SERVER-33561 Add a FCV parser file, refactoring FCV code

1 files changed, 170 insertions, 0 deletions

diff --git a/src/mongo/db/commands/feature_compatibility_version_parser.cpp b/src/mongo/db/commands/feature_compatibility_version_parser.cpp
new file mode 100644
index 00000000000..8aea75ac1a9
--- /dev/null
+++ b/src/mongo/db/commands/feature_compatibility_version_parser.cpp
@@ -0,0 +1,170 @@
+/**
+ *    Copyright (C) 2018 MongoDB Inc.
+ *
+ *    This program is free software: you can redistribute it and/or  modify
+ *    it under the terms of the GNU Affero General Public License, version 3,
+ *    as published by the Free Software Foundation.
+ *
+ *    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
+ *    GNU Affero General Public License for more details.
+ *
+ *    You should have received a copy of the GNU Affero General Public License
+ *    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ *    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 GNU Affero General 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.
+ */
+
+#include "mongo/platform/basic.h"
+
+#include "mongo/db/commands/feature_compatibility_version_parser.h"
+
+#include "mongo/base/status.h"
+#include "mongo/bson/bsonobj.h"
+#include "mongo/db/commands/feature_compatibility_version_documentation.h"
+
+namespace mongo {
+
+constexpr StringData FeatureCompatibilityVersionParser::kVersion36;
+constexpr StringData FeatureCompatibilityVersionParser::kVersion40;
+constexpr StringData FeatureCompatibilityVersionParser::kVersionDowngradingTo36;
+constexpr StringData FeatureCompatibilityVersionParser::kVersionUpgradingTo40;
+constexpr StringData FeatureCompatibilityVersionParser::kVersionUnset;
+
+constexpr StringData FeatureCompatibilityVersionParser::kParameterName;
+constexpr StringData FeatureCompatibilityVersionParser::kVersionField;
+constexpr StringData FeatureCompatibilityVersionParser::kTargetVersionField;
+
+StatusWith<ServerGlobalParams::FeatureCompatibility::Version>
+FeatureCompatibilityVersionParser::parse(const BSONObj& featureCompatibilityVersionDoc) {
+    ServerGlobalParams::FeatureCompatibility::Version version =
+        ServerGlobalParams::FeatureCompatibility::Version::kUnsetDefault36Behavior;
+    std::string versionString;
+    std::string targetVersionString;
+
+    for (auto&& elem : featureCompatibilityVersionDoc) {
+        auto fieldName = elem.fieldNameStringData();
+        if (fieldName == "_id") {
+            continue;
+        } else if (fieldName == kVersionField || fieldName == kTargetVersionField) {
+            if (elem.type() != BSONType::String) {
+                return Status(
+                    ErrorCodes::TypeMismatch,
+                    str::stream()
+                        << fieldName
+                        << " must be of type String, but was of type "
+                        << typeName(elem.type())
+                        << ". Contents of "
+                        << kParameterName
+                        << " document in "
+                        << "admin.system.version"  // TODO: NamespaceString constant (SERVER-33562)
+                        << ": "
+                        << featureCompatibilityVersionDoc
+                        << ". See "
+                        << feature_compatibility_version_documentation::kCompatibilityLink
+                        << ".");
+            }
+
+            if (elem.String() != kVersion40 && elem.String() != kVersion36) {
+                return Status(
+                    ErrorCodes::BadValue,
+                    str::stream()
+                        << "Invalid value for "
+                        << fieldName
+                        << ", found "
+                        << elem.String()
+                        << ", expected '"
+                        << kVersion40
+                        << "' or '"
+                        << kVersion36
+                        << "'. Contents of "
+                        << kParameterName
+                        << " document in "
+                        << "admin.system.version"  // TODO: NamespaceString constant (SERVER-33562)
+                        << ": "
+                        << featureCompatibilityVersionDoc
+                        << ". See "
+                        << feature_compatibility_version_documentation::kCompatibilityLink
+                        << ".");
+            }
+
+            if (fieldName == kVersionField) {
+                versionString = elem.String();
+            } else if (fieldName == kTargetVersionField) {
+                targetVersionString = elem.String();
+            }
+        } else {
+            return Status(
+                ErrorCodes::BadValue,
+                str::stream()
+                    << "Unrecognized field '"
+                    << fieldName
+                    << "'. Contents of "
+                    << kParameterName
+                    << " document in "
+                    << "admin.system.version"  // TODO: NamespaceString constant (SERVER-33562)
+                    << ": "
+                    << featureCompatibilityVersionDoc
+                    << ". See "
+                    << feature_compatibility_version_documentation::kCompatibilityLink
+                    << ".");
+        }
+    }
+
+    if (versionString == kVersion36) {
+        if (targetVersionString == kVersion40) {
+            version = ServerGlobalParams::FeatureCompatibility::Version::kUpgradingTo40;
+        } else if (targetVersionString == kVersion36) {
+            version = ServerGlobalParams::FeatureCompatibility::Version::kDowngradingTo36;
+        } else {
+            version = ServerGlobalParams::FeatureCompatibility::Version::kFullyDowngradedTo36;
+        }
+    } else if (versionString == kVersion40) {
+        if (targetVersionString == kVersion40 || targetVersionString == kVersion36) {
+            return Status(
+                ErrorCodes::BadValue,
+                str::stream()
+                    << "Invalid state for "
+                    << kParameterName
+                    << " document in "
+                    << "admin.system.version"  // TODO: NamespaceString constant (SERVER-33562)
+                    << ": "
+                    << featureCompatibilityVersionDoc
+                    << ". See "
+                    << feature_compatibility_version_documentation::kCompatibilityLink
+                    << ".");
+        } else {
+            version = ServerGlobalParams::FeatureCompatibility::Version::kFullyUpgradedTo40;
+        }
+    } else {
+        return Status(
+            ErrorCodes::BadValue,
+            str::stream()
+                << "Missing required field '"
+                << kVersionField
+                << "''. Contents of "
+                << kParameterName
+                << " document in "
+                << "admin.system.version"  // TODO: NamespaceString constant (SERVER-33562)
+                << ": "
+                << featureCompatibilityVersionDoc
+                << ". See "
+                << feature_compatibility_version_documentation::kCompatibilityLink
+                << ".");
+    }
+
+    return version;
+}
+
+}  // namespace mongo