add describe_local_ring for Hadoop's benefit

patch by Piotr Kołaczkowski; reviewed by jbellis for CASSANDRA-6268

CHANGES.txt

@@ -14,6 +14,7 @@
  * Warn when collection read has > 65K elements (CASSANDRA-5428)
  * Fix cache persistence when both row and key cache are enabled 
    (CASSANDRA-6413)
+ * (Hadoop) add describe_local_ring (CASSANDRA-6268)
 
 
 1.2.12

interface/cassandra.thrift

@@ -55,7 +55,7 @@ namespace rb CassandraThrift
 # An effort should be made not to break forward-client-compatibility either
 # (e.g. one should avoid removing obsolete fields from the IDL), but no
 # guarantees in this respect are made by the Cassandra project.
-const string VERSION = "19.36.1"
+const string VERSION = "19.36.2"
 
 
 #
@@ -718,6 +718,11 @@ service Cassandra {
   list<TokenRange> describe_ring(1:required string keyspace)
                    throws (1:InvalidRequestException ire),
 
+
+  /** same as describe_ring, but considers only nodes in the local DC */
+  list<TokenRange> describe_local_ring(1:required string keyspace)
+                   throws (1:InvalidRequestException ire),
+
   /** get the mapping between token->node ip
       without taking replication into consideration
       https://issues.apache.org/jira/browse/CASSANDRA-4092 */

interface/thrift/gen-java/org/apache/cassandra/thrift/CfDef.java

@@ -32,10 +32,15 @@ import java.util.ArrayList;
 import java.util.Map;
 import java.util.HashMap;
 import java.util.EnumMap;
+import java.util.Set;
+import java.util.HashSet;
 import java.util.EnumSet;
 import java.util.Collections;
 import java.util.BitSet;
 import java.nio.ByteBuffer;
+import java.util.Arrays;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 public class CfDef implements org.apache.thrift.TBase<CfDef, CfDef._Fields>, java.io.Serializable, Cloneable {
   private static final org.apache.thrift.protocol.TStruct STRUCT_DESC = new org.apache.thrift.protocol.TStruct("CfDef");
@@ -62,6 +67,7 @@ public class CfDef implements org.apache.thrift.TBase<CfDef, CfDef._Fields>, jav
   private static final org.apache.thrift.protocol.TField BLOOM_FILTER_FP_CHANCE_FIELD_DESC = new org.apache.thrift.protocol.TField("bloom_filter_fp_chance", org.apache.thrift.protocol.TType.DOUBLE, (short)33);
   private static final org.apache.thrift.protocol.TField CACHING_FIELD_DESC = new org.apache.thrift.protocol.TField("caching", org.apache.thrift.protocol.TType.STRING, (short)34);
   private static final org.apache.thrift.protocol.TField DCLOCAL_READ_REPAIR_CHANCE_FIELD_DESC = new org.apache.thrift.protocol.TField("dclocal_read_repair_chance", org.apache.thrift.protocol.TType.DOUBLE, (short)37);
+  private static final org.apache.thrift.protocol.TField POPULATE_IO_CACHE_ON_FLUSH_FIELD_DESC = new org.apache.thrift.protocol.TField("populate_io_cache_on_flush", org.apache.thrift.protocol.TType.BOOL, (short)38);
   private static final org.apache.thrift.protocol.TField ROW_CACHE_SIZE_FIELD_DESC = new org.apache.thrift.protocol.TField("row_cache_size", org.apache.thrift.protocol.TType.DOUBLE, (short)9);
   private static final org.apache.thrift.protocol.TField KEY_CACHE_SIZE_FIELD_DESC = new org.apache.thrift.protocol.TField("key_cache_size", org.apache.thrift.protocol.TType.DOUBLE, (short)11);
   private static final org.apache.thrift.protocol.TField ROW_CACHE_SAVE_PERIOD_IN_SECONDS_FIELD_DESC = new org.apache.thrift.protocol.TField("row_cache_save_period_in_seconds", org.apache.thrift.protocol.TType.I32, (short)19);
@@ -72,7 +78,6 @@ public class CfDef implements org.apache.thrift.TBase<CfDef, CfDef._Fields>, jav
   private static final org.apache.thrift.protocol.TField MERGE_SHARDS_CHANCE_FIELD_DESC = new org.apache.thrift.protocol.TField("merge_shards_chance", org.apache.thrift.protocol.TType.DOUBLE, (short)25);
   private static final org.apache.thrift.protocol.TField ROW_CACHE_PROVIDER_FIELD_DESC = new org.apache.thrift.protocol.TField("row_cache_provider", org.apache.thrift.protocol.TType.STRING, (short)27);
   private static final org.apache.thrift.protocol.TField ROW_CACHE_KEYS_TO_SAVE_FIELD_DESC = new org.apache.thrift.protocol.TField("row_cache_keys_to_save", org.apache.thrift.protocol.TType.I32, (short)31);
-  private static final org.apache.thrift.protocol.TField POPULATE_IO_CACHE_ON_FLUSH_FIELD_DESC = new org.apache.thrift.protocol.TField("populate_io_cache_on_flush", org.apache.thrift.protocol.TType.BOOL, (short)38);
 
