SERVER-74006 Introduce abstraction for accessing the cluster-wide maxWireVersion

4 files changed, 124 insertions, 0 deletions

diff --git a/src/mongo/transport/SConscript b/src/mongo/transport/SConscript
index 6903da79f4d..84680f2813a 100644
--- a/src/mongo/transport/SConscript
+++ b/src/mongo/transport/SConscript
@@ -4,6 +4,15 @@ Import('env')
 
 env = env.Clone()
 
+env.SConscript(
+    dirs=[
+        'grpc',
+    ],
+    exports=[
+        'env',
+    ],
+)
+
 env.Library(
     target='transport_layer_common',
     source=[
@@ -59,6 +68,7 @@ tlEnv.Library(
         'transport_layer_manager.cpp',
     ],
     LIBDEPS=[
+        'grpc/grpc_transport_layer' if env.TargetOSIs('linux') else [],
         'transport_layer',
     ],
     LIBDEPS_PRIVATE=[
diff --git a/src/mongo/transport/grpc/SConscript b/src/mongo/transport/grpc/SConscript
new file mode 100644
index 00000000000..d093c777ed9
--- /dev/null
+++ b/src/mongo/transport/grpc/SConscript
@@ -0,0 +1,15 @@
+# -*- mode: python -*-
+
+Import('env')
+
+env = env.Clone()
+
+env.Library(
+    target='grpc_transport_layer',
+    source=[
+        'wire_version_provider.cpp',
+    ],
+    LIBDEPS=[
+        '$BUILD_DIR/mongo/db/wire_version',
+    ],
+)
diff --git a/src/mongo/transport/grpc/wire_version_provider.cpp b/src/mongo/transport/grpc/wire_version_provider.cpp
new file mode 100644
index 00000000000..c3084c13742
--- /dev/null
+++ b/src/mongo/transport/grpc/wire_version_provider.cpp
@@ -0,0 +1,40 @@
+/**
+ *    Copyright (C) 2023-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/transport/grpc/wire_version_provider.h"
+
+#include "mongo/db/wire_version.h"
+
+namespace mongo::transport::grpc {
+
+int WireVersionProvider::getClusterMaxWireVersion() const {
+    return WireSpec::instance().get()->incomingExternalClient.maxWireVersion;
+}
+
+}  // namespace mongo::transport::grpc
diff --git a/src/mongo/transport/grpc/wire_version_provider.h b/src/mongo/transport/grpc/wire_version_provider.h
new file mode 100644
index 00000000000..a391948bbf5
--- /dev/null
+++ b/src/mongo/transport/grpc/wire_version_provider.h
@@ -0,0 +1,59 @@
+/**
+ *    Copyright (C) 2023-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/db/wire_version.h"
+
+namespace mongo::transport::grpc {
+
+class WireVersionProvider {
+public:
+    WireVersionProvider() = default;
+    WireVersionProvider(const WireVersionProvider&) = delete;
+    WireVersionProvider& operator=(const WireVersionProvider&) = delete;
+
+    /**
+     * Gets this server's understanding of the minimum maxWireVersion value for all servers in the
+     * cluster. This is used to gossip the wire version gRPC clients should use when constructing
+     * commands, as per the MongoDB gRPC Protocol.
+     *
+     * If this server is a mongos, "all servers in the cluster" refers to all the mongoses in the
+     * sharded cluster. If this server is a mongod, "all servers in the cluster" refers to that
+     * mongod alone, since gRPC clients only support direct connections to mongods and do not
+     * support communicating with entire replica sets.
+     *
+     * Currently, this method just returns this server's maxWireVersion, since the current version
+     * is the only server version that supports gRPC. In the future, the provider will be augmented
+     * to account for the other servers in the cluster.
+     */
+    int getClusterMaxWireVersion() const;
+};
+
+}  // namespace mongo::transport::grpc