[Backport 2.x] Read write ephemeral objects for remote publication of cluster state

server/src/main/java/org/opensearch/cluster/RepositoryCleanupInProgress.java

@@ -45,6 +45,7 @@
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
+import java.util.Objects;
 
 /**
  * Information passed during repository cleanup
@@ -118,6 +119,24 @@
         return LegacyESVersion.V_7_4_0;
     }
 
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) {
+            return true;
+        }
+        if (o == null || getClass() != o.getClass()) {
+            return false;
+        }
+
+        RepositoryCleanupInProgress that = (RepositoryCleanupInProgress) o;
+        return entries.equals(that.entries);
+    }
+
+    @Override
+    public int hashCode() {
+        return 31 + entries.hashCode();
+    }
+
     /**
      * Entry in the collection.
      *
@@ -155,6 +174,23 @@
             out.writeLong(repositoryStateId);
         }
 
+        @Override
+        public boolean equals(Object o) {
+            if (this == o) {
+                return true;
+            }
+            if (o == null || getClass() != o.getClass()) {
+                return false;
+            }
+            RepositoryCleanupInProgress.Entry that = (RepositoryCleanupInProgress.Entry) o;
+            return repository.equals(that.repository) && repositoryStateId == that.repositoryStateId;
+        }
+
+        @Override
+        public int hashCode() {
+            return Objects.hash(repository, repositoryStateId);
+        }
+
         @Override
         public String toString() {
             return "{" + repository + '}' + '{' + repositoryStateId + '}';

server/src/main/java/org/opensearch/cluster/metadata/Metadata.java

@@ -978,6 +978,10 @@ public static boolean isTemplatesMetadataEqual(Metadata metadata1, Metadata meta
         return metadata1.templates.equals(metadata2.templates);
     }
 
+    public static boolean isHashesOfConsistentSettingsEqual(Metadata metadata1, Metadata metadata2) {
+        return metadata1.hashesOfConsistentSettings.equals(metadata2.hashesOfConsistentSettings);
+    }
+
     public static boolean isCustomMetadataEqual(Metadata metadata1, Metadata metadata2) {
         int customCount1 = 0;
         for (Map.Entry<String, Custom> cursor : metadata1.customs.entrySet()) {

server/src/main/java/org/opensearch/cluster/routing/RoutingTable.java

@@ -79,7 +79,7 @@ public class RoutingTable implements Iterable<IndexRoutingTable>, Diffable<Routi
     // index to IndexRoutingTable map
     private final Map<String, IndexRoutingTable> indicesRouting;
 
-    private RoutingTable(long version, final Map<String, IndexRoutingTable> indicesRouting) {
+    public RoutingTable(long version, final Map<String, IndexRoutingTable> indicesRouting) {
         this.version = version;
         this.indicesRouting = Collections.unmodifiableMap(indicesRouting);
     }

server/src/main/java/org/opensearch/cluster/routing/remote/InternalRemoteRoutingTableService.java

@@ -33,6 +33,7 @@
 import org.opensearch.common.util.io.IOUtils;
 import org.opensearch.core.action.ActionListener;
 import org.opensearch.core.common.bytes.BytesReference;
+import org.opensearch.core.index.Index;
 import org.opensearch.gateway.remote.ClusterMetadataManifest;
 import org.opensearch.gateway.remote.RemoteStateTransferException;
 import org.opensearch.gateway.remote.routingtable.RemoteIndexRoutingTable;
@@ -44,11 +45,14 @@
 import org.opensearch.repositories.RepositoriesService;
 import org.opensearch.repositories.Repository;
 import org.opensearch.repositories.blobstore.BlobStoreRepository;
+import org.opensearch.threadpool.ThreadPool;
 
 import java.io.IOException;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.Map;
+import java.util.Optional;
+import java.util.concurrent.ExecutorService;
 import java.util.function.Function;
 import java.util.function.Supplier;
 import java.util.stream.Collectors;
@@ -97,11 +101,13 @@ public class InternalRemoteRoutingTableService extends AbstractLifecycleComponen
     private BlobStoreRepository blobStoreRepository;
     private RemoteStoreEnums.PathType pathType;
     private RemoteStoreEnums.PathHashAlgorithm pathHashAlgo;
+    private ThreadPool threadPool;
 
