SERVER-74380 Make the router loop not invariant on unexpected namespacesr6.0.6-rc0

1 files changed, 125 insertions, 0 deletions

diff --git a/src/mongo/s/router_role.h b/src/mongo/s/router_role.h
new file mode 100644
index 00000000000..6cfd1d9e546
--- /dev/null
+++ b/src/mongo/s/router_role.h
@@ -0,0 +1,125 @@
+/**
+ *    Copyright (C) 2022-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/bson/bsonobjbuilder.h"
+#include "mongo/db/namespace_string.h"
+#include "mongo/db/operation_context.h"
+#include "mongo/s/catalog_cache.h"
+
+namespace mongo {
+namespace sharding {
+namespace router {
+
+class RouterBase {
+protected:
+    RouterBase(ServiceContext* service);
+
+    struct RouteContext {
+        const std::string comment;
+        int numAttempts{0};
+    };
+
+    ServiceContext* const _service;
+};
+
+// Both the router classes below declare the scope in which their 'route' method is executed as a
+// router for the relevant database or collection. These classes are the only way to obtain routing
+// information for a given entry.
+
+/**
+ * This class should mostly be used for routing of DDL operations which need to be coordinated from
+ * the primary shard of the database.
+ */
+class DBPrimaryRouter : public RouterBase {
+public:
+    DBPrimaryRouter(ServiceContext* service, StringData db);
+
+    template <typename F>
+    auto route(OperationContext* opCtx, StringData comment, F&& callbackFn) {
+        RouteContext context{comment.toString()};
+        while (true) {
+            auto cdb = _getRoutingInfo(opCtx);
+            try {
+                return callbackFn(opCtx, cdb);
+            } catch (const DBException& ex) {
+                _onException(&context, ex.toStatus());
+            }
+        }
+    }
+
+    static void appendDDLRoutingTokenToCommand(const DatabaseType& dbt, BSONObjBuilder* builder);
+
+    static void appendCRUDUnshardedRoutingTokenToCommand(const ShardId& shardId,
+                                                         const DatabaseVersion& dbVersion,
+                                                         BSONObjBuilder* builder);
+
+private:
+    CachedDatabaseInfo _getRoutingInfo(OperationContext* opCtx) const;
+    void _onException(RouteContext* context, Status s);
+
+    std::string _db;
+};
+
+/**
+ * This class should mostly be used for routing CRUD operations which need to have a view of the
+ * entire routing table for a collection.
+ */
+class CollectionRouter : public RouterBase {
+public:
+    CollectionRouter(ServiceContext* service, NamespaceString nss);
+
+    template <typename F>
+    auto route(OperationContext* opCtx, StringData comment, F&& callbackFn) {
+        RouteContext context{comment.toString()};
+        while (true) {
+            auto cm = _getRoutingInfo(opCtx);
+            try {
+                return callbackFn(opCtx, cm);
+            } catch (const DBException& ex) {
+                _onException(&context, ex.toStatus());
+            }
+        }
+    }
+
+    static void appendCRUDRoutingTokenToCommand(const ShardId& shardId,
+                                                const ChunkManager& cm,
+                                                BSONObjBuilder* builder);
+
+private:
+    ChunkManager _getRoutingInfo(OperationContext* opCtx) const;
+    void _onException(RouteContext* context, Status s);
+
+    NamespaceString _nss;
+};
+
+}  // namespace router
+}  // namespace sharding
+}  // namespace mongo