEvent(tEvent *TableEvent, isBulkSync bool) bool
 			break
 		}
 	}
+	nDB.RUnlock()
 
 	if !ok || network.leaving || !nodePresent {
 		// I'm out of the network OR the event owner is not anymore part of the network so do not propagate
 		return false
 	}
 
+	nDB.Lock()
+	// Hold the lock until after we broadcast the event to watchers so that
+	// the new watch receives either the synthesized event or the event we
+	// broadcast, never both.
+	defer nDB.Unlock()
 	var entryPresent bool
 	prev, err := nDB.getEntry(tEvent.TableName, tEvent.NetworkID, tEvent.Key)
 	if err == nil {