Update Shallow Snapshot flows to support remote path type & hash algo

Signed-off-by: Ashish Singh <ssashish@amazon.com>

server/src/internalClusterTest/java/org/opensearch/remotestore/RemoteRestoreSnapshotIT.java

@@ -20,6 +20,7 @@
 import org.opensearch.client.Requests;
 import org.opensearch.cluster.ClusterState;
 import org.opensearch.cluster.metadata.IndexMetadata;
+import org.opensearch.common.Nullable;
 import org.opensearch.common.io.PathUtils;
 import org.opensearch.common.settings.Settings;
 import org.opensearch.common.util.io.IOUtils;
@@ -47,6 +48,7 @@
 import java.util.Arrays;
 import java.util.List;
 import java.util.Map;
+import java.util.Objects;
 import java.util.Optional;
 import java.util.concurrent.ExecutionException;
 import java.util.stream.Collectors;
@@ -284,7 +286,7 @@ public void testRemoteStoreCustomDataOnIndexCreationAndRestore() {
 
         indexDocuments(client, indexName1, randomIntBetween(5, 10));
         ensureGreen(indexName1);
-        validatePathType(indexName1, PathType.FIXED, PathHashAlgorithm.FNV_1A);
+        validatePathType(indexName1, PathType.FIXED);
 
         logger.info("--> snapshot");
         SnapshotInfo snapshotInfo = createSnapshot(snapshotRepoName, snapshotName1, new ArrayList<>(Arrays.asList(indexName1)));
@@ -301,7 +303,7 @@ public void testRemoteStoreCustomDataOnIndexCreationAndRestore() {
             .get();
         assertEquals(RestStatus.ACCEPTED, restoreSnapshotResponse.status());
         ensureGreen(restoredIndexName1version1);
-        validatePathType(restoredIndexName1version1, PathType.FIXED, PathHashAlgorithm.FNV_1A);
+        validatePathType(restoredIndexName1version1, PathType.FIXED);
 
         client(clusterManagerNode).admin()
             .cluster()
@@ -327,16 +329,22 @@ public void testRemoteStoreCustomDataOnIndexCreationAndRestore() {
         validatePathType(indexName2, PathType.HASHED_PREFIX, PathHashAlgorithm.FNV_1A);
 
         // Validating that custom data has not changed for indexes which were created before the cluster setting got updated
-        validatePathType(indexName1, PathType.FIXED, PathHashAlgorithm.FNV_1A);
+        validatePathType(indexName1, PathType.FIXED);
     }
 
-    private void validatePathType(String index, PathType pathType, PathHashAlgorithm pathHashAlgorithm) {
+    private void validatePathType(String index, PathType pathType) {
+        validatePathType(index, pathType, null);
+    }
+
+    private void validatePathType(String index, PathType pathType, @Nullable PathHashAlgorithm pathHashAlgorithm) {
         ClusterState state = client().admin().cluster().prepareState().execute().actionGet().getState();
         // Validate that the remote_store custom data is present in index metadata for the created index.
         Map<String, String> remoteCustomData = state.metadata().index(index).getCustomData(IndexMetadata.REMOTE_STORE_CUSTOM_KEY);
         assertNotNull(remoteCustomData);
         assertEquals(pathType.name(), remoteCustomData.get(PathType.NAME));
-        assertEquals(pathHashAlgorithm.name(), remoteCustomData.get(PathHashAlgorithm.NAME));
+        if (Objects.nonNull(pathHashAlgorithm)) {
+            assertEquals(pathHashAlgorithm.name(), remoteCustomData.get(PathHashAlgorithm.NAME));
+        }
     }
 
     public void testRestoreInSameRemoteStoreEnabledIndex() throws IOException {

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

@@ -206,8 +206,9 @@ public MetadataCreateIndexService(
 
         // Task is onboarded for throttling, it will get retried from associated TransportClusterManagerNodeAction.
         createIndexTaskKey = clusterService.registerClusterManagerTask(ClusterManagerTaskKeys.CREATE_INDEX_KEY, true);
+        Supplier<Version> minNodeVersionSupplier = () -> clusterService.state().nodes().getMinNodeVersion();
         remoteStorePathStrategyResolver = isRemoteDataAttributePresent(settings)
-            ? new RemoteStorePathStrategyResolver(clusterService.getClusterSettings())
+            ? new RemoteStorePathStrategyResolver(clusterService.getClusterSettings(), minNodeVersionSupplier)
             : null;
     }
 
