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Posted to commits@cassandra.apache.org by sn...@apache.org on 2015/11/27 13:58:09 UTC

cassandra git commit: Warn or fail when changing cluster topology live

Repository: cassandra
Updated Branches:
  refs/heads/cassandra-2.1 8cd13f138 -> 7650fc196


Warn or fail when changing cluster topology live

patch by Stefania; reviewed by Paulo Motta for CASSANDRA-10243


Project: http://git-wip-us.apache.org/repos/asf/cassandra/repo
Commit: http://git-wip-us.apache.org/repos/asf/cassandra/commit/7650fc19
Tree: http://git-wip-us.apache.org/repos/asf/cassandra/tree/7650fc19
Diff: http://git-wip-us.apache.org/repos/asf/cassandra/diff/7650fc19

Branch: refs/heads/cassandra-2.1
Commit: 7650fc196341bd673626054593f2ce6e895d7783
Parents: 8cd13f1
Author: Stefania <st...@datastax.com>
Authored: Fri Nov 27 13:49:15 2015 +0100
Committer: Robert Stupp <sn...@snazy.de>
Committed: Fri Nov 27 13:49:15 2015 +0100

----------------------------------------------------------------------
 CHANGES.txt                                     |   1 +
 NEWS.txt                                        |   6 +
 build.xml                                       |   1 +
 src/java/org/apache/cassandra/gms/Gossiper.java |  28 +-
 .../locator/GossipingPropertyFileSnitch.java    | 107 ++-----
 .../cassandra/locator/PropertyFileSnitch.java   |  74 ++++-
 .../cassandra/locator/SnitchProperties.java     |   5 +
 .../locator/YamlFileNetworkTopologySnitch.java  | 111 +++++--
 .../cassandra/service/MigrationManager.java     |   4 +-
 .../apache/cassandra/service/StorageProxy.java  |  10 +-
 .../cassandra/service/StorageService.java       |  32 +-
 .../GossipingPropertyFileSnitchTest.java        |  35 +-
 .../locator/PropertyFileSnitchTest.java         | 321 +++++++++++++++++++
 .../YamlFileNetworkTopologySnitchTest.java      | 293 +++++++++++++++--
 14 files changed, 823 insertions(+), 205 deletions(-)
----------------------------------------------------------------------


http://git-wip-us.apache.org/repos/asf/cassandra/blob/7650fc19/CHANGES.txt
----------------------------------------------------------------------
diff --git a/CHANGES.txt b/CHANGES.txt
index 111852c..a2f7b6e 100644
--- a/CHANGES.txt
+++ b/CHANGES.txt
@@ -1,4 +1,5 @@
 2.1.12
+ * Warn or fail when changing cluster topology live (CASSANDRA-10243)
  * Status command in debian/ubuntu init script doesn't work (CASSANDRA-10213)
  * Some DROP ... IF EXISTS incorrectly result in exceptions on non-existing KS (CASSANDRA-10658)
  * DeletionTime.compareTo wrong in rare cases (CASSANDRA-10749)

http://git-wip-us.apache.org/repos/asf/cassandra/blob/7650fc19/NEWS.txt
----------------------------------------------------------------------
diff --git a/NEWS.txt b/NEWS.txt
index 54a6b79..cae8dfb 100644
--- a/NEWS.txt
+++ b/NEWS.txt
@@ -32,6 +32,12 @@ New features
     - 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.
+
 
 2.1.11
 =====

http://git-wip-us.apache.org/repos/asf/cassandra/blob/7650fc19/build.xml
----------------------------------------------------------------------
diff --git a/build.xml b/build.xml
index 28a8f74..45bb13f 100644
--- a/build.xml
+++ b/build.xml
@@ -1528,6 +1528,7 @@
       <sourceFolder url="file://$MODULE_DIR$/test/long" isTestSource="true" />
       <sourceFolder url="file://$MODULE_DIR$/test/pig" isTestSource="true" />
       <sourceFolder url="file://$MODULE_DIR$/test/microbench" isTestSource="true" />
+      <sourceFolder url="file://$MODULE_DIR$/test/conf" type="java-test-resource" />
       <sourceFolder url="file://$MODULE_DIR$/test/resources" type="java-test-resource" />
       <excludeFolder url="file://$MODULE_DIR$/.idea" />
       <excludeFolder url="file://$MODULE_DIR$/.settings" />

http://git-wip-us.apache.org/repos/asf/cassandra/blob/7650fc19/src/java/org/apache/cassandra/gms/Gossiper.java
----------------------------------------------------------------------
diff --git a/src/java/org/apache/cassandra/gms/Gossiper.java b/src/java/org/apache/cassandra/gms/Gossiper.java
index 2f69d66..09851b2 100644
--- a/src/java/org/apache/cassandra/gms/Gossiper.java
+++ b/src/java/org/apache/cassandra/gms/Gossiper.java
@@ -256,24 +256,12 @@ public class Gossiper implements IFailureDetectionEventListener, GossiperMBean
         subscribers.remove(subscriber);
     }
 
-    public Set<InetAddress> getLiveMembers()
+    public Set<InetAddress> getLiveEndpoints()
     {
-        Set<InetAddress> liveMembers = new HashSet<InetAddress>(liveEndpoints);
-        if (!liveMembers.contains(FBUtilities.getBroadcastAddress()))
-            liveMembers.add(FBUtilities.getBroadcastAddress());
-        return liveMembers;
-    }
-
-    public Set<InetAddress> getLiveTokenOwners()
-    {
-        Set<InetAddress> tokenOwners = new HashSet<InetAddress>();
-        for (InetAddress member : getLiveMembers())
-        {
-            EndpointState epState = endpointStateMap.get(member);
-            if (epState != null && !isDeadState(epState) && StorageService.instance.getTokenMetadata().isMember(member))
-                tokenOwners.add(member);
-        }
-        return tokenOwners;
+        Set<InetAddress> liveEndpoints = new HashSet<InetAddress>(this.liveEndpoints);
+        if (!liveEndpoints.contains(FBUtilities.getBroadcastAddress()))
+            liveEndpoints.add(FBUtilities.getBroadcastAddress());
+        return liveEndpoints;
     }
 
     /**
@@ -981,7 +969,8 @@ public class Gossiper implements IFailureDetectionEventListener, GossiperMBean
         MessagingService.instance().sendRR(echoMessage, addr, echoHandler);
     }
 
-    private void realMarkAlive(final InetAddress addr, final EndpointState localState)
+    @VisibleForTesting
+    public void realMarkAlive(final InetAddress addr, final EndpointState localState)
     {
         if (logger.isTraceEnabled())
             logger.trace("marking as alive {}", addr);
@@ -998,7 +987,8 @@ public class Gossiper implements IFailureDetectionEventListener, GossiperMBean
             logger.trace("Notified " + subscribers);
     }
 
-    private void markDead(InetAddress addr, EndpointState localState)
+    @VisibleForTesting
+    public void markDead(InetAddress addr, EndpointState localState)
     {
         if (logger.isTraceEnabled())
             logger.trace("marking as down {}", addr);

http://git-wip-us.apache.org/repos/asf/cassandra/blob/7650fc19/src/java/org/apache/cassandra/locator/GossipingPropertyFileSnitch.java
----------------------------------------------------------------------
diff --git a/src/java/org/apache/cassandra/locator/GossipingPropertyFileSnitch.java b/src/java/org/apache/cassandra/locator/GossipingPropertyFileSnitch.java
index f3f38a0..e2449ae 100644
--- a/src/java/org/apache/cassandra/locator/GossipingPropertyFileSnitch.java
+++ b/src/java/org/apache/cassandra/locator/GossipingPropertyFileSnitch.java
@@ -1,4 +1,4 @@
-/**
+/*
  * Licensed to the Apache Software Foundation (ASF) under one
  * or more contributor license agreements.  See the NOTICE file
  * distributed with this work for additional information
@@ -32,8 +32,6 @@ import org.apache.cassandra.gms.EndpointState;
 import org.apache.cassandra.gms.Gossiper;
 import org.apache.cassandra.service.StorageService;
 import org.apache.cassandra.utils.FBUtilities;
-import org.apache.cassandra.utils.ResourceWatcher;
-import org.apache.cassandra.utils.WrappedRunnable;
 
 
 public class GossipingPropertyFileSnitch extends AbstractNetworkTopologySnitch// implements IEndpointStateChangeSubscriber
@@ -42,28 +40,23 @@ public class GossipingPropertyFileSnitch extends AbstractNetworkTopologySnitch//
 
     private PropertyFileSnitch psnitch;
 