   public String keyspace; // required
   public String name; // required
@@ -331,16 +336,16 @@ public class CfDef implements org.apache.thrift.TBase<CfDef, CfDef._Fields>, jav
   private static final int __REPLICATE_ON_WRITE_ISSET_ID = 5;
   private static final int __BLOOM_FILTER_FP_CHANCE_ISSET_ID = 6;
   private static final int __DCLOCAL_READ_REPAIR_CHANCE_ISSET_ID = 7;
-  private static final int __ROW_CACHE_SIZE_ISSET_ID = 8;
+  private static final int __POPULATE_IO_CACHE_ON_FLUSH_ISSET_ID = 8;
-  private static final int __KEY_CACHE_SIZE_ISSET_ID = 9;
+  private static final int __ROW_CACHE_SIZE_ISSET_ID = 9;
-  private static final int __ROW_CACHE_SAVE_PERIOD_IN_SECONDS_ISSET_ID = 10;
+  private static final int __KEY_CACHE_SIZE_ISSET_ID = 10;
-  private static final int __KEY_CACHE_SAVE_PERIOD_IN_SECONDS_ISSET_ID = 11;
+  private static final int __ROW_CACHE_SAVE_PERIOD_IN_SECONDS_ISSET_ID = 11;
-  private static final int __MEMTABLE_FLUSH_AFTER_MINS_ISSET_ID = 12;
+  private static final int __KEY_CACHE_SAVE_PERIOD_IN_SECONDS_ISSET_ID = 12;
-  private static final int __MEMTABLE_THROUGHPUT_IN_MB_ISSET_ID = 13;
+  private static final int __MEMTABLE_FLUSH_AFTER_MINS_ISSET_ID = 13;
-  private static final int __MEMTABLE_OPERATIONS_IN_MILLIONS_ISSET_ID = 14;
+  private static final int __MEMTABLE_THROUGHPUT_IN_MB_ISSET_ID = 14;
-  private static final int __MERGE_SHARDS_CHANCE_ISSET_ID = 15;
+  private static final int __MEMTABLE_OPERATIONS_IN_MILLIONS_ISSET_ID = 15;
-  private static final int __ROW_CACHE_KEYS_TO_SAVE_ISSET_ID = 16;
+  private static final int __MERGE_SHARDS_CHANCE_ISSET_ID = 16;
-  private static final int __POPULATE_IO_CACHE_ISSET_ID = 17;
+  private static final int __ROW_CACHE_KEYS_TO_SAVE_ISSET_ID = 17;
   private BitSet __isset_bit_vector = new BitSet(18);
 
