SERVER-45904 Create a standalone collection sharding state factory

 create mode 100644 src/mongo/db/s/collection_sharding_state_factory_shard.h
 create mode 100644 src/mongo/db/s/collection_sharding_state_factory_standalone.cpp
 create mode 100644 src/mongo/db/s/collection_sharding_state_factory_standalone.h

1 files changed, 57 insertions, 0 deletions

diff --git a/src/mongo/db/s/collection_sharding_state_factory_shard.h b/src/mongo/db/s/collection_sharding_state_factory_shard.h
new file mode 100644
index 00000000000..f24929b4694
--- /dev/null
+++ b/src/mongo/db/s/collection_sharding_state_factory_shard.h
@@ -0,0 +1,57 @@
+/**
+ *    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
+
+#include "mongo/db/s/collection_sharding_state.h"
+#include "mongo/executor/task_executor.h"
+
+namespace mongo {
+
+class CollectionShardingStateFactoryShard final : public CollectionShardingStateFactory {
+public:
+    CollectionShardingStateFactoryShard(ServiceContext* serviceContext);
+
+    ~CollectionShardingStateFactoryShard();
+
+    void join() override;
+
+    std::unique_ptr<CollectionShardingState> make(const NamespaceString& nss) override;
+
+private:
+    std::shared_ptr<executor::TaskExecutor> _getExecutor();
+
+    // Serializes the instantiation of the task executor
+    Mutex _mutex = MONGO_MAKE_LATCH("CollectionShardingStateFactoryShard::_mutex");
+
+    // Required to be a shared_ptr since it is used as an executor for ExecutorFutures.
+    std::shared_ptr<executor::TaskExecutor> _taskExecutor = {nullptr};
+};
+
+}  // namespace mongo