-    private volatile String myDC;
-    private volatile String myRack;
-    private volatile boolean preferLocal;
-    private AtomicReference<ReconnectableSnitchHelper> snitchHelperReference;
-    private volatile boolean gossipStarted;
+    private final String myDC;
+    private final String myRack;
+    private final boolean preferLocal;
+    private final AtomicReference<ReconnectableSnitchHelper> snitchHelperReference;
 
     private Map<InetAddress, Map<String, String>> savedEndpoints;
     private static final String DEFAULT_DC = "UNKNOWN_DC";
     private static final String DEFAULT_RACK = "UNKNOWN_RACK";
 
-    private static final int DEFAULT_REFRESH_PERIOD_IN_SECONDS = 60;
-    
     public GossipingPropertyFileSnitch() throws ConfigurationException
     {
-        this(DEFAULT_REFRESH_PERIOD_IN_SECONDS);
-    }
-
-    public GossipingPropertyFileSnitch(int refreshPeriodInSeconds) throws ConfigurationException
-    {
-        snitchHelperReference = new AtomicReference<ReconnectableSnitchHelper>();
+        SnitchProperties properties = loadConfiguration();
 
-        reloadConfiguration(false);
+        myDC = properties.get("dc", DEFAULT_DC).trim();
+        myRack = properties.get("rack", DEFAULT_RACK).trim();
+        preferLocal = Boolean.parseBoolean(properties.get("prefer_local", "false"));
+        snitchHelperReference = new AtomicReference<>();
 
         try
         {
@@ -74,23 +67,15 @@ public class GossipingPropertyFileSnitch extends AbstractNetworkTopologySnitch//
         {
             logger.info("Unable to load {}; compatibility mode disabled", PropertyFileSnitch.SNITCH_PROPERTIES_FILENAME);
         }
+    }
 
-        try
-        {
-            FBUtilities.resourceToFile(SnitchProperties.RACKDC_PROPERTY_FILENAME);
-            Runnable runnable = new WrappedRunnable()
-            {
-                protected void runMayThrow() throws ConfigurationException
-                {
-                    reloadConfiguration(true);
-                }
-            };
-            ResourceWatcher.watch(SnitchProperties.RACKDC_PROPERTY_FILENAME, runnable, refreshPeriodInSeconds * 1000);
-        }
-        catch (ConfigurationException ex)
-        {
-            logger.error("{} found, but does not look like a plain file. Will not watch it for changes", SnitchProperties.RACKDC_PROPERTY_FILENAME);
-        }
+    private static SnitchProperties loadConfiguration() throws ConfigurationException
+    {
+        final SnitchProperties properties = new SnitchProperties();
+        if (!properties.contains("dc") || !properties.contains("rack"))
+            throw new ConfigurationException("DC or rack not found in snitch properties, check your configuration in: " + SnitchProperties.RACKDC_PROPERTY_FILENAME);
+
+        return properties;
     }
 
     /**
@@ -156,56 +141,18 @@ public class GossipingPropertyFileSnitch extends AbstractNetworkTopologySnitch//
         Gossiper.instance.addLocalApplicationState(ApplicationState.INTERNAL_IP,
                 StorageService.instance.valueFactory.internalIP(FBUtilities.getLocalAddress().getHostAddress()));
 
-        reloadGossiperState();
-
-        gossipStarted = true;
+        loadGossiperState();
     }
-    
-    private void reloadConfiguration(boolean isUpdate) throws ConfigurationException
-    {
-        final SnitchProperties properties = new SnitchProperties();
-
-        String newDc = properties.get("dc", null);
-        String newRack = properties.get("rack", null);
-        if (newDc == null || newRack == null)
-            throw new ConfigurationException("DC or rack not found in snitch properties, check your configuration in: " + SnitchProperties.RACKDC_PROPERTY_FILENAME);
-
-        newDc = newDc.trim();
-        newRack = newRack.trim();
-        final boolean newPreferLocal = Boolean.parseBoolean(properties.get("prefer_local", "false"));
 
-        if (!newDc.equals(myDC) || !newRack.equals(myRack) || (preferLocal != newPreferLocal))
-        {
-            myDC = newDc;
-            myRack = newRack;
-            preferLocal = newPreferLocal;
-
-            reloadGossiperState();
-
-            if (StorageService.instance != null)
-            {
-                if (isUpdate)
-                    StorageService.instance.updateTopology(FBUtilities.getBroadcastAddress());
-                else
-                    StorageService.instance.getTokenMetadata().invalidateCachedRings();
-            }
+    private void loadGossiperState()
+    {
+        assert Gossiper.instance != null;
 
-            if (gossipStarted)
-                StorageService.instance.gossipSnitchInfo();
-        }
-    }
+        ReconnectableSnitchHelper pendingHelper = new ReconnectableSnitchHelper(this, myDC, preferLocal);
+        Gossiper.instance.register(pendingHelper);
 
-    private void reloadGossiperState()
-    {
-        if (Gossiper.instance != null)
-        {
-            ReconnectableSnitchHelper pendingHelper = new ReconnectableSnitchHelper(this, myDC, preferLocal);
-            Gossiper.instance.register(pendingHelper);
-            
-            pendingHelper = snitchHelperReference.getAndSet(pendingHelper);
-            if (pendingHelper != null)
-                Gossiper.instance.unregister(pendingHelper);
-        }
-        // else this will eventually rerun at gossiperStarting()
+        pendingHelper = snitchHelperReference.getAndSet(pendingHelper);
+        if (pendingHelper != null)
+            Gossiper.instance.unregister(pendingHelper);
     }
 }

http://git-wip-us.apache.org/repos/asf/cassandra/blob/7650fc19/src/java/org/apache/cassandra/locator/PropertyFileSnitch.java
----------------------------------------------------------------------
diff --git a/src/java/org/apache/cassandra/locator/PropertyFileSnitch.java b/src/java/org/apache/cassandra/locator/PropertyFileSnitch.java
index f293081..6115572 100644
--- a/src/java/org/apache/cassandra/locator/PropertyFileSnitch.java
+++ b/src/java/org/apache/cassandra/locator/PropertyFileSnitch.java
@@ -23,12 +23,16 @@ import java.net.UnknownHostException;
 import java.util.Arrays;
 import java.util.HashMap;
 import java.util.Map;
+import java.util.Objects;
 import java.util.Properties;
+import java.util.Set;
 
+import com.google.common.collect.Sets;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
 import org.apache.cassandra.exceptions.ConfigurationException;
+import org.apache.cassandra.gms.Gossiper;
 import org.apache.cassandra.io.util.FileUtils;
 import org.apache.cassandra.service.StorageService;
 import org.apache.cassandra.utils.FBUtilities;
@@ -51,6 +55,7 @@ public class PropertyFileSnitch extends AbstractNetworkTopologySnitch
     private static final Logger logger = LoggerFactory.getLogger(PropertyFileSnitch.class);
 
     public static final String SNITCH_PROPERTIES_FILENAME = "cassandra-topology.properties";
+    private static final int DEFAULT_REFRESH_PERIOD_IN_SECONDS = 5;
 
     private static volatile Map<InetAddress, String[]> endpointMap;
     private static volatile String[] defaultDCRack;
@@ -59,6 +64,11 @@ public class PropertyFileSnitch extends AbstractNetworkTopologySnitch
 
     public PropertyFileSnitch() throws ConfigurationException
     {
+        this(DEFAULT_REFRESH_PERIOD_IN_SECONDS);
+    }
+
+    public PropertyFileSnitch(int refreshPeriodInSeconds) throws ConfigurationException
+    {
         reloadConfiguration(false);
 
         try
@@ -71,7 +81,7 @@ public class PropertyFileSnitch extends AbstractNetworkTopologySnitch
                     reloadConfiguration(true);
                 }
             };
-            ResourceWatcher.watch(SNITCH_PROPERTIES_FILENAME, runnable, 60 * 1000);
+            ResourceWatcher.watch(SNITCH_PROPERTIES_FILENAME, runnable, refreshPeriodInSeconds * 1000);
         }
         catch (ConfigurationException ex)
         {
@@ -85,7 +95,7 @@ public class PropertyFileSnitch extends AbstractNetworkTopologySnitch
      * @param endpoint endpoint to process
      * @return a array of string with the first index being the data center and the second being the rack
      */
-    public String[] getEndpointInfo(InetAddress endpoint)
+    public static String[] getEndpointInfo(InetAddress endpoint)
     {
         String[] rawEndpointInfo = getRawEndpointInfo(endpoint);
         if (rawEndpointInfo == null)
@@ -93,7 +103,7 @@ public class PropertyFileSnitch extends AbstractNetworkTopologySnitch
         return rawEndpointInfo;
     }
 