@@ -575,22 +576,18 @@ public void addRemoteStorePathStrategyInCustomData(IndexMetadata.Builder tmpImdB
         if (remoteStorePathStrategyResolver != null) {
             // It is possible that remote custom data exists already. In such cases, we need to only update the path type
             // in the remote store custom data map.
-            Map<String, String> existingRemoteCustomData = tmpImdBuilder.removeCustom(IndexMetadata.REMOTE_STORE_CUSTOM_KEY);
-            Map<String, String> remoteCustomData = existingRemoteCustomData == null
-                ? new HashMap<>()
-                : new HashMap<>(existingRemoteCustomData);
+            Map<String, String> existingCustomData = tmpImdBuilder.removeCustom(IndexMetadata.REMOTE_STORE_CUSTOM_KEY);
+            assert assertNullOldType == false || Objects.isNull(existingCustomData);
+
             // Determine the path type for use using the remoteStorePathResolver.
             RemoteStorePathStrategy newPathStrategy = remoteStorePathStrategyResolver.get();
-            String oldPathType = remoteCustomData.put(PathType.NAME, newPathStrategy.getType().name());
-            String oldHashAlgorithm = remoteCustomData.put(PathHashAlgorithm.NAME, newPathStrategy.getHashAlgorithm().name());
-            assert !assertNullOldType || (Objects.isNull(oldPathType) && Objects.isNull(oldHashAlgorithm));
+            Map<String, String> remoteCustomData = new HashMap<>();
+            remoteCustomData.put(PathType.NAME, newPathStrategy.getType().name());
+            if (Objects.nonNull(newPathStrategy.getHashAlgorithm())) {
+                remoteCustomData.put(PathHashAlgorithm.NAME, newPathStrategy.getHashAlgorithm().name());
+            }
             logger.trace(
-                () -> new ParameterizedMessage(
-                    "Added newPathStrategy={}, replaced oldPathType={} oldHashAlgorithm={}",
-                    newPathStrategy,
-                    oldPathType,
-                    oldHashAlgorithm
-                )
+                () -> new ParameterizedMessage("Added newStrategy={}, replaced oldStrategy={}", remoteCustomData, existingCustomData)
             );
             tmpImdBuilder.putCustom(IndexMetadata.REMOTE_STORE_CUSTOM_KEY, remoteCustomData);
         }

server/src/main/java/org/opensearch/index/IndexSettings.java

@@ -63,6 +63,7 @@
 import java.util.List;
 import java.util.Locale;
 import java.util.Map;
+import java.util.Objects;
 import java.util.Optional;
 import java.util.concurrent.TimeUnit;
 import java.util.function.Consumer;
@@ -1910,12 +1911,11 @@ public void setDocIdFuzzySetFalsePositiveProbability(double docIdFuzzySetFalsePo
 
     public RemoteStorePathStrategy getRemoteStorePathStrategy() {
         Map<String, String> remoteCustomData = indexMetadata.getCustomData(IndexMetadata.REMOTE_STORE_CUSTOM_KEY);
-        if (remoteCustomData != null
-            && remoteCustomData.containsKey(PathType.NAME)
-            && remoteCustomData.containsKey(PathHashAlgorithm.NAME)) {
+        if (remoteCustomData != null && remoteCustomData.containsKey(PathType.NAME)) {
             PathType pathType = PathType.parseString(remoteCustomData.get(PathType.NAME));
-            PathHashAlgorithm pathHashAlgorithm = PathHashAlgorithm.parseString(remoteCustomData.get(PathHashAlgorithm.NAME));
-            return new RemoteStorePathStrategy(pathType, pathHashAlgorithm);
+            String hashAlgoStr = remoteCustomData.get(PathHashAlgorithm.NAME);
+            PathHashAlgorithm hashAlgorithm = Objects.nonNull(hashAlgoStr) ? PathHashAlgorithm.parseString(hashAlgoStr) : null;
+            return new RemoteStorePathStrategy(pathType, hashAlgorithm);
         }
         return new RemoteStorePathStrategy(PathType.FIXED);
     }

server/src/main/java/org/opensearch/index/remote/RemoteStoreEnums.java

@@ -13,9 +13,13 @@
 import org.opensearch.common.hash.FNV1a;
 import org.opensearch.index.remote.RemoteStorePathStrategy.PathInput;
 
