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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/exec/requires_collection_stage.h"
namespace mongo {
/**
* Implements "fast count" by asking the underlying RecordStore for its number of records, applying
* the skip and limit it necessary. The result is stored in '_specificStats'. Only used to answer
* count commands when both the query and hint are empty.
*/
class RecordStoreFastCountStage final : public RequiresCollectionStage {
public:
static const char* kStageType;
RecordStoreFastCountStage(OperationContext* opCtx,
Collection* collection,
long long skip,
long long limit);
bool isEOF() override {
return _commonStats.isEOF;
}
StageState doWork(WorkingSetID* out) override;
StageType stageType() const override {
return StageType::STAGE_RECORD_STORE_FAST_COUNT;
}
std::unique_ptr<PlanStageStats> getStats() override;
const SpecificStats* getSpecificStats() const override {
return &_specificStats;
}
protected:
void doSaveStateRequiresCollection() override {}
void doRestoreStateRequiresCollection() override {}
private:
long long _skip = 0;
long long _limit = 0;
CountStats _specificStats;
};
} // namepace mongo
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