CASSANDRA-21539: Remove hostname from ClientsTable and GossipInfoTable to avoid reverse-DNS lookups

CHANGES.txt

@@ -5,6 +5,7 @@
  * Avoid using ObjectUtils.getFirstNonNull in Schema (CASSANDRA-21394)
  * Allow nodetool garbagecollect to take a user defined list of SSTables (CASSANDRA-16767)
  * Add a guardrail for misprepared statements (CASSANDRA-21139)
+ * Remove hostname from ClientsTable and GossipInfoTable (CASSANDRA-21539)
 Merged from 6.0:
  * Reduce allocations in DefaultQueryOptions (CASSANDRA-21467)
  * Allow unreserved keywords as user and identity names in USER and IDENTITY statements (CASSANDRA-21510)

doc/modules/cassandra/pages/managing/operating/virtualtables.adoc

@@ -175,7 +175,7 @@ We shall discuss some of the virtual tables in more detail next.
 
 The `clients` virtual table lists all active connections (connected
 clients) including their ip address, port, client_options, connection stage, driver
-name, driver version, hostname, protocol version, request count, ssl
+name, driver version, protocol version, request count, ssl
 enabled, ssl protocol and user name:
 
 [source, console]
@@ -190,7 +190,6 @@ cqlsh> SELECT * FROM system_views.clients;
  connection_stage | ready
  driver_name      | DataStax Python Driver
  driver_version   | 3.25.0
- hostname         | localhost
  protocol_version | 5
  request_count    | 16
  ssl_cipher_suite | null
@@ -206,7 +205,6 @@ cqlsh> SELECT * FROM system_views.clients;
  connection_stage | ready
  driver_name      | DataStax Python Driver
  driver_version   | 3.25.0
- hostname         | localhost
  protocol_version | 5
  request_count    | 4
  ssl_cipher_suite | null
@@ -222,7 +220,6 @@ cqlsh> SELECT * FROM system_views.clients;
  connection_stage | ready
  driver_name      | DataStax Java driver for Apache Cassandra(R)
  driver_version   | 4.13.0
- hostname         | localhost
  protocol_version | 5
  request_count    | 18
  ssl_cipher_suite | null
@@ -238,7 +235,6 @@ cqlsh> SELECT * FROM system_views.clients;
  connection_stage | ready
  driver_name      | DataStax Java driver for Apache Cassandra(R)
  driver_version   | 4.13.0
- hostname         | localhost
  protocol_version | 5
  request_count    | 7
  ssl_cipher_suite | null
@@ -275,7 +271,6 @@ VIRTUAL TABLE system_views.clients (
   connection_stage text,
   driver_name text,
   driver_version text,
-  hostname text,
   protocol_version int,
   request_count bigint,
   ssl_cipher_suite text,
@@ -673,10 +668,10 @@ results in:
 +
 [source, cql]
 ----
- address   | port  | connection_stage | driver_name            | driver_version | hostname  | protocol_version | request_count | ssl_cipher_suite | ssl_enabled | ssl_protocol | username
------------+-------+------------------+------------------------+----------------+-----------|||+------------------+---------------+------------------+-------------+--------------+-----------
- 127.0.0.1 | 37308 |            ready | DataStax Python Driver |   3.21.0.post0 | localhost |                4 |            17 |             null |       False |         null | anonymous
- 127.0.0.1 | 37310 |            ready | DataStax Python Driver |   3.21.0.post0 | localhost |                4 |             8 |             null |       False |         null | anonymous
+ address   | port  | connection_stage | driver_name            | driver_version | protocol_version | request_count | ssl_cipher_suite | ssl_enabled | ssl_protocol | username
+-----------+-------+------------------+------------------------+----------------+------------------+---------------+------------------+-------------+--------------+-----------
+ 127.0.0.1 | 37308 |            ready | DataStax Python Driver |   3.21.0.post0 |                4 |            17 |             null |       False |         null | anonymous
+ 127.0.0.1 | 37310 |            ready | DataStax Python Driver |   3.21.0.post0 |                4 |             8 |             null |       False |         null | anonymous
 
