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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 "mongo/db/pipeline/document_source.h"
#include "mongo/db/pipeline/expression_context.h"
#include "mongo/db/pipeline/tee_buffer.h"
namespace mongo {
class Document;
class ExpressionContext;
class Value;
/**
* This stage acts as a proxy between a pipeline within a $facet stage and the buffer of incoming
* documents held in a TeeBuffer stage. It will simply open an iterator on the TeeBuffer stage, and
* answer calls to getNext() by advancing said iterator.
*/
class DocumentSourceTeeConsumer : public DocumentSource {
public:
static boost::intrusive_ptr<DocumentSourceTeeConsumer> create(
const boost::intrusive_ptr<ExpressionContext>& expCtx,
size_t facetId,
const boost::intrusive_ptr<TeeBuffer>& bufferSource);
StageConstraints constraints(Pipeline::SplitState pipeState) const final {
return {StreamType::kStreaming,
PositionRequirement::kNone,
HostTypeRequirement::kNone,
DiskUseRequirement::kNoDiskUse,
FacetRequirement::kAllowed,
TransactionRequirement::kAllowed};
}
GetNextResult getNext() final;
/**
* Returns SEE_NEXT, since it requires no fields, and changes nothing about the documents.
*/
DepsTracker::State getDependencies(DepsTracker* deps) const final {
return DepsTracker::State::SEE_NEXT;
}
Value serialize(boost::optional<ExplainOptions::Verbosity> explain = boost::none) const final;
protected:
void doDispose() final;
private:
DocumentSourceTeeConsumer(const boost::intrusive_ptr<ExpressionContext>& expCtx,
size_t facetId,
const boost::intrusive_ptr<TeeBuffer>& bufferSource);
size_t _facetId;
boost::intrusive_ptr<TeeBuffer> _bufferSource;
};
} // namespace mongo
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