StatusWith<stdx::unordered_set<NamespaceString>> ViewCatalog::_validatePipeline_inlock(
OperationContext* opCtx, const ViewDefinition& viewDef) const {
AggregationRequest request(viewDef.viewOn(), viewDef.pipeline());
const LiteParsedPipeline liteParsedPipeline(request);
const auto involvedNamespaces = liteParsedPipeline.getInvolvedNamespaces();
// Verify that this is a legitimate pipeline specification by making sure it parses
// correctly. In order to parse a pipeline we need to resolve any namespaces involved to a
// collection and a pipeline, but in this case we don't need this map to be accurate since
// we will not be evaluating the pipeline.
StringMap<ExpressionContext::ResolvedNamespace> resolvedNamespaces;
for (auto&& nss : involvedNamespaces) {
resolvedNamespaces[nss.coll()] = {nss, {}};
}
boost::intrusive_ptr<ExpressionContext> expCtx =
new ExpressionContext(opCtx,
request,
CollatorInterface::cloneCollator(viewDef.defaultCollator()),
// We can use a stub MongoProcessInterface because we are only parsing
// the Pipeline for validation here. We won't do anything with the
// pipeline that will require a real implementation.
std::make_shared<StubMongoProcessInterface>(),
std::move(resolvedNamespaces));
// Save this to a variable to avoid reading the atomic variable multiple times.
auto currentFCV = serverGlobalParams.featureCompatibility.getVersion();
// If the feature compatibility version is not 4.0, and we are validating features as master,
// ban the use of new agg features introduced in 4.0 to prevent them from being persisted in the
// catalog.
if (serverGlobalParams.validateFeaturesAsMaster.load() &&
currentFCV != ServerGlobalParams::FeatureCompatibility::Version::kFullyUpgradedTo40) {
expCtx->maxFeatureCompatibilityVersion = currentFCV;
}
auto pipelineStatus = Pipeline::parse(viewDef.pipeline(), std::move(expCtx));
if (!pipelineStatus.isOK()) {
return pipelineStatus.getStatus();
}
// Validate that the view pipeline does not contain any ineligible stages.
auto sources = pipelineStatus.getValue()->getSources();
if (!sources.empty() && sources.front()->constraints().isChangeStreamStage()) {
return {ErrorCodes::OptionNotSupportedOnView,
"$changeStream cannot be used in a view definition"};
}
return std::move(involvedNamespaces);
}
Status ViewCatalog::_upsertIntoGraph(OperationContext* txn, const ViewDefinition& viewDef) {
// Performs the insert into the graph.
auto doInsert = [this, &txn](const ViewDefinition& viewDef, bool needsValidation) -> Status {
// Parse the pipeline for this view to get the namespaces it references.
AggregationRequest request(viewDef.viewOn(), viewDef.pipeline());
boost::intrusive_ptr<ExpressionContext> expCtx = new ExpressionContext(txn, request);
auto pipelineStatus = Pipeline::parse(viewDef.pipeline(), expCtx);
if (!pipelineStatus.isOK()) {
uassert(40255,
str::stream() << "Invalid pipeline for existing view " << viewDef.name().ns()
<< "; "
<< pipelineStatus.getStatus().reason(),
!needsValidation);
return pipelineStatus.getStatus();
}
std::vector<NamespaceString> refs = pipelineStatus.getValue()->getInvolvedCollections();
refs.push_back(viewDef.viewOn());
if (needsValidation) {
return _viewGraph.insertAndValidate(viewDef.name(), refs);
} else {
_viewGraph.insertWithoutValidating(viewDef.name(), refs);
return Status::OK();
}
};
if (_viewGraphNeedsRefresh) {
_viewGraph.clear();
for (auto&& iter : _viewMap) {
auto status = doInsert(*(iter.second.get()), false);
// If we cannot fully refresh the graph, we will keep '_viewGraphNeedsRefresh' true.
if (!status.isOK()) {
return status;
}
}
// Only if the inserts completed without error will we no longer need a refresh.
_viewGraphNeedsRefresh = false;
}
// Remove the view definition first in case this is an update. If it is not in the graph, it
// is simply a no-op.
