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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 <memory>
#include "mongo/bson/bsonobj.h"
#include "mongo/db/namespace_string.h"
#include "mongo/db/pipeline/aggregation_request.h"
#include "mongo/db/pipeline/dependencies.h"
#include "mongo/db/pipeline/document_source_cursor.h"
#include "mongo/db/pipeline/document_source_group.h"
#include "mongo/db/query/plan_executor.h"
namespace mongo {
class Collection;
class DocumentSourceCursor;
class DocumentSourceMatch;
class DocumentSourceSort;
class ExpressionContext;
class OperationContext;
class Pipeline;
struct PlanSummaryStats;
/**
* PipelineD is an extension of the Pipeline class, but with additional material that references
* symbols that are not available in mongos, where the remainder of the Pipeline class also
* functions. PipelineD is a friend of Pipeline so that it can have equal access to Pipeline's
* members.
*
* See the friend declaration in Pipeline.
*/
class PipelineD {
public:
/**
* If the first stage in the pipeline does not generate its own output documents, attaches a
* cursor document source to the front of the pipeline which will output documents from the
* collection to feed into the pipeline.
*
* This method looks for early pipeline stages that can be folded into the underlying
* PlanExecutor, and removes those stages from the pipeline when they can be absorbed by the
* PlanExecutor. For example, an early $match can be removed and replaced with a
* DocumentSourceCursor containing a PlanExecutor that will do an index scan.
*
* Callers must take care to ensure that 'nss' is locked in at least IS-mode.
*
* When not null, 'aggRequest' provides access to pipeline command options such as hint.
*/
static void prepareCursorSource(Collection* collection,
const NamespaceString& nss,
const AggregationRequest* aggRequest,
Pipeline* pipeline);
/**
* Prepare a generic DocumentSourceCursor for 'pipeline'.
*/
static void prepareGenericCursorSource(Collection* collection,
const NamespaceString& nss,
const AggregationRequest* aggRequest,
Pipeline* pipeline);
/**
* Prepare a special DocumentSourceGeoNearCursor for 'pipeline'. Unlike
* 'prepareGenericCursorSource()', throws if 'collection' does not exist, as the $geoNearCursor
* requires a 2d or 2dsphere index.
*/
static void prepareGeoNearCursorSource(Collection* collection,
const NamespaceString& nss,
const AggregationRequest* aggRequest,
Pipeline* pipeline);
static std::string getPlanSummaryStr(const Pipeline* pipeline);
static void getPlanSummaryStats(const Pipeline* pipeline, PlanSummaryStats* statsOut);
static Timestamp getLatestOplogTimestamp(const Pipeline* pipeline);
private:
PipelineD(); // does not exist: prevent instantiation
/**
* Creates a PlanExecutor to be used in the initial cursor source. If the query system can use
* an index to provide a more efficient sort or projection, the sort and/or projection will be
* incorporated into the PlanExecutor.
*
* 'sortObj' will be set to an empty object if the query system cannot provide a non-blocking
* sort, and 'projectionObj' will be set to an empty object if the query system cannot provide a
* covered projection.
*
* Set 'rewrittenGroupStage' when the pipeline uses $match+$sort+$group stages that are
* compatible with a DISTINCT_SCAN plan that visits the first document in each group
* (SERVER-9507).
*/
static StatusWith<std::unique_ptr<PlanExecutor, PlanExecutor::Deleter>> prepareExecutor(
OperationContext* opCtx,
Collection* collection,
const NamespaceString& nss,
Pipeline* pipeline,
const boost::intrusive_ptr<ExpressionContext>& expCtx,
bool oplogReplay,
const boost::intrusive_ptr<DocumentSourceSort>& sortStage,
std::unique_ptr<GroupFromFirstDocumentTransformation> rewrittenGroupStage,
const DepsTracker& deps,
const BSONObj& queryObj,
const AggregationRequest* aggRequest,
const MatchExpressionParser::AllowedFeatureSet& matcherFeatures,
BSONObj* sortObj,
BSONObj* projectionObj);
/**
* Adds 'cursor' to the front of 'pipeline', using 'deps' to inform the cursor of its
* dependencies. If specified, 'queryObj', 'sortObj' and 'projectionObj' are passed to the
* cursor for explain reporting.
*/
static void addCursorSource(Pipeline* pipeline,
boost::intrusive_ptr<DocumentSourceCursor> cursor,
DepsTracker deps,
const BSONObj& queryObj = BSONObj(),
const BSONObj& sortObj = BSONObj(),
const BSONObj& projectionObj = BSONObj());
};
} // namespace mongo
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