diff options
Diffstat (limited to 'src/mongo/db/exec/sbe/stages/co_scan.h')
-rw-r--r-- | src/mongo/db/exec/sbe/stages/co_scan.h | 59 |
1 files changed, 59 insertions, 0 deletions
diff --git a/src/mongo/db/exec/sbe/stages/co_scan.h b/src/mongo/db/exec/sbe/stages/co_scan.h new file mode 100644 index 00000000000..f88f3762852 --- /dev/null +++ b/src/mongo/db/exec/sbe/stages/co_scan.h @@ -0,0 +1,59 @@ +/** + * Copyright (C) 2019-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/exec/sbe/stages/stages.h" + +namespace mongo::sbe { +/** + * This is a CoScan PlanStage. It delivers an infinite stream of getNext() calls. Also, it does not + * define any slots; i.e. it does not produce any results. + * + * On its face value this does not seem to be very useful but it is handy when we have to construct + * a data stream when there is not any physical source (i.e. no collection to read from). + * Typical use cases are: inner side of Traverse, outer side of Nested Loops, constants, etc. + */ +class CoScanStage final : public PlanStage { +public: + CoScanStage(); + + std::unique_ptr<PlanStage> clone() const final; + + void prepare(CompileCtx& ctx) final; + value::SlotAccessor* getAccessor(CompileCtx& ctx, value::SlotId slot) final; + void open(bool reOpen) final; + PlanState getNext() final; + void close() final; + + std::unique_ptr<PlanStageStats> getStats() const final; + const SpecificStats* getSpecificStats() const final; + std::vector<DebugPrinter::Block> debugPrint() const final; +}; +} // namespace mongo::sbe |