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/**
* Copyright (C) 2019-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.
*/
#define MONGO_LOGV2_DEFAULT_COMPONENT ::mongo::logv2::LogComponent::kQuery
#include "mongo/platform/basic.h"
#include "mongo/db/query/plan_executor_sbe.h"
#include "mongo/db/db_raii.h"
#include "mongo/db/exec/sbe/expressions/expression.h"
#include "mongo/db/exec/sbe/values/bson.h"
#include "mongo/db/query/plan_explainer_factory.h"
#include "mongo/db/query/plan_insert_listener.h"
#include "mongo/db/query/sbe_stage_builder.h"
#include "mongo/logv2/log.h"
#include "mongo/s/resharding/resume_token_gen.h"
namespace mongo {
// This failpoint is defined by the classic executor but is also accessed here.
extern FailPoint planExecutorHangBeforeShouldWaitForInserts;
PlanExecutorSBE::PlanExecutorSBE(OperationContext* opCtx,
std::unique_ptr<CanonicalQuery> cq,
std::unique_ptr<optimizer::AbstractABTPrinter> optimizerData,
sbe::CandidatePlans candidates,
bool returnOwnedBson,
NamespaceString nss,
bool isOpen,
std::unique_ptr<PlanYieldPolicySBE> yieldPolicy)
: _state{isOpen ? State::kOpened : State::kClosed},
_opCtx(opCtx),
_nss(std::move(nss)),
_mustReturnOwnedBson(returnOwnedBson),
_root{std::move(candidates.winner().root)},
_rootData{std::move(candidates.winner().data)},
_solution{std::move(candidates.winner().solution)},
_stash{std::move(candidates.winner().results)},
_cq{std::move(cq)},
_yieldPolicy(std::move(yieldPolicy)) {
invariant(!_nss.isEmpty());
invariant(_root);
if (auto slot = _rootData.outputs.getIfExists(stage_builder::PlanStageSlots::kResult); slot) {
_result = _root->getAccessor(_rootData.ctx, *slot);
uassert(4822865, "Query does not have result slot.", _result);
}
if (auto slot = _rootData.outputs.getIfExists(stage_builder::PlanStageSlots::kRecordId); slot) {
_resultRecordId = _root->getAccessor(_rootData.ctx, *slot);
uassert(4822866, "Query does not have recordId slot.", _resultRecordId);
}
if (_rootData.shouldTrackLatestOplogTimestamp) {
_oplogTs = _rootData.env->getAccessor(_rootData.env->getSlot("oplogTs"_sd));
}
if (_rootData.shouldUseTailableScan) {
_resumeRecordIdSlot = _rootData.env->getSlot("resumeRecordId"_sd);
}
if (!_stash.empty()) {
// The PlanExecutor keeps an extra reference to the last object pulled out of the PlanStage
// tree. This is because we want to ensure that the caller of PlanExecutor::getNext() does
// not free the object and leave a dangling pointer in the PlanStage tree.
_lastGetNext = _stash.back().first;
}
// Callers are allowed to disable yielding for this plan by passing a null yield policy.
if (_yieldPolicy) {
// Clear any formerly registered plans and register '_root' to yield. This is needed because
// multiple candidate plans may have been registered during runtime planning, before the
// PlanExecutor was created. All but one candidate plan ('_root') have since been discarded.
_yieldPolicy->clearRegisteredPlans();
_yieldPolicy->registerPlan(_root.get());
}
const auto isMultiPlan = candidates.plans.size() > 1;
if (!_cq || !_cq->getExpCtx()->explain) {
// If we're not in explain mode, there is no need to keep rejected candidate plans around.
candidates.plans.clear();
} else {
// Keep only rejected candidate plans.
candidates.plans.erase(candidates.plans.begin() + candidates.winnerIdx);
}
if (_solution) {
_secondaryNssVector = _solution->getAllSecondaryNamespaces(_nss);
}
_planExplainer = plan_explainer_factory::make(_root.get(),
&_rootData,
_solution.get(),
std::move(optimizerData),
std::move(candidates.plans),
isMultiPlan,
_rootData.debugInfo);
}
void PlanExecutorSBE::saveState() {
if (_isSaveRecoveryUnitAcrossCommandsEnabled) {
_root->saveState(false /* NOT relinquishing cursor */);
// Put the RU into 'kCommit' mode so that subsequent calls to abandonSnapshot() keep
// cursors positioned. This ensures that no pointers into memory owned by the storage
// engine held by the SBE PlanStage tree become invalid while the executor is in a saved
// state.