     public InternalRemoteRoutingTableService(
         Supplier<RepositoriesService> repositoriesService,
         Settings settings,
-        ClusterSettings clusterSettings
+        ClusterSettings clusterSettings,
+        ThreadPool threadpool
     ) {
         assert isRemoteRoutingTableEnabled(settings) : "Remote routing table is not enabled";
         this.repositoriesService = repositoriesService;
@@ -110,6 +116,7 @@ public InternalRemoteRoutingTableService(
         this.pathHashAlgo = clusterSettings.get(REMOTE_ROUTING_TABLE_PATH_HASH_ALGO_SETTING);
         clusterSettings.addSettingsUpdateConsumer(REMOTE_ROUTING_TABLE_PATH_TYPE_SETTING, this::setPathTypeSetting);
         clusterSettings.addSettingsUpdateConsumer(REMOTE_ROUTING_TABLE_PATH_HASH_ALGO_SETTING, this::setPathHashAlgoSetting);
+        this.threadPool = threadpool;
     }
 
     private void setPathTypeSetting(RemoteStoreEnums.PathType pathType) {
@@ -266,6 +273,68 @@ private void uploadIndex(
         }
     }
 
+    @Override
+    public CheckedRunnable<IOException> getAsyncIndexRoutingReadAction(
+        String uploadedFilename,
+        Index index,
+        LatchedActionListener<IndexRoutingTable> latchedActionListener
+    ) {
+        int idx = uploadedFilename.lastIndexOf("/");
+        String blobFileName = uploadedFilename.substring(idx + 1);
+        BlobContainer blobContainer = blobStoreRepository.blobStore()
+            .blobContainer(BlobPath.cleanPath().add(uploadedFilename.substring(0, idx)));
+
+        return () -> readAsync(
+            blobContainer,
+            blobFileName,
+            index,
+            threadPool.executor(ThreadPool.Names.REMOTE_STATE_READ),
+            ActionListener.wrap(
+                response -> latchedActionListener.onResponse(response.getIndexRoutingTable()),
+                latchedActionListener::onFailure
+            )
+        );
+    }
+
+    private void readAsync(
+        BlobContainer blobContainer,
+        String name,
+        Index index,
+        ExecutorService executorService,
+        ActionListener<RemoteIndexRoutingTable> listener
+    ) {
+        executorService.execute(() -> {
+            try {
+                listener.onResponse(read(blobContainer, name, index));
+            } catch (Exception e) {
+                listener.onFailure(e);
+            }
+        });
+    }
+
+    private RemoteIndexRoutingTable read(BlobContainer blobContainer, String path, Index index) {
+        try {
+            return new RemoteIndexRoutingTable(blobContainer.readBlob(path), index);
+        } catch (IOException | AssertionError e) {
+            logger.error(() -> new ParameterizedMessage("RoutingTable read failed for path {}", path), e);
+            throw new RemoteStateTransferException("Failed to read RemoteRoutingTable from Manifest with error ", e);
+        }
+    }
+
+    @Override
+    public List<ClusterMetadataManifest.UploadedIndexMetadata> getUpdatedIndexRoutingTableMetadata(
+        List<String> updatedIndicesRouting,
+        List<ClusterMetadataManifest.UploadedIndexMetadata> allIndicesRouting
+    ) {
+        return updatedIndicesRouting.stream().map(idx -> {
+            Optional<ClusterMetadataManifest.UploadedIndexMetadata> uploadedIndexMetadataOptional = allIndicesRouting.stream()
+                .filter(idx2 -> idx2.getIndexName().equals(idx))
+                .findFirst();
+            assert uploadedIndexMetadataOptional.isPresent() == true;
+            return uploadedIndexMetadataOptional.get();
+        }).collect(Collectors.toList());
+    }
+
     private String getIndexRoutingFileName(long term, long version) {
         return String.join(
             DELIMITER,

server/src/main/java/org/opensearch/cluster/routing/remote/NoopRemoteRoutingTableService.java

@@ -16,6 +16,7 @@
 import org.opensearch.common.CheckedRunnable;
 import org.opensearch.common.blobstore.BlobPath;
 import org.opensearch.common.lifecycle.AbstractLifecycleComponent;
+import org.opensearch.core.index.Index;
 import org.opensearch.gateway.remote.ClusterMetadataManifest;
 
 import java.io.IOException;
@@ -57,6 +58,26 @@
         List<ClusterMetadataManifest.UploadedIndexMetadata> indicesRoutingUploaded,
         List<String> indicesRoutingToDelete
     ) {
+        // noop
+        return List.of();
+    }
+
+    @Override
+    public CheckedRunnable<IOException> getAsyncIndexRoutingReadAction(
+        String uploadedFilename,
+        Index index,
+        LatchedActionListener<IndexRoutingTable> latchedActionListener
+    ) {
+        // noop
+        return () -> {};
+    }
+
+    @Override
+    public List<ClusterMetadataManifest.UploadedIndexMetadata> getUpdatedIndexRoutingTableMetadata(
+        List<String> updatedIndicesRouting,
+        List<ClusterMetadataManifest.UploadedIndexMetadata> allIndicesRouting
+    ) {
+        // noop
         return List.of();
     }
 

server/src/main/java/org/opensearch/cluster/routing/remote/RemoteRoutingTableService.java

