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/**
* 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/pipeline/document_source.h"
namespace mongo {
/**
* An internal stage available for testing. Acts as a simple passthrough of intermediate results
* from the source stage, but forces the pipeline to split at the point where this stage appears
* (assuming that no earlier splitpoints exist). Takes a single parameter, 'mergeType', which can be
* one of 'primaryShard', 'anyShard' or 'mongos' to control where the merge may occur. Omitting this
* parameter or specifying 'mongos' produces the default merging behaviour; the merge half of the
* pipeline will be executed on mongoS if all other stages are eligible, and will be sent to a
* random participating shard otherwise.
*/
class DocumentSourceInternalSplitPipeline final : public DocumentSource {
public:
static constexpr StringData kStageName = "$_internalSplitPipeline"_sd;
static boost::intrusive_ptr<DocumentSource> createFromBson(
BSONElement, const boost::intrusive_ptr<ExpressionContext>&);
static boost::intrusive_ptr<DocumentSource> create(
const boost::intrusive_ptr<ExpressionContext>& expCtx, HostTypeRequirement mergeType) {
return new DocumentSourceInternalSplitPipeline(expCtx, mergeType);
}
const char* getSourceName() const final {
return kStageName.rawData();
}
boost::optional<DistributedPlanLogic> distributedPlanLogic() final {
// {shardsStage, mergingStage, sortPattern}
return DistributedPlanLogic{nullptr, this, boost::none};
}
StageConstraints constraints(Pipeline::SplitState pipeState) const final {
return {StreamType::kStreaming,
PositionRequirement::kNone,
_mergeType,
DiskUseRequirement::kNoDiskUse,
FacetRequirement::kAllowed,
TransactionRequirement::kAllowed,
_mergeType == HostTypeRequirement::kMongoS ? LookupRequirement::kNotAllowed
: LookupRequirement::kAllowed,
UnionRequirement::kAllowed};
}
void addVariableRefs(std::set<Variables::Id>* refs) const final {}
private:
DocumentSourceInternalSplitPipeline(const boost::intrusive_ptr<ExpressionContext>& expCtx,
HostTypeRequirement mergeType)
: DocumentSource(kStageName, expCtx), _mergeType(mergeType) {}
GetNextResult doGetNext() final;
Value serialize(SerializationOptions opts = SerializationOptions()) const final override;
HostTypeRequirement _mergeType = HostTypeRequirement::kNone;
};
} // namespace mongo
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