/**
* Copyright (C) 2014 MongoDB Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License, version 3,
* as published by the Free Software Foundation.
*
* 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
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see .
*
* 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 GNU Affero General 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/db/storage/record_fetcher.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* txn,
WorkingSet* ws,
Collection* collection)
: PlanStage(kStageType, txn),
_collection(collection),
_ws(ws),
_wsidForFetch(_ws->allocate()) {}
void MultiIteratorStage::addIterator(unique_ptr it) {
_iterators.push_back(std::move(it));
}
PlanStage::StageState MultiIteratorStage::work(WorkingSetID* out) {
if (_collection == NULL) {
Status status(ErrorCodes::InternalError, "MultiIteratorStage died on null collection");
*out = WorkingSetCommon::allocateStatusMember(_ws, status);
return PlanStage::DEAD;
}
boost::optional record;
try {
while (!_iterators.empty()) {
if (auto fetcher = _iterators.back()->fetcherForNext()) {
// Pass the RecordFetcher off up.
WorkingSetMember* member = _ws->get(_wsidForFetch);
member->setFetcher(fetcher.release());
*out = _wsidForFetch;
return NEED_YIELD;
}
record = _iterators.back()->next();
if (record)
break;
_iterators.pop_back();
}
} catch (const WriteConflictException& wce) {
// 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->loc = record->id;
member->obj = {getOpCtx()->recoveryUnit()->getSnapshotId(), record->data.releaseToBson()};
_ws->transitionToLocAndObj(*out);
return PlanStage::ADVANCED;
}
bool MultiIteratorStage::isEOF() {
return _collection == NULL || _iterators.empty();
}
void MultiIteratorStage::kill() {
_collection = NULL;
_iterators.clear();
}
void MultiIteratorStage::doSaveState() {
for (auto&& iterator : _iterators) {
iterator->save();
}
}
void MultiIteratorStage::doRestoreState() {
for (auto&& iterator : _iterators) {
if (!iterator->restore()) {
kill();
}
}
}
void MultiIteratorStage::doDetachFromOperationContext() {
for (auto&& iterator : _iterators) {
iterator->detachFromOperationContext();
}
}
void MultiIteratorStage::doReattachToOperationContext() {
for (auto&& iterator : _iterators) {
iterator->reattachToOperationContext(getOpCtx());
}
}
void MultiIteratorStage::doInvalidate(OperationContext* txn,
const RecordId& dl,
InvalidationType type) {
switch (type) {
case INVALIDATION_DELETION:
for (size_t i = 0; i < _iterators.size(); i++) {
_iterators[i]->invalidate(txn, dl);
}
break;
case INVALIDATION_MUTATION:
// no-op
break;
}
}
unique_ptr MultiIteratorStage::getStats() {
unique_ptr ret =
make_unique(CommonStats(kStageType), STAGE_MULTI_ITERATOR);
ret->specific = make_unique();
return ret;
}
} // namespace mongo