 (2 rows)
 ----

src/java/org/apache/cassandra/db/virtual/ClientsTable.java

@@ -38,7 +38,6 @@ final class ClientsTable extends AbstractVirtualTable
 {
     private static final String ADDRESS = "address";
     private static final String PORT = "port";
-    private static final String HOSTNAME = "hostname";
     private static final String USERNAME = "username";
     private static final String CONNECTION_STAGE = "connection_stage";
     private static final String PROTOCOL_VERSION = "protocol_version";
@@ -61,7 +60,6 @@ final class ClientsTable extends AbstractVirtualTable
                            .partitioner(new LocalPartitioner(InetAddressType.instance))
                            .addPartitionKeyColumn(ADDRESS, InetAddressType.instance)
                            .addClusteringColumn(PORT, Int32Type.instance)
-                           .addRegularColumn(HOSTNAME, UTF8Type.instance)
                            .addRegularColumn(USERNAME, UTF8Type.instance)
                            .addRegularColumn(CONNECTION_STAGE, UTF8Type.instance)
                            .addRegularColumn(PROTOCOL_VERSION, Int32Type.instance)
@@ -88,7 +86,6 @@ public DataSet data()
             InetSocketAddress remoteAddress = client.remoteAddress();
 
             result.row(remoteAddress.getAddress(), remoteAddress.getPort())
-                  .column(HOSTNAME, remoteAddress.getHostName())
                   .column(USERNAME, client.username().orElse(null))
                   .column(CONNECTION_STAGE, toLowerCaseLocalized(client.stage().toString()))
                   .column(PROTOCOL_VERSION, client.protocolVersion())

src/java/org/apache/cassandra/db/virtual/GossipInfoTable.java

@@ -48,7 +48,6 @@ final class GossipInfoTable extends AbstractVirtualTable
 
     static final String ADDRESS = "address";
     static final String PORT = "port";
-    static final String HOSTNAME = "hostname";
     static final String GENERATION = "generation";
     static final String HEARTBEAT = "heartbeat";
 
@@ -98,7 +97,6 @@ public DataSet data()
             EndpointState localState = new EndpointState(entry.getValue());
 
             SimpleDataSet dataSet = result.row(endpoint.getAddress(), endpoint.getPort())
-                                          .column(HOSTNAME, endpoint.getHostName())
                                           .column(GENERATION, getGeneration(localState))
                                           .column(HEARTBEAT, getHeartBeat(localState));
 
@@ -175,7 +173,6 @@ private static TableMetadata buildTableMetadata(String keyspace)
                                                      .partitioner(new LocalPartitioner(InetAddressType.instance))
                                                      .addPartitionKeyColumn(ADDRESS, InetAddressType.instance)
                                                      .addClusteringColumn(PORT, Int32Type.instance)
-                                                     .addRegularColumn(HOSTNAME, UTF8Type.instance)
                                                      .addRegularColumn(GENERATION, Int32Type.instance)
                                                      .addRegularColumn(HEARTBEAT, Int32Type.instance);
 

test/unit/org/apache/cassandra/db/virtual/ClientsTableTest.java

@@ -70,6 +70,7 @@ public void testSelectAll()
         shouldUseEncryption(true);
         shouldUseClientCertificate(true);
         ResultSet result = executeNet("SELECT * FROM vts.clients");
+        assertThat(result.getColumnDefinitions().size()).isEqualTo(15);
         for (Row r : result)
         {
             Assert.assertEquals(InetAddress.getLoopbackAddress(), r.getInet("address"));
@@ -78,7 +79,6 @@ public void testSelectAll()
             Assert.assertNotNull(r.getMap("client_options", String.class, String.class));
             Assert.assertTrue(r.getLong("request_count") > 0 );
             // the following are questionable if they belong here
-            Assert.assertEquals("localhost", r.getString("hostname"));
             Assertions.assertThat(r.getMap("client_options", String.class, String.class))
                       .hasEntrySatisfying("DRIVER_VERSION", value -> assertThat(value.contains(r.getString("driver_name"))))
                       .hasEntrySatisfying("DRIVER_VERSION", value -> assertThat(value.contains(r.getString("driver_version"))));

test/unit/org/apache/cassandra/db/virtual/GossipInfoTableTest.java

@@ -70,13 +70,12 @@ public void testSelectAllWithStateTransitions() throws Throwable
 
             assertThat(resultSet.size()).isEqualTo(1);
             UntypedResultSet.Row row = resultSet.one();
-            assertThat(row.getColumns().size()).isEqualTo(66);
+            assertThat(row.getColumns().size()).isEqualTo(65);
 
             assertThat(endpoint).isNotNull();
             assertThat(localState).isNotNull();
             assertThat(row.getInetAddress("address")).isEqualTo(endpoint.getAddress());
             assertThat(row.getInt("port")).isEqualTo(endpoint.getPort());
-            assertThat(row.getString("hostname")).isEqualTo(endpoint.getHostName());
             assertThat(row.getInt("generation")).isEqualTo(localState.getHeartBeatState().getGeneration());
             assertThat(row.getInt("heartbeat")).isNotNull();