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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 <boost/scoped_ptr.hpp>
#include <string>
#include "mongo/base/status.h"
#include "mongo/db/diskloc.h"
#include "mongo/db/query/runner.h"
namespace mongo {
class BSONObj;
class CanonicalQuery;
class Collection;
class DiskLoc;
class PlanStage;
class TypeExplain;
struct PlanInfo;
/**
*/
class IDHackRunner : public Runner {
public:
/** Takes ownership of all the arguments -collection. */
IDHackRunner(const Collection* collection, CanonicalQuery* query);
IDHackRunner(Collection* collection, const BSONObj& key);
virtual ~IDHackRunner();
Runner::RunnerState getNext(BSONObj* objOut, DiskLoc* dlOut);
virtual bool isEOF();
virtual void saveState();
virtual bool restoreState();
virtual void setYieldPolicy(Runner::YieldPolicy policy);
virtual void invalidate(const DiskLoc& dl, InvalidationType type);
virtual const std::string& ns();
virtual void kill();
virtual const Collection* collection() { return _collection; }
virtual Status getInfo(TypeExplain** explain,
PlanInfo** planInfo) const;
/**
* ID Hack has a very strict criteria for the queries it supports.
*/
static bool supportsQuery(const CanonicalQuery& query);
private:
/**
* ID Hack queries are only covered with the projection {_id: 1}.
*/
bool hasCoveredProjection() const;
/**
* If '_query' has a projection, then apply it, returning the result in 'objOut'.
* The diskloc 'loc' contains the BSONObj to transform.
*
* Otherwise do nothing and return false.
*/
bool applyProjection(const DiskLoc& loc, BSONObj* objOut) const;
// Not owned here.
const Collection* _collection;
// The value to match against the _id field.
BSONObj _key;
// TODO: When we combine the canonicalize and getRunner steps into one we can get rid of
// this.
boost::scoped_ptr<CanonicalQuery> _query;
// Are we allowed to release the lock?
Runner::YieldPolicy _policy;
// Did someone call kill() on us?
bool _killed;
// Have we returned our one document?
bool _done;
// If we're yielding to fetch a document, what is it's diskloc? It may be invalidated
// while we're yielded.
DiskLoc _locFetching;
// Number of index keys scanned: should be either 0 or 1.
int _nscanned;
// Number of objects scanned: should be either 0 or 1.
int _nscannedObjects;
};
} // namespace mongo
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