_opCtx->recoveryUnit()->setAbandonSnapshotMode(RecoveryUnit::AbandonSnapshotMode::kCommit);
_opCtx->recoveryUnit()->abandonSnapshot();
} else {
_root->saveState(true /* relinquish cursor */);
}
_yieldPolicy->setYieldable(nullptr);
_lastGetNext = BSONObj();
}
void PlanExecutorSBE::restoreState(const RestoreContext& context) {
_yieldPolicy->setYieldable(context.collection());
if (_isSaveRecoveryUnitAcrossCommandsEnabled) {
_root->restoreState(false /* NOT relinquishing cursor */);
// Put the RU back into 'kAbort' mode. Since the executor is now in a restored state, calls
// to doAbandonSnapshot() only happen if the query has failed and the executor will not be
// used again. In this case, we do not rely on the guarantees provided by 'kCommit' mode.
_opCtx->recoveryUnit()->setAbandonSnapshotMode(RecoveryUnit::AbandonSnapshotMode::kAbort);
} else {
_root->restoreState(true /* relinquish cursor */);
}
}
void PlanExecutorSBE::detachFromOperationContext() {
invariant(_opCtx);
_root->detachFromOperationContext();
_opCtx = nullptr;
}
void PlanExecutorSBE::reattachToOperationContext(OperationContext* opCtx) {
invariant(!_opCtx);
_root->attachToOperationContext(opCtx);
_opCtx = opCtx;
}
void PlanExecutorSBE::markAsKilled(Status killStatus) {
invariant(!killStatus.isOK());
// If killed multiple times, only retain the first status.
if (_killStatus.isOK()) {
_killStatus = killStatus;
}
}
void PlanExecutorSBE::dispose(OperationContext* opCtx) {
if (_state != State::kClosed) {
_root->close();
_state = State::kClosed;
}
_isDisposed = true;
}
void PlanExecutorSBE::stashResult(const BSONObj& obj) {
invariant(_state == State::kOpened);
invariant(!_isDisposed);
_stash.push_front({obj.getOwned(), boost::none});
}
PlanExecutor::ExecState PlanExecutorSBE::getNextDocument(Document* objOut, RecordId* dlOut) {
invariant(!_isDisposed);
checkFailPointPlanExecAlwaysFails();
Document obj;
auto result = getNextImpl(&obj, dlOut);
if (result == PlanExecutor::ExecState::ADVANCED) {
*objOut = std::move(obj);
}
return result;
}
PlanExecutor::ExecState PlanExecutorSBE::getNext(BSONObj* out, RecordId* dlOut) {
invariant(!_isDisposed);
checkFailPointPlanExecAlwaysFails();
BSONObj obj;
auto result = getNextImpl(&obj, dlOut);
if (result == PlanExecutor::ExecState::ADVANCED) {
*out = std::move(obj);
}
return result;
}
template <typename ObjectType>
sbe::PlanState fetchNextImpl(sbe::PlanStage* root,
sbe::value::SlotAccessor* resultSlot,
sbe::value::SlotAccessor* recordIdSlot,
ObjectType* out,
RecordId* dlOut,
bool returnOwnedBson);
template <typename ObjectType>
PlanExecutor::ExecState PlanExecutorSBE::getNextImpl(ObjectType* out, RecordId* dlOut) {
constexpr bool isDocument = std::is_same_v<ObjectType, Document>;
constexpr bool isBson = std::is_same_v<ObjectType, BSONObj>;
static_assert(isDocument || isBson);
invariant(!_isDisposed);
checkFailPointPlanExecAlwaysFails();
if (!_stash.empty()) {
auto&& [doc, recordId] = _stash.front();
if constexpr (isBson) {
*out = std::move(doc);
} else {
*out = Document{std::move(doc)};
}
if (dlOut && recordId) {
*dlOut = *recordId;
}
_stash.pop_front();
return PlanExecutor::ExecState::ADVANCED;
} else if (_root->getCommonStats()->isEOF) {
// If we had stashed elements and consumed them all, but the PlanStage is also
// already exhausted, we can return EOF straight away. Otherwise, proceed with
// fetching the next document.