-    private String[] getRawEndpointInfo(InetAddress endpoint)
+    private static String[] getRawEndpointInfo(InetAddress endpoint)
     {
         String[] value = endpointMap.get(endpoint);
         if (value == null)
@@ -132,7 +142,8 @@ public class PropertyFileSnitch extends AbstractNetworkTopologySnitch
 
     public void reloadConfiguration(boolean isUpdate) throws ConfigurationException
     {
-        HashMap<InetAddress, String[]> reloadedMap = new HashMap<InetAddress, String[]>();
+        HashMap<InetAddress, String[]> reloadedMap = new HashMap<>();
+        String[] reloadedDefaultDCRack = null;
 
         Properties properties = new Properties();
         InputStream stream = null;
@@ -155,18 +166,18 @@ public class PropertyFileSnitch extends AbstractNetworkTopologySnitch
             String key = (String) entry.getKey();
             String value = (String) entry.getValue();
 
-            if (key.equals("default"))
+            if ("default".equals(key))
             {
                 String[] newDefault = value.split(":");
                 if (newDefault.length < 2)
-                    defaultDCRack = new String[] { "default", "default" };
+                    reloadedDefaultDCRack = new String[] { "default", "default" };
                 else
-                    defaultDCRack = new String[] { newDefault[0].trim(), newDefault[1].trim() };
+                    reloadedDefaultDCRack = new String[] { newDefault[0].trim(), newDefault[1].trim() };
             }
             else
             {
                 InetAddress host;
-                String hostString = key.replace("/", "");
+                String hostString = StringUtils.remove(key, '/');
                 try
                 {
                     host = InetAddress.getByName(hostString);
@@ -183,18 +194,24 @@ public class PropertyFileSnitch extends AbstractNetworkTopologySnitch
                 reloadedMap.put(host, token);
             }
         }
-        if (defaultDCRack == null && !reloadedMap.containsKey(FBUtilities.getBroadcastAddress()))
-            throw new ConfigurationException(String.format("Snitch definitions at %s do not define a location for this node's broadcast address %s, nor does it provides a default",
+        if (reloadedDefaultDCRack == null && !reloadedMap.containsKey(FBUtilities.getBroadcastAddress()))
+            throw new ConfigurationException(String.format("Snitch definitions at %s do not define a location for " +
+                                                           "this node's broadcast address %s, nor does it provides a default",
                                                            SNITCH_PROPERTIES_FILENAME, FBUtilities.getBroadcastAddress()));
 
+        if (isUpdate && !livenessCheck(reloadedMap, reloadedDefaultDCRack))
+            return;
+
         if (logger.isDebugEnabled())
         {
             StringBuilder sb = new StringBuilder();
             for (Map.Entry<InetAddress, String[]> entry : reloadedMap.entrySet())
-                sb.append(entry.getKey()).append(":").append(Arrays.toString(entry.getValue())).append(", ");
+                sb.append(entry.getKey()).append(':').append(Arrays.toString(entry.getValue())).append(", ");
             logger.debug("Loaded network topology from property file: {}", StringUtils.removeEnd(sb.toString(), ", "));
         }
 
+
+        defaultDCRack = reloadedDefaultDCRack;
         endpointMap = reloadedMap;
         if (StorageService.instance != null) // null check tolerates circular dependency; see CASSANDRA-4145
         {
@@ -208,6 +225,41 @@ public class PropertyFileSnitch extends AbstractNetworkTopologySnitch
             StorageService.instance.gossipSnitchInfo();
     }
 
+    /**
+     * We cannot update rack or data-center for a live node, see CASSANDRA-10243.
+     *
+     * @param reloadedMap - the new map of hosts to dc:rack properties
+     * @param reloadedDefaultDCRack - the default dc:rack or null if no default
+     * @return true if we can continue updating (no live host had dc or rack updated)
+     */
+    private static boolean livenessCheck(HashMap<InetAddress, String[]> reloadedMap, String[] reloadedDefaultDCRack)
+    {
+        // If the default has changed we must check all live hosts but hopefully we will find a live
+        // host quickly and interrupt the loop. Otherwise we only check the live hosts that were either
+        // in the old set or in the new set
+        Set<InetAddress> hosts = Arrays.equals(defaultDCRack, reloadedDefaultDCRack)
+                                 ? Sets.intersection(StorageService.instance.getLiveMembers(), // same default
+                                                     Sets.union(endpointMap.keySet(), reloadedMap.keySet()))
+                                 : StorageService.instance.getLiveMembers(); // default updated
+
+        for (InetAddress host : hosts)
+        {
+            String[] origValue = endpointMap.containsKey(host) ? endpointMap.get(host) : defaultDCRack;
+            String[] updateValue = reloadedMap.containsKey(host) ? reloadedMap.get(host) : reloadedDefaultDCRack;
+
+            if (!Arrays.equals(origValue, updateValue))
+            {
+                logger.error("Cannot update data center or rack from {} to {} for live host {}, property file NOT RELOADED",
+                             origValue,
+                             updateValue,
+                             host);
+                 return false;
+            }
+        }
+
+        return true;
+    }
+
     @Override
     public void gossiperStarting()
     {

http://git-wip-us.apache.org/repos/asf/cassandra/blob/7650fc19/src/java/org/apache/cassandra/locator/SnitchProperties.java
----------------------------------------------------------------------
diff --git a/src/java/org/apache/cassandra/locator/SnitchProperties.java b/src/java/org/apache/cassandra/locator/SnitchProperties.java
index be89fcf..8fdda7a 100644
--- a/src/java/org/apache/cassandra/locator/SnitchProperties.java
+++ b/src/java/org/apache/cassandra/locator/SnitchProperties.java
@@ -66,4 +66,9 @@ public class SnitchProperties
     {
         return properties.getProperty(propertyName, defaultValue);
     }
+
+    public boolean contains(String propertyName)
+    {
+        return properties.containsKey(propertyName);
+    }
 }

http://git-wip-us.apache.org/repos/asf/cassandra/blob/7650fc19/src/java/org/apache/cassandra/locator/YamlFileNetworkTopologySnitch.java
----------------------------------------------------------------------
diff --git a/src/java/org/apache/cassandra/locator/YamlFileNetworkTopologySnitch.java b/src/java/org/apache/cassandra/locator/YamlFileNetworkTopologySnitch.java
index 4139662..870eea8 100644
--- a/src/java/org/apache/cassandra/locator/YamlFileNetworkTopologySnitch.java
+++ b/src/java/org/apache/cassandra/locator/YamlFileNetworkTopologySnitch.java
@@ -23,6 +23,7 @@ import java.util.Collections;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
+import java.util.Set;
 
 import org.apache.cassandra.exceptions.ConfigurationException;
 import org.apache.cassandra.gms.ApplicationState;
@@ -40,7 +41,9 @@ import org.yaml.snakeyaml.TypeDescription;
 import org.yaml.snakeyaml.Yaml;
 import org.yaml.snakeyaml.constructor.Constructor;
 
+import com.google.common.annotations.VisibleForTesting;
 import com.google.common.base.Objects;
+import com.google.common.collect.Sets;
 import com.google.common.net.InetAddresses;
 
 /**
@@ -60,10 +63,10 @@ public class YamlFileNetworkTopologySnitch
     /**
      * How often to check the topology configuration file, in milliseconds; defaults to one minute.
      */
-    private static final int CHECK_PERIOD_IN_MS = 60 * 1000;
+    private static final int CHECK_PERIOD_IN_MS = 5 * 1000;
 
     /** Default name for the topology configuration file. */
-    private static final String DEFAULT_TOPOLOGY_CONFIG_FILENAME = "cassandra-topology.yaml";
+    static final String DEFAULT_TOPOLOGY_CONFIG_FILENAME = "cassandra-topology.yaml";
 
     /** Node data map, keyed by broadcast address. */
     private volatile Map<InetAddress, NodeData> nodeDataMap;
@@ -196,44 +199,29 @@ public class YamlFileNetworkTopologySnitch
         public String dc_local_address;
     }
 