+import java.util.HashMap;
 import java.util.Locale;
+import java.util.Map;
+import java.util.Objects;
 import java.util.Set;
 
+import static java.util.Collections.unmodifiableMap;
 import static org.opensearch.index.remote.RemoteStoreEnums.DataType.DATA;
 import static org.opensearch.index.remote.RemoteStoreEnums.DataType.METADATA;
 
@@ -78,9 +82,10 @@ public String getName() {
      */
     @PublicApi(since = "2.14.0")
     public enum PathType {
-        FIXED {
+        FIXED(0) {
             @Override
             public BlobPath generatePath(PathInput pathInput, PathHashAlgorithm hashAlgorithm) {
+                assert Objects.isNull(hashAlgorithm) : "hashAlgorithm is expected to be null with fixed remote store path type";
                 // Hash algorithm is not used in FIXED path type
                 return pathInput.basePath()
                     .add(pathInput.indexUUID())
@@ -94,7 +99,7 @@ boolean requiresHashAlgorithm() {
                 return false;
             }
         },
-        HASHED_PREFIX {
+        HASHED_PREFIX(1) {
             @Override
             public BlobPath generatePath(PathInput pathInput, PathHashAlgorithm hashAlgorithm) {
                 // TODO - We need to implement this, keeping the same path as Fixed for sake of multiple tests that can fail otherwise.
@@ -112,6 +117,33 @@ boolean requiresHashAlgorithm() {
             }
         };
 
+        private final int code;
+
+        PathType(int code) {
+            this.code = code;
+        }
+
+        public int getCode() {
+            return code;
+        }
+
+        private static final Map<Integer, PathType> CODE_TO_ENUM;
+        static {
+            PathType[] values = values();
+            Map<Integer, PathType> codeToStatus = new HashMap<>(values.length);
+            for (PathType value : values) {
+                codeToStatus.put(value.code, value);
+            }
+            CODE_TO_ENUM = unmodifiableMap(codeToStatus);
+        }
+
+        /**
+         * Turn a status code into a {@link PathType}.
+         */
+        public static PathType fromCode(int code) {
+            return CODE_TO_ENUM.get(code);
+        }
+
         /**
          * This method generates the path for the given path input which constitutes multiple fields and characteristics
          * of the data.
@@ -131,7 +163,7 @@ public BlobPath path(PathInput pathInput, PathHashAlgorithm hashAlgorithm) {
             return generatePath(pathInput, hashAlgorithm);
         }
 
-        abstract BlobPath generatePath(PathInput pathInput, PathHashAlgorithm hashAlgorithm);
+        protected abstract BlobPath generatePath(PathInput pathInput, PathHashAlgorithm hashAlgorithm);
 
         abstract boolean requiresHashAlgorithm();
 
@@ -158,7 +190,7 @@ public static PathType parseString(String pathType) {
     @PublicApi(since = "2.14.0")
     public enum PathHashAlgorithm {
 
-        FNV_1A {
+        FNV_1A(0) {
             @Override
             long hash(PathInput pathInput) {
                 String input = pathInput.indexUUID() + pathInput.shardId() + pathInput.dataCategory().getName() + pathInput.dataType()
@@ -167,6 +199,33 @@ long hash(PathInput pathInput) {
             }
         };
 
+        private final int code;
+
+        PathHashAlgorithm(int code) {
+            this.code = code;
+        }
+
+        public int getCode() {
+            return code;
+        }
+
+        private static final Map<Integer, PathHashAlgorithm> CODE_TO_ENUM;
+        static {
+            PathHashAlgorithm[] values = values();
+            Map<Integer, PathHashAlgorithm> codeToStatus = new HashMap<>(values.length);
+            for (PathHashAlgorithm value : values) {
+                codeToStatus.put(value.code, value);
+            }
+            CODE_TO_ENUM = unmodifiableMap(codeToStatus);
+        }
+
+        /**
+         * Turn a status code into a {@link PathHashAlgorithm}.
+         */
+        public static PathHashAlgorithm fromCode(int code) {
+            return CODE_TO_ENUM.get(code);
+        }
+
         abstract long hash(PathInput pathInput);
 