_root->close();
_state = State::kClosed;
if (!_resumeRecordIdSlot) {
return PlanExecutor::ExecState::IS_EOF;
}
}
// Capped insert data; declared outside the loop so we hold a shared pointer to the capped
// insert notifier the entire time we are in the loop. Holding a shared pointer to the capped
// insert notifier is necessary for the notifierVersion to advance.
//
// Note that we need to hold a database intent lock before acquiring a notifier.
boost::optional<AutoGetCollectionForReadMaybeLockFree> coll;
insert_listener::CappedInsertNotifierData cappedInsertNotifierData;
if (insert_listener::shouldListenForInserts(_opCtx, _cq.get())) {
if (!_opCtx->lockState()->isCollectionLockedForMode(_nss, MODE_IS)) {
coll.emplace(_opCtx, _nss);
}
cappedInsertNotifierData.notifier =
insert_listener::getCappedInsertNotifier(_opCtx, _nss, _yieldPolicy.get());
}
for (;;) {
if (_state == State::kClosed) {
if (_resumeRecordIdSlot) {
uassert(4946306,
"Collection scan was asked to track resume token, but found a result "
"without a valid RecordId",
_tagLastRecordId == sbe::value::TypeTags::RecordId ||
_tagLastRecordId == sbe::value::TypeTags::Nothing);
_rootData.env->resetSlot(
*_resumeRecordIdSlot, _tagLastRecordId, _valLastRecordId, false);
}
_state = State::kOpened;
_root->open(false);
}
invariant(_state == State::kOpened);
auto result =
fetchNextImpl(_root.get(), _result, _resultRecordId, out, dlOut, _mustReturnOwnedBson);
if (result == sbe::PlanState::IS_EOF) {
_root->close();
_state = State::kClosed;
_lastGetNext = BSONObj();
if (MONGO_unlikely(planExecutorHangBeforeShouldWaitForInserts.shouldFail(
[this](const BSONObj& data) {
if (data.hasField("namespace") &&
_nss != NamespaceString(data.getStringField("namespace"))) {
return false;
}
return true;
}))) {
LOGV2(5567001,
"PlanExecutor - planExecutorHangBeforeShouldWaitForInserts fail point "
"enabled. Blocking until fail point is disabled");
planExecutorHangBeforeShouldWaitForInserts.pauseWhileSet();
}
if (!insert_listener::shouldWaitForInserts(_opCtx, _cq.get(), _yieldPolicy.get())) {
return PlanExecutor::ExecState::IS_EOF;
}
insert_listener::waitForInserts(_opCtx, _yieldPolicy.get(), &cappedInsertNotifierData);
// There may be more results, keep going.
continue;
} else if (_resumeRecordIdSlot) {
invariant(_resultRecordId);
std::tie(_tagLastRecordId, _valLastRecordId) = _resultRecordId->getViewOfValue();
}
invariant(result == sbe::PlanState::ADVANCED);
if (_mustReturnOwnedBson) {
if constexpr (isBson) {
_lastGetNext = *out;
} else {
auto bson = out->toBsonIfTriviallyConvertible();
if (bson) {
// This basically means that the 'Document' is just a wrapper around BSON
// returned by the plan. In this case, 'out' must own it.
invariant(out->isOwned());
_lastGetNext = *bson;
} else {
// 'Document' was created from 'sbe::Object' and there is no backing BSON for
// it.
_lastGetNext = BSONObj();
}
}
}
return PlanExecutor::ExecState::ADVANCED;
}
}
// Explicitly instantiate the only 2 types supported by 'PlanExecutorSBE::getNextImpl'.
