check max validate depth

src/graph/validator/AssignmentValidator.cpp

@@ -13,6 +13,7 @@ namespace graph {
 
 Status AssignmentValidator::validateImpl() {
   auto *assignSentence = static_cast<AssignmentSentence *>(sentence_);
+
   NG_RETURN_IF_ERROR(validator_->validate());
 
   auto outputs = validator_->outputCols();

src/graph/validator/SequentialValidator.cpp

@@ -18,7 +18,6 @@ namespace graph {
 // Validator of sequential sentences which combine multiple sentences, e.g. GO ...; GO ...;
 // Call validator of sub-sentences.
 Status SequentialValidator::validateImpl() {
-  Status status;
   if (sentence_->kind() != Sentence::Kind::kSequential) {
     return Status::SemanticError(
         "Sequential validator validates a SequentialSentences, but %ld is "

src/graph/validator/Validator.cpp

@@ -39,17 +39,25 @@
 #include "graph/visitor/DeduceTypeVisitor.h"
 #include "graph/visitor/EvaluableExprVisitor.h"
 #include "parser/Sentence.h"
-
+DEFINE_uint32(max_statements,
+              1024,
+              "threshold for maximun number of statements that can be validate");
 namespace nebula {
 namespace graph {
 
+thread_local uint32_t Validator::maxStatements_ = 0;
+
 Validator::Validator(Sentence* sentence, QueryContext* qctx)
     : sentence_(DCHECK_NOTNULL(sentence)),
       qctx_(DCHECK_NOTNULL(qctx)),
       vctx_(DCHECK_NOTNULL(qctx->vctx())) {}
 
 // Create validator according to sentence type.
 std::unique_ptr<Validator> Validator::makeValidator(Sentence* sentence, QueryContext* context) {
+  if (++maxStatements_ > FLAGS_max_statements * 2) {
+    throw std::runtime_error(
+        fmt::format("the number of statements exceeds max_statements : {}", FLAGS_max_statements));
+  }
   auto kind = sentence->kind();
   switch (kind) {
     case Sentence::Kind::kExplain:
@@ -273,22 +281,27 @@ std::unique_ptr<Validator> Validator::makeValidator(Sentence* sentence, QueryCon
 Status Validator::validate(Sentence* sentence, QueryContext* qctx) {
   DCHECK(sentence != nullptr);
   DCHECK(qctx != nullptr);
-
   // Check if space chosen from session. if chosen, add it to context.
   auto session = qctx->rctx()->session();
   if (session->space().id > kInvalidSpaceID) {
     auto spaceInfo = session->space();
     qctx->vctx()->switchToSpace(std::move(spaceInfo));
   }
+  try {
+    auto validator = makeValidator(sentence, qctx);
+    NG_RETURN_IF_ERROR(validator->validate());
 
-  auto validator = makeValidator(sentence, qctx);
-  NG_RETURN_IF_ERROR(validator->validate());
-
-  auto root = validator->root();
-  if (!root) {
-    return Status::SemanticError("Get null plan from sequential validator");
+    auto root = validator->root();
+    if (!root) {
+      return