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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/multi_iterator.h"
#include "mongo/db/concurrency/write_conflict_exception.h"
#include "mongo/db/exec/working_set_common.h"
#include "mongo/stdx/memory.h"
namespace mongo {
using std::unique_ptr;
using std::vector;
using stdx::make_unique;
const char* MultiIteratorStage::kStageType = "MULTI_ITERATOR";
MultiIteratorStage::MultiIteratorStage(OperationContext* opCtx,
WorkingSet* ws,
Collection* collection)
: RequiresCollectionStage(kStageType, opCtx, collection), _ws(ws) {}
void MultiIteratorStage::addIterator(unique_ptr<RecordCursor> it) {
_iterators.push_back(std::move(it));
}
PlanStage::StageState MultiIteratorStage::doWork(WorkingSetID* out) {
boost::optional<Record> record;
try {
while (!_iterators.empty()) {
record = _iterators.back()->next();
if (record)
break;
_iterators.pop_back();
}
} catch (const WriteConflictException&) {
// If _advance throws a WCE we shouldn't have moved.
invariant(!_iterators.empty());
*out = WorkingSet::INVALID_ID;
return NEED_YIELD;
}
if (!record)
return IS_EOF;
*out = _ws->allocate();
WorkingSetMember* member = _ws->get(*out);
member->recordId = record->id;
member->obj = {getOpCtx()->recoveryUnit()->getSnapshotId(), record->data.releaseToBson()};
_ws->transitionToRecordIdAndObj(*out);
return PlanStage::ADVANCED;
}
bool MultiIteratorStage::isEOF() {
return _iterators.empty();
}
void MultiIteratorStage::saveState(RequiresCollTag) {
for (auto&& iterator : _iterators) {
iterator->save();
}
}
void MultiIteratorStage::restoreState(RequiresCollTag) {
for (auto&& iterator : _iterators) {
const bool couldRestore = iterator->restore();
uassert(50991, "could not restore cursor for MULTI_ITERATOR stage", couldRestore);
}
}
void MultiIteratorStage::doDetachFromOperationContext() {
for (auto&& iterator : _iterators) {
iterator->detachFromOperationContext();
}
}
void MultiIteratorStage::doReattachToOperationContext() {
for (auto&& iterator : _iterators) {
iterator->reattachToOperationContext(getOpCtx());
}
}
unique_ptr<PlanStageStats> MultiIteratorStage::getStats() {
unique_ptr<PlanStageStats> ret =
make_unique<PlanStageStats>(_commonStats, STAGE_MULTI_ITERATOR);
ret->specific = make_unique<CollectionScanStats>();
return ret;
}
} // namespace mongo
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