Address PR comments

Signed-off-by: Sachin Kale <kalsac@amazon.com>

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

@@ -460,19 +460,9 @@ private void recoverFromRemoteStore(IndexShard indexShard, Repository repository
             indexShard.syncSegmentsFromRemoteSegmentStore(true);
 
             if (repository != null) {
-                FileTransferTracker fileTransferTracker = new FileTransferTracker(shardId);
-                assert repository instanceof BlobStoreRepository : "repository should be instance of BlobStoreRepository";
-                BlobStoreRepository blobStoreRepository = (BlobStoreRepository) repository;
-                TranslogTransferManager translogTransferManager = new TranslogTransferManager(
-                    new BlobStoreTransferService(
-                        blobStoreRepository.blobStore(),
-                        indexShard.getThreadPool().executor(ThreadPool.Names.TRANSLOG_TRANSFER)
-                    ),
-                    blobStoreRepository.basePath().add(shardId.getIndex().getUUID()).add(String.valueOf(shardId.id())),
-                    fileTransferTracker,
-                    fileTransferTracker::exclusionFilter
-                );
-                RemoteFsTranslog.download(translogTransferManager, indexShard.shardPath().resolveTranslog());
+                syncTranslogFilesFromRemoteTranslog(indexShard, repository);
+            } else {
+                bootstrap(indexShard, store);
             }
 
             assert indexShard.shardRouting.primary() : "only primary shards can recover from store";
@@ -489,6 +479,22 @@ private void recoverFromRemoteStore(IndexShard indexShard, Repository repository
         }
     }
 
+    private void syncTranslogFilesFromRemoteTranslog(IndexShard indexShard, Repository repository) throws IOException {
+        FileTransferTracker fileTransferTracker = new FileTransferTracker(shardId);
+        assert repository instanceof BlobStoreRepository : "repository should be instance of BlobStoreRepository";
+        BlobStoreRepository blobStoreRepository = (BlobStoreRepository) repository;
+        TranslogTransferManager translogTransferManager = new TranslogTransferManager(
+            new BlobStoreTransferService(
+                blobStoreRepository.blobStore(),
+                indexShard.getThreadPool().executor(ThreadPool.Names.TRANSLOG_TRANSFER)
+            ),
+            blobStoreRepository.basePath().add(shardId.getIndex().getUUID()).add(String.valueOf(shardId.id())),
+            fileTransferTracker,
+            fileTransferTracker::exclusionFilter
+        );
+        RemoteFsTranslog.download(translogTransferManager, indexShard.shardPath().resolveTranslog());
+    }
+
     /**
      * Recovers the state of the shard from the store.
      */

server/src/main/java/org/opensearch/index/translog/transfer/TranslogTransferManager.java

@@ -134,32 +134,29 @@ public boolean transferSnapshot(TransferSnapshot transferSnapshot, TranslogTrans
 
     public boolean downloadTranslog(String primaryTerm, String generation, Path location, boolean latest) throws IOException {
         logger.info("Downloading translog files with: Primry Term = {}, Generation = {}, Location = {}", primaryTerm, generation, location);
-        String checkpointFilename = "translog-" + generation + ".ckp";
+        String ckpFileName = "translog-" + generation + ".ckp";
         if (latest) {
-            checkpointFilename = "translog.ckp";
-        }
-        if (Files.exists(location.resolve(checkpointFilename)) == false) {
-            try (
-                InputStream checkpointFileInputStream = transferService.downloadBlob(
-                    remoteBaseTransferPath.add(primaryTerm),
-                    "translog-" + generation + ".ckp"
-                )
-            ) {
-                Files.copy(checkpointFileInputStream, location.resolve(checkpointFilename));
-            }
+            String ckpWithoutGenerationFileName = "translog.ckp";
+            downloadToFS(ckpFileName, ckpWithoutGenerationFileName, location, primaryTerm);
         }
+        // Download Checkpoint file from remote and store on FS
+        downloadToFS(ckpFileName, location, primaryTerm);
+        // Download translog file from remote and store on FS
         String translogFilename = "translog-" + generation + ".tlog";
-        if (Files.exists(location.resolve(translogFilename)) == false) {
-            try (
-                InputStream translogFileInputStream = transferService.downloadBlob(
-                    remoteBaseTransferPath.add(primaryTerm),
-                    "translog-" + generation + ".tlog"
-                )
-            ) {
-                Files.copy(translogFileInputStream, location.resolve(translogFilename));
+        downloadToFS(translogFilename, location, primaryTerm);
+        return true;
+    }
+
+    private void downloadToFS(String fileName, Path location, String primaryTerm) throws IOException {
+        downloadToFS(fileName, fileName, location, primaryTerm);
+    }
+
+    private void downloadToFS(String remoteFileName, String localFileName, Path location, String primaryTerm) throws IOException {
+        if (Files.exists(location.resolve(localFileName)) == false) {
+            try (InputStream inputStream = transferService.downloadBlob(remoteBaseTransferPath.add(primaryTerm), remoteFileName)) {
+                Files.copy(inputStream, location.resolve(localFileName));
             }
         }
-        return true;
     }
 
     public TranslogTransferMetadata readMetadata() throws IOException {

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

@@ -326,10 +326,17 @@ public void testReadLocationDownload() throws IOException {
             Files.delete(file);
         }
 
-        translog = create(translogDir, repository, translogUUID);
+        // Creating RemoteFsTranslog with the same location
+        Translog newTranslog = create(translogDir, repository, translogUUID);
         i = 0;
         for (Translog.Operation op : ops) {
-            assertEquals(op, translog.readOperation(locs.get(i++)));
+            assertEquals(op, newTranslog.readOperation(locs.get(i++)));
+        }
+        try {
+            newTranslog.close();
+        } catch (Exception e) {
+            // Ignoring this exception for now. Once the download flow populates FileTracker,
+            // we can remove this try-catch block
         }
     }