@@ -18,14 +18,17 @@
 import org.opensearch.common.lifecycle.LifecycleComponent;
 import org.opensearch.core.common.io.stream.StreamInput;
 import org.opensearch.core.common.io.stream.StreamOutput;
+import org.opensearch.core.index.Index;
 import org.opensearch.gateway.remote.ClusterMetadataManifest;
 
 import java.io.IOException;
 import java.util.List;
 import java.util.Map;
 
 /**
- * Interface for RemoteRoutingTableService. Exposes methods to orchestrate upload and download of routing table from remote store.
+ * A Service which provides APIs to upload and download routing table from remote store.
+ *
+ * @opensearch.internal
  */
 public interface RemoteRoutingTableService extends LifecycleComponent {
     public static final DiffableUtils.NonDiffableValueSerializer<String, IndexRoutingTable> CUSTOM_ROUTING_TABLE_VALUE_SERIALIZER =
@@ -43,6 +46,17 @@ public IndexRoutingTable read(StreamInput in, String key) throws IOException {
 
     List<IndexRoutingTable> getIndicesRouting(RoutingTable routingTable);
 
+    CheckedRunnable<IOException> getAsyncIndexRoutingReadAction(
+        String uploadedFilename,
+        Index index,
+        LatchedActionListener<IndexRoutingTable> latchedActionListener
+    );
+
+    List<ClusterMetadataManifest.UploadedIndexMetadata> getUpdatedIndexRoutingTableMetadata(
+        List<String> updatedIndicesRouting,
+        List<ClusterMetadataManifest.UploadedIndexMetadata> allIndicesRouting
+    );
+
     DiffableUtils.MapDiff<String, IndexRoutingTable, Map<String, IndexRoutingTable>> getIndicesRoutingMapDiff(
         RoutingTable before,
         RoutingTable after

server/src/main/java/org/opensearch/cluster/routing/remote/RemoteRoutingTableServiceFactory.java

@@ -11,6 +11,7 @@
 import org.opensearch.common.settings.ClusterSettings;
 import org.opensearch.common.settings.Settings;
 import org.opensearch.repositories.RepositoriesService;
+import org.opensearch.threadpool.ThreadPool;
 
 import java.util.function.Supplier;
 
@@ -26,15 +27,17 @@ public class RemoteRoutingTableServiceFactory {
      * @param repositoriesService repositoriesService
      * @param settings settings
      * @param clusterSettings clusterSettings
+     * @param threadPool threadPool
      * @return RemoteRoutingTableService
      */
     public static RemoteRoutingTableService getService(
         Supplier<RepositoriesService> repositoriesService,
         Settings settings,
-        ClusterSettings clusterSettings
+        ClusterSettings clusterSettings,
+        ThreadPool threadPool
     ) {
         if (isRemoteRoutingTableEnabled(settings)) {
-            return new InternalRemoteRoutingTableService(repositoriesService, settings, clusterSettings);
+            return new InternalRemoteRoutingTableService(repositoriesService, settings, clusterSettings, threadPool);
         }
         return new NoopRemoteRoutingTableService();
     }

server/src/main/java/org/opensearch/common/settings/ClusterSettings.java

@@ -726,6 +726,7 @@ public void apply(Settings value, Settings current, Settings previous) {
                 INDEX_METADATA_UPLOAD_TIMEOUT_SETTING,
                 GLOBAL_METADATA_UPLOAD_TIMEOUT_SETTING,
                 METADATA_MANIFEST_UPLOAD_TIMEOUT_SETTING,
+                RemoteClusterStateService.REMOTE_STATE_READ_TIMEOUT_SETTING,
                 RemoteStoreNodeService.REMOTE_STORE_COMPATIBILITY_MODE_SETTING,
                 RemoteStoreNodeService.MIGRATION_DIRECTION_SETTING,