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/**
* Copyright (C) 2014 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/catalog/collection.h"
#include "mongo/db/exec/plan_stage.h"
#include "mongo/db/exec/plan_stats.h"
#include "mongo/db/record_id.h"
namespace mongo {
/**
* Iterates over a collection using multiple underlying RecordIterators.
*
* This is a special stage which is not used automatically by queries. It is intended for
* special commands that work with RecordIterators. For example, it is used by the
* parallelCollectionScan and repairCursor commands
*/
class MultiIteratorStage : public PlanStage {
public:
MultiIteratorStage(OperationContext* txn, WorkingSet* ws, Collection* collection);
~MultiIteratorStage() { }
/**
* Takes ownership of 'it'.
*/
void addIterator(RecordIterator* it);
virtual PlanStage::StageState work(WorkingSetID* out);
virtual bool isEOF();
void kill();
virtual void saveState();
virtual void restoreState(OperationContext* opCtx);
virtual void invalidate(OperationContext* txn, const DiskLoc& dl, InvalidationType type);
//
// These should not be used.
//
virtual PlanStageStats* getStats() { return NULL; }
virtual CommonStats* getCommonStats() { return NULL; }
virtual SpecificStats* getSpecificStats() { return NULL; }
virtual std::vector<PlanStage*> getChildren() const;
virtual StageType stageType() const { return STAGE_MULTI_ITERATOR; }
private:
/**
* @return if more data
*/
DiskLoc _advance();
OperationContext* _txn;
Collection* _collection;
OwnedPointerVector<RecordIterator> _iterators;
// Not owned by us.
WorkingSet* _ws;
// We allocate a working set member with this id on construction of the stage. It gets
// used for all fetch requests, changing the DiskLoc as appropriate.
const WorkingSetID _wsidForFetch;
};
} // namespace mongo
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