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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 <vector>
#include "mongo/base/status.h"
#include "mongo/db/diskloc.h"
#include "mongo/db/jsobj.h"
#include "mongo/db/index/index_cursor.h"
#include "mongo/db/index/index_descriptor.h"
#include "mongo/db/structure/btree/btree_interface.h"
namespace mongo {
class BtreeIndexCursor : public IndexCursor {
public:
virtual ~BtreeIndexCursor();
bool isEOF() const;
/**
* Called from btree_logic.cpp when we're about to delete a Btree bucket.
*/
static void aboutToDeleteBucket(const DiskLoc& bucket);
virtual Status setOptions(const CursorOptions& options);
virtual Status seek(const BSONObj& position);
// Btree-specific seeking functions.
Status seek(const std::vector<const BSONElement*>& position,
const std::vector<bool>& inclusive);
/**
* Seek to the key 'position'. If 'afterKey' is true, seeks to the first
* key that is oriented after 'position'.
*
* Btree-specific.
*/
void seek(const BSONObj& position, bool afterKey);
Status skip(const BSONObj& keyBegin,
int keyBeginLen,
bool afterKey,
const std::vector<const BSONElement*>& keyEnd,
const std::vector<bool>& keyEndInclusive);
virtual BSONObj getKey() const;
virtual DiskLoc getValue() const;
virtual void next();
/**
* BtreeIndexCursor-only.
* Returns true if 'this' points at the same exact key as 'other'.
* Returns false otherwise.
*/
bool pointsAt(const BtreeIndexCursor& other);
virtual Status savePosition();
virtual Status restorePosition();
virtual std::string toString();
private:
// We keep the constructor private and only allow the AM to create us.
friend class BtreeBasedAccessMethod;
/**
* head is the head of the Btree.
* interface is an abstraction to hide the fact that we have two types of Btrees.
*
* 'this' will forward by default. Call setOptions to change this.
* XXX: put options in ctor(?)
*
* Intentionally private, we're friends with the only class allowed to call it.
*/
BtreeIndexCursor(const DiskLoc head,
BtreeInterface* newInterface);
bool isSavedPositionValid();
/**
* Move to the next (or previous depending on the direction) key. Used by normal getNext
* and also skipping unused keys.
*/
void advance();
// For handling bucket deletion.
static unordered_set<BtreeIndexCursor*> _activeCursors;
static SimpleMutex _activeCursorsMutex;
// For saving/restoring position.
BtreeInterface::SavedPositionData _savedData;
int _direction;
// Not owned here.
BtreeInterface* _interface;
// TODO: Have some kind of BtreeInterface::BtreePosition to encapsulate this.
// What are we looking at RIGHT NOW? We look at a bucket.
DiskLoc _bucket;
// And we look at an offset in the bucket.
int _keyOffset;
};
} // namespace mongo
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