1 files changed, 36 insertions, 0 deletions
diff --git a/src/seastar/include/seastar/util/used_size.hh b/src/seastar/include/seastar/util/used_size.hh
new file mode 100644
index 000000000..7b4212d7e
--- /dev/null
+++ b/src/seastar/include/seastar/util/used_size.hh
@@ -0,0 +1,36 @@
+/*
+ * This file is open source software, licensed to you under the terms
+ * of the Apache License, Version 2.0 (the "License").  See the NOTICE file
+ * distributed with this work for additional information regarding copyright
+ * ownership.  You may not use this file except in compliance with the License.
+ *
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+/*
+ * Copyright (C) 2020 ScyllaDB Ltd.
+ */
+
+#pragma once
+
+#include <stddef.h>
+#include <type_traits>
+
+namespace seastar {
+namespace internal {
+// Empty types have a size of 1, but that byte is not actually
+// used. This helper is used to avoid accessing that byte.
+template<typename T>
+struct used_size {
+    static constexpr size_t value = std::is_empty<T>::value ? 0 : sizeof(T);
+};
+}
+}