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+/**
+ * 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/db/clientcursor.h"
+#include "mongo/db/namespace_string.h"
+#include "mongo/db/operation_context.h"
+#include "mongo/db/pipeline/external_data_source_option_gen.h"
+
+namespace mongo {
+/**
+ * This class makes sure that virtual collections that are created for external data sources are
+ * dropped when it's destroyed.
+ */
+class ExternalDataSourceScopeGuard {
+public:
+ // Makes ExternalDataSourceScopeGuard a decoration of ClientCursor.
+ static const ClientCursor::Decoration<std::shared_ptr<ExternalDataSourceScopeGuard>> get;
+
+ // Updates the operation context of decorated ExternalDataSourceScopeGuard object of 'cursor'
+ // so that it can drop virtual collections in the new 'opCtx'.
+ static void updateOperationContext(const ClientCursor* cursor, OperationContext* opCtx) {
+ if (auto self = get(cursor); self) {
+ get(cursor)->_opCtx = opCtx;
+ }
+ }
+
+ ExternalDataSourceScopeGuard() : _opCtx(nullptr), _toBeDroppedVirtualCollections() {}
+
+ ExternalDataSourceScopeGuard(
+ OperationContext* opCtx,
+ const std::vector<std::pair<NamespaceString, std::vector<ExternalDataSourceInfo>>>&
+ usedExternalDataSources);
+
+ // It does not make sense to support copy ctor because this object must drop created virtual
+ // collections.
+ ExternalDataSourceScopeGuard(const ExternalDataSourceScopeGuard&) = delete;
+
+ ExternalDataSourceScopeGuard(ExternalDataSourceScopeGuard&& other) noexcept
+ : _opCtx(other._opCtx),
+ _toBeDroppedVirtualCollections(std::move(other._toBeDroppedVirtualCollections)) {
+ // Ownership of created virtual collections are moved to this object and the other object
+ // must not try to drop them any more.
+ other._opCtx = nullptr;
+ }
+
+ ~ExternalDataSourceScopeGuard() {
+ dropVirtualCollections();
+ }
+
+private:
+ void dropVirtualCollections() noexcept;
+
+ OperationContext* _opCtx;
+ std::vector<NamespaceString> _toBeDroppedVirtualCollections;
+};
+} // namespace mongo