Remove potential gossip deadlock during decommission

Remove unnecessary updating of local app state when leaving

Patch by Sam Tunnicliffe; reviewed by Marcus Eriksson for
CASSANDRA-21143

Author: beobal

CHANGES.txt

@@ -1,4 +1,5 @@
 5.1
+ * Avoid potential gossip thread deadlock during decommission (CASSANDRA-21143)
  * Improve construction of consensus groups for range movements (CASSANDRA-21142)
  * Support compaction_read_disk_access_mode for cursor-based compaction (CASSANDRA-21147)
  * Allow value/element indexing on frozen collections in SAI (CASSANDRA-18492)

src/java/org/apache/cassandra/gms/Gossiper.java

@@ -2194,16 +2194,6 @@ public void unsafeBroadcastLeftStatus(InetAddressAndPort left,
             toSend.forceNewerGenerationUnsafe();
             toSend.markDead();
             VersionedValue value = StorageService.instance.valueFactory.left(tokens, computeExpireTime());
-
-            if (left.equals(getBroadcastAddressAndPort()))
-            {
-                // Adding local state bumps the value's version. To keep this consistent across
-                // the cluster, re-fetch it before broadcasting.
-                Gossiper.instance.addLocalApplicationState(ApplicationState.STATUS_WITH_PORT, value);
-                value = Gossiper.instance.endpointStateMap.get(getBroadcastAddressAndPort())
-                                                          .getApplicationState(ApplicationState.STATUS_WITH_PORT);
-            }
-
             toSend.addApplicationState(ApplicationState.STATUS_WITH_PORT, value);
             GossipDigestAck2 payload = new GossipDigestAck2(Collections.singletonMap(left, toSend));
             logger.info("Sending app state with status {} to {}", value.value, sendTo);