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/**
* Copyright (C) 2013 10gen 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 <queue>
#include <vector>
#include "mongo/db/exec/plan_stage.h"
#include "mongo/db/jsobj.h"
#include "mongo/db/matcher/expression.h"
#include "mongo/db/record_id.h"
#include "mongo/platform/unordered_set.h"
namespace mongo {
/**
* Reads from N children, each of which must have a valid RecordId. Assumes each child produces
* RecordIds in sorted order. Outputs the intersection of the RecordIds outputted by the
* children.
*
* Preconditions: Valid RecordId. More than one child.
*
* Any RecordId that we keep a reference to that is invalidated before we are able to return it
* is fetched and added to the WorkingSet as "flagged for further review." Because this stage
* operates with RecordIds, we are unable to evaluate the AND for the invalidated RecordId, and it
* must be fully matched later.
*/
class AndSortedStage : public PlanStage {
public:
AndSortedStage(WorkingSet* ws, const Collection* collection);
virtual ~AndSortedStage();
void addChild(PlanStage* child);
virtual StageState work(WorkingSetID* out);
virtual bool isEOF();
virtual void saveState();
virtual void restoreState(OperationContext* opCtx);
virtual void invalidate(OperationContext* txn, const RecordId& dl, InvalidationType type);
virtual std::vector<PlanStage*> getChildren() const;
virtual StageType stageType() const {
return STAGE_AND_SORTED;
}
virtual PlanStageStats* getStats();
virtual const CommonStats* getCommonStats() const;
virtual const SpecificStats* getSpecificStats() const;
static const char* kStageType;
private:
// Find a node to AND against.
PlanStage::StageState getTargetLoc(WorkingSetID* out);
// Move a child which hasn't advanced to the target node forward.
// Returns the target node in 'out' if all children successfully advance to it.
PlanStage::StageState moveTowardTargetLoc(WorkingSetID* out);
// Not owned by us.
const Collection* _collection;
// Not owned by us.
WorkingSet* _ws;
// Owned by us.
std::vector<PlanStage*> _children;
// The current node we're AND-ing against.
size_t _targetNode;
RecordId _targetLoc;
WorkingSetID _targetId;
// Nodes we're moving forward until they hit the element we're AND-ing.
// Everything in here has not advanced to _targetLoc yet.
// These are indices into _children.
std::queue<size_t> _workingTowardRep;
// If any child hits EOF or if we have any errors, we're EOF.
bool _isEOF;
// Stats
CommonStats _commonStats;
AndSortedStats _specificStats;
};
} // namespace mongo
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