SERVER-50367 Add IDL support for feature flags

3 files changed, 98 insertions, 0 deletions

diff --git a/src/mongo/idl/SConscript b/src/mongo/idl/SConscript
index 28bcb2724b5..dd13816c007 100644
--- a/src/mongo/idl/SConscript
+++ b/src/mongo/idl/SConscript
@@ -32,11 +32,13 @@ env.CppUnitTest(
     target='idl_test',
     source=[
         'config_option_test.cpp',
+        'feature_flag_test.cpp',
         'idl_test.cpp',
         'server_parameter_specialized_test.cpp',
         'server_parameter_with_storage_test.cpp',
         env.Idlc('config_option_no_init_test.idl')[0],
         env.Idlc('config_option_test.idl')[0],
+        env.Idlc('feature_flag_test.idl')[0],
         env.Idlc('server_parameter_specialized_test.idl')[0],
         env.Idlc('server_parameter_with_storage_test.idl')[0],
         env.Idlc('unittest.idl')[0],
diff --git a/src/mongo/idl/feature_flag_test.cpp b/src/mongo/idl/feature_flag_test.cpp
new file mode 100644
index 00000000000..cb111756272
--- /dev/null
+++ b/src/mongo/idl/feature_flag_test.cpp
@@ -0,0 +1,60 @@
+/**
+ *    Copyright (C) 2020-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.
+ */
+
+#include "mongo/platform/basic.h"
+
+#include "mongo/idl/feature_flag_test_gen.h"
+#include "mongo/unittest/unittest.h"
+
+namespace mongo {
+
+namespace {
+
+ServerParameter* getServerParameter(const std::string& name) {
+    const auto& spMap = ServerParameterSet::getGlobal()->getMap();
+    const auto& spIt = spMap.find(name);
+    ASSERT(spIt != spMap.end());
+
+    auto* sp = spIt->second;
+    ASSERT(sp);
+    return sp;
+}
+
+TEST(IDLFeatureFlag, Basic) {
+    // true is set by "default" attribute in the IDL file.
+    ASSERT_EQ(feature_flags::gFeatureFlagToaster, true);
+
+    auto* featureFlagToaster = getServerParameter("featureFlagToaster");
+    ASSERT_OK(featureFlagToaster->setFromString("false"));
+    ASSERT_EQ(feature_flags::gFeatureFlagToaster, false);
+    ASSERT_NOT_OK(featureFlagToaster->setFromString("alpha"));
+}
+
+}  // namespace
+}  // namespace mongo
diff --git a/src/mongo/idl/feature_flag_test.idl b/src/mongo/idl/feature_flag_test.idl
new file mode 100644
index 00000000000..c756ca5a90f
--- /dev/null
+++ b/src/mongo/idl/feature_flag_test.idl
@@ -0,0 +1,36 @@
+#    Copyright (C) 2020-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.
+#
+
+global:
+  cpp_namespace: "mongo::feature_flags"
+
+feature_flags:
+    featureFlagToaster:
+      description: "Create a feature flag"
+      cpp_varname: gFeatureFlagToaster
+      default: true