SERVER-69871 Move feature_flag unit into server_base

1 files changed, 77 insertions, 0 deletions

diff --git a/src/mongo/db/feature_compatibility_version_parser.h b/src/mongo/db/feature_compatibility_version_parser.h
new file mode 100644
index 00000000000..0a9cc4eb238
--- /dev/null
+++ b/src/mongo/db/feature_compatibility_version_parser.h
@@ -0,0 +1,77 @@
+/**
+ *    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/util/version/releases.h"
+
+namespace mongo {
+/**
+ * Helpers to parse featureCompatibilityVersion document BSON objects into
+ * multiversion::FeatureCompatibilityVersion enums.
+ *
+ * Also, act as helpers to serialize and deserialize "fcv_string" idl type.
+ */
+class FeatureCompatibilityVersionParser {
+public:
+    /**
+     * Used to verify that the FCV value provided is valid and equal to one of
+     * { lastLTS, lastContinuous, latest }.
+     *
+     * Note: Deserializer for "fcv_string" idl type.
+     */
+    static multiversion::FeatureCompatibilityVersion parseVersion(StringData versionString);
+
+    // Used to parse FCV values for feature flags. It is acceptable to have feature flag versions
+    // that are not one of { lastLTS, lastContinuous, latest } while the server code is
+    // transitioning to the next LTS release. This is to avoid having the upgrade of FCV constants
+    // be blocked on old code removal.
+    static multiversion::FeatureCompatibilityVersion parseVersionForFeatureFlags(
+        StringData versionString);
+
+    /**
+     * Note: Serializer for "fcv_string" idl type.
+     */
+    static StringData serializeVersion(multiversion::FeatureCompatibilityVersion version);
+
+    static StringData serializeVersionForFeatureFlags(
+        multiversion::FeatureCompatibilityVersion version);
+
+    static Status validatePreviousVersionField(multiversion::FeatureCompatibilityVersion version);
+
+    /**
+     * Parses the featureCompatibilityVersion document from the server configuration collection
+     * (admin.system.version), and returns the state represented by the combination of the
+     * targetVersion and version.
+     */
+    static StatusWith<multiversion::FeatureCompatibilityVersion> parse(
+        const BSONObj& featureCompatibilityVersionDoc);
+};
+
+}  // namespace mongo