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/**
* Copyright (C) 2018-present MongoDB, Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the Server Side Public License, version 1,
* as published by MongoDB, Inc.
*
* 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
* Server Side Public License for more details.
*
* You should have received a copy of the Server Side Public License
* along with this program. If not, see
* <http://www.mongodb.com/licensing/server-side-public-license>.
*
* 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 Server Side 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/catalog/collection.h"
#include "mongo/db/exec/requires_index_stage.h"
#include "mongo/db/matcher/expression.h"
#include "mongo/db/operation_context.h"
#include "mongo/db/record_id.h"
#include "mongo/db/storage/sorted_data_interface.h"
#include "mongo/stdx/unordered_set.h"
namespace mongo {
class WorkingSet;
struct CountScanParams {
CountScanParams(const IndexDescriptor* descriptor,
std::string indexName,
BSONObj keyPattern,
MultikeyPaths multikeyPaths,
bool multikey)
: indexDescriptor(descriptor),
name(std::move(indexName)),
keyPattern(std::move(keyPattern)),
multikeyPaths(std::move(multikeyPaths)),
isMultiKey(multikey) {
invariant(descriptor);
}
CountScanParams(OperationContext* opCtx,
const CollectionPtr& collection,
const IndexDescriptor* descriptor)
: CountScanParams(descriptor,
descriptor->indexName(),
descriptor->keyPattern(),
descriptor->getEntry()->getMultikeyPaths(opCtx, collection),
descriptor->getEntry()->isMultikey(opCtx, collection)) {}
const IndexDescriptor* indexDescriptor;
std::string name;
BSONObj keyPattern;
MultikeyPaths multikeyPaths;
bool isMultiKey;
BSONObj startKey;
bool startKeyInclusive{true};
BSONObj endKey;
bool endKeyInclusive{true};
};
/**
* Used by the count command. Scans an index from a start key to an end key. Creates a
* WorkingSetMember for each matching index key in RID_AND_OBJ state. It has a null record id and an
* empty object with a null snapshot id rather than real data. Returning real data is unnecessary
* since all we need is the count.
*
* Only created through the getExecutorCount() path, as count is the only operation that doesn't
* care about its data.
*/
class CountScan final : public RequiresIndexStage {
public:
CountScan(ExpressionContext* expCtx,
const CollectionPtr& collection,
CountScanParams params,
WorkingSet* workingSet);
StageState doWork(WorkingSetID* out) final;
bool isEOF() final;
void doDetachFromOperationContext() final;
void doReattachToOperationContext() final;
StageType stageType() const final {
return STAGE_COUNT_SCAN;
}
std::unique_ptr<PlanStageStats> getStats() final;
const SpecificStats* getSpecificStats() const final;
static const char* kStageType;
protected:
void doSaveStateRequiresIndex() final;
void doRestoreStateRequiresIndex() final;
private:
// The WorkingSet we annotate with results. Not owned by us.
WorkingSet* _workingSet;
const BSONObj _keyPattern;
const bool _shouldDedup;
const BSONObj _startKey;
const bool _startKeyInclusive = true;
const BSONObj _endKey;
const bool _endKeyInclusive = true;
std::unique_ptr<SortedDataInterface::Cursor> _cursor;
// The set of record ids we've returned so far. Used to avoid returning duplicates, if
// '_shouldDedup' is set to true.
stdx::unordered_set<RecordId, RecordId::Hasher> _returned;
CountScanStats _specificStats;
};
} // namespace mongo
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