Bugfix in snapshot V2 restore flow

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

@@ -421,8 +421,8 @@ public void testIndexDeletionNoPinnedTimestamps() throws Exception {
         client().admin().indices().prepareDelete(INDEX_NAME).get();
 
         assertBusy(() -> {
-            assertEquals(0, Files.list(translogMetadataPath).collect(Collectors.toList()).size());
-            assertEquals(0, Files.list(translogDataPath).collect(Collectors.toList()).size());
+            assertEquals(1, Files.list(translogMetadataPath).collect(Collectors.toList()).size());
+            assertEquals(4, Files.list(translogDataPath).collect(Collectors.toList()).size());
         });
     }
 
@@ -490,7 +490,7 @@ public void testIndexDeletionWithPinnedTimestamps() throws Exception {
 
         assertBusy(() -> {
             List<Path> metadataFiles = Files.list(translogMetadataPath).collect(Collectors.toList());
-            assertEquals(1, metadataFiles.size());
+            assertEquals(2, metadataFiles.size());
 
             verifyTranslogDataFileCount(metadataFiles, translogDataPath);
         });

server/src/internalClusterTest/java/org/opensearch/remotestore/RestoreShallowSnapshotV2IT.java

@@ -27,22 +27,26 @@
 import org.opensearch.common.blobstore.BlobPath;
 import org.opensearch.common.io.PathUtils;
 import org.opensearch.common.settings.Settings;
+import org.opensearch.common.unit.TimeValue;
 import org.opensearch.common.util.io.IOUtils;
 import org.opensearch.core.index.Index;
 import org.opensearch.core.rest.RestStatus;
 import org.opensearch.index.IndexService;
 import org.opensearch.index.IndexSettings;
+import org.opensearch.index.mapper.MapperService;
 import org.opensearch.index.remote.RemoteStoreEnums;
 import org.opensearch.index.shard.IndexShard;
 import org.opensearch.indices.IndicesService;
 import org.opensearch.indices.RemoteStoreSettings;
 import org.opensearch.indices.recovery.RecoveryState;
 import org.opensearch.indices.replication.common.ReplicationType;
+import org.opensearch.node.remotestore.RemoteStorePinnedTimestampService;
 import org.opensearch.repositories.blobstore.BlobStoreRepository;
 import org.opensearch.snapshots.AbstractSnapshotIntegTestCase;
 import org.opensearch.snapshots.SnapshotInfo;
 import org.opensearch.snapshots.SnapshotRestoreException;
 import org.opensearch.snapshots.SnapshotState;
+import org.opensearch.test.BackgroundIndexer;
 import org.opensearch.test.InternalTestCluster;
 import org.opensearch.test.OpenSearchIntegTestCase;
 import org.junit.After;
@@ -53,15 +57,18 @@
 import java.nio.file.Path;
 import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.Objects;
 import java.util.Optional;
 import java.util.concurrent.ExecutionException;
+import java.util.concurrent.TimeUnit;
 import java.util.stream.Collectors;
 import java.util.stream.Stream;
 
 import static org.opensearch.cluster.metadata.IndexMetadata.SETTING_REMOTE_STORE_ENABLED;
+import static org.opensearch.index.query.QueryBuilders.matchAllQuery;
 import static org.opensearch.index.remote.RemoteStoreEnums.DataCategory.SEGMENTS;
 import static org.opensearch.index.remote.RemoteStoreEnums.DataCategory.TRANSLOG;
 import static org.opensearch.index.remote.RemoteStoreEnums.DataType.DATA;
@@ -885,4 +892,88 @@ public void testRestoreOperationsUsingDifferentRepos() throws Exception {
         ensureGreen(indexName1);
         assertDocsPresentInIndex(client, indexName1, 3 * numDocsInIndex1);
     }
+
+    public void testContinuousIndexing() throws Exception {
+        internalCluster().startClusterManagerOnlyNode();
+        internalCluster().startDataOnlyNode();
+        String index = "test-index";
+        String snapshotRepo = "test-restore-snapshot-repo";
+        String baseSnapshotName = "snapshot_";
+        Path absolutePath1 = randomRepoPath().toAbsolutePath();
+        logger.info("Snapshot Path [{}]", absolutePath1);
+
+        createRepository(snapshotRepo, "fs", getRepositorySettings(absolutePath1, true));
+
+        Client client = client();
+        Settings indexSettings = Settings.builder()
+            .put(super.indexSettings())
+            .put(IndexMetadata.SETTING_NUMBER_OF_SHARDS, 1)
+            .put(IndexMetadata.SETTING_NUMBER_OF_REPLICAS, 0)
+            .build();
+
+        createIndex(index, indexSettings);
+        ensureGreen(index);
+
+        RemoteStorePinnedTimestampService remoteStorePinnedTimestampService = internalCluster().getInstance(
+            RemoteStorePinnedTimestampService.class,
+            primaryNodeName(index)
+        );
+
+        remoteStorePinnedTimestampService.rescheduleAsyncUpdatePinnedTimestampTask(TimeValue.timeValueSeconds(randomIntBetween(1, 5)));
+        RemoteStoreSettings.setPinnedTimestampsLookbackInterval(TimeValue.timeValueSeconds(randomIntBetween(1, 5)));
+
+        long totalDocs = 0;
+        Map<String, Long> snapshots = new HashMap<>();
+        int numDocs = randomIntBetween(200, 300);
+        totalDocs += numDocs;
+        try (BackgroundIndexer indexer = new BackgroundIndexer(index, MapperService.SINGLE_MAPPING_NAME, client(), numDocs)) {
+            int numberOfSnapshots = 5;
+            for (int i = 0; i < numberOfSnapshots; i++) {
+                logger.info("--> waiting for {} docs to be indexed ...", numDocs);
+                long finalTotalDocs1 = totalDocs;
+                assertBusy(() -> assertEquals(finalTotalDocs1, indexer.totalIndexedDocs()), 120, TimeUnit.SECONDS);
+                logger.info("--> {} total docs indexed", totalDocs);
+                String snapshotName = baseSnapshotName + i;
+                createSnapshot(snapshotRepo, snapshotName, new ArrayList<>());
+                snapshots.put(snapshotName, totalDocs);
+                if (i < numberOfSnapshots - 1) {
+                    numDocs = randomIntBetween(200, 300);
+                    indexer.continueIndexing(numDocs);
+                    totalDocs += numDocs;
+                }
+            }
+        }
+
+        logger.info("Snapshots Status: " + snapshots);
+
+        for (String snapshot : snapshots.keySet()) {
+            logger.info("Restoring snapshot: {}", snapshot);
+            assertAcked(client().admin().indices().delete(new DeleteIndexRequest(index)).get());
+
+            RestoreSnapshotResponse restoreSnapshotResponse1 = client.admin()
+                .cluster()
+                .prepareRestoreSnapshot(snapshotRepo, snapshot)
+                .setWaitForCompletion(true)
+                .setIndices()
+                .get();
+
+            assertEquals(RestStatus.OK, restoreSnapshotResponse1.status());
+
+            // Verify restored index's stats
+            ensureGreen(TimeValue.timeValueSeconds(60), index);
+            long finalTotalDocs = totalDocs;
+            assertBusy(() -> {
+                Long hits = client().prepareSearch(index)
+                    .setQuery(matchAllQuery())
+                    .setSize((int) finalTotalDocs)
+                    .storedFields()
+                    .execute()
+                    .actionGet()
+                    .getHits()
+                    .getTotalHits().value;
+
+                assertEquals(snapshots.get(snapshot), hits);
+            });
+        }
+    }
 }