   public static final Map<_Fields, org.apache.thrift.meta_data.FieldMetaData> metaDataMap;
@@ -375,7 +380,7 @@ public class CfDef implements org.apache.thrift.TBase<CfDef, CfDef._Fields>, jav
         new org.apache.thrift.meta_data.FieldValueMetaData(org.apache.thrift.protocol.TType.I32)));
     tmpMap.put(_Fields.REPLICATE_ON_WRITE, new org.apache.thrift.meta_data.FieldMetaData("replicate_on_write", org.apache.thrift.TFieldRequirementType.OPTIONAL, 
         new org.apache.thrift.meta_data.FieldValueMetaData(org.apache.thrift.protocol.TType.BOOL)));
-    tmpMap.put(_Fields.KEY_VALIDATION_CLASS, new org.apache.thrift.meta_data.FieldMetaData("key_validation_class", org.apache.thrift.TFieldRequirementType.OPTIONAL,
+    tmpMap.put(_Fields.KEY_VALIDATION_CLASS, new org.apache.thrift.meta_data.FieldMetaData("key_validation_class", org.apache.thrift.TFieldRequirementType.OPTIONAL, 
         new org.apache.thrift.meta_data.FieldValueMetaData(org.apache.thrift.protocol.TType.STRING)));
     tmpMap.put(_Fields.KEY_ALIAS, new org.apache.thrift.meta_data.FieldMetaData("key_alias", org.apache.thrift.TFieldRequirementType.OPTIONAL, 
         new org.apache.thrift.meta_data.FieldValueMetaData(org.apache.thrift.protocol.TType.STRING        , true)));
@@ -395,9 +400,9 @@ public class CfDef implements org.apache.thrift.TBase<CfDef, CfDef._Fields>, jav
         new org.apache.thrift.meta_data.FieldValueMetaData(org.apache.thrift.protocol.TType.STRING)));
     tmpMap.put(_Fields.DCLOCAL_READ_REPAIR_CHANCE, new org.apache.thrift.meta_data.FieldMetaData("dclocal_read_repair_chance", org.apache.thrift.TFieldRequirementType.OPTIONAL, 
         new org.apache.thrift.meta_data.FieldValueMetaData(org.apache.thrift.protocol.TType.DOUBLE)));
-    tmpMap.put(_Fields.POPULATE_IO_CACHE_ON_FLUSH, new org.apache.thrift.meta_data.FieldMetaData("populate_io_cache_on_flush", org.apache.thrift.TFieldRequirementType.OPTIONAL,
+    tmpMap.put(_Fields.POPULATE_IO_CACHE_ON_FLUSH, new org.apache.thrift.meta_data.FieldMetaData("populate_io_cache_on_flush", org.apache.thrift.TFieldRequirementType.OPTIONAL, 
         new org.apache.thrift.meta_data.FieldValueMetaData(org.apache.thrift.protocol.TType.BOOL)));
-    tmpMap.put(_Fields.ROW_CACHE_SIZE, new org.apache.thrift.meta_data.FieldMetaData("row_cache_size", org.apache.thrift.TFieldRequirementType.OPTIONAL,
+    tmpMap.put(_Fields.ROW_CACHE_SIZE, new org.apache.thrift.meta_data.FieldMetaData("row_cache_size", org.apache.thrift.TFieldRequirementType.OPTIONAL, 
         new org.apache.thrift.meta_data.FieldValueMetaData(org.apache.thrift.protocol.TType.DOUBLE)));
     tmpMap.put(_Fields.KEY_CACHE_SIZE, new org.apache.thrift.meta_data.FieldMetaData("key_cache_size", org.apache.thrift.TFieldRequirementType.OPTIONAL, 
         new org.apache.thrift.meta_data.FieldValueMetaData(org.apache.thrift.protocol.TType.DOUBLE)));
@@ -429,6 +434,7 @@ public class CfDef implements org.apache.thrift.TBase<CfDef, CfDef._Fields>, jav
     this.caching = "keys_only";
 
     this.dclocal_read_repair_chance = 0;
+
   }
 
   public CfDef(
@@ -485,6 +491,7 @@ public class CfDef implements org.apache.thrift.TBase<CfDef, CfDef._Fields>, jav
     }
     if (other.isSetKey_alias()) {
       this.key_alias = org.apache.thrift.TBaseHelper.copyBinary(other.key_alias);
+;
     }
     if (other.isSetCompaction_strategy()) {
       this.compaction_strategy = other.compaction_strategy;
@@ -575,10 +582,11 @@ public class CfDef implements org.apache.thrift.TBase<CfDef, CfDef._Fields>, jav
     setBloom_filter_fp_chanceIsSet(false);
     this.bloom_filter_fp_chance = 0.0;
     this.caching = "keys_only";
+
     this.dclocal_read_repair_chance = 0;
+
     setPopulate_io_cache_on_flushIsSet(false);
     this.populate_io_cache_on_flush = false;
-
     setRow_cache_sizeIsSet(false);
     this.row_cache_size = 0.0;
     setKey_cache_sizeIsSet(false);
@@ -1154,16 +1162,6 @@ public class CfDef implements org.apache.thrift.TBase<CfDef, CfDef._Fields>, jav
     return this;
   }
 
