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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/structure/record_store.h"
namespace mongo {
class CappedRecordStoreV1;
struct Extent;
/**
* This class iterates over a capped collection identified by 'ns'.
* The collection must exist when the constructor is called.
*
* If start is not DiskLoc(), the iteration begins at that DiskLoc.
*
* If tailable is true, getNext() can be called after isEOF. It will use the last valid
* returned DiskLoc and try to find the next record from that.
*/
class CappedRecordStoreV1Iterator : public RecordIterator {
public:
CappedRecordStoreV1Iterator( const CappedRecordStoreV1* collection,
const DiskLoc& start,
bool tailable,
const CollectionScanParams::Direction& dir );
virtual ~CappedRecordStoreV1Iterator() { }
// If this is a tailable cursor, isEOF could change its mind after a call to getNext().
virtual bool isEOF();
virtual DiskLoc getNext();
virtual DiskLoc curr();
virtual void invalidate(const DiskLoc& dl);
virtual void prepareToYield();
virtual bool recoverFromYield();
virtual const Record* recordFor( const DiskLoc& loc ) const;
private:
/**
* Internal collection navigation helper methods.
*/
DiskLoc getNextCapped(const DiskLoc& dl);
DiskLoc prevLoop(const DiskLoc& curr);
DiskLoc nextLoop(const DiskLoc& prev);
// some helpers - these move to RecordStore probably
Extent* _getExtent( const DiskLoc& loc );
DiskLoc _getNextRecord( const DiskLoc& loc );
DiskLoc _getPrevRecord( const DiskLoc& loc );
// The collection we're iterating over.
const CappedRecordStoreV1* _recordStore;
// The result returned on the next call to getNext().
DiskLoc _curr;
// If we're tailable, we try to progress from the last valid result when we hit the end.
DiskLoc _prev;
bool _tailable;
CollectionScanParams::Direction _direction;
// If invalidate kills the DiskLoc we need to move forward, we kill the iterator. See the
// comment in the body of invalidate(...).
bool _killedByInvalidate;
};
} // namespace mongo
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