Fix based on review

Author: KodaiD

core/src/main/java/com/scalar/db/storage/objectstorage/MutateStatementHandler.java

@@ -10,7 +10,9 @@
 import com.scalar.db.exception.storage.RetriableExecutionException;
 import java.util.Collections;
 import java.util.List;
+import javax.annotation.concurrent.ThreadSafe;
 
+@ThreadSafe
 public class MutateStatementHandler extends StatementHandler {
   public MutateStatementHandler(
       ObjectStorageWrapper wrapper, TableMetadataManager metadataManager) {

core/src/main/java/com/scalar/db/storage/objectstorage/ObjectStorageAdmin.java

@@ -20,7 +20,9 @@
 import java.util.Set;
 import java.util.stream.Collectors;
 import javax.annotation.Nullable;
+import javax.annotation.concurrent.ThreadSafe;
 
+@ThreadSafe
 public class ObjectStorageAdmin implements DistributedStorageAdmin {
   public static final String NAMESPACE_METADATA_TABLE = "namespaces";
   public static final String TABLE_METADATA_TABLE = "metadata";
@@ -48,6 +50,29 @@ public ObjectStorageAdmin(DatabaseConfig databaseConfig) {
     metadataNamespace = objectStorageConfig.getMetadataNamespace();
   }
 
+  private static String getTableMetadataKey(String namespace, String table) {
+    return String.join(
+        String.valueOf(ObjectStorageUtils.CONCATENATED_KEY_DELIMITER), namespace, table);
+  }
+
+  private static String getNamespaceNameFromTableMetadataKey(String tableMetadataKey) {
+    List<String> parts =
+        Splitter.on(ObjectStorageUtils.CONCATENATED_KEY_DELIMITER).splitToList(tableMetadataKey);
+    if (parts.size() != 2 || parts.get(0).isEmpty()) {
+      throw new IllegalArgumentException("Invalid table metadata key: " + tableMetadataKey);
+    }
+    return parts.get(0);
+  }
+
+  private static String getTableNameFromTableMetadataKey(String tableMetadataKey) {
+    List<String> parts =
+        Splitter.on(ObjectStorageUtils.CONCATENATED_KEY_DELIMITER).splitToList(tableMetadataKey);
+    if (parts.size() != 2 || parts.get(1).isEmpty()) {
+      throw new IllegalArgumentException("Invalid table metadata key: " + tableMetadataKey);
+    }
+    return parts.get(1);
+  }
+
   @Override
   public StorageInfo getStorageInfo(String namespace) throws ExecutionException {
     return STORAGE_INFO;
@@ -450,29 +475,6 @@ private void deleteTableData(String namespace, String table) throws ExecutionExc
     }
   }
 
-  private static String getTableMetadataKey(String namespace, String table) {
-    return String.join(
-        String.valueOf(ObjectStorageUtils.CONCATENATED_KEY_DELIMITER), namespace, table);
-  }
-
-  private static String getNamespaceNameFromTableMetadataKey(String tableMetadataKey) {
-    List<String> parts =
-        Splitter.on(ObjectStorageUtils.CONCATENATED_KEY_DELIMITER).splitToList(tableMetadataKey);
-    if (parts.size() != 2 || parts.get(0).isEmpty()) {
-      throw new IllegalArgumentException("Invalid table metadata key: " + tableMetadataKey);
-    }
-    return parts.get(0);
-  }
-
-  private static String getTableNameFromTableMetadataKey(String tableMetadataKey) {
-    List<String> parts =
-        Splitter.on(ObjectStorageUtils.CONCATENATED_KEY_DELIMITER).splitToList(tableMetadataKey);
-    if (parts.size() != 2 || parts.get(1).isEmpty()) {
-      throw new IllegalArgumentException("Invalid table metadata key: " + tableMetadataKey);
-    }
-    return parts.get(1);
-  }
-
   private void checkTableMetadata(TableMetadata metadata) {
     Set<String> secondaryIndexNames = metadata.getSecondaryIndexNames();
     if (!secondaryIndexNames.isEmpty()) {

core/src/main/java/com/scalar/db/storage/objectstorage/ObjectStorageWrapper.java

@@ -2,7 +2,9 @@
 
 import java.util.Optional;
 import java.util.Set;
+import javax.annotation.concurrent.ThreadSafe;
 
+@ThreadSafe
 public interface ObjectStorageWrapper {
 
   /**

core/src/main/java/com/scalar/db/storage/objectstorage/blobstorage/BlobStorageWrapper.java

@@ -22,7 +22,9 @@
 import java.util.Optional;
 import java.util.Set;
 import java.util.stream.Collectors;
+import javax.annotation.concurrent.ThreadSafe;
 
+@ThreadSafe
 public class BlobStorageWrapper implements ObjectStorageWrapper {
   private final BlobContainerClient client;
   private final Duration requestTimeoutInSeconds;

core/src/main/java/com/scalar/db/storage/objectstorage/s3/S3Wrapper.java

@@ -12,6 +12,7 @@
 import java.util.List;
 import java.util.Optional;
 import java.util.Set;
+import javax.annotation.concurrent.ThreadSafe;
 import software.amazon.awssdk.auth.credentials.AwsBasicCredentials;
 import software.amazon.awssdk.auth.credentials.StaticCredentialsProvider;
 import software.amazon.awssdk.core.ResponseBytes;
@@ -32,6 +33,7 @@
 import software.amazon.awssdk.services.s3.model.S3Exception;
 import software.amazon.awssdk.services.s3.multipart.MultipartConfiguration;
 
+@ThreadSafe
 public class S3Wrapper implements ObjectStorageWrapper {
   public static final int BATCH_DELETE_SIZE_LIMIT = 1000;
   private final S3AsyncClient client;