template PlanExecutor::ExecState PlanExecutorSBE::getNextImpl<BSONObj>(BSONObj* out,
RecordId* dlOut);
template PlanExecutor::ExecState PlanExecutorSBE::getNextImpl<Document>(Document* out,
RecordId* dlOut);
Timestamp PlanExecutorSBE::getLatestOplogTimestamp() const {
if (_rootData.shouldTrackLatestOplogTimestamp) {
tassert(5567201,
"The '_oplogTs' accessor should be populated when "
"'shouldTrackLatestOplogTimestamp' is true",
_oplogTs);
auto [tag, val] = _oplogTs->getViewOfValue();
if (tag != sbe::value::TypeTags::Nothing) {
const auto msgTag = tag;
uassert(4822868,
str::stream() << "Collection scan was asked to track latest operation time, "
"but found a result without a valid 'ts' field: "
<< msgTag,
tag == sbe::value::TypeTags::Timestamp);
return Timestamp{sbe::value::bitcastTo<uint64_t>(val)};
}
}
return {};
}
BSONObj PlanExecutorSBE::getPostBatchResumeToken() const {
if (_rootData.shouldTrackResumeToken) {
invariant(_resultRecordId);
auto [tag, val] = _resultRecordId->getViewOfValue();
if (tag != sbe::value::TypeTags::Nothing) {
const auto msgTag = tag;
uassert(4822869,
str::stream() << "Collection scan was asked to track resume token, "
"but found a result without a valid RecordId: "
<< msgTag,
tag == sbe::value::TypeTags::RecordId);
BSONObjBuilder builder;
sbe::value::getRecordIdView(val)->serializeToken("$recordId", &builder);
return builder.obj();
}
}
if (_rootData.shouldTrackLatestOplogTimestamp) {
return ResumeTokenOplogTimestamp{getLatestOplogTimestamp()}.toBSON();
}
return {};
}
namespace {
Document convertToDocument(const sbe::value::Object& obj);
Value convertToValue(sbe::value::TypeTags tag, sbe::value::Value val) {
switch (tag) {
case sbe::value::TypeTags::Nothing:
return Value();
case sbe::value::TypeTags::NumberInt32:
return Value(sbe::value::bitcastTo<int32_t>(val));
case sbe::value::TypeTags::NumberInt64:
return Value(sbe::value::bitcastTo<long long>(val));
case sbe::value::TypeTags::NumberDouble:
return Value(sbe::value::bitcastTo<double>(val));
case sbe::value::TypeTags::NumberDecimal:
return Value(sbe::value::bitcastTo<Decimal128>(val));
case sbe::value::TypeTags::Date:
return Value(Date_t::fromMillisSinceEpoch(sbe::value::bitcastTo<int64_t>(val)));
case sbe::value::TypeTags::Timestamp:
return Value(Timestamp(sbe::value::bitcastTo<uint64_t>(val)));
case sbe::value::TypeTags::Boolean:
return Value(sbe::value::bitcastTo<bool>(val));
case sbe::value::TypeTags::Null:
return Value(BSONNULL);
case sbe::value::TypeTags::StringSmall:
case sbe::value::TypeTags::StringBig:
case sbe::value::TypeTags::bsonString:
case sbe::value::TypeTags::bsonSymbol:
return Value(sbe::value::getStringOrSymbolView(tag, val));
case sbe::value::TypeTags::Array:
case sbe::value::TypeTags::ArraySet: {
std::vector<Value> vals;
auto enumerator = sbe::value::ArrayEnumerator{tag, val};
while (!enumerator.atEnd()) {
auto [arrTag, arrVal] = enumerator.getViewOfValue();
enumerator.advance();
vals.push_back(convertToValue(arrTag, arrVal));
}
return Value(std::move(vals));
}
case sbe::value::TypeTags::Object:
return Value(convertToDocument(*sbe::value::getObjectView(val)));
case sbe::value::TypeTags::ObjectId:
return Value(OID::from(sbe::value::getObjectIdView(val)->data()));
case sbe::value::TypeTags::MinKey:
return Value(kMinBSONKey);
case sbe::value::TypeTags::MaxKey:
return Value(kMaxBSONKey);
case sbe::value::TypeTags::bsonObject:
return Value(BSONObj{sbe::value::bitcastTo<const char*>(val)});
case sbe::value::TypeTags::bsonArray:
return Value(BSONArray{BSONObj{sbe::value::bitcastTo<const char*>(val)}});
case sbe::value::TypeTags::bsonObjectId:
return Value(OID::from(sbe::value::bitcastTo<const char*>(val)));
case sbe::value::TypeTags::bsonBinData:
