Remove Discovery interface (#77996)

* Remove Discovery interface

Today there's only one implementation of the `o.e.d.Discovery` interface
in use anywhere, namely `o.e.c.c.Coordinator`. This commit folds the
interface into the implementing class and deletes the associated dead
code in `GatewayService` and friends that was being maintained in 7.x to
preserve compatibility with 6.x.

* Remove action from operator-privileges test list

Author: DaveCTurner

server/src/internalClusterTest/java/org/elasticsearch/cluster/coordination/RareClusterStateIT.java

@@ -30,7 +30,6 @@
 import org.elasticsearch.cluster.service.ClusterService;
 import org.elasticsearch.common.settings.Settings;
 import org.elasticsearch.core.TimeValue;
-import org.elasticsearch.discovery.Discovery;
 import org.elasticsearch.index.Index;
 import org.elasticsearch.index.IndexService;
 import org.elasticsearch.index.mapper.DocumentMapper;
@@ -129,12 +128,12 @@ private <Req extends ActionRequest, Res extends ActionResponse> ActionFuture<Res
             ActionRequestBuilder<Req, Res> req) throws Exception {
         // Wait for no publication in progress to not accidentally cancel a publication different from the one triggered by the given
         // request.
-        final Coordinator masterCoordinator = (Coordinator) internalCluster().getCurrentMasterNodeInstance(Discovery.class);
+        final Coordinator masterCoordinator = internalCluster().getCurrentMasterNodeInstance(Coordinator.class);
         assertBusy(() -> {
             assertFalse(masterCoordinator.publicationInProgress());
             final long applierVersion = masterCoordinator.getApplierState().version();
-            for (Discovery instance : internalCluster().getInstances(Discovery.class)) {
-                assertEquals(((Coordinator) instance).getApplierState().version(), applierVersion);
+            for (Coordinator instance : internalCluster().getInstances(Coordinator.class)) {
+                assertEquals(instance.getApplierState().version(), applierVersion);
             }
         });
         ActionFuture<Res> future = req.execute();

server/src/internalClusterTest/java/org/elasticsearch/cluster/coordination/ZenDiscoveryIT.java

@@ -23,7 +23,6 @@
 import org.elasticsearch.common.xcontent.ToXContent;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 import org.elasticsearch.common.xcontent.XContentFactory;
-import org.elasticsearch.discovery.Discovery;
 import org.elasticsearch.discovery.DiscoveryStats;
 import org.elasticsearch.test.ESIntegTestCase;
 import org.elasticsearch.test.TestCustomMetadata;
@@ -81,7 +80,7 @@ public void testHandleNodeJoin_incompatibleClusterState() {
         String masterNode = internalCluster().startMasterOnlyNode();
         String node1 = internalCluster().startNode();
         ClusterService clusterService = internalCluster().getInstance(ClusterService.class, node1);
-        Coordinator coordinator = (Coordinator) internalCluster().getInstance(Discovery.class, masterNode);
+        Coordinator coordinator = internalCluster().getInstance(Coordinator.class, masterNode);
         final ClusterState state = clusterService.state();
         Metadata.Builder mdBuilder = Metadata.builder(state.metadata());
         mdBuilder.putCustom(CustomMetadata.TYPE, new CustomMetadata("data"));

server/src/internalClusterTest/java/org/elasticsearch/gateway/MetadataNodesIT.java

@@ -14,7 +14,6 @@
 import org.elasticsearch.cluster.metadata.IndexMetadata;
 import org.elasticsearch.common.collect.ImmutableOpenMap;
 import org.elasticsearch.common.settings.Settings;
-import org.elasticsearch.discovery.Discovery;
 import org.elasticsearch.env.NodeEnvironment;
 import org.elasticsearch.index.Index;
 import org.elasticsearch.test.ESIntegTestCase;
@@ -184,7 +183,7 @@ private boolean indexDirectoryExists(String nodeName, Index index) {
     }
 
     private ImmutableOpenMap<String, IndexMetadata> getIndicesMetadataOnNode(String nodeName) {
-        final Coordinator coordinator = (Coordinator) internalCluster().getInstance(Discovery.class, nodeName);
+        final Coordinator coordinator = internalCluster().getInstance(Coordinator.class, nodeName);
         return coordinator.getApplierState().getMetadata().getIndices();
     }
 }