-  public boolean getPopulate_io_cache_on_flush() {
-    return this.populate_io_cache_on_flush;
-  }
-
-  public CfDef setPopulate_io_cache_on_flush(boolean populate_io_cache_on_flush) {
-    this.populate_io_cache_on_flush = populate_io_cache_on_flush;
-    setPopulate_io_cache_on_flushIsSet(true);
-    return this;
-  }
-
   public void unsetDclocal_read_repair_chance() {
     __isset_bit_vector.clear(__DCLOCAL_READ_REPAIR_CHANCE_ISSET_ID);
   }
@@ -1177,17 +1175,27 @@ public class CfDef implements org.apache.thrift.TBase<CfDef, CfDef._Fields>, jav
     __isset_bit_vector.set(__DCLOCAL_READ_REPAIR_CHANCE_ISSET_ID, value);
   }
 
+  public boolean isPopulate_io_cache_on_flush() {
+    return this.populate_io_cache_on_flush;
+  }
+
+  public CfDef setPopulate_io_cache_on_flush(boolean populate_io_cache_on_flush) {
+    this.populate_io_cache_on_flush = populate_io_cache_on_flush;
+    setPopulate_io_cache_on_flushIsSet(true);
+    return this;
+  }
+
   public void unsetPopulate_io_cache_on_flush() {
-    __isset_bit_vector.clear(__POPULATE_IO_CACHE_ISSET_ID);
+    __isset_bit_vector.clear(__POPULATE_IO_CACHE_ON_FLUSH_ISSET_ID);
   }
 
   /** Returns true if field populate_io_cache_on_flush is set (has been assigned a value) and false otherwise */
   public boolean isSetPopulate_io_cache_on_flush() {
-    return __isset_bit_vector.get(__POPULATE_IO_CACHE_ISSET_ID);
+    return __isset_bit_vector.get(__POPULATE_IO_CACHE_ON_FLUSH_ISSET_ID);
   }
 
   public void setPopulate_io_cache_on_flushIsSet(boolean value) {
-    __isset_bit_vector.set(__POPULATE_IO_CACHE_ISSET_ID, value);
+    __isset_bit_vector.set(__POPULATE_IO_CACHE_ON_FLUSH_ISSET_ID, value);
   }
 
   /**
@@ -1663,7 +1671,7 @@ public class CfDef implements org.apache.thrift.TBase<CfDef, CfDef._Fields>, jav
       if (value == null) {
         unsetPopulate_io_cache_on_flush();
       } else {
-        setPopulate_io_cache_on_flush((Boolean) value);
+        setPopulate_io_cache_on_flush((Boolean)value);
       }
       break;
 
@@ -1819,7 +1827,7 @@ public class CfDef implements org.apache.thrift.TBase<CfDef, CfDef._Fields>, jav
       return Double.valueOf(getDclocal_read_repair_chance());
 
     case POPULATE_IO_CACHE_ON_FLUSH:
-      return Boolean.valueOf(getPopulate_io_cache_on_flush());
+      return Boolean.valueOf(isPopulate_io_cache_on_flush());
 
     case ROW_CACHE_SIZE:
       return Double.valueOf(getRow_cache_size());
@@ -2146,10 +2154,10 @@ public class CfDef implements org.apache.thrift.TBase<CfDef, CfDef._Fields>, jav
     boolean this_present_populate_io_cache_on_flush = true && this.isSetPopulate_io_cache_on_flush();
     boolean that_present_populate_io_cache_on_flush = true && that.isSetPopulate_io_cache_on_flush();
     if (this_present_populate_io_cache_on_flush || that_present_populate_io_cache_on_flush) {
-        if (!(this_present_populate_io_cache_on_flush && that_present_populate_io_cache_on_flush))
+      if (!(this_present_populate_io_cache_on_flush && that_present_populate_io_cache_on_flush))
-            return false;
+        return false;
-        if (this.populate_io_cache_on_flush != that.populate_io_cache_on_flush)
+      if (this.populate_io_cache_on_flush != that.populate_io_cache_on_flush)
-            return false;
+        return false;
     }
 
     boolean this_present_row_cache_size = true && this.isSetRow_cache_size();
@@ -2362,7 +2370,7 @@ public class CfDef implements org.apache.thrift.TBase<CfDef, CfDef._Fields>, jav
     boolean present_populate_io_cache_on_flush = true && (isSetPopulate_io_cache_on_flush());
     builder.append(present_populate_io_cache_on_flush);
     if (present_populate_io_cache_on_flush)
-        builder.append(populate_io_cache_on_flush);
+      builder.append(populate_io_cache_on_flush);
 