-    /**
-     * Loads the topology configuration file.
-     *
-     * @throws ConfigurationException
-     *             on failure
-     */
-    private synchronized void loadTopologyConfiguration(boolean isUpdate)
-            throws ConfigurationException
+    public TopologyConfig readConfig() throws ConfigurationException
     {
-        logger.debug("Loading topology configuration from {}",
-                topologyConfigFilename);
+        final TypeDescription topologyConfigTypeDescription = new TypeDescription(TopologyConfig.class);
+        topologyConfigTypeDescription.putListPropertyType("topology", Datacenter.class);
 
-        final TypeDescription topologyConfigTypeDescription = new TypeDescription(
-                TopologyConfig.class);
-        topologyConfigTypeDescription.putListPropertyType("topology",
-                Datacenter.class);
-
-        final TypeDescription topologyTypeDescription = new TypeDescription(
-                Datacenter.class);
+        final TypeDescription topologyTypeDescription = new TypeDescription(Datacenter.class);
         topologyTypeDescription.putListPropertyType("racks", Rack.class);
 
-        final TypeDescription rackTypeDescription = new TypeDescription(
-                Rack.class);
+        final TypeDescription rackTypeDescription = new TypeDescription(Rack.class);
         rackTypeDescription.putListPropertyType("nodes", Node.class);
 
-        final Constructor configConstructor = new Constructor(
-                TopologyConfig.class);
+        final Constructor configConstructor = new Constructor(TopologyConfig.class);
         configConstructor.addTypeDescription(topologyConfigTypeDescription);
         configConstructor.addTypeDescription(topologyTypeDescription);
         configConstructor.addTypeDescription(rackTypeDescription);
 
         final InputStream configFileInputStream = getClass().getClassLoader()
-                .getResourceAsStream(topologyConfigFilename);
+                                                            .getResourceAsStream(topologyConfigFilename);
         if (configFileInputStream == null)
         {
             throw new ConfigurationException(
-                    "Could not read topology config file "
-                            + topologyConfigFilename);
+                                            "Could not read topology config file "
+                                            + topologyConfigFilename);
         }
         Yaml yaml;
         TopologyConfig topologyConfig;
@@ -246,7 +234,30 @@ public class YamlFileNetworkTopologySnitch
         {
             FileUtils.closeQuietly(configFileInputStream);
         }
-        final Map<InetAddress, NodeData> nodeDataMap = new HashMap<InetAddress, NodeData>();
+
+        return topologyConfig;
+    }
+
+    /**
+     * Loads the topology configuration file.
+     *
+     * @throws ConfigurationException
+     *             on failure
+     */
+    private synchronized void loadTopologyConfiguration(boolean isUpdate)
+            throws ConfigurationException
+    {
+        logger.debug("Loading topology configuration from {}",
+                     topologyConfigFilename);
+
+        loadTopologyConfiguration(isUpdate, readConfig());
+    }
+
+    @VisibleForTesting
+    synchronized void loadTopologyConfiguration(boolean isUpdate, TopologyConfig topologyConfig)
+            throws ConfigurationException
+    {
+        final Map<InetAddress, NodeData> nodeDataMap = new HashMap<>();
 
         if (topologyConfig.topology == null)
         {
@@ -336,6 +347,9 @@ public class YamlFileNetworkTopologySnitch
         defaultNodeData.datacenter = topologyConfig.default_dc_name;
         defaultNodeData.rack = topologyConfig.default_rack_name;
 
+        if (isUpdate && !livenessCheck(nodeDataMap, defaultNodeData))
+            return;
+
         // YAML configuration looks good; now make the changes
 
         this.nodeDataMap = nodeDataMap;
@@ -360,6 +374,41 @@ public class YamlFileNetworkTopologySnitch
     }
 
     /**
+     * We cannot update rack or data-center for a live node, see CASSANDRA-10243.
+     *
+     * @param reloadedMap - the new map of hosts to NodeData
+     * @param reloadedDefaultData - the default NodeData
+     * @return true if we can continue updating (no live host had dc or rack updated)
+     */
+    private boolean livenessCheck(Map<InetAddress, NodeData> reloadedMap, NodeData reloadedDefaultData)
+    {
+        // If the default has changed we must check all live hosts but hopefully we will find a live
+        // host quickly and interrupt the loop. Otherwise we only check the live hosts that were either
+        // in the old set or in the new set
+        Set<InetAddress> hosts = NodeData.isSameDcRack(defaultNodeData, reloadedDefaultData)
+                                 ? Sets.intersection(StorageService.instance.getLiveMembers(), // same default
+                                                     Sets.union(nodeDataMap.keySet(), reloadedMap.keySet()))
+                                 : StorageService.instance.getLiveMembers(); // default updated
+
+        for (InetAddress host : hosts)
+        {
+            NodeData origValue = nodeDataMap.containsKey(host) ? nodeDataMap.get(host) : defaultNodeData;
+            NodeData updateValue = reloadedMap.containsKey(host) ? reloadedMap.get(host) : reloadedDefaultData;
+
+            if (!NodeData.isSameDcRack(origValue, updateValue))
+            {
+                logger.error("Cannot update data center or rack from {} to {} for live host {}, property file NOT RELOADED",
+                             new String[] { origValue.datacenter, origValue.rack }, // same format as error in PropertyFileSnitch,
+                             new String[] { updateValue.datacenter, updateValue.rack },
+                             host);
+                return false;
+            }
+        }
+
+        return true;
+    }
+
+    /**
      * be careful about just blindly updating ApplicationState.INTERNAL_IP everytime we read the yaml file,
      * as that can cause connections to get unnecessarily reset (via IESCS.onChange()).
      */
@@ -382,7 +431,7 @@ public class YamlFileNetworkTopologySnitch
     /**
      * Topology data for a node.
      */
-    private class NodeData
+    private static final class NodeData
     {
         /** Data center name. */
         public String datacenter;
@@ -402,6 +451,12 @@ public class YamlFileNetworkTopologySnitch
                     .add("rack", rack).add("dcLocalAddress", dcLocalAddress)
                     .toString();
         }
+
+        public static boolean isSameDcRack(NodeData a, NodeData b)
+        {
+            return a == b ||
+                   (a != null && Objects.equal(a.datacenter, b.datacenter) && Objects.equal(a.rack, b.rack));
+        }
     }
 
     /**

http://git-wip-us.apache.org/repos/asf/cassandra/blob/7650fc19/src/java/org/apache/cassandra/service/MigrationManager.java
----------------------------------------------------------------------
diff --git a/src/java/org/apache/cassandra/service/MigrationManager.java b/src/java/org/apache/cassandra/service/MigrationManager.java
index bebfa43..3539602 100644
--- a/src/java/org/apache/cassandra/service/MigrationManager.java
+++ b/src/java/org/apache/cassandra/service/MigrationManager.java
@@ -395,7 +395,7 @@ public class MigrationManager
             }
         });
 
-        for (InetAddress endpoint : Gossiper.instance.getLiveMembers())
+        for (InetAddress endpoint : Gossiper.instance.getLiveEndpoints())
         {
             // only push schema to nodes with known and equal versions
             if (!endpoint.equals(FBUtilities.getBroadcastAddress()) &&
@@ -439,7 +439,7 @@ public class MigrationManager
 
         Schema.instance.clear();
 
-        Set<InetAddress> liveEndpoints = Gossiper.instance.getLiveMembers();
+        Set<InetAddress> liveEndpoints = Gossiper.instance.getLiveEndpoints();
         liveEndpoints.remove(FBUtilities.getBroadcastAddress());
 
         // force migration if there are nodes around

http://git-wip-us.apache.org/repos/asf/cassandra/blob/7650fc19/src/java/org/apache/cassandra/service/StorageProxy.java
----------------------------------------------------------------------
diff --git a/src/java/org/apache/cassandra/service/StorageProxy.java b/src/java/org/apache/cassandra/service/StorageProxy.java
index b701015..0e90ea6 100644
--- a/src/java/org/apache/cassandra/service/StorageProxy.java
+++ b/src/java/org/apache/cassandra/service/StorageProxy.java
@@ -1863,7 +1863,7 @@ public class StorageProxy implements StorageProxyMBean
     {
         final String myVersion = Schema.instance.getVersion().toString();
         final Map<InetAddress, UUID> versions = new ConcurrentHashMap<InetAddress, UUID>();
-        final Set<InetAddress> liveHosts = Gossiper.instance.getLiveMembers();
+        final Set<InetAddress> liveHosts = Gossiper.instance.getLiveEndpoints();
         final CountDownLatch latch = new CountDownLatch(liveHosts.size());
 
         IAsyncCallback<UUID> cb = new IAsyncCallback<UUID>()
@@ -1897,7 +1897,7 @@ public class StorageProxy implements StorageProxyMBean
 
