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);
}
Status ViewCatalog::dropView(OperationContext* opCtx, const NamespaceString& viewName) {
stdx::lock_guard<stdx::mutex> lk(_mutex);
_requireValidCatalog(lk, opCtx);
// Save a copy of the view definition in case we need to roll back.
auto viewPtr = _lookup(lk, opCtx, viewName.ns());
if (!viewPtr) {
return {ErrorCodes::NamespaceNotFound,
str::stream() << "cannot drop missing view: " << viewName.ns()};
}
ViewDefinition savedDefinition = *viewPtr;
invariant(_valid.load());
_durable->remove(opCtx, viewName);
_viewGraph.remove(savedDefinition.name());
_viewMap.erase(viewName.ns());
opCtx->recoveryUnit()->onRollback([this, viewName, savedDefinition]() {
this->_viewGraphNeedsRefresh = true;
this->_viewMap[viewName.ns()] = std::make_shared<ViewDefinition>(savedDefinition);
});
// We may get invalidated, but we're exclusively locked, so the change must be ours.
opCtx->recoveryUnit()->onCommit(
[this](boost::optional<Timestamp>) { this->_valid.store(true); });
return Status::OK();
}
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::_validateCollation_inlock(OperationContext* opCtx,
const ViewDefinition& view,
const std::vector<NamespaceString>& refs) {
for (auto&& potentialViewNss : refs) {
auto otherView = _lookup_inlock(opCtx, potentialViewNss.ns());
if (otherView &&
!CollatorInterface::collatorsMatch(view.defaultCollator(),
otherView->defaultCollator())) {
return {ErrorCodes::OptionNotSupportedOnView,
str::stream() << "View " << view.name().toString()
<< " has conflicting collation with view "
<< otherView->name().toString()};
}
}
return Status::OK();
}
void ViewGraph::insertWithoutValidating(const ViewDefinition& view,
const std::vector<NamespaceString>& refs,
int pipelineSize) {
uint64_t nodeId = _getNodeId(view.name());
// Note, the parent pointers of this node are set when the parents are inserted.
// This sets the children pointers of the node for this view, as well as the parent
// pointers for its children.
Node* node = &(_graph[nodeId]);
invariant(node->children.empty());
invariant(!static_cast<bool>(node->collator));
node->size = pipelineSize;
node->collator = view.defaultCollator();
for (const NamespaceString& childNss : refs) {
uint64_t childId = _getNodeId(childNss);
node->children.insert(childId);
_graph[childId].parents.insert(nodeId);
}
}
StatusWith<stdx::unordered_set<NamespaceString>> ViewCatalog::_validatePipeline(
WithLock lk, 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),
boost::none);
// 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 4.2, and we are validating features as master,
// ban the use of new agg features introduced in 4.2 to prevent them from being persisted in the
// catalog.
if (serverGlobalParams.validateFeaturesAsMaster.load() &&
currentFCV != ServerGlobalParams::FeatureCompatibility::Version::kFullyUpgradedTo42) {
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.
const auto& sources = pipelineStatus.getValue()->getSources();
if (!sources.empty()) {
const auto firstPersistentStage =
std::find_if(sources.begin(), sources.end(), [](const auto& source) {
return source->constraints().writesPersistentData();
});
if (sources.front()->constraints().isChangeStreamStage()) {
return {ErrorCodes::OptionNotSupportedOnView,
"$changeStream cannot be used in a view definition"};
} else if (firstPersistentStage != sources.end()) {
mongo::StringBuilder errorMessage;
errorMessage << "The aggregation stage " << firstPersistentStage->get()->getSourceName()
<< " in location " << std::distance(sources.begin(), firstPersistentStage)
<< " of the pipeline cannot be used in the view definition of "
<< viewDef.name().ns() << " because it writes to disk";
return {ErrorCodes::OptionNotSupportedOnView, errorMessage.str()};
}
}
return std::move(involvedNamespaces);
}
Status ViewGraph::insertAndValidate(const ViewDefinition& view,
const std::vector<NamespaceString>& refs,
int pipelineSize) {
insertWithoutValidating(view, refs, pipelineSize);
// Perform validation on this newly inserted view. Note, if the graph was put in an invalid
// state through unvalidated inserts (e.g. if the user manually edits system.views)
// this may not necessarily be detected. We only check for errors introduced by this view.
const auto& viewNss = view.name();
uint64_t nodeId = _getNodeId(viewNss);
// If the graph fails validation for any reason, the insert is automatically rolled back on
// exiting this method.
auto rollBackInsert = [&]() -> auto {
remove(viewNss);
};
auto guard = MakeGuard(rollBackInsert);
// Check for cycles and get the height of the children.
StatsMap statsMap;
std::vector<uint64_t> cycleVertices;
cycleVertices.reserve(kMaxViewDepth);
auto childRes = _validateChildren(nodeId, nodeId, 0, &statsMap, &cycleVertices);
if (!childRes.isOK()) {
return childRes;
}
// Subtract one since the child height includes the non-view leaf node(s).
int childrenHeight = statsMap[nodeId].height - 1;
int childrenSize = statsMap[nodeId].cumulativeSize;
// Get the height of the parents to obtain the diameter through this node, as well as the size
// of the pipeline to check if if the combined pipeline exceeds the max size.
statsMap.clear();
auto parentRes = _validateParents(nodeId, 0, &statsMap);
if (!parentRes.isOK()) {
return parentRes;
}
// Check the combined heights of the children and parents.
int parentsHeight = statsMap[nodeId].height;
// Subtract one since the parent and children heights include the current node.
int diameter = parentsHeight + childrenHeight - 1;
if (diameter > kMaxViewDepth) {
return {ErrorCodes::ViewDepthLimitExceeded,
str::stream() << "View depth limit exceeded; maximum depth is " << kMaxViewDepth};
}
// Check the combined sizes of the children and parents.
int parentsSize = statsMap[nodeId].cumulativeSize;
// Subtract the current node's size since the parent and children sizes include the current
// node.
const Node& currentNode = _graph[nodeId];
int pipelineTotalSize = parentsSize + childrenSize - currentNode.size;
if (pipelineTotalSize > kMaxViewPipelineSizeBytes) {
return {ErrorCodes::ViewPipelineMaxSizeExceeded,
str::stream() << "Operation would result in a resolved view pipeline that exceeds "
"the maximum size of "
<< kMaxViewPipelineSizeBytes
<< " bytes"};
}
guard.Dismiss();
return Status::OK();
}