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/**
* Copyright (C) 2016 MongoDB Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License, version 3,
* as published by the Free Software Foundation.
*
* 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
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
* 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 GNU Affero General 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"
#include "mongo/db/pipeline/document_source_match.h"
#include "mongo/db/pipeline/document_source_unwind.h"
#include "mongo/db/pipeline/expression.h"
#include "mongo/db/pipeline/lookup_set_cache.h"
#include "mongo/db/pipeline/value_comparator.h"
namespace mongo {
/**
* Queries separate collection for equality matches with documents in the pipeline collection.
* Adds matching documents to a new array field in the input document.
*/
class DocumentSourceLookUp final : public DocumentSourceNeedsMongod,
public SplittableDocumentSource {
public:
static std::unique_ptr<LiteParsedDocumentSourceOneForeignCollection> liteParse(
const AggregationRequest& request, const BSONElement& spec);
GetNextResult getNext() final;
const char* getSourceName() const final;
void serializeToArray(
std::vector<Value>& array,
boost::optional<ExplainOptions::Verbosity> explain = boost::none) const final;
/**
* Returns the 'as' path, and possibly fields modified by an absorbed $unwind.
*/
GetModPathsReturn getModifiedPaths() const final;
bool canSwapWithMatch() const final {
return true;
}
/**
* Attempts to combine with a subsequent $unwind stage, setting the internal '_unwindSrc'
* field.
*/
Pipeline::SourceContainer::iterator doOptimizeAt(Pipeline::SourceContainer::iterator itr,
Pipeline::SourceContainer* container) final;
GetDepsReturn getDependencies(DepsTracker* deps) const final;
void dispose() final;
BSONObjSet getOutputSorts() final {
return DocumentSource::truncateSortSet(pSource->getOutputSorts(), {_as.fullPath()});
}
bool needsPrimaryShard() const final {
return true;
}
boost::intrusive_ptr<DocumentSource> getShardSource() final {
return nullptr;
}
boost::intrusive_ptr<DocumentSource> getMergeSource() final {
return this;
}
void addInvolvedCollections(std::vector<NamespaceString>* collections) const final {
collections->push_back(_fromNs);
}
void doDetachFromOperationContext() final;
void doReattachToOperationContext(OperationContext* opCtx) final;
static boost::intrusive_ptr<DocumentSource> createFromBson(
BSONElement elem, const boost::intrusive_ptr<ExpressionContext>& pExpCtx);
/**
* Builds the BSONObj used to query the foreign collection and wraps it in a $match.
*/
static BSONObj makeMatchStageFromInput(const Document& input,
const FieldPath& localFieldName,
const std::string& foreignFieldName,
const BSONObj& additionalFilter);
/**
* Helper to absorb an $unwind stage. Only used for testing this special behavior.
*/
void setUnwindStage(const boost::intrusive_ptr<DocumentSourceUnwind>& unwind) {
invariant(!_handlingUnwind);
_unwindSrc = unwind;
_handlingUnwind = true;
}
private:
DocumentSourceLookUp(NamespaceString fromNs,
std::string as,
std::string localField,
std::string foreignField,
const boost::intrusive_ptr<ExpressionContext>& pExpCtx);
Value serialize(boost::optional<ExplainOptions::Verbosity> explain = boost::none) const final {
// Should not be called; use serializeToArray instead.
MONGO_UNREACHABLE;
}
GetNextResult unwindResult();
NamespaceString _fromNs;
FieldPath _as;
FieldPath _localField;
FieldPath _foreignField;
std::string _foreignFieldFieldName;
boost::optional<BSONObj> _additionalFilter;
// The ExpressionContext used when performing aggregation pipelines against the '_fromNs'
// namespace.
boost::intrusive_ptr<ExpressionContext> _fromExpCtx;
// The aggregation pipeline to perform against the '_fromNs' namespace.
std::vector<BSONObj> _fromPipeline;
boost::intrusive_ptr<DocumentSourceMatch> _matchSrc;
boost::intrusive_ptr<DocumentSourceUnwind> _unwindSrc;
bool _handlingUnwind = false;
bool _handlingMatch = false;
// The following members are used to hold onto state across getNext() calls when
// '_handlingUnwind' is true.
long long _cursorIndex = 0;
boost::intrusive_ptr<Pipeline> _pipeline;
boost::optional<Document> _input;
boost::optional<Document> _nextValue;
};
} // namespace mongo
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