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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 <boost/intrusive_ptr.hpp>
#include <boost/optional.hpp>
#include <memory>
#include <vector>
#include "mongo/db/pipeline/document_source.h"
#include "mongo/db/pipeline/lite_parsed_document_source.h"
#include "mongo/db/pipeline/lite_parsed_pipeline.h"
#include "mongo/db/pipeline/pipeline.h"
namespace mongo {
class BSONElement;
class TeeBuffer;
class DocumentSourceTeeConsumer;
class ExpressionContext;
class NamespaceString;
/**
* A $facet stage contains multiple sub-pipelines. Each input to the $facet stage will feed into
* each of the sub-pipelines. The $facet stage is blocking, and outputs only one document,
* containing an array of results for each sub-pipeline.
*
* For example, {$facet: {facetA: [{$skip: 1}], facetB: [{$limit: 1}]}} would describe a $facet
* stage which will produce a document like the following:
* {facetA: [<all input documents except the first one>], facetB: [<the first document>]}.
*/
class DocumentSourceFacet final : public DocumentSource {
public:
struct FacetPipeline {
FacetPipeline(std::string name, std::unique_ptr<Pipeline, PipelineDeleter> pipeline)
: name(std::move(name)), pipeline(std::move(pipeline)) {}
std::string name;
std::unique_ptr<Pipeline, PipelineDeleter> pipeline;
};
class LiteParsed : public LiteParsedDocumentSource {
public:
static std::unique_ptr<LiteParsed> parse(const AggregationRequest& request,
const BSONElement& spec);
LiteParsed(std::vector<LiteParsedPipeline> liteParsedPipelines, PrivilegeVector privileges)
: _liteParsedPipelines(std::move(liteParsedPipelines)),
_requiredPrivileges(std::move(privileges)) {}
PrivilegeVector requiredPrivileges(bool isMongos) const final {
return _requiredPrivileges;
}
stdx::unordered_set<NamespaceString> getInvolvedNamespaces() const final;
bool allowShardedForeignCollection(NamespaceString nss) const final;
bool allowedToPassthroughFromMongos() const {
// If any of the sub-pipelines doesn't allow pass through, then return false.
return std::all_of(_liteParsedPipelines.cbegin(),
_liteParsedPipelines.cend(),
[](const auto& subPipeline) {
return subPipeline.allowedToPassthroughFromMongos();
});
}
private:
const std::vector<LiteParsedPipeline> _liteParsedPipelines;
const PrivilegeVector _requiredPrivileges;
};
static boost::intrusive_ptr<DocumentSource> createFromBson(
BSONElement elem, const boost::intrusive_ptr<ExpressionContext>& pExpCtx);
static boost::intrusive_ptr<DocumentSourceFacet> create(
std::vector<FacetPipeline> facetPipelines,
const boost::intrusive_ptr<ExpressionContext>& expCtx);
/**
* Blocking call. Will consume all input and produces one output document.
*/
GetNextResult getNext() final;
/**
* Optimizes inner pipelines.
*/
boost::intrusive_ptr<DocumentSource> optimize() final;
/**
* Takes a union of all sub-pipelines, and adds them to 'deps'.
*/
DepsTracker::State getDependencies(DepsTracker* deps) const final;
const char* getSourceName() const final {
return "$facet";
}
/**
* Sets 'source' as the source of '_teeBuffer'.
*/
void setSource(DocumentSource* source) final;
/**
* The $facet stage must be run on the merging shard.
*
* TODO SERVER-24154: Should be smarter about splitting so that parts of the sub-pipelines can
* potentially be run in parallel on multiple shards.
*/
boost::optional<DistributedPlanLogic> distributedPlanLogic() final {
// {shardsStage, mergingStage, sortPattern}
return DistributedPlanLogic{nullptr, this, boost::none};
}
const std::vector<FacetPipeline>& getFacetPipelines() const {
return _facets;
}
auto& getFacetPipelines() {
return _facets;
}
// The following are overridden just to forward calls to sub-pipelines.
void addInvolvedCollections(stdx::unordered_set<NamespaceString>* involvedNssSet) const final;
void detachFromOperationContext() final;
void reattachToOperationContext(OperationContext* opCtx) final;
StageConstraints constraints(Pipeline::SplitState pipeState) const final;
bool usedDisk() final;
protected:
void doDispose() final;
private:
DocumentSourceFacet(std::vector<FacetPipeline> facetPipelines,
const boost::intrusive_ptr<ExpressionContext>& expCtx);
Value serialize(boost::optional<ExplainOptions::Verbosity> explain = boost::none) const final;
boost::intrusive_ptr<TeeBuffer> _teeBuffer;
std::vector<FacetPipeline> _facets;
bool _done = false;
};
} // namespace mongo
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