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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 "mongo/db/diskloc.h"
#include "mongo/db/exec/collection_scan_common.h"
#include "mongo/db/exec/plan_stage.h"
#include "mongo/db/matcher/expression.h"
namespace mongo {
class RecordIterator;
class WorkingSet;
/**
* Scans over a collection, starting at the DiskLoc provided in params and continuing until
* there are no more records in the collection.
*
* Preconditions: Valid DiskLoc.
*/
class CollectionScan : public PlanStage {
public:
CollectionScan(const CollectionScanParams& params,
WorkingSet* workingSet,
const MatchExpression* filter);
virtual StageState work(WorkingSetID* out);
virtual bool isEOF();
virtual void invalidate(const DiskLoc& dl, InvalidationType type);
virtual void prepareToYield();
virtual void recoverFromYield();
virtual PlanStageStats* getStats();
static const char* kStageType;
private:
/**
* Returns true if the record 'loc' references is in memory, false otherwise.
*/
bool diskLocInMemory(DiskLoc loc);
// WorkingSet is not owned by us.
WorkingSet* _workingSet;
// The filter is not owned by us.
const MatchExpression* _filter;
scoped_ptr<RecordIterator> _iter;
CollectionScanParams _params;
// True if Database::getCollection(_ns) == NULL on our first call to work.
bool _nsDropped;
// Stats
CommonStats _commonStats;
CollectionScanStats _specificStats;
};
} // namespace mongo
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