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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.
*/
#include "mongo/platform/basic.h"
#include "mongo/db/exec/record_store_fast_count.h"
namespace mongo {
const char* RecordStoreFastCountStage::kStageType = "RECORD_STORE_FAST_COUNT";
RecordStoreFastCountStage::RecordStoreFastCountStage(ExpressionContext* expCtx,
const CollectionPtr& collection,
long long skip,
long long limit)
: RequiresCollectionStage(kStageType, expCtx, collection), _skip(skip), _limit(limit) {
invariant(_skip >= 0);
invariant(_limit >= 0);
}
std::unique_ptr<PlanStageStats> RecordStoreFastCountStage::getStats() {
auto planStats = std::make_unique<PlanStageStats>(_commonStats, STAGE_RECORD_STORE_FAST_COUNT);
planStats->specific = std::make_unique<CountStats>(_specificStats);
return planStats;
}
PlanStage::StageState RecordStoreFastCountStage::doWork(WorkingSetID* out) {
// This stage never returns a working set member.
*out = WorkingSet::INVALID_ID;
long long nCounted = collection()->numRecords(opCtx());
if (_skip) {
nCounted -= _skip;
if (nCounted < 0) {
nCounted = 0;
}
}
long long limit = _limit;
if (limit < 0) {
limit = -limit;
}
if (limit < nCounted && 0 != limit) {
nCounted = limit;
}
_specificStats.nCounted = nCounted;
_specificStats.nSkipped = _skip;
_commonStats.isEOF = true;
return PlanStage::IS_EOF;
}
} // namespace mongo
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