1 files changed, 77 insertions, 0 deletions
diff --git a/src/rocksdb/db/wide/wide_column_serialization.h b/src/rocksdb/db/wide/wide_column_serialization.h
new file mode 100644
index 000000000..f0ffbd392
--- /dev/null
+++ b/src/rocksdb/db/wide/wide_column_serialization.h
@@ -0,0 +1,77 @@
+//  Copyright (c) Meta Platforms, Inc. and affiliates.
+//  This source code is licensed under both the GPLv2 (found in the
+//  COPYING file in the root directory) and Apache 2.0 License
+//  (found in the LICENSE.Apache file in the root directory).
+
+#pragma once
+
+#include <cstdint>
+#include <string>
+
+#include "rocksdb/rocksdb_namespace.h"
+#include "rocksdb/status.h"
+#include "rocksdb/wide_columns.h"
+
+namespace ROCKSDB_NAMESPACE {
+
+class Slice;
+
+// Wide-column serialization/deserialization primitives.
+//
+// The two main parts of the layout are 1) a sorted index containing the column
+// names and column value sizes and 2) the column values themselves. Keeping the
+// index and the values separate will enable selectively reading column values
+// down the line. Note that currently the index has to be fully parsed in order
+// to find out the offset of each column value.
+//
+// Legend: cn = column name, cv = column value, cns = column name size, cvs =
+// column value size.
+//
+//      +----------+--------------+----------+-------+----------+---...
+//      | version  | # of columns |  cns 1   | cn 1  |  cvs 1   |
+//      +----------+--------------+------------------+--------- +---...
+//      | varint32 |   varint32   | varint32 | bytes | varint32 |
+//      +----------+--------------+----------+-------+----------+---...
+//
+//      ... continued ...
+//
+//          ...---+----------+-------+----------+-------+---...---+-------+
+//                |  cns N   | cn N  |  cvs N   | cv 1  |         | cv N  |
+//          ...---+----------+-------+----------+-------+---...---+-------+
+//                | varint32 | bytes | varint32 | bytes |         | bytes |
+//          ...---+----------+-------+----------+-------+---...---+-------+
+
+class WideColumnSerialization {
+ public:
+  static Status Serialize(const WideColumns& columns, std::string& output);
+  static Status Serialize(const Slice& value_of_default,
+                          const WideColumns& other_columns,
+                          std::string& output);
+
+  static Status Deserialize(Slice& input, WideColumns& columns);
+
+  static WideColumns::const_iterator Find(const WideColumns& columns,
+                                          const Slice& column_name);
+  static Status GetValueOfDefaultColumn(Slice& input, Slice& value);
+
+  static constexpr uint32_t kCurrentVersion = 1;
+
+ private:
+  static Status SerializeImpl(const Slice* value_of_default,
+                              const WideColumns& columns, std::string& output);
+};
+
+inline Status WideColumnSerialization::Serialize(const WideColumns& columns,
+                                                 std::string& output) {
+  constexpr Slice* value_of_default = nullptr;
+
+  return SerializeImpl(value_of_default, columns, output);
+}
+
+inline Status WideColumnSerialization::Serialize(
+    const Slice& value_of_default, const WideColumns& other_columns,
+    std::string& output) {
+  return SerializeImpl(&value_of_default, other_columns, output);
+}
+
+}  // namespace ROCKSDB_NAMESPACE