1 files changed, 75 insertions, 0 deletions
diff --git a/src/mongo/s/database_version.h b/src/mongo/s/database_version.h
new file mode 100644
index 00000000000..f015bdff692
--- /dev/null
+++ b/src/mongo/s/database_version.h
@@ -0,0 +1,75 @@
+/**
+ *    Copyright (C) 2018-present MongoDB, Inc.
+ *
+ *    This program is free software: you can redistribute it and/or modify
+ *    it under the terms of the Server Side Public License, version 1,
+ *    as published by MongoDB, Inc.
+ *
+ *    This program is distributed in the hope that it will be useful,
+ *    but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *    Server Side Public License for more details.
+ *
+ *    You should have received a copy of the Server Side Public License
+ *    along with this program. If not, see
+ *    <http://www.mongodb.com/licensing/server-side-public-license>.
+ *
+ *    As a special exception, the copyright holders give permission to link the
+ *    code of portions of this program with the OpenSSL library under certain
+ *    conditions as described in each individual source file and distribute
+ *    linked combinations including the program with the OpenSSL library. You
+ *    must comply with the Server Side Public License in all respects for
+ *    all of the code used other than as permitted herein. If you modify file(s)
+ *    with this exception, you may extend this exception to your version of the
+ *    file(s), but you are not obligated to do so. If you do not wish to do so,
+ *    delete this exception statement from your version. If you delete this
+ *    exception statement from all source files in the program, then also delete
+ *    it in the license file.
+ */
+
+#pragma once
+
+#include "mongo/s/database_version_gen.h"
+
+namespace mongo {
+
+class DatabaseVersion : private DatabaseVersionBase {
+public:
+    using DatabaseVersionBase::getLastMod;
+    using DatabaseVersionBase::toBSON;
+
+    // It returns a new DatabaseVersion marked as fixed. A fixed database version is used to
+    // distinguish databases that do not have entries in the sharding catalog, such as 'config' and
+    // 'admin'
+    static DatabaseVersion makeFixed();
+
+    DatabaseVersion() = default;
+
+    explicit DatabaseVersion(const BSONObj& obj) {
+        DatabaseVersionBase::parseProtected(IDLParserErrorContext("DatabaseVersion"), obj);
+    }
+
+    explicit DatabaseVersion(mongo::UUID uuid) : DatabaseVersionBase(/* lastMod */ 1) {
+        setUuid(uuid);
+    }
+
+    DatabaseVersion makeUpdated() const;
+
+    bool operator==(const DatabaseVersion& other) const {
+        return getUuid() == other.getUuid() && getLastMod() == other.getLastMod();
+    }
+
+    bool operator!=(const DatabaseVersion& other) const {
+        return !(*this == other);
+    }
+
+    bool isFixed() const {
+        return getLastMod() == 0;
+    }
+
+    mongo::UUID getUuid() const {
+        return *DatabaseVersionBase::getUuid();
+    }
+};
+
+}  // namespace mongo