SERVER-37086 Create IDLServerParameter class

4 files changed, 328 insertions, 0 deletions

diff --git a/src/mongo/idl/SConscript b/src/mongo/idl/SConscript
index b7fdf916c29..5908d8f9d3d 100644
--- a/src/mongo/idl/SConscript
+++ b/src/mongo/idl/SConscript
@@ -27,3 +27,24 @@ env.CppUnitTest(
         '$BUILD_DIR/mongo/idl/idl_parser',
     ],
 )
+
+env.Library(
+    target='server_parameter',
+    source=[
+        'server_parameter.cpp',
+    ],
+    LIBDEPS=[
+        '$BUILD_DIR/mongo/base',
+        '$BUILD_DIR/mongo/db/server_parameters',
+    ],
+)
+
+env.CppUnitTest(
+    target='idl_server_parameter_test',
+    source=[
+        'server_parameter_test.cpp',
+    ],
+    LIBDEPS=[
+        'server_parameter',
+    ],
+)
diff --git a/src/mongo/idl/server_parameter.cpp b/src/mongo/idl/server_parameter.cpp
new file mode 100644
index 00000000000..8555b3a39ca
--- /dev/null
+++ b/src/mongo/idl/server_parameter.cpp
@@ -0,0 +1,95 @@
+/**
+ *    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.
+ */
+
+#define MONGO_LOG_DEFAULT_COMPONENT ::mongo::logger::LogComponent::kControl
+
+#include "mongo/idl/server_parameter.h"
+
+#include "mongo/util/log.h"
+
+namespace mongo {
+using SPT = ServerParameterType;
+
+IDLServerParameter::IDLServerParameter(StringData name, ServerParameterType paramType)
+    : ServerParameter(ServerParameterSet::getGlobal(),
+                      name,
+                      paramType == SPT::kStartupOnly || paramType == SPT::kStartupAndRuntime,
+                      paramType == SPT::kRuntimeOnly || paramType == SPT::kStartupAndRuntime) {}
+
+void IDLServerParameter::append(OperationContext* opCtx,
+                                BSONObjBuilder& b,
+                                const std::string& name) {
+    invariant(_appendBSON,
+              "append() called on IDLServerParamter with no appendBSON implementation");
+    _appendBSON(opCtx, &b, name);
+}
+
+IDLServerParameterDeprecatedAlias::IDLServerParameterDeprecatedAlias(StringData name,
+                                                                     ServerParameter* sp)
+    : ServerParameter(ServerParameterSet::getGlobal(),
+                      name,
+                      sp->allowedToChangeAtStartup(),
+                      sp->allowedToChangeAtRuntime()),
+      _sp(sp) {}
+
+Status IDLServerParameter::set(const BSONElement& newValueElement) {
+    invariant(_fromBSON, "set() called on IDLServerParamter with no fromBSON implementation");
+    if (!_fromBSON) {
+        return {ErrorCodes::BadValue, "Unable to set parameter with no setter callback"};
+    }
+    return _fromBSON(newValueElement);
+}
+
+Status IDLServerParameter::setFromString(const std::string& str) {
+    invariant(_fromString,
+              "setFromString() called on IDLServerParamter with no setFromString implementation");
+    return _fromString(str);
+}
+
+void IDLServerParameterDeprecatedAlias::append(OperationContext* opCtx,
+                                               BSONObjBuilder& b,
+                                               const std::string& fieldName) {
+    warning() << "Use of deprecated server parameter '" << name() << "', please use '"
+              << _sp->name() << "' instead.";
+    _sp->append(opCtx, b, fieldName);
+}
+
+Status IDLServerParameterDeprecatedAlias::set(const BSONElement& newValueElement) {
+    warning() << "Use of deprecared server parameter '" << name() << "', please use '"
+              << _sp->name() << "' instead.";
+    return _sp->set(newValueElement);
+}
+
+Status IDLServerParameterDeprecatedAlias::setFromString(const std::string& str) {
+    warning() << "Use of deprecared server parameter '" << name() << "', please use '"
+              << _sp->name() << "' instead.";
+    return _sp->setFromString(str);
+}
+
+}  // namespace mongo
diff --git a/src/mongo/idl/server_parameter.h b/src/mongo/idl/server_parameter.h
new file mode 100644
index 00000000000..5022bb00327
--- /dev/null
+++ b/src/mongo/idl/server_parameter.h
@@ -0,0 +1,123 @@
+/**
+ *    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
+/* The contents of this file are meant to be used by
+ * code generated from idlc.py.
+ *
+ * It should not be instantiated directly from mongo code,
+ * rather parameters should be defined in .idl files.
+ */
+
+#include <functional>
+#include <string>
+
+#include "mongo/base/status.h"
+#include "mongo/bson/bsonelement.h"
+#include "mongo/bson/bsonobjbuilder.h"
+#include "mongo/db/server_parameters.h"
+
+namespace mongo {
+
+/**
+ * Specialization of ServerParameter used by IDL generator.
