From f6deca3db2ec173c8d0b2cd33ef2660012ae3f69 Mon Sep 17 00:00:00 2001
From: Marcus Olsson <marcus.olsson@ericsson.com>
Date: Fri, 4 Dec 2015 14:21:15 -0500
Subject: [PATCH] Disable reloading of GossipingPropertyFileSnitch

Patch by molsson; reviewed by pmotta for CASSANDRA-9474
---
 CHANGES.txt                                   |  1 +
 NEWS.txt                                      | 16 +++++++-------
 .../apache/cassandra/db/SystemKeyspace.java   | 21 ++++++++++++++++---
 3 files changed, 26 insertions(+), 12 deletions(-)

diff --git a/CHANGES.txt b/CHANGES.txt
index 1a2887a796..46cda65a98 100644
--- a/CHANGES.txt
+++ b/CHANGES.txt
@@ -1,4 +1,5 @@
 2.1.13
+ * Disable reloading of GossipingPropertyFileSnitch (CASSANDRA-9474)
  * Fix Stress profile parsing on Windows (CASSANDRA-10808)
 
 
diff --git a/NEWS.txt b/NEWS.txt
index cae8dfb387..7a15d0245e 100644
--- a/NEWS.txt
+++ b/NEWS.txt
@@ -24,20 +24,18 @@ New features
     - DTCS option max_sstable_age_days is now deprecated and defaults to 1000 days.
     - Native protocol server now allows both SSL and non-SSL connections on
       the same port.
-    - Switching racks is no longer an allowed operation on a node which has
-      data. Instead, the node will need to be decommissioned and rebootstrapped.
-      If moving from the SimpleSnitch, make sure the rack containing all current
-      nodes is named "rack1". To override this behavior when manually wiping
-      the node and bootstrapping, use -Dcassandra.ignore_rack=true.
     - a new validate(key, cf) method is added to PerRowSecondaryIndex. A default
       implementation is provided, so no changes are required to custom implementations.
 
 Operations
 ------------
-    - Changing rack or dc of live nodes is no longer possible for PropertyFileSnitch
-      and YamlFileNetworkTopologySnitch. Reloading the configuration file of
-      GossipingPropertyFileSnitch has been disabled, CASSANDRA-10243.
-
+    - Switching data center or racks is no longer an allowed operation on a node
+      which has data. Instead, the node will need to be decommissioned and
+      rebootstrapped. If moving from the SimpleSnitch, make sure that the data
+      center and rack containing all current nodes is named "datacenter1" and
+      "rack1". To override this behaviour use -Dcassandra.ignore_rack=true and/or
+      -Dcassandra.ignore_dc=true.
+    - Reloading the configuration file of GossipingPropertyFileSnitch has been disabled.
 
 2.1.11
 =====
diff --git a/src/java/org/apache/cassandra/db/SystemKeyspace.java b/src/java/org/apache/cassandra/db/SystemKeyspace.java
index c600652105..1f66b1b7b3 100644
--- a/src/java/org/apache/cassandra/db/SystemKeyspace.java
+++ b/src/java/org/apache/cassandra/db/SystemKeyspace.java
@@ -614,11 +614,26 @@ public class SystemKeyspace
             }
         }
 
+        String req = "SELECT rack, data_center FROM system.%s WHERE key='%s'";
+        UntypedResultSet result = executeInternal(String.format(req, LOCAL_CF, LOCAL_KEY));
+
+        if (!Boolean.getBoolean("cassandra.ignore_dc"))
+        {
+            // Look up the dc (return it if found)
+            if (!result.isEmpty() && result.one().has("data_center"))
+            {
+                String storedDc = result.one().getString("data_center");
+                String currentDc = DatabaseDescriptor.getEndpointSnitch().getDatacenter(FBUtilities.getBroadcastAddress());
+                if (!storedDc.equals(currentDc))
+                {
+                    throw new ConfigurationException("Cannot start node if snitch's data center (" + currentDc + ") differs from previous data center (" + storedDc + "). " +
+                                                     "Please fix the snitch configuration, decommission and rebootstrap this node or use the flag -Dcassandra.ignore_dc=true.");
+                }
+            }
+        }
+
         if (!Boolean.getBoolean("cassandra.ignore_rack"))
         {
-            String req = "SELECT rack FROM system.%s WHERE key='%s'";
-            UntypedResultSet result = executeInternal(String.format(req, LOCAL_CF, LOCAL_KEY));
-
             // Look up the Rack (return it if found)
             if (!result.isEmpty() && result.one().has("rack"))
             {