         public static PathHashAlgorithm parseString(String pathHashAlgorithm) {

server/src/main/java/org/opensearch/index/remote/RemoteStorePathStrategy.java

@@ -36,7 +36,7 @@ public RemoteStorePathStrategy(PathType type) {
     }
 
     public RemoteStorePathStrategy(PathType type, PathHashAlgorithm hashAlgorithm) {
-        assert type.requiresHashAlgorithm() == false || Objects.nonNull(hashAlgorithm);
+        assert (type.requiresHashAlgorithm() == false && Objects.isNull(hashAlgorithm)) || Objects.nonNull(hashAlgorithm);
         this.type = Objects.requireNonNull(type);
         this.hashAlgorithm = hashAlgorithm;
     }
@@ -55,7 +55,7 @@ public String toString() {
     }
 
     public BlobPath generatePath(PathInput pathInput) {
-        return type.generatePath(pathInput, hashAlgorithm);
+        return type.path(pathInput, hashAlgorithm);
     }
 
     /**

server/src/main/java/org/opensearch/index/remote/RemoteStorePathStrategyResolver.java

@@ -8,11 +8,14 @@
 
 package org.opensearch.index.remote;
 
+import org.opensearch.Version;
 import org.opensearch.common.settings.ClusterSettings;
 import org.opensearch.index.remote.RemoteStoreEnums.PathHashAlgorithm;
 import org.opensearch.index.remote.RemoteStoreEnums.PathType;
 import org.opensearch.indices.IndicesService;
 
+import java.util.function.Supplier;
+
 /**
  * Determines the {@link RemoteStorePathStrategy} at the time of index metadata creation.
  *
@@ -22,13 +25,22 @@ public class RemoteStorePathStrategyResolver {
 
     private volatile PathType type;
 
-    public RemoteStorePathStrategyResolver(ClusterSettings clusterSettings) {
+    private final Supplier<Version> minNodeVersionSupplier;
+
+    public RemoteStorePathStrategyResolver(ClusterSettings clusterSettings, Supplier<Version> minNodeVersionSupplier) {
+        this.minNodeVersionSupplier = minNodeVersionSupplier;
         type = clusterSettings.get(IndicesService.CLUSTER_REMOTE_STORE_PATH_PREFIX_TYPE_SETTING);
         clusterSettings.addSettingsUpdateConsumer(IndicesService.CLUSTER_REMOTE_STORE_PATH_PREFIX_TYPE_SETTING, this::setType);
     }
 
     public RemoteStorePathStrategy get() {
-        return new RemoteStorePathStrategy(type, PathHashAlgorithm.FNV_1A);
+        PathType pathType;
+        PathHashAlgorithm pathHashAlgorithm;
+        // Min node version check ensures that we are enabling the new prefix type only when all the nodes understand it.
+        pathType = Version.CURRENT.compareTo(minNodeVersionSupplier.get()) <= 0 ? type : PathType.FIXED;
+        // If the path type is fixed, hash algorithm is not applicable.
+        pathHashAlgorithm = pathType == PathType.FIXED ? null : PathHashAlgorithm.FNV_1A;
+        return new RemoteStorePathStrategy(pathType, pathHashAlgorithm);
     }
 
     private void setType(PathType type) {

server/src/main/java/org/opensearch/index/shard/StoreRecovery.java

@@ -58,8 +58,6 @@
 import org.opensearch.index.engine.Engine;
 import org.opensearch.index.engine.EngineException;
 import org.opensearch.index.mapper.MapperService;
-import org.opensearch.index.remote.RemoteStoreEnums.PathType;
-import org.opensearch.index.remote.RemoteStorePathStrategy;
 import org.opensearch.index.seqno.SequenceNumbers;
 import org.opensearch.index.snapshots.IndexShardRestoreFailedException;
 import org.opensearch.index.snapshots.blobstore.RemoteStoreShardShallowCopySnapshot;
@@ -412,8 +410,7 @@ void recoverFromSnapshotAndRemoteStore(
                     remoteStoreRepository,
                     indexUUID,
                     shardId,
-                    new RemoteStorePathStrategy(PathType.FIXED)
-                    // TODO - The path type needs to be obtained from RemoteStoreShardShallowCopySnapshot
+                    shallowCopyShardMetadata.getRemoteStorePathStrategy()
                 );
                 sourceRemoteDirectory.initializeToSpecificCommit(
                     primaryTerm,