+ */
+class IDLServerParameter : public ServerParameter {
+public:
+    IDLServerParameter(StringData name, ServerParameterType paramType);
+
+    /**
+     * Define a callback for populating a BSONObj with the current setting.
+     */
+    using appendBSON_t = void(OperationContext*, BSONObjBuilder*, StringData);
+    void setAppendBSON(std::function<appendBSON_t> appendBSON) {
+        _appendBSON = std::move(appendBSON);
+    }
+
+    /**
+     * Encode the setting into BSON object.
+     *
+     * Typically invoked by {getParameter:...} to produce a dictionary
+     * of SCP settings.
+     */
+    void append(OperationContext* opCtx, BSONObjBuilder& b, const std::string& name) final;
+
+    /**
+     * Define a callback for setting the value from a BSONElement.
+     */
+    using fromBSON_t = Status(const BSONElement&);
+    void setFromBSON(std::function<fromBSON_t> fromBSON) {
+        _fromBSON = std::move(fromBSON);
+    }
+
+    /**
+     * Update the underlying value using a BSONElement.
+     *
+     * Allows setting non-basic values (e.g. vector<string>)
+     * via the {setParameter: ...} call.
+     */
+    Status set(const BSONElement& newValueElement) final;
+
+    /**
+     * Define a callback for setting the value from a string.
+     */
+    using fromString_t = Status(StringData);
+    void setFromString(std::function<fromString_t> fromString) {
+        _fromString = std::move(fromString);
+    }
+
+    /**
+     * Update the underlying value from a string.
+     *
+     * Typically invoked from commandline --setParameter usage.
+     */
+    Status setFromString(const std::string& str) final;
+
+protected:
+    std::function<appendBSON_t> _appendBSON;
+    std::function<fromBSON_t> _fromBSON;
+    std::function<fromString_t> _fromString;
+};
+
+/**
+ * Proxy instance for deprecated aliases of set parameters.
+ */
+class IDLServerParameterDeprecatedAlias : ServerParameter {
+public:
+    IDLServerParameterDeprecatedAlias(StringData name, ServerParameter* sp);
+
+    void append(OperationContext* opCtx, BSONObjBuilder& b, const std::string& name) final;
+    Status set(const BSONElement& newValueElement) final;
+    Status setFromString(const std::string& str) final;
+
+private:
+    ServerParameter* _sp;
+};
+
+}  // namespace mongo
diff --git a/src/mongo/idl/server_parameter_test.cpp b/src/mongo/idl/server_parameter_test.cpp
new file mode 100644
index 00000000000..37ea4312577
--- /dev/null
+++ b/src/mongo/idl/server_parameter_test.cpp
@@ -0,0 +1,89 @@
+/**
+ *    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.
+ */
+
+#include "mongo/platform/basic.h"
+
+#include "mongo/idl/server_parameter.h"
+#include "mongo/unittest/unittest.h"
+
+namespace mongo {
+namespace {
+
+TEST(ServerParameter, setAppendBSON) {
+    IDLServerParameter param("setAppendBSON"_sd, ServerParameterType::kStartupOnly);
+
+    param.setAppendBSON([](OperationContext*, BSONObjBuilder* builder, StringData name) {
+        builder->append(name, 42);
+    });
+    BSONObjBuilder builder;
+    param.append(nullptr, builder, param.name());
+    auto obj = builder.obj();
+    ASSERT_EQ(obj.nFields(), 1);
+    ASSERT_EQ(obj[param.name()].Int(), 42);
+}
+
+TEST(ServerParameter, setFromString) {
+    IDLServerParameter param("setFromString"_sd, ServerParameterType::kStartupOnly);
+
+    param.setFromString([](StringData) { return Status::OK(); });
+    ASSERT_OK(param.setFromString("A value"));
+
+    param.setFromString([](StringData) { return Status(ErrorCodes::BadValue, "Can't set me."); });
+    ASSERT_NOT_OK(param.setFromString("A value"));
+}
+
+TEST(ServerParameter, setFromBSON) {
+    IDLServerParameter param("setFromBSON"_sd, ServerParameterType::kStartupOnly);
+    BSONElement elem;
+
+    param.setFromBSON([](const BSONElement&) { return Status::OK(); });
+    ASSERT_OK(param.set(elem));
+
+    param.setFromBSON(
+        [](const BSONElement&) { return Status(ErrorCodes::BadValue, "Can't set me."); });
+    ASSERT_NOT_OK(param.set(elem));
+}
+
+TEST(ServerParameter, deprecatedAlias) {
+    IDLServerParameter param("basename"_sd, ServerParameterType::kStartupOnly);
+    IDLServerParameterDeprecatedAlias alias("aliasname"_sd, &param);
+    std::string value;
+    param.setFromString([&value](StringData str) {
+        value = str.toString();
+        return Status::OK();
+    });
+    ASSERT_OK(param.setFromString("alpha"));
+    ASSERT_EQ("alpha", value);
+
+    ASSERT_OK(alias.setFromString("bravo"));
+    ASSERT_EQ("bravo", value);
+}
+
+}  // namespace
+}  // namespace mongo