_viewGraph.remove(viewDef.name());
return doInsert(viewDef, true);
}
Status ViewCatalog::_upsertIntoGraph(OperationContext* opCtx, const ViewDefinition& viewDef) {
// Performs the insert into the graph.
auto doInsert = [this, &opCtx](const ViewDefinition& viewDef, bool needsValidation) -> Status {
// Validate that the pipeline is eligible to serve as a view definition. If it is, this
// will also return the set of involved namespaces.
auto pipelineStatus = _validatePipeline_inlock(opCtx, viewDef);
if (!pipelineStatus.isOK()) {
if (needsValidation) {
uassertStatusOKWithContext(pipelineStatus.getStatus(),
str::stream() << "Invalid pipeline for view "
<< viewDef.name().ns());
}
return pipelineStatus.getStatus();
}
auto involvedNamespaces = pipelineStatus.getValue();
std::vector<NamespaceString> refs(involvedNamespaces.begin(), involvedNamespaces.end());
refs.push_back(viewDef.viewOn());
int pipelineSize = 0;
for (auto obj : viewDef.pipeline()) {
pipelineSize += obj.objsize();
}
if (needsValidation) {
// Check the collation of all the dependent namespaces before updating the graph.
auto collationStatus = _validateCollation_inlock(opCtx, viewDef, refs);
if (!collationStatus.isOK()) {
return collationStatus;
}
return _viewGraph.insertAndValidate(viewDef, refs, pipelineSize);
} else {
_viewGraph.insertWithoutValidating(viewDef, refs, pipelineSize);
return Status::OK();
}
};
if (_viewGraphNeedsRefresh) {
_viewGraph.clear();
for (auto&& iter : _viewMap) {
auto status = doInsert(*(iter.second.get()), false);
// If we cannot fully refresh the graph, we will keep '_viewGraphNeedsRefresh' true.
if (!status.isOK()) {
return status;
}
}
// Only if the inserts completed without error will we no longer need a refresh.
opCtx->recoveryUnit()->onRollback([this]() { this->_viewGraphNeedsRefresh = true; });
_viewGraphNeedsRefresh = false;
}
// Remove the view definition first in case this is an update. If it is not in the graph, it
// is simply a no-op.
_viewGraph.remove(viewDef.name());
return doInsert(viewDef, true);
}
StatusWith<stdx::unordered_set<NamespaceString>> ViewCatalog::_validatePipeline_inlock(
OperationContext* opCtx, const ViewDefinition& viewDef) const {
AggregationRequest request(viewDef.viewOn(), viewDef.pipeline());
const LiteParsedPipeline liteParsedPipeline(request);
const auto involvedNamespaces = liteParsedPipeline.getInvolvedNamespaces();
// Verify that this is a legitimate pipeline specification by making sure it parses
// correctly. In order to parse a pipeline we need to resolve any namespaces involved to a
// collection and a pipeline, but in this case we don't need this map to be accurate since
// we will not be evaluating the pipeline.
StringMap<ExpressionContext::ResolvedNamespace> resolvedNamespaces;
for (auto&& nss : involvedNamespaces) {
resolvedNamespaces[nss.coll()] = {nss, {}};
}
boost::intrusive_ptr<ExpressionContext> expCtx =
new ExpressionContext(opCtx,
request,
CollatorInterface::cloneCollator(viewDef.defaultCollator()),
// We can use a stub MongoProcessInterface because we are only parsing
// the Pipeline for validation here. We won't do anything with the
// pipeline that will require a real implementation.
std::make_shared<StubMongoProcessInterface>(),
std::move(resolvedNamespaces));
auto pipelineStatus = Pipeline::parse(viewDef.pipeline(), std::move(expCtx));
if (!pipelineStatus.isOK()) {
return pipelineStatus.getStatus();
}
// Validate that the view pipeline does not contain any ineligible stages.
auto sources = pipelineStatus.getValue()->getSources();
if (!sources.empty() && sources.front()->constraints().isChangeStreamStage()) {
return {ErrorCodes::OptionNotSupportedOnView,
"$changeStream cannot be used in a view definition"};
}
return std::move(involvedNamespaces);
}
StatusWith<ResolvedViewDefinition> ViewCatalog::resolveView(OperationContext* txn,
const NamespaceString& nss) {
const NamespaceString* resolvedNss = &nss;
std::vector<BSONObj> resolvedPipeline;
for (std::uint32_t i = 0; i < ViewCatalog::kMaxViewDepth; i++) {
ViewDefinition* view = lookup(resolvedNss->ns());
if (!view)
return StatusWith<ResolvedViewDefinition>({*resolvedNss, resolvedPipeline});
resolvedNss = &(view->viewOn());
// Prepend the underlying view's pipeline to the current working pipeline.
const std::vector<BSONObj>& toPrepend = view->pipeline();
resolvedPipeline.insert(resolvedPipeline.begin(), toPrepend.begin(), toPrepend.end());
}
return {ErrorCodes::ViewDepthLimitExceeded,
str::stream() << "View depth too deep or view cycle detected; maximum depth is "
<< kMaxViewDepth};
}