         // maps versions to hosts that are on that version.
         Map<String, List<String>> results = new HashMap<String, List<String>>();
-        Iterable<InetAddress> allHosts = Iterables.concat(Gossiper.instance.getLiveMembers(), Gossiper.instance.getUnreachableMembers());
+        Iterable<InetAddress> allHosts = Iterables.concat(Gossiper.instance.getLiveEndpoints(), Gossiper.instance.getUnreachableMembers());
         for (InetAddress host : allHosts)
         {
             UUID version = versions.get(host);
@@ -2125,12 +2125,12 @@ public class StorageProxy implements StorageProxyMBean
             // Since the truncate operation is so aggressive and is typically only
             // invoked by an admin, for simplicity we require that all nodes are up
             // to perform the operation.
-            int liveMembers = Gossiper.instance.getLiveMembers().size();
+            int liveMembers = Gossiper.instance.getLiveEndpoints().size();
             throw new UnavailableException(ConsistencyLevel.ALL, liveMembers + Gossiper.instance.getUnreachableMembers().size(), liveMembers);
         }
 
-        Set<InetAddress> allEndpoints = Gossiper.instance.getLiveTokenOwners();
-        
+        Set<InetAddress> allEndpoints = StorageService.instance.getLiveMembers(true);
+
         int blockFor = allEndpoints.size();
         final TruncateResponseHandler responseHandler = new TruncateResponseHandler(blockFor);
 

http://git-wip-us.apache.org/repos/asf/cassandra/blob/7650fc19/src/java/org/apache/cassandra/service/StorageService.java
----------------------------------------------------------------------
diff --git a/src/java/org/apache/cassandra/service/StorageService.java b/src/java/org/apache/cassandra/service/StorageService.java
index 03c1960..5503123 100644
--- a/src/java/org/apache/cassandra/service/StorageService.java
+++ b/src/java/org/apache/cassandra/service/StorageService.java
@@ -17,8 +17,6 @@
  */
 package org.apache.cassandra.service;
 
-import static java.nio.charset.StandardCharsets.ISO_8859_1;
-
 import java.io.ByteArrayInputStream;
 import java.io.DataInputStream;
 import java.io.File;
@@ -574,7 +572,7 @@ public class StorageService extends NotificationBroadcasterSupport implements IE
         while (true)
         {
             Uninterruptibles.sleepUninterruptibly(1, TimeUnit.SECONDS);
-            for (InetAddress address : Gossiper.instance.getLiveMembers())
+            for (InetAddress address : Gossiper.instance.getLiveEndpoints())
             {
                 if (!Gossiper.instance.isFatClient(address))
                     break outer;
@@ -2303,9 +2301,33 @@ public class StorageService extends NotificationBroadcasterSupport implements IE
 
     public List<String> getLiveNodes()
     {
-        return stringify(Gossiper.instance.getLiveMembers());
+        return stringify(Gossiper.instance.getLiveEndpoints());
+    }
+
+    public Set<InetAddress> getLiveMembers()
+    {
+        return getLiveMembers(false);
+    }
+
+    public Set<InetAddress> getLiveMembers(boolean excludeDeadStates)
+    {
+        Set<InetAddress> ret = new HashSet<>();
+        for (InetAddress ep : Gossiper.instance.getLiveEndpoints())
+        {
+            if (excludeDeadStates)
+            {
+                EndpointState epState = Gossiper.instance.getEndpointStateForEndpoint(ep);
+                if (epState == null || Gossiper.instance.isDeadState(epState))
+                    continue;
+            }
+
+            if (tokenMetadata.isMember(ep))
+                ret.add(ep);
+        }
+        return ret;
     }
 
+
     public List<String> getUnreachableNodes()
     {
         return stringify(Gossiper.instance.getUnreachableMembers());
@@ -3746,7 +3768,7 @@ public class StorageService extends NotificationBroadcasterSupport implements IE
         if (endpoint.equals(myAddress))
              throw new UnsupportedOperationException("Cannot remove self");
 
-        if (Gossiper.instance.getLiveMembers().contains(endpoint))
+        if (Gossiper.instance.getLiveEndpoints().contains(endpoint))
             throw new UnsupportedOperationException("Node " + endpoint + " is alive and owns this ID. Use decommission command to remove it from the ring");
 
         // A leaving endpoint that is dead is already being removed.

http://git-wip-us.apache.org/repos/asf/cassandra/blob/7650fc19/test/unit/org/apache/cassandra/locator/GossipingPropertyFileSnitchTest.java
----------------------------------------------------------------------
diff --git a/test/unit/org/apache/cassandra/locator/GossipingPropertyFileSnitchTest.java b/test/unit/org/apache/cassandra/locator/GossipingPropertyFileSnitchTest.java
index 9026ebf..80d4559 100644
--- a/test/unit/org/apache/cassandra/locator/GossipingPropertyFileSnitchTest.java
+++ b/test/unit/org/apache/cassandra/locator/GossipingPropertyFileSnitchTest.java
@@ -17,12 +17,9 @@
  */
 package org.apache.cassandra.locator;
 
-import java.nio.file.Files;
-import java.nio.file.Path;
-import java.nio.file.Paths;
+import org.junit.Test;
 
 import org.apache.cassandra.utils.FBUtilities;
-import org.junit.Test;
 
 /**
  * Unit tests for {@link GossipingPropertyFileSnitch}.
@@ -30,30 +27,12 @@ import org.junit.Test;
 public class GossipingPropertyFileSnitchTest
 {
     @Test
-    public void testAutoReloadConfig() throws Exception
+    public void testLoadConfig() throws Exception
     {
-        String confFile = FBUtilities.resourceToFile(SnitchProperties.RACKDC_PROPERTY_FILENAME);
-        
-        final GossipingPropertyFileSnitch snitch = new GossipingPropertyFileSnitch(/*refreshPeriodInSeconds*/1);
-        YamlFileNetworkTopologySnitchTest.checkEndpoint(snitch, FBUtilities.getBroadcastAddress().getHostAddress(), "DC1", "RAC1");
-
-        final Path effectiveFile = Paths.get(confFile);
-        final Path backupFile = Paths.get(confFile + ".bak");
-        final Path modifiedFile = Paths.get(confFile + ".mod");
-        
-        try
-        {
-            Files.copy(effectiveFile, backupFile);
-            Files.copy(modifiedFile, effectiveFile, java.nio.file.StandardCopyOption.REPLACE_EXISTING);
-            
-            Thread.sleep(1500);
-            
-            YamlFileNetworkTopologySnitchTest.checkEndpoint(snitch, FBUtilities.getBroadcastAddress().getHostAddress(), "DC2", "RAC2");
-        }
-        finally
-        {
-            Files.copy(backupFile, effectiveFile, java.nio.file.StandardCopyOption.REPLACE_EXISTING);
-            Files.delete(backupFile);
-        }
+        final GossipingPropertyFileSnitch snitch = new GossipingPropertyFileSnitch();
+        YamlFileNetworkTopologySnitchTest.checkEndpoint(snitch,
+                                                        FBUtilities.getBroadcastAddress().getHostAddress(),
+                                                        "DC1",
+                                                        "RAC1");
     }
 }

