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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/ensure_sorted.h"
#include "mongo/db/exec/scoped_timer.h"
#include "mongo/db/exec/working_set_computed_data.h"
#include "mongo/db/query/find_common.h"
#include "mongo/stdx/memory.h"
namespace mongo {
using std::unique_ptr;
using stdx::make_unique;
const char* EnsureSortedStage::kStageType = "ENSURE_SORTED";
EnsureSortedStage::EnsureSortedStage(OperationContext* opCtx,
BSONObj pattern,
WorkingSet* ws,
PlanStage* child)
: PlanStage(kStageType, opCtx), _ws(ws) {
_children.emplace_back(child);
_pattern = FindCommon::transformSortSpec(pattern);
}
bool EnsureSortedStage::isEOF() {
return child()->isEOF();
}
PlanStage::StageState EnsureSortedStage::doWork(WorkingSetID* out) {
StageState stageState = child()->work(out);
if (PlanStage::ADVANCED == stageState) {
// We extract the sort key from the WSM's computed data. This must have been generated
// by a SortKeyGeneratorStage descendent in the execution tree.
WorkingSetMember* member = _ws->get(*out);
auto sortKeyComputedData =
static_cast<const SortKeyComputedData*>(member->getComputed(WSM_SORT_KEY));
BSONObj curSortKey = sortKeyComputedData->getSortKey();
invariant(!curSortKey.isEmpty());
if (!_prevSortKey.isEmpty() && !isInOrder(_prevSortKey, curSortKey)) {
// 'member' is out of order. Drop it from the result set.
_ws->free(*out);
++_specificStats.nDropped;
return PlanStage::NEED_TIME;
}
invariant(curSortKey.isOwned());
_prevSortKey = curSortKey;
return PlanStage::ADVANCED;
}
return stageState;
}
unique_ptr<PlanStageStats> EnsureSortedStage::getStats() {
_commonStats.isEOF = isEOF();
unique_ptr<PlanStageStats> ret = make_unique<PlanStageStats>(_commonStats, STAGE_ENSURE_SORTED);
ret->specific = make_unique<EnsureSortedStats>(_specificStats);
ret->children.emplace_back(child()->getStats());
return ret;
}
const SpecificStats* EnsureSortedStage::getSpecificStats() const {
return &_specificStats;
}
bool EnsureSortedStage::isInOrder(const BSONObj& lhsSortKey, const BSONObj& rhsSortKey) const {
// No need to compare with a collator, since the sort keys were extracted by the
// SortKeyGenerator, which has already mapped strings to their comparison keys.
return lhsSortKey.woCompare(rhsSortKey, _pattern, /*considerFieldName*/ false) <= 0;
}
} // namespace mongo
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