     boolean present_row_cache_size = true && (isSetRow_cache_size());
     builder.append(present_row_cache_size);
@@ -2973,10 +2981,10 @@ public class CfDef implements org.apache.thrift.TBase<CfDef, CfDef._Fields>, jav
           if (field.type == org.apache.thrift.protocol.TType.BOOL) {
             this.populate_io_cache_on_flush = iprot.readBool();
             setPopulate_io_cache_on_flushIsSet(true);
-          } else {
+          } else { 
             org.apache.thrift.protocol.TProtocolUtil.skip(iprot, field.type);
           }
-          break;  
+          break;
         case 9: // ROW_CACHE_SIZE
           if (field.type == org.apache.thrift.protocol.TType.DOUBLE) {
             this.row_cache_size = iprot.readDouble();
@@ -3479,9 +3487,9 @@ public class CfDef implements org.apache.thrift.TBase<CfDef, CfDef._Fields>, jav
     }
     if (isSetPopulate_io_cache_on_flush()) {
       if (!first) sb.append(", ");
-        sb.append("populate_io_cache_on_flush:");
+      sb.append("populate_io_cache_on_flush:");
-        sb.append(this.populate_io_cache_on_flush);
+      sb.append(this.populate_io_cache_on_flush);
-        first = false;
+      first = false;
     }
     if (isSetRow_cache_size()) {
       if (!first) sb.append(", ");

interface/thrift/gen-java/org/apache/cassandra/thrift/Constants.java

@@ -44,6 +44,6 @@ import org.slf4j.LoggerFactory;
 
 public class Constants {
 
-  public static final String VERSION = "19.36.1";
+  public static final String VERSION = "19.36.2";
 
 }

src/java/org/apache/cassandra/hadoop/AbstractColumnFamilyInputFormat.java

@@ -19,12 +19,7 @@ package org.apache.cassandra.hadoop;
 
 import java.io.IOException;
 import java.net.InetAddress;
-import java.util.ArrayList;
+import java.util.*;
-import java.util.Collections;
-import java.util.HashMap;
-import java.util.List;
-import java.util.Map;
-import java.util.Random;
 import java.util.concurrent.Callable;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Future;
@@ -130,6 +125,7 @@ public abstract class AbstractColumnFamilyInputFormat<K, Y> extends InputFormat<
         partitioner = ConfigHelper.getInputPartitioner(context.getConfiguration());
         logger.debug("partitioner is " + partitioner);
 
+
         // cannonical ranges, split into pieces, fetching the splits in parallel
         ExecutorService executor = new ThreadPoolExecutor(0, 128, 60L, TimeUnit.SECONDS, new LinkedBlockingQueue<Runnable>());
         List<InputSplit> splits = new ArrayList<InputSplit>();
@@ -326,7 +322,7 @@ public abstract class AbstractColumnFamilyInputFormat<K, Y> extends InputFormat<
         List<TokenRange> map;
         try
         {
-            map = client.describe_ring(ConfigHelper.getInputKeyspace(conf));
+            map = client.describe_local_ring(ConfigHelper.getInputKeyspace(conf));
         }
         catch (InvalidRequestException e)
         {

src/java/org/apache/cassandra/service/StorageService.java

@@ -34,6 +34,7 @@ import javax.management.Notification;
 import javax.management.NotificationBroadcasterSupport;
 import javax.management.ObjectName;
 
+import com.google.common.base.Predicate;
 import com.google.common.collect.*;
 
 import com.google.common.util.concurrent.AtomicDouble;
@@ -1079,16 +1080,62 @@ public class StorageService extends NotificationBroadcasterSupport implements IE
     }
 