http://git-wip-us.apache.org/repos/asf/cassandra/blob/7650fc19/test/unit/org/apache/cassandra/locator/PropertyFileSnitchTest.java
----------------------------------------------------------------------
diff --git a/test/unit/org/apache/cassandra/locator/PropertyFileSnitchTest.java b/test/unit/org/apache/cassandra/locator/PropertyFileSnitchTest.java
new file mode 100644
index 0000000..24b8c77
--- /dev/null
+++ b/test/unit/org/apache/cassandra/locator/PropertyFileSnitchTest.java
@@ -0,0 +1,321 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.cassandra.locator;
+
+import java.io.IOException;
+import java.net.InetAddress;
+import java.nio.charset.StandardCharsets;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.nio.file.StandardOpenOption;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import java.util.UUID;
+
+import org.apache.cassandra.dht.IPartitioner;
+import org.apache.cassandra.dht.RandomPartitioner;
+import org.apache.cassandra.dht.Token;
+import org.apache.cassandra.exceptions.ConfigurationException;
+import org.apache.cassandra.gms.ApplicationState;
+import org.apache.cassandra.gms.Gossiper;
+import org.apache.cassandra.gms.VersionedValue;
+import org.apache.cassandra.service.StorageService;
+import org.apache.cassandra.utils.FBUtilities;
+
+import org.junit.Before;
+import org.junit.Test;
+
+/**
+ * Unit tests for {@link PropertyFileSnitch}.
+ */
+public class PropertyFileSnitchTest
+{
+    private Path effectiveFile;
+    private Path backupFile;
+
+    private VersionedValue.VersionedValueFactory valueFactory;
+    private Map<InetAddress, Set<Token>> tokenMap;
+
+    @Before
+    public void setup() throws ConfigurationException, IOException
+    {
+        String confFile = FBUtilities.resourceToFile(PropertyFileSnitch.SNITCH_PROPERTIES_FILENAME);
+        effectiveFile = Paths.get(confFile);
+        backupFile = Paths.get(confFile + ".bak");
+
+        restoreOrigConfigFile();
+
+        InetAddress[] hosts = {
+            InetAddress.getByName("127.0.0.1"), // this exists in the config file
+            InetAddress.getByName("127.0.0.2"), // this exists in the config file
+            InetAddress.getByName("127.0.0.9"), // this does not exist in the config file
+        };
+
+        IPartitioner partitioner = new RandomPartitioner();
+        valueFactory = new VersionedValue.VersionedValueFactory(partitioner);
+        tokenMap = new HashMap<>();
+
+        for (InetAddress host : hosts)
+        {
+            Set<Token> tokens = Collections.singleton(partitioner.getRandomToken());
+            Gossiper.instance.initializeNodeUnsafe(host, UUID.randomUUID(), 1);
+            Gossiper.instance.injectApplicationState(host, ApplicationState.TOKENS, valueFactory.tokens(tokens));
+
+            setNodeShutdown(host);
+            tokenMap.put(host, tokens);
+        }
+    }
+
+    private void restoreOrigConfigFile() throws IOException
+    {
+        if (Files.exists(backupFile))
+        {
+            Files.copy(backupFile, effectiveFile, java.nio.file.StandardCopyOption.REPLACE_EXISTING);
+            Files.delete(backupFile);
+        }
+    }
+
+    private void replaceConfigFile(Map<String, String> replacements) throws IOException
+    {
+        List<String> lines = Files.readAllLines(effectiveFile, StandardCharsets.UTF_8);
+        List<String> newLines = new ArrayList<>(lines.size());
+        Set<String> replaced = new HashSet<>();
+
+        for (String line : lines)
+        {
+            String[] info = line.split("=");
+            if (info.length == 2 && replacements.containsKey(info[0]))
+            {
+                String replacement = replacements.get(info[0]);
+                if (!replacement.isEmpty()) // empty means remove this line
+                    newLines.add(info[0] + '=' + replacement);
+
+                replaced.add(info[0]);
+            }
+            else
+            {
+                newLines.add(line);
+            }
+        }
+
+        // add any new lines that were not replaced
+        for (Map.Entry<String, String> replacement : replacements.entrySet())
+        {
+            if (replaced.contains(replacement.getKey()))
+                continue;
+
+            if (!replacement.getValue().isEmpty()) // empty means remove this line so do nothing here
+                newLines.add(replacement.getKey() + '=' + replacement.getValue());
+        }
+
+        Files.write(effectiveFile, newLines, StandardCharsets.UTF_8, StandardOpenOption.TRUNCATE_EXISTING);
+    }
+
+    private void setNodeShutdown(InetAddress host)
+    {
+        StorageService.instance.getTokenMetadata().removeEndpoint(host);
+        Gossiper.instance.injectApplicationState(host, ApplicationState.STATUS, valueFactory.shutdown(true));
+        Gossiper.instance.markDead(host, Gossiper.instance.getEndpointStateForEndpoint(host));
+    }
+
+    private void setNodeLive(InetAddress host)
+    {
+        Gossiper.instance.injectApplicationState(host, ApplicationState.STATUS, valueFactory.normal(tokenMap.get(host)));
+        Gossiper.instance.realMarkAlive(host, Gossiper.instance.getEndpointStateForEndpoint(host));
+        StorageService.instance.getTokenMetadata().updateNormalTokens(tokenMap.get(host), host);
+    }
+
+    /**
+     * Test that changing rack for a host in the configuration file is only effective if the host is not live.
+     * The original configuration file contains: 127.0.0.1=DC1:RAC1
+     */
+    @Test
+    public void testChangeHostRack() throws Exception
+    {
+        final InetAddress host = InetAddress.getByName("127.0.0.1");
+        final PropertyFileSnitch snitch = new PropertyFileSnitch(/*refreshPeriodInSeconds*/1);
+        YamlFileNetworkTopologySnitchTest.checkEndpoint(snitch, host.getHostAddress(), "DC1", "RAC1");
+
+        try
+        {
+            setNodeLive(host);
+
+            Files.copy(effectiveFile, backupFile);
+            replaceConfigFile(Collections.singletonMap(host.getHostAddress(), "DC1:RAC2"));
+
+            Thread.sleep(1500);
+            YamlFileNetworkTopologySnitchTest.checkEndpoint(snitch, host.getHostAddress(), "DC1", "RAC1");
+
+            setNodeShutdown(host);
+            replaceConfigFile(Collections.singletonMap(host.getHostAddress(), "DC1:RAC2"));
+
+            Thread.sleep(1500);
+            YamlFileNetworkTopologySnitchTest.checkEndpoint(snitch, host.getHostAddress(), "DC1", "RAC2");
+        }
+        finally
+        {
+            restoreOrigConfigFile();
+            setNodeShutdown(host);
+        }
+    }
+
+    /**
+     * Test that changing dc for a host in the configuration file is only effective if the host is not live.
+     * The original configuration file contains: 127.0.0.1=DC1:RAC1
+     */
+    @Test
+    public void testChangeHostDc() throws Exception
+    {
+        final InetAddress host = InetAddress.getByName("127.0.0.1");
+        final PropertyFileSnitch snitch = new PropertyFileSnitch(/*refreshPeriodInSeconds*/1);
+        YamlFileNetworkTopologySnitchTest.checkEndpoint(snitch, host.getHostAddress(), "DC1", "RAC1");
+
+        try
+        {
+            setNodeLive(host);
+
+            Files.copy(effectiveFile, backupFile);
+            replaceConfigFile(Collections.singletonMap(host.getHostAddress(), "DC2:RAC1"));
+
+            Thread.sleep(1500);
+            YamlFileNetworkTopologySnitchTest.checkEndpoint(snitch, host.getHostAddress(), "DC1", "RAC1");
+
+            setNodeShutdown(host);
+            replaceConfigFile(Collections.singletonMap(host.getHostAddress(), "DC2:RAC1"));
+
+            Thread.sleep(1500);
+            YamlFileNetworkTopologySnitchTest.checkEndpoint(snitch, host.getHostAddress(), "DC2", "RAC1");
+        }
+        finally
+        {
+            restoreOrigConfigFile();
+            setNodeShutdown(host);
+        }
+    }
+
+    /**
+     * Test that adding a host to the configuration file changes the host dc and rack only if the host
+     * is not live. The original configuration file does not contain 127.0.0.9 and so it should use
+     * the default default=DC1:r1.
+     */
+    @Test
+    public void testAddHost() throws Exception
+    {
+        final InetAddress host = InetAddress.getByName("127.0.0.9");
+        final PropertyFileSnitch snitch = new PropertyFileSnitch(/*refreshPeriodInSeconds*/1);
+        YamlFileNetworkTopologySnitchTest.checkEndpoint(snitch, host.getHostAddress(), "DC1", "r1"); // default
+
+        try
+        {
+            setNodeLive(host);
+
+            Files.copy(effectiveFile, backupFile);
+            replaceConfigFile(Collections.singletonMap(host.getHostAddress(), "DC2:RAC2")); // add this line if not yet there
+
+            Thread.sleep(1500);
+            YamlFileNetworkTopologySnitchTest.checkEndpoint(snitch, host.getHostAddress(), "DC1", "r1"); // unchanged
+
+            setNodeShutdown(host);
+            replaceConfigFile(Collections.singletonMap(host.getHostAddress(), "DC2:RAC2")); // add this line if not yet there
+
+            Thread.sleep(1500);
+            YamlFileNetworkTopologySnitchTest.checkEndpoint(snitch, host.getHostAddress(), "DC2", "RAC2"); // changed
+        }
+        finally
+        {
+            restoreOrigConfigFile();
+            setNodeShutdown(host);
+        }
+    }
+
+    /**
+     * Test that removing a host from the configuration file changes the host rack only if the host
+     * is not live. The original configuration file contains 127.0.0.2=DC1:RAC2 and default=DC1:r1 so removing
+     * this host should result in a different rack if the host is not live.
+     */
+    @Test
+    public void testRemoveHost() throws Exception
+    {
+        final InetAddress host = InetAddress.getByName("127.0.0.2");
+        final PropertyFileSnitch snitch = new PropertyFileSnitch(/*refreshPeriodInSeconds*/1);
+        YamlFileNetworkTopologySnitchTest.checkEndpoint(snitch, host.getHostAddress(), "DC1", "RAC2");
+
+        try
+        {
+            setNodeLive(host);
+
+            Files.copy(effectiveFile, backupFile);
+            replaceConfigFile(Collections.singletonMap(host.getHostAddress(), "")); // removes line if found
+
+            Thread.sleep(1500);
+            YamlFileNetworkTopologySnitchTest.checkEndpoint(snitch, host.getHostAddress(), "DC1", "RAC2"); // unchanged
+
+            setNodeShutdown(host);
+            replaceConfigFile(Collections.singletonMap(host.getHostAddress(), "")); // removes line if found
+
+            Thread.sleep(1500);
+            YamlFileNetworkTopologySnitchTest.checkEndpoint(snitch, host.getHostAddress(), "DC1", "r1"); // default
+        }
+        finally
+        {
+            restoreOrigConfigFile();
+            setNodeShutdown(host);
+        }
+    }
+
+    /**
+     * Test that we can change the default only if this does not result in any live node changing dc or rack.
+     * The configuration file contains default=DC1:r1 and we change it to default=DC2:r2. Let's use host 127.0.0.9
+     * since it is not in the configuration file.
+     */
+    @Test
+    public void testChangeDefault() throws Exception
+    {
+        final InetAddress host = InetAddress.getByName("127.0.0.9");
+        final PropertyFileSnitch snitch = new PropertyFileSnitch(/*refreshPeriodInSeconds*/1);
+        YamlFileNetworkTopologySnitchTest.checkEndpoint(snitch, host.getHostAddress(), "DC1", "r1"); // default
+
+        try
+        {
+            setNodeLive(host);
+
+            Files.copy(effectiveFile, backupFile);
+            replaceConfigFile(Collections.singletonMap("default", "DC2:r2")); // change default
+
+            Thread.sleep(1500);
+            YamlFileNetworkTopologySnitchTest.checkEndpoint(snitch, host.getHostAddress(), "DC1", "r1"); // unchanged
+
+            setNodeShutdown(host);
+            replaceConfigFile(Collections.singletonMap("default", "DC2:r2")); // change default again (refresh file update)
+
+            Thread.sleep(1500);
+            YamlFileNetworkTopologySnitchTest.checkEndpoint(snitch, host.getHostAddress(), "DC2", "r2"); // default updated
+        }
+        finally
+        {
+            restoreOrigConfigFile();
+            setNodeShutdown(host);
+        }
+    }
+}