return Value(BSONBinData(sbe::value::getBSONBinData(tag, val),
sbe::value::getBSONBinDataSize(tag, val),
sbe::value::getBSONBinDataSubtype(tag, val)));
case sbe::value::TypeTags::bsonUndefined:
return Value(BSONUndefined);
case sbe::value::TypeTags::bsonRegex: {
auto regex = sbe::value::getBsonRegexView(val);
return Value(BSONRegEx(regex.pattern, regex.flags));
}
case sbe::value::TypeTags::bsonJavascript:
return Value(sbe::value::getBsonJavascriptView(val));
case sbe::value::TypeTags::bsonDBPointer: {
auto dbptr = sbe::value::getBsonDBPointerView(val);
return Value(BSONDBRef(dbptr.ns, OID::from(dbptr.id)));
}
case sbe::value::TypeTags::bsonCodeWScope: {
auto bcws = sbe::value::getBsonCodeWScopeView(val);
return Value(BSONCodeWScope(bcws.code, BSONObj(bcws.scope)));
}
default:
MONGO_UNREACHABLE;
}
}
Document convertToDocument(const sbe::value::Object& obj) {
MutableDocument doc;
for (size_t idx = 0; idx < obj.size(); ++idx) {
auto [tag, val] = obj.getAt(idx);
const auto& name = obj.field(idx);
doc.addField(name, convertToValue(tag, val));
}
return doc.freeze();
}
} // namespace
template <typename ObjectType>
sbe::PlanState fetchNextImpl(sbe::PlanStage* root,
sbe::value::SlotAccessor* resultSlot,
sbe::value::SlotAccessor* recordIdSlot,
ObjectType* out,
RecordId* dlOut,
bool returnOwnedBson) {
constexpr bool isDocument = std::is_same_v<ObjectType, Document>;
constexpr bool isBson = std::is_same_v<ObjectType, BSONObj>;
static_assert(isDocument || isBson);
invariant(out);
auto state = root->getNext();
if (state == sbe::PlanState::IS_EOF) {
tassert(5609900,
"Root stage returned EOF but root stage's CommonStats 'isEOF' field is false",
root->getCommonStats()->isEOF);
return state;
}
invariant(state == sbe::PlanState::ADVANCED);
if (resultSlot) {
auto [tag, val] = resultSlot->getViewOfValue();
if (tag == sbe::value::TypeTags::Object) {
if constexpr (isBson) {
BSONObjBuilder bb;
sbe::bson::convertToBsonObj(bb, sbe::value::getObjectView(val));
*out = bb.obj();
} else {
*out = convertToDocument(*sbe::value::getObjectView(val));
}
} else if (tag == sbe::value::TypeTags::bsonObject) {
BSONObj result;
if (returnOwnedBson) {
auto [ownedTag, ownedVal] = resultSlot->copyOrMoveValue();
auto sharedBuf =
SharedBuffer(UniqueBuffer::reclaim(sbe::value::bitcastTo<char*>(ownedVal)));
result = BSONObj{std::move(sharedBuf)};
} else {
result = BSONObj{sbe::value::bitcastTo<const char*>(val)};
}
if constexpr (isBson) {
*out = std::move(result);
} else {
*out = Document{std::move(result)};
}
} else {
// The query is supposed to return an object.
MONGO_UNREACHABLE;
}
}
if (dlOut) {
invariant(recordIdSlot);
auto [tag, val] = recordIdSlot->getViewOfValue();
if (tag == sbe::value::TypeTags::RecordId) {
*dlOut = *sbe::value::getRecordIdView(val);
}
}
return state;
}
template sbe::PlanState fetchNextImpl<BSONObj>(sbe::PlanStage* root,
sbe::value::SlotAccessor* resultSlot,
sbe::value::SlotAccessor* recordIdSlot,
BSONObj* out,
RecordId* dlOut,
bool returnOwnedBson);
template sbe::PlanState fetchNextImpl<Document>(sbe::PlanStage* root,
sbe::value::SlotAccessor* resultSlot,
sbe::value::SlotAccessor* recordIdSlot,
Document* out,
RecordId* dlOut,
bool returnOwnedBson);
// NOTE: We intentionally do not expose overload for the 'Document' type. The only interface to get
// result from plan in 'Document' type is to call 'PlanExecutorSBE::getNextDocument()'.
sbe::PlanState fetchNext(sbe::PlanStage* root,
sbe::value::SlotAccessor* resultSlot,
sbe::value::SlotAccessor* recordIdSlot,
BSONObj* out,
RecordId* dlOut,
bool returnOwnedBson) {
return fetchNextImpl(root, resultSlot, recordIdSlot, out, dlOut, returnOwnedBson);
}
} // namespace mongo
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