     public Map<Range<Token>, List<InetAddress>> getRangeToAddressMap(String keyspace)
+    {
+        return getRangeToAddressMap(keyspace, tokenMetadata.sortedTokens());
+    }
+
+    public Map<Range<Token>, List<InetAddress>> getRangeToAddressMapInLocalDC(String keyspace)
+    {
+        Predicate<InetAddress> isLocalDC = new Predicate<InetAddress>()
+        {
+            public boolean apply(InetAddress address)
+            {
+                return isLocalDC(address);
+            }
+        };
+
+        Map<Range<Token>, List<InetAddress>> origMap = getRangeToAddressMap(keyspace, getTokensInLocalDC());
+        Map<Range<Token>, List<InetAddress>> filteredMap = Maps.newHashMap();
+        for (Map.Entry<Range<Token>, List<InetAddress>> entry : origMap.entrySet())
+        {
+            List<InetAddress> endpointsInLocalDC = Lists.newArrayList(Collections2.filter(entry.getValue(), isLocalDC));
+            filteredMap.put(entry.getKey(), endpointsInLocalDC);
+        }
+
+        return filteredMap;
+    }
+
+    private List<Token> getTokensInLocalDC()
+    {
+        List<Token> filteredTokens = Lists.newArrayList();
+        for (Token token : tokenMetadata.sortedTokens())
+        {
+            InetAddress endpoint = tokenMetadata.getEndpoint(token);
+            if (isLocalDC(endpoint))
+                filteredTokens.add(token);
+        }
+        return filteredTokens;
+    }
+
+    private boolean isLocalDC(InetAddress targetHost)
+    {
+        String remoteDC = DatabaseDescriptor.getEndpointSnitch().getDatacenter(targetHost);
+        String localDC = DatabaseDescriptor.getEndpointSnitch().getDatacenter(FBUtilities.getBroadcastAddress());
+        return remoteDC.equals(localDC);
+    }
+
+    private Map<Range<Token>, List<InetAddress>> getRangeToAddressMap(String keyspace, List<Token> sortedTokens)
     {
         // some people just want to get a visual representation of things. Allow null and set it to the first
         // non-system table.
         if (keyspace == null)
             keyspace = Schema.instance.getNonSystemTables().get(0);
 
-        List<Range<Token>> ranges = getAllRanges(tokenMetadata.sortedTokens());
+        List<Range<Token>> ranges = getAllRanges(sortedTokens);
         return constructRangeToEndpointMap(keyspace, ranges);
     }
 
+
     /**
      * The same as {@code describeRing(String)} but converts TokenRange to the String for JMX compatibility
      *
@@ -1125,6 +1172,19 @@ public class StorageService extends NotificationBroadcasterSupport implements IE
      * @throws InvalidRequestException if there is no ring information available about keyspace
      */
     public List<TokenRange> describeRing(String keyspace) throws InvalidRequestException
+    {
+        return describeRing(keyspace, false);
+    }
+
+    /**
+     * The same as {@code describeRing(String)} but considers only the part of the ring formed by nodes in the local DC.
+     */
+    public List<TokenRange> describeLocalRing(String keyspace) throws InvalidRequestException
+    {
+        return describeRing(keyspace, true);
+    }
+
+    private List<TokenRange> describeRing(String keyspace, boolean includeOnlyLocalDC) throws InvalidRequestException
     {
         if (keyspace == null || Table.open(keyspace).getReplicationStrategy() instanceof LocalStrategy)
             throw new InvalidRequestException("There is no ring for the keyspace: " + keyspace);
@@ -1132,7 +1192,12 @@ public class StorageService extends NotificationBroadcasterSupport implements IE
         List<TokenRange> ranges = new ArrayList<TokenRange>();
         Token.TokenFactory tf = getPartitioner().getTokenFactory();
 
-        for (Map.Entry<Range<Token>, List<InetAddress>> entry : getRangeToAddressMap(keyspace).entrySet())
+        Map<Range<Token>, List<InetAddress>> rangeToAddressMap =
+                includeOnlyLocalDC
+                        ? getRangeToAddressMapInLocalDC(keyspace)
+                        : getRangeToAddressMap(keyspace);
+
+        for (Map.Entry<Range<Token>, List<InetAddress>> entry : rangeToAddressMap.entrySet())
         {
             Range range = entry.getKey();
             List<InetAddress> addresses = entry.getValue();

src/java/org/apache/cassandra/thrift/CassandraServer.java

@@ -1183,6 +1183,19 @@ public class CassandraServer implements Cassandra.Iface
         }
     }
 
+    @Override
+    public List<TokenRange> describe_local_ring(String keyspace) throws InvalidRequestException, TException
+    {
+        try
+        {
+            return StorageService.instance.describeLocalRing(keyspace);
+        }
+        catch (RequestValidationException e)
+        {
+            throw ThriftConversion.toThrift(e);
+        }
+    }
+
     public Map<String, String> describe_token_map() throws InvalidRequestException
     {
         return StorageService.instance.getTokenToEndpointMap();