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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/db/exec/and_sorted.h"
#include <memory>
#include "mongo/db/exec/and_common.h"
#include "mongo/db/exec/scoped_timer.h"
#include "mongo/db/exec/working_set_common.h"
#include "mongo/util/str.h"
namespace mongo {
using std::numeric_limits;
using std::unique_ptr;
using std::vector;
// static
const char* AndSortedStage::kStageType = "AND_SORTED";
AndSortedStage::AndSortedStage(ExpressionContext* expCtx, WorkingSet* ws)
: PlanStage(kStageType, expCtx),
_ws(ws),
_targetNode(numeric_limits<size_t>::max()),
_targetId(WorkingSet::INVALID_ID),
_isEOF(false) {}
void AndSortedStage::addChild(std::unique_ptr<PlanStage> child) {
_children.emplace_back(std::move(child));
}
bool AndSortedStage::isEOF() {
return _isEOF;
}
PlanStage::StageState AndSortedStage::doWork(WorkingSetID* out) {
if (isEOF()) {
return PlanStage::IS_EOF;
}
if (0 == _specificStats.failedAnd.size()) {
_specificStats.failedAnd.resize(_children.size());
}
// If we don't have any nodes that we're work()-ing until they hit a certain RecordId...
if (0 == _workingTowardRep.size()) {
// Get a target RecordId.
return getTargetRecordId(out);
}
// Move nodes toward the target RecordId.
// If all nodes reach the target RecordId, return it. The next call to work() will set a new
// target.
return moveTowardTargetRecordId(out);
}
PlanStage::StageState AndSortedStage::getTargetRecordId(WorkingSetID* out) {
verify(numeric_limits<size_t>::max() == _targetNode);
verify(WorkingSet::INVALID_ID == _targetId);
verify(RecordId() == _targetRecordId);
// Pick one, and get a RecordId to work toward.
WorkingSetID id = WorkingSet::INVALID_ID;
StageState state = _children[0]->work(&id);
if (PlanStage::ADVANCED == state) {
WorkingSetMember* member = _ws->get(id);
// The child must give us a WorkingSetMember with a record id, since we intersect index keys
// based on the record id. The planner ensures that the child stage can never produce an WSM
// with no record id.
invariant(member->hasRecordId());
// We have a value from one child to AND with.
_targetNode = 0;
_targetId = id;
_targetRecordId = member->recordId;
// Ensure that the BSONObj underlying the WorkingSetMember is owned in case we yield.
member->makeObjOwnedIfNeeded();
// We have to AND with all other children.
for (size_t i = 1; i < _children.size(); ++i) {
_workingTowardRep.push(i);
}
return PlanStage::NEED_TIME;
} else if (PlanStage::IS_EOF == state) {
_isEOF = true;
return state;
} else {
if (PlanStage::NEED_YIELD == state) {
*out = id;
}
// NEED_TIME, NEED_YIELD.
return state;
}
}
PlanStage::StageState AndSortedStage::moveTowardTargetRecordId(WorkingSetID* out) {
verify(numeric_limits<size_t>::max() != _targetNode);
verify(WorkingSet::INVALID_ID != _targetId);
// We have nodes that haven't hit _targetRecordId yet.
size_t workingChildNumber = _workingTowardRep.front();
auto& next = _children[workingChildNumber];
WorkingSetID id = WorkingSet::INVALID_ID;
StageState state = next->work(&id);
if (PlanStage::ADVANCED == state) {
WorkingSetMember* member = _ws->get(id);
// The child must give us a WorkingSetMember with a record id, since we intersect index keys
// based on the record id. The planner ensures that the child stage can never produce an WSM
// with no record id.
invariant(member->hasRecordId());
if (member->recordId == _targetRecordId) {
// The front element has hit _targetRecordId. Don't move it forward anymore/work on
// another element.
_workingTowardRep.pop();
AndCommon::mergeFrom(_ws, _targetId, *member);
_ws->free(id);
if (0 == _workingTowardRep.size()) {
WorkingSetID toReturn = _targetId;
_targetNode = numeric_limits<size_t>::max();
_targetId = WorkingSet::INVALID_ID;
_targetRecordId = RecordId();
*out = toReturn;
return PlanStage::ADVANCED;
}
// More children need to be advanced to _targetRecordId.
return PlanStage::NEED_TIME;
} else if (member->recordId < _targetRecordId) {
// The front element of _workingTowardRep hasn't hit the thing we're AND-ing with
// yet. Try again later.
_ws->free(id);
return PlanStage::NEED_TIME;
} else {
// member->recordId > _targetRecordId.
// _targetRecordId wasn't successfully AND-ed with the other sub-plans. We toss it and
// try AND-ing with the next value.
_specificStats.failedAnd[_targetNode]++;
_ws->free(_targetId);
_targetNode = workingChildNumber;
_targetRecordId = member->recordId;
_targetId = id;
// Ensure that the BSONObj underlying the WorkingSetMember is owned in case we yield.
member->makeObjOwnedIfNeeded();
_workingTowardRep = std::queue<size_t>();
for (size_t i = 0; i < _children.size(); ++i) {
if (workingChildNumber != i) {
_workingTowardRep.push(i);
}
}
// Need time to chase after the new _targetRecordId.
return PlanStage::NEED_TIME;
}
} else if (PlanStage::IS_EOF == state) {
_isEOF = true;
_ws->free(_targetId);
return state;
} else {
if (PlanStage::NEED_YIELD == state) {
*out = id;
}
return state;
}
}
unique_ptr<PlanStageStats> AndSortedStage::getStats() {
_commonStats.isEOF = isEOF();
unique_ptr<PlanStageStats> ret =
std::make_unique<PlanStageStats>(_commonStats, STAGE_AND_SORTED);
ret->specific = std::make_unique<AndSortedStats>(_specificStats);
for (size_t i = 0; i < _children.size(); ++i) {
ret->children.emplace_back(_children[i]->getStats());
}
return ret;
}
const SpecificStats* AndSortedStage::getSpecificStats() const {
return &_specificStats;
}
} // namespace mongo
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