http://git-wip-us.apache.org/repos/asf/cassandra/blob/7650fc19/test/unit/org/apache/cassandra/locator/YamlFileNetworkTopologySnitchTest.java
----------------------------------------------------------------------
diff --git a/test/unit/org/apache/cassandra/locator/YamlFileNetworkTopologySnitchTest.java b/test/unit/org/apache/cassandra/locator/YamlFileNetworkTopologySnitchTest.java
index af1a7e9..9507f25 100644
--- a/test/unit/org/apache/cassandra/locator/YamlFileNetworkTopologySnitchTest.java
+++ b/test/unit/org/apache/cassandra/locator/YamlFileNetworkTopologySnitchTest.java
@@ -17,11 +17,28 @@
  */
 package org.apache.cassandra.locator;
 
+import java.io.IOException;
 import java.net.InetAddress;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.Set;
+import java.util.UUID;
 
+import org.apache.cassandra.dht.IPartitioner;
+import org.apache.cassandra.dht.RandomPartitioner;
+import org.apache.cassandra.dht.Token;
 import org.apache.cassandra.exceptions.ConfigurationException;
+import org.apache.cassandra.gms.ApplicationState;
+import org.apache.cassandra.gms.Gossiper;
+import org.apache.cassandra.gms.VersionedValue;
+import org.apache.cassandra.service.StorageService;
 import org.apache.cassandra.utils.FBUtilities;
+
+import static org.apache.cassandra.locator.YamlFileNetworkTopologySnitch.*;
+
 import org.junit.Assert;
+import org.junit.Before;
 import org.junit.Test;
 
 import com.google.common.net.InetAddresses;
@@ -31,54 +48,58 @@ import com.google.common.net.InetAddresses;
  */
 public class YamlFileNetworkTopologySnitchTest
 {
+    private String confFile;
 
-    /**
-     * Testing variant of {@link YamlFileNetworkTopologySnitch}.
-     * 
-     */
-    private class TestYamlFileNetworkTopologySnitch
-            extends YamlFileNetworkTopologySnitch
+    private VersionedValue.VersionedValueFactory valueFactory;
+    private Map<InetAddress, Set<Token>> tokenMap;
+
+    @Before
+    public void setup() throws ConfigurationException, IOException
     {
+        confFile = YamlFileNetworkTopologySnitch.DEFAULT_TOPOLOGY_CONFIG_FILENAME;
+
+        InetAddress[] hosts = {
+                              InetAddress.getByName("127.0.0.1"), // this exists in the config file
+                              InetAddress.getByName("127.0.0.2"), // this exists in the config file
+                              InetAddress.getByName("127.0.0.9"), // this does not exist in the config file
+        };
 
-        /**
-         * Constructor.
-         * 
-         * @throws ConfigurationException
-         *             on configuration error
-         */
-        public TestYamlFileNetworkTopologySnitch(
-                final String topologyConfigFilename)
-                throws ConfigurationException
+        IPartitioner partitioner = new RandomPartitioner();
+        valueFactory = new VersionedValue.VersionedValueFactory(partitioner);
+        tokenMap = new HashMap<>();
+
+        for (InetAddress host : hosts)
         {
-            super(topologyConfigFilename);
+            Set<Token> tokens = Collections.singleton(partitioner.getRandomToken());
+            Gossiper.instance.initializeNodeUnsafe(host, UUID.randomUUID(), 1);
+            Gossiper.instance.injectApplicationState(host, ApplicationState.TOKENS, valueFactory.tokens(tokens));
+
+            setNodeShutdown(host);
+            tokenMap.put(host, tokens);
         }
     }
 
     /**
      * A basic test case.
-     * 
-     * @throws Exception
-     *             on failure
+     *
+     * @throws Exception on failure
      */
     @Test
     public void testBasic() throws Exception
     {
-        final TestYamlFileNetworkTopologySnitch snitch = new TestYamlFileNetworkTopologySnitch(
-                "cassandra-topology.yaml");
-        checkEndpoint(snitch, FBUtilities.getBroadcastAddress()
-                .getHostAddress(), "DC1", "RAC1");
+        final YamlFileNetworkTopologySnitch snitch = new YamlFileNetworkTopologySnitch(confFile);
+        checkEndpoint(snitch, FBUtilities.getBroadcastAddress().getHostAddress(), "DC1", "RAC1");
         checkEndpoint(snitch, "192.168.1.100", "DC1", "RAC1");
         checkEndpoint(snitch, "10.0.0.12", "DC1", "RAC2");
         checkEndpoint(snitch, "127.0.0.3", "DC1", "RAC3");
         checkEndpoint(snitch, "10.20.114.10", "DC2", "RAC1");
         checkEndpoint(snitch, "127.0.0.8", "DC3", "RAC8");
         checkEndpoint(snitch, "6.6.6.6", "DC1", "r1");
-
     }
 
     /**
      * Asserts that a snitch's determination of data center and rack for an endpoint match what we expect.
-     * 
+     *
      * @param snitch
      *            snitch
      * @param endpointString
@@ -89,12 +110,230 @@ public class YamlFileNetworkTopologySnitchTest
      *            expected rack
      */
     public static void checkEndpoint(final AbstractNetworkTopologySnitch snitch,
-            final String endpointString, final String expectedDatacenter,
-            final String expectedRack)
+                                     final String endpointString, final String expectedDatacenter,
+                                     final String expectedRack)
     {
         final InetAddress endpoint = InetAddresses.forString(endpointString);
         Assert.assertEquals(expectedDatacenter, snitch.getDatacenter(endpoint));
         Assert.assertEquals(expectedRack, snitch.getRack(endpoint));
     }
 
