KAFKA-18373: Remove ZkMetadataCache

core/src/main/scala/kafka/cluster/Partition.scala

@@ -23,7 +23,7 @@ import kafka.controller.StateChangeLogger
 import kafka.log._
 import kafka.log.remote.RemoteLogManager
 import kafka.server._
-import kafka.server.metadata.{KRaftMetadataCache, ZkMetadataCache}
+import kafka.server.metadata.KRaftMetadataCache
 import kafka.server.share.DelayedShareFetch
 import kafka.utils.CoreUtils.{inReadLock, inWriteLock}
 import kafka.utils._
@@ -1086,11 +1086,6 @@ class Partition(val topicPartition: TopicPartition,
           !kRaftMetadataCache.isBrokerShuttingDown(followerReplicaId) &&
           isBrokerEpochIsrEligible(storedBrokerEpoch, cachedBrokerEpoch)
 
-      // In ZK mode, we just ensure the broker is alive. Although we do not check for shutting down brokers here,
-      // the controller will block them from being added to ISR.
-      case zkMetadataCache: ZkMetadataCache =>
-        zkMetadataCache.hasAliveBroker(followerReplicaId)
-
       case _ => true
     }
   }

core/src/main/scala/kafka/server/MetadataCache.scala

@@ -17,12 +17,11 @@
 
 package kafka.server
 
-import kafka.server.metadata.{KRaftMetadataCache, ZkMetadataCache}
+import kafka.server.metadata.KRaftMetadataCache
 import org.apache.kafka.admin.BrokerMetadata
 import org.apache.kafka.common.message.{MetadataResponseData, UpdateMetadataRequestData}
 import org.apache.kafka.common.network.ListenerName
 import org.apache.kafka.common.{Cluster, Node, TopicPartition, Uuid}
-import org.apache.kafka.server.BrokerFeatures
 import org.apache.kafka.server.common.{FinalizedFeatures, KRaftVersion, MetadataVersion}
 
 import java.util
@@ -117,13 +116,6 @@ trait MetadataCache {
 }
 
 object MetadataCache {
-  def zkMetadataCache(brokerId: Int,
-                      metadataVersion: MetadataVersion,
-                      brokerFeatures: BrokerFeatures = BrokerFeatures.createEmpty())
-  : ZkMetadataCache = {
-    new ZkMetadataCache(brokerId, metadataVersion, brokerFeatures)
-  }
-
   def kRaftMetadataCache(
     brokerId: Int,
     kraftVersionSupplier: Supplier[KRaftVersion]

core/src/test/scala/unit/kafka/cluster/ReplicaTest.scala

@@ -17,15 +17,13 @@
 package kafka.cluster
 
 import kafka.log.UnifiedLog
-import kafka.server.metadata.{KRaftMetadataCache, ZkMetadataCache}
+import kafka.server.metadata.KRaftMetadataCache
 import org.apache.kafka.common.TopicPartition
 import org.apache.kafka.common.errors.NotLeaderOrFollowerException
 import org.apache.kafka.server.util.MockTime
 import org.apache.kafka.storage.internals.log.LogOffsetMetadata
 import org.junit.jupiter.api.Assertions.{assertEquals, assertFalse, assertThrows, assertTrue}
 import org.junit.jupiter.api.{BeforeEach, Test}
-import org.junit.jupiter.params.ParameterizedTest
-import org.junit.jupiter.params.provider.ValueSource
 import org.mockito.Mockito.{mock, when}
 
 object ReplicaTest {
@@ -320,16 +318,10 @@ class ReplicaTest {
     assertFalse(isCaughtUp(leaderEndOffset = 16L))
   }
 
-  @ParameterizedTest
-  @ValueSource(booleans = Array(true, false))
-  def testFenceStaleUpdates(isKraft: Boolean): Unit = {
-    val metadataCache = if (isKraft) {
-      val kRaftMetadataCache = mock(classOf[KRaftMetadataCache])
-      when(kRaftMetadataCache.getAliveBrokerEpoch(BrokerId)).thenReturn(Option(2L))
-      kRaftMetadataCache
-    } else {
-      mock(classOf[ZkMetadataCache])
-    }
+  @Test
+  def testFenceStaleUpdates(): Unit = {
+    val metadataCache = mock(classOf[KRaftMetadataCache])
+    when(metadataCache.getAliveBrokerEpoch(BrokerId)).thenReturn(Option(2L))
 
     val replica = new Replica(BrokerId, Partition, metadataCache)
     replica.updateFetchStateOrThrow(
@@ -339,24 +331,13 @@ class ReplicaTest {
       leaderEndOffset = 10L,
       brokerEpoch = 2L
     )
-    if (isKraft) {
-      assertThrows(classOf[NotLeaderOrFollowerException], () => replica.updateFetchStateOrThrow(
-        followerFetchOffsetMetadata = new LogOffsetMetadata(5L),
-        followerStartOffset = 2L,
-        followerFetchTimeMs = 3,
-        leaderEndOffset = 10L,
-        brokerEpoch = 1L
-      ))
-    } else {
-      // No exception to expect under ZK mode.
-      replica.updateFetchStateOrThrow(
-        followerFetchOffsetMetadata = new LogOffsetMetadata(5L),
-        followerStartOffset = 2L,
-        followerFetchTimeMs = 3,
-        leaderEndOffset = 10L,
-        brokerEpoch = 1L
-      )
-    }
+    assertThrows(classOf[NotLeaderOrFollowerException], () => replica.updateFetchStateOrThrow(
+      followerFetchOffsetMetadata = new LogOffsetMetadata(5L),
+      followerStartOffset = 2L,
+      followerFetchTimeMs = 3,
+      leaderEndOffset = 10L,
+      brokerEpoch = 1L
+    ))
     replica.updateFetchStateOrThrow(
       followerFetchOffsetMetadata = new LogOffsetMetadata(5L),
       followerStartOffset = 2L,

core/src/test/scala/unit/kafka/server/ApiVersionManagerTest.scala

@@ -16,12 +16,11 @@
  */
 package kafka.server
 
-import kafka.server.metadata.ZkMetadataCache
 import org.apache.kafka.clients.NodeApiVersions
 import org.apache.kafka.common.message.ApiMessageType.ListenerType
 import org.apache.kafka.common.protocol.ApiKeys
 import org.apache.kafka.server.BrokerFeatures
-import org.apache.kafka.server.common.MetadataVersion
+import org.apache.kafka.server.common.KRaftVersion
 import org.junit.jupiter.api.{Disabled, Test}
 import org.junit.jupiter.api.Assertions._
 import org.junit.jupiter.params.ParameterizedTest
@@ -32,7 +31,7 @@ import scala.jdk.CollectionConverters._
 
 class ApiVersionManagerTest {
   private val brokerFeatures = BrokerFeatures.createDefault(true)
-  private val metadataCache = new ZkMetadataCache(1, MetadataVersion.latestTesting(), brokerFeatures)
+  private val metadataCache = MetadataCache.kRaftMetadataCache(1, () => KRaftVersion.LATEST_PRODUCTION)
 
   @ParameterizedTest
   @EnumSource(classOf[ListenerType])

core/src/test/scala/unit/kafka/server/KafkaApisTest.scala

@@ -525,7 +525,6 @@ class KafkaApisTest extends Logging {
 
     val capturedResponse = verifyNoThrottling[AbstractResponse](request)
     assertEquals(expectedResponse.data, capturedResponse.data)
-
   }
 
   private def authorizeResource(authorizer: Authorizer,