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/**
* Copyright (C) 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 <boost/scoped_ptr.hpp>
#include "mongo/db/exec/plan_stage.h"
#include "mongo/db/diskloc.h"
#include "mongo/db/index/btree_index_cursor.h"
#include "mongo/db/index/index_access_method.h"
#include "mongo/db/jsobj.h"
#include "mongo/db/matcher/expression.h"
#include "mongo/db/operation_context.h"
#include "mongo/platform/unordered_set.h"
namespace mongo {
class IndexAccessMethod;
class IndexDescriptor;
class WorkingSet;
struct CountParams {
CountParams() : descriptor(NULL) { }
// What index are we traversing?
const IndexDescriptor* descriptor;
BSONObj startKey;
bool startKeyInclusive;
BSONObj endKey;
bool endKeyInclusive;
};
/**
* Used by the count command. Scans an index from a start key to an end key. Does not create
* any WorkingSetMember(s) for any of the data, instead returning ADVANCED to indicate to the
* caller that another result should be counted.
*
* Only created through the getExecutorCount path, as count is the only operation that doesn't
* care about its data.
*/
class Count : public PlanStage {
public:
Count(OperationContext* txn, const CountParams& params, WorkingSet* workingSet);
virtual ~Count() { }
virtual StageState work(WorkingSetID* out);
virtual bool isEOF();
virtual void prepareToYield();
virtual void recoverFromYield(OperationContext* opCtx);
virtual void invalidate(const DiskLoc& dl, InvalidationType type);
virtual std::vector<PlanStage*> getChildren() const;
virtual StageType stageType() const { return STAGE_COUNT; }
virtual PlanStageStats* getStats();
virtual const CommonStats* getCommonStats();
virtual const SpecificStats* getSpecificStats();
static const char* kStageType;
private:
/**
* Initialize the underlying IndexCursor
*/
void initIndexCursor();
/**
* See if we've hit the end yet.
*/
void checkEnd();
// transactional context for read locks. Not owned by us
OperationContext* _txn;
// The WorkingSet we annotate with results. Not owned by us.
WorkingSet* _workingSet;
// Index access. Both pointers below are owned by Collection -> IndexCatalog.
const IndexDescriptor* _descriptor;
const IndexAccessMethod* _iam;
// Our start cursor is _btreeCursor.
boost::scoped_ptr<BtreeIndexCursor> _btreeCursor;
// Our end marker.
boost::scoped_ptr<BtreeIndexCursor> _endCursor;
// Could our index have duplicates? If so, we use _returned to dedup.
unordered_set<DiskLoc, DiskLoc::Hasher> _returned;
CountParams _params;
bool _hitEnd;
bool _shouldDedup;
CommonStats _commonStats;
CountStats _specificStats;
};
} // namespace mongo
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