+
+    private static TopologyConfig moveNode(TopologyConfig topologyConfig,
+                                           String broadcastAddress, String dcLocalAddress,
+                                           String oldDC, String newDC,
+                                           String oldRack, String newRack)
+    {
+
+        for (Datacenter dc : topologyConfig.topology)
+        {
+            if (oldDC != null && oldRack != null)
+            {
+                if (dc.dc_name.equals(oldDC))
+                {
+                    for (Rack rack : dc.racks)
+                    {
+                        if (rack.rack_name.equals(oldRack))
+                        {
+                            for (Node node : rack.nodes)
+                            {
+                                if (node.broadcast_address.equals(broadcastAddress))
+                                {
+                                    rack.nodes.remove(node);
+                                    break;
+                                }
+                            }
+                        }
+                    }
+                }
+            }
+
+            if (newDC != null && newRack != null)
+            {
+                if (dc.dc_name.equals(newDC))
+                {
+                    for (Rack rack : dc.racks)
+                    {
+                        if (rack.rack_name.equals(newRack))
+                        {
+                            Node node = new Node();
+                            node.broadcast_address = broadcastAddress;
+                            node.dc_local_address = dcLocalAddress;
+                            rack.nodes.add(node);
+                        }
+                    }
+                }
+            }
+        }
+
+        return topologyConfig;
+    }
+
+    private void setNodeShutdown(InetAddress host)
+    {
+        StorageService.instance.getTokenMetadata().removeEndpoint(host);
+        Gossiper.instance.injectApplicationState(host, ApplicationState.STATUS, valueFactory.shutdown(true));
+        Gossiper.instance.markDead(host, Gossiper.instance.getEndpointStateForEndpoint(host));
+    }
+
+    private void setNodeLive(InetAddress host)
+    {
+        Gossiper.instance.injectApplicationState(host, ApplicationState.STATUS, valueFactory.normal(tokenMap.get(host)));
+        Gossiper.instance.realMarkAlive(host, Gossiper.instance.getEndpointStateForEndpoint(host));
+        StorageService.instance.getTokenMetadata().updateNormalTokens(tokenMap.get(host), host);
+    }
+
+    /**
+     * Test that changing rack for a host in the configuration file is only effective if the host is not live.
+     * The original configuration file contains DC1, RAC1 for broadcast address 127.0.0.1 and dc_local_address 9.0.0.1.
+     */
+    @Test
+    public void testChangeHostRack() throws Exception
+    {
+        final InetAddress host = InetAddress.getByName("127.0.0.1");
+        final YamlFileNetworkTopologySnitch snitch = new YamlFileNetworkTopologySnitch(confFile);
+        checkEndpoint(snitch, host.getHostAddress(), "DC1", "RAC1");
+
+        try
+        {
+            final TopologyConfig topologyConfig = snitch.readConfig();
+            moveNode(topologyConfig, host.getHostAddress(), "9.0.0.1", "DC1", "DC1", "RAC1", "RAC2");
+
+            setNodeLive(host);
+            snitch.loadTopologyConfiguration(true, topologyConfig);
+            checkEndpoint(snitch, host.getHostAddress(), "DC1", "RAC1");
+
+            setNodeShutdown(host);
+            snitch.loadTopologyConfiguration(true, topologyConfig);
+            checkEndpoint(snitch, host.getHostAddress(), "DC1", "RAC2");
+        }
+        finally
+        {
+            setNodeShutdown(host);
+        }
+    }
+
+    /**
+     * Test that changing dc for a host in the configuration file is only effective if the host is not live.
+     * The original configuration file contains DC1, RAC1 for broadcast address 127.0.0.1 and dc_local_address 9.0.0.1.
+     */
+    @Test
+    public void testChangeHostDc() throws Exception
+    {
+        final InetAddress host = InetAddress.getByName("127.0.0.1");
+        final YamlFileNetworkTopologySnitch snitch = new YamlFileNetworkTopologySnitch(confFile);
+        checkEndpoint(snitch, host.getHostAddress(), "DC1", "RAC1");
+
+        try
+        {
+            final TopologyConfig topologyConfig = snitch.readConfig();
+            moveNode(topologyConfig, host.getHostAddress(), "9.0.0.1", "DC1", "DC2", "RAC1", "RAC1");
+
+            setNodeLive(host);
+            snitch.loadTopologyConfiguration(true, topologyConfig);
+            checkEndpoint(snitch, host.getHostAddress(), "DC1", "RAC1");
+
+            setNodeShutdown(host);
+            snitch.loadTopologyConfiguration(true, topologyConfig);
+            checkEndpoint(snitch, host.getHostAddress(), "DC2", "RAC1");
+        }
+        finally
+        {
+            setNodeShutdown(host);
+        }
+    }
+
+    /**
+     * Test that adding a host to the configuration file changes the host dc and rack only if the host
+     * is not live. The original configuration file does not contain 127.0.0.9 and so it should use
+     * the default data center DC1 and rack r1.
+     */
+    @Test
+    public void testAddHost() throws Exception
+    {
+        final InetAddress host = InetAddress.getByName("127.0.0.9");
+        final YamlFileNetworkTopologySnitch snitch = new YamlFileNetworkTopologySnitch(confFile);
+        checkEndpoint(snitch, host.getHostAddress(), "DC1", "r1"); // default
+
+        try
+        {
+            final TopologyConfig topologyConfig = snitch.readConfig();
+            moveNode(topologyConfig, host.getHostAddress(), "9.0.0.9", null, "DC2", null, "RAC2");
+
+            setNodeLive(host);
+            snitch.loadTopologyConfiguration(true, topologyConfig);
+            checkEndpoint(snitch, host.getHostAddress(), "DC1", "r1"); // unchanged
+
+            setNodeShutdown(host);
+            snitch.loadTopologyConfiguration(true, topologyConfig);
+            checkEndpoint(snitch, host.getHostAddress(), "DC2", "RAC2"); // changed
+        }
+        finally
+        {
+            setNodeShutdown(host);
+        }
+    }
+
+    /**
+     * Test that removing a host from the configuration file changes the host rack only if the host
+     * is not live. The original configuration file contains 127.0.0.2 in DC1, RAC2 and default DC1, r1 so removing
+     * this host should result in a different rack if the host is not live.
+     */
+    @Test
+    public void testRemoveHost() throws Exception
+    {
+        final InetAddress host = InetAddress.getByName("127.0.0.2");
+        final YamlFileNetworkTopologySnitch snitch = new YamlFileNetworkTopologySnitch(confFile);
+        checkEndpoint(snitch, host.getHostAddress(), "DC1", "RAC2");
+
+        try
+        {
+            final TopologyConfig topologyConfig = snitch.readConfig();
+            moveNode(topologyConfig, host.getHostAddress(), "9.0.0.2", "DC1", null, "RAC2", null);
+
+            setNodeLive(host);
+            snitch.loadTopologyConfiguration(true, topologyConfig);
+            checkEndpoint(snitch, host.getHostAddress(), "DC1", "RAC2"); // unchanged
+
+            setNodeShutdown(host);
+            snitch.loadTopologyConfiguration(true, topologyConfig);
+            checkEndpoint(snitch, host.getHostAddress(), "DC1", "r1"); // default
+        }
+        finally
+        {
+            setNodeShutdown(host);
+        }
+    }
+
+    /**
+     * Test that we can change the default only if this does not result in any live node changing dc or rack.
+     * The configuration file contains default DC1 and r1 and we change it to DC2 and r2. Let's use host 127.0.0.9
+     * since it is not in the configuration file.
+     */
+    @Test
+    public void testChangeDefault() throws Exception
+    {
+        final InetAddress host = InetAddress.getByName("127.0.0.9");
+        final YamlFileNetworkTopologySnitch snitch = new YamlFileNetworkTopologySnitch(confFile);
+        checkEndpoint(snitch, host.getHostAddress(), "DC1", "r1"); // default
+
+        try
+        {
+            final TopologyConfig topologyConfig = snitch.readConfig();
+            topologyConfig.default_dc_name = "DC2";
+            topologyConfig.default_rack_name = "r2";
+
+            setNodeLive(host);
+            snitch.loadTopologyConfiguration(true, topologyConfig);
+            checkEndpoint(snitch, host.getHostAddress(), "DC1", "r1"); // unchanged
+
+            setNodeShutdown(host);
+            snitch.loadTopologyConfiguration(true, topologyConfig);
+            checkEndpoint(snitch, host.getHostAddress(), "DC2", "r2"); // default updated
+        }
+        finally
+        {
+            setNodeShutdown(host);
+        }
+    }
 }