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/**
* Copyright (C) 2013-2014 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 <memory>
#include "mongo/db/exec/collection_scan_common.h"
#include "mongo/db/exec/plan_stage.h"
#include "mongo/db/matcher/expression.h"
#include "mongo/db/record_id.h"
namespace mongo {
class RecordCursor;
class WorkingSet;
class OperationContext;
/**
* Scans over a collection, starting at the RecordId provided in params and continuing until
* there are no more records in the collection.
*
* Preconditions: Valid RecordId.
*/
class CollectionScan : public PlanStage {
public:
CollectionScan(OperationContext* txn,
const CollectionScanParams& params,
WorkingSet* workingSet,
const MatchExpression* filter);
virtual StageState work(WorkingSetID* out);
virtual bool isEOF();
virtual void invalidate(OperationContext* txn, const RecordId& dl, InvalidationType type);
virtual void saveState();
virtual void restoreState(OperationContext* opCtx);
virtual std::vector<PlanStage*> getChildren() const;
virtual StageType stageType() const {
return STAGE_COLLSCAN;
}
virtual PlanStageStats* getStats();
virtual const CommonStats* getCommonStats() const;
virtual const SpecificStats* getSpecificStats() const;
static const char* kStageType;
private:
/**
* If the member (with id memberID) passes our filter, set *out to memberID and return that
* ADVANCED. Otherwise, free memberID and return NEED_TIME.
*/
StageState returnIfMatches(WorkingSetMember* member, WorkingSetID memberID, WorkingSetID* out);
// transactional context for read locks. Not owned by us
OperationContext* _txn;
// WorkingSet is not owned by us.
WorkingSet* _workingSet;
// The filter is not owned by us.
const MatchExpression* _filter;
std::unique_ptr<RecordCursor> _cursor;
CollectionScanParams _params;
bool _isDead;
RecordId _lastSeenId; // Null if nothing has been returned from _cursor yet.
// We allocate a working set member with this id on construction of the stage. It gets
// used for all fetch requests, changing the RecordId as appropriate.
const WorkingSetID _wsidForFetch;
// Stats
CommonStats _commonStats;
CollectionScanStats _specificStats;
};
} // namespace mongo
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