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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/>.
*/
#pragma once
#include "mongo/db/diskloc.h"
#include "mongo/db/jsobj.h"
#include "mongo/db/matcher.h"
#include "mongo/db/exec/plan_stage.h"
#include "mongo/platform/unordered_set.h"
namespace mongo {
class IndexAccessMethod;
class IndexCursor;
class IndexDescriptor;
class IndexScanParams;
class WorkingSet;
/**
* Stage scans over an index from startKey to endKey, returning results that pass the provided
* filter. Internally dedups on DiskLoc.
*
* Sub-stage preconditions: None. Is a leaf and consumes no stage data.
*/
class IndexScan : public PlanStage {
public:
IndexScan(const IndexScanParams& params, WorkingSet* workingSet, Matcher* matcher);
virtual ~IndexScan() { }
virtual StageState work(WorkingSetID* out);
virtual bool isEOF();
virtual void prepareToYield();
virtual void recoverFromYield();
virtual void invalidate(const DiskLoc& dl);
private:
/** See if the cursor is pointing at or past _endKey, if _endKey is non-empty. */
void checkEnd();
// The WorkingSet we annotate with results. Not owned by us.
WorkingSet* _workingSet;
// Index access.
scoped_ptr<IndexAccessMethod> _iam;
scoped_ptr<IndexCursor> _indexCursor;
scoped_ptr<IndexDescriptor> _descriptor;
// Bounds for the cursor. TODO: take a set of bounds.
BSONObj _startKey;
BSONObj _endKey;
bool _endKeyInclusive;
int _direction;
bool _hitEnd;
// Contains expressions only over fields in the index key. We assume this is built
// correctly by whomever creates this class.
scoped_ptr<Matcher> _matcher;
// Could our index have duplicates? If so, we use _returned to dedup.
bool _shouldDedup;
unordered_set<DiskLoc, DiskLoc::Hasher> _returned;
// For yielding.
BSONObj _savedKey;
DiskLoc _savedLoc;
// True if there was a yield and the yield changed the cursor position.
bool _yieldMovedCursor;
// This is IndexScanParams::limit. See comment there.
int _numWanted;
};
struct IndexScanParams {
IndexScanParams() : descriptor(NULL), endKeyInclusive(true), direction(1), limit(0),
forceBtreeAccessMethod(false) { }
IndexDescriptor* descriptor;
BSONObj startKey;
BSONObj endKey;
bool endKeyInclusive;
int direction;
// This only matters for 2d indices and will be ignored by every other index.
int limit;
// Special indices internally open an IndexCursor over themselves but as a straight Btree.
bool forceBtreeAccessMethod;
};
} // namespace mongo
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