server/src/main/java/org/opensearch/index/store/RemoteSegmentStoreDirectory.java

@@ -39,6 +39,7 @@
 import org.opensearch.index.store.lockmanager.RemoteStoreMetadataLockManager;
 import org.opensearch.index.store.remote.metadata.RemoteSegmentMetadata;
 import org.opensearch.index.store.remote.metadata.RemoteSegmentMetadataHandler;
+import org.opensearch.indices.RemoteStoreSettings;
 import org.opensearch.indices.replication.checkpoint.ReplicationCheckpoint;
 import org.opensearch.node.remotestore.RemoteStorePinnedTimestampService;
 import org.opensearch.threadpool.ThreadPool;
@@ -891,6 +892,16 @@ public void deleteStaleSegments(int lastNMetadataFilesToKeep) throws IOException
             lastSuccessfulFetchOfPinnedTimestamps
         );
 
+        if (metadataFilesEligibleToDelete.isEmpty()) {
+            logger.debug("No metadata files are eligible to be deleted based on lastNMetadataFilesToKeep and age");
+            return;
+        }
+
+        // If pinned timestamps are enabled, make sure to not delete last metadata file.
+        if (RemoteStoreSettings.isPinnedTimestampsEnabled()) {
+            metadataFilesEligibleToDelete.remove(sortedMetadataFileList.get(0));
+        }
+
         List<String> metadataFilesToBeDeleted = metadataFilesEligibleToDelete.stream()
             .filter(metadataFile -> allLockFiles.contains(metadataFile) == false)
             .collect(Collectors.toList());
@@ -905,7 +916,7 @@ public void deleteStaleSegments(int lastNMetadataFilesToKeep) throws IOException
         Set<String> activeSegmentRemoteFilenames = new HashSet<>();
 
         final Set<String> metadataFilesToFilterActiveSegments = getMetadataFilesToFilterActiveSegments(
-            lastNMetadataFilesToKeep,
+            sortedMetadataFileList.indexOf(metadataFilesEligibleToDelete.get(0)),
             sortedMetadataFileList,
             allLockFiles
         );

server/src/main/java/org/opensearch/index/translog/RemoteFsTimestampAwareTranslog.java

@@ -189,7 +189,7 @@ public void onResponse(List<BlobMetadata> blobMetadata) {
                     List<String> metadataFilesToBeDeleted = getMetadataFilesToBeDeleted(metadataFiles, indexDeleted);
 
                     // If index is not deleted, make sure to keep latest metadata file
-                    if (indexDeleted == false) {
+                    if (indexDeleted == false || RemoteStoreSettings.isPinnedTimestampsEnabled()) {
                         metadataFilesToBeDeleted.remove(metadataFiles.get(0));
                     }
 

server/src/test/java/org/opensearch/index/translog/RemoteFsTimestampAwareTranslogTests.java

@@ -285,9 +285,9 @@ public void testIndexDeletionWithNoPinnedTimestampNoRecentMdFiles() throws Excep
         assertBusy(() -> assertTrue(translog.isRemoteGenerationDeletionPermitsAvailable()));
 
         assertBusy(() -> {
-            assertEquals(0, blobStoreTransferService.listAll(getTranslogDirectory().add(METADATA_DIR)).size());
+            assertEquals(1, blobStoreTransferService.listAll(getTranslogDirectory().add(METADATA_DIR)).size());
             assertEquals(
-                0,
+                12,
                 blobStoreTransferService.listAll(getTranslogDirectory().add(DATA_DIR).add(String.valueOf(primaryTerm.get()))).size()
             );
         });