server/src/main/java/org/elasticsearch/action/ActionModule.java

@@ -244,7 +244,6 @@
 import org.elasticsearch.common.settings.IndexScopedSettings;
 import org.elasticsearch.common.settings.Settings;
 import org.elasticsearch.common.settings.SettingsFilter;
-import org.elasticsearch.gateway.TransportNodesListGatewayMetaState;
 import org.elasticsearch.gateway.TransportNodesListGatewayStartedShards;
 import org.elasticsearch.index.seqno.GlobalCheckpointSyncAction;
 import org.elasticsearch.index.seqno.RetentionLeaseActions;
@@ -628,7 +627,6 @@ public <Request extends ActionRequest, Response extends ActionResponse> void reg
         // internal actions
         actions.register(GlobalCheckpointSyncAction.TYPE, GlobalCheckpointSyncAction.class);
         actions.register(TransportNodesSnapshotsStatus.TYPE, TransportNodesSnapshotsStatus.class);
-        actions.register(TransportNodesListGatewayMetaState.TYPE, TransportNodesListGatewayMetaState.class);
         actions.register(TransportVerifyShardBeforeCloseAction.TYPE, TransportVerifyShardBeforeCloseAction.class);
         actions.register(TransportVerifyShardIndexBlockAction.TYPE, TransportVerifyShardIndexBlockAction.class);
         actions.register(TransportNodesListGatewayStartedShards.TYPE, TransportNodesListGatewayStartedShards.class);

server/src/main/java/org/elasticsearch/cluster/ClusterState.java

@@ -9,10 +9,10 @@
 package org.elasticsearch.cluster;
 
 import com.carrotsearch.hppc.cursors.ObjectObjectCursor;
-
 import org.elasticsearch.Version;
 import org.elasticsearch.cluster.block.ClusterBlock;
 import org.elasticsearch.cluster.block.ClusterBlocks;
+import org.elasticsearch.cluster.coordination.ClusterStatePublisher;
 import org.elasticsearch.cluster.coordination.CoordinationMetadata;
 import org.elasticsearch.cluster.coordination.CoordinationMetadata.VotingConfigExclusion;
 import org.elasticsearch.cluster.coordination.CoordinationMetadata.VotingConfiguration;
@@ -40,7 +40,6 @@
 import org.elasticsearch.common.settings.Settings;
 import org.elasticsearch.common.xcontent.ToXContentFragment;
 import org.elasticsearch.common.xcontent.XContentBuilder;
-import org.elasticsearch.discovery.Discovery;
 
 import java.io.IOException;
 import java.util.EnumSet;
@@ -54,8 +53,8 @@
  * <p>
  * The cluster state object is immutable with the exception of the {@link RoutingNodes} structure, which is built on demand from the {@link
  * RoutingTable}. The cluster state can be updated only on the master node. All updates are performed by on a single thread and controlled
- * by the {@link ClusterService}. After every update the {@link Discovery#publish} method publishes a new version of the cluster state to
- * all other nodes in the cluster.
+ * by the {@link ClusterService}. After every update the {@link ClusterStatePublisher#publish} method publishes a new version of the cluster
+ * state to all other nodes in the cluster.
  * <p>
  * Implements the {@link Diffable} interface in order to support publishing of cluster state differences instead of the entire state on each
  * change. The publishing mechanism only sends differences to a node if this node was present in the previous version of the cluster state.

server/src/main/java/org/elasticsearch/cluster/coordination/Coordinator.java

@@ -14,8 +14,8 @@
 import org.apache.lucene.util.SetOnce;
 import org.elasticsearch.action.ActionListener;
 import org.elasticsearch.cluster.ClusterName;
-import org.elasticsearch.cluster.ClusterStatePublicationEvent;
 import org.elasticsearch.cluster.ClusterState;
+import org.elasticsearch.cluster.ClusterStatePublicationEvent;
 import org.elasticsearch.cluster.ClusterStateTaskConfig;
 import org.elasticsearch.cluster.ClusterStateUpdateTask;
 import org.elasticsearch.cluster.LocalClusterUpdateTask;
@@ -34,25 +34,24 @@
 import org.elasticsearch.cluster.service.ClusterApplier;
 import org.elasticsearch.cluster.service.ClusterApplierService;
 import org.elasticsearch.cluster.service.MasterService;
-import org.elasticsearch.common.util.BigArrays;
-import org.elasticsearch.core.Nullable;
 import org.elasticsearch.common.Priority;
 import org.elasticsearch.common.Strings;
 import org.elasticsearch.common.component.AbstractLifecycleComponent;
 import org.elasticsearch.common.io.stream.NamedWriteableRegistry;
-import org.elasticsearch.core.Releasable;
 import org.elasticsearch.common.settings.ClusterSettings;
 import org.elasticsearch.common.settings.Setting;
 import org.elasticsearch.common.settings.Settings;
 import org.elasticsearch.common.transport.TransportAddress;
-import org.elasticsearch.core.Releasables;
-import org.elasticsearch.core.TimeValue;
+import org.elasticsearch.common.util.BigArrays;
 import org.elasticsearch.common.util.concurrent.EsExecutors;
 import org.elasticsearch.common.util.concurrent.ListenableFuture;
 import org.elasticsearch.common.xcontent.XContentHelper;
 import org.elasticsearch.common.xcontent.json.JsonXContent;
+import org.elasticsearch.core.Nullable;
+import org.elasticsearch.core.Releasable;
+import org.elasticsearch.core.Releasables;
+import org.elasticsearch.core.TimeValue;
 import org.elasticsearch.discovery.ConfiguredHostsResolver;
-import org.elasticsearch.discovery.Discovery;
 import org.elasticsearch.discovery.DiscoveryModule;
 import org.elasticsearch.discovery.DiscoveryStats;
 import org.elasticsearch.discovery.HandshakingTransportAddressConnector;
@@ -88,7 +87,7 @@
 import static org.elasticsearch.gateway.GatewayService.STATE_NOT_RECOVERED_BLOCK;
 import static org.elasticsearch.monitor.StatusInfo.Status.UNHEALTHY;
 
-public class Coordinator extends AbstractLifecycleComponent implements Discovery {
+public class Coordinator extends AbstractLifecycleComponent implements ClusterStatePublisher {
 
     private static final Logger logger = LogManager.getLogger(Coordinator.class);
 
@@ -729,7 +728,6 @@ protected void doStart() {
         }
     }
 
-    @Override
     public DiscoveryStats stats() {
         return new DiscoveryStats(
             new PendingClusterStateStats(0, 0, 0),
@@ -738,7 +736,6 @@ public DiscoveryStats stats() {
         );
     }
 
-    @Override
     public void startInitialJoin() {
         synchronized (mutex) {
             becomeCandidate("startInitialJoin");

server/src/main/java/org/elasticsearch/cluster/service/MasterService.java

@@ -42,7 +42,6 @@
 import org.elasticsearch.common.util.concurrent.ThreadContext;
 import org.elasticsearch.core.Nullable;
 import org.elasticsearch.core.TimeValue;
-import org.elasticsearch.discovery.Discovery;
 import org.elasticsearch.node.Node;
 import org.elasticsearch.threadpool.Scheduler;
 import org.elasticsearch.threadpool.ThreadPool;
@@ -462,7 +461,7 @@ void clusterStatePublished(ClusterStatePublicationEvent clusterStatePublicationE
             taskInputs.executor.clusterStatePublished(clusterStatePublicationEvent);
         }
 
-        Discovery.AckListener createAckListener(ThreadPool threadPool, ClusterState newClusterState) {
+        ClusterStatePublisher.AckListener createAckListener(ThreadPool threadPool, ClusterState newClusterState) {
             return new DelegatingAckListener(nonFailedTasks.stream()
                 .filter(task -> task.listener instanceof AckedClusterStateTaskListener)
                 .map(task -> new AckCountDownListener((AckedClusterStateTaskListener) task.listener, newClusterState.version(),
@@ -632,30 +631,30 @@ private void logExecutionTime(TimeValue executionTime, String activity, String s
         }
     }
 
-    private static class DelegatingAckListener implements Discovery.AckListener {
+    private static class DelegatingAckListener implements ClusterStatePublisher.AckListener {
 
-        private final List<Discovery.AckListener> listeners;
+        private final List<ClusterStatePublisher.AckListener> listeners;
 
-        private DelegatingAckListener(List<Discovery.AckListener> listeners) {
+        private DelegatingAckListener(List<ClusterStatePublisher.AckListener> listeners) {
             this.listeners = listeners;
         }
 
         @Override
         public void onCommit(TimeValue commitTime) {
-            for (Discovery.AckListener listener : listeners) {
+            for (ClusterStatePublisher.AckListener listener : listeners) {
                 listener.onCommit(commitTime);
             }
         }
 
         @Override
         public void onNodeAck(DiscoveryNode node, @Nullable Exception e) {
-            for (Discovery.AckListener listener : listeners) {
+            for (ClusterStatePublisher.AckListener listener : listeners) {
                 listener.onNodeAck(node, e);
             }
         }
     }
 
-    private static class AckCountDownListener implements Discovery.AckListener {
+    private static class AckCountDownListener implements ClusterStatePublisher.AckListener {
 
         private static final Logger logger = LogManager.getLogger(AckCountDownListener.class);
 

server/src/main/java/org/elasticsearch/discovery/Discovery.java

@@ -70,7 +70,7 @@ public class DiscoveryModule {
     public static final Setting<String> ELECTION_STRATEGY_SETTING =
         new Setting<>("cluster.election.strategy", DEFAULT_ELECTION_STRATEGY, Function.identity(), Property.NodeScope);
 
-    private final Discovery discovery;
+    private final Coordinator coordinator;
 
     public DiscoveryModule(
         Settings settings,
@@ -145,7 +145,7 @@ public DiscoveryModule(
         }
 
         if (ZEN2_DISCOVERY_TYPE.equals(discoveryType) || SINGLE_NODE_DISCOVERY_TYPE.equals(discoveryType)) {
-            discovery = new Coordinator(
+            coordinator = new Coordinator(
                 NODE_NAME_SETTING.get(settings),
                 settings,
                 clusterSettings,
@@ -173,7 +173,7 @@ public static boolean isSingleNodeDiscovery(Settings settings) {
         return SINGLE_NODE_DISCOVERY_TYPE.equals(DISCOVERY_TYPE_SETTING.get(settings));
     }
 
-    public Discovery getDiscovery() {
-        return discovery;
+    public Coordinator getCoordinator() {
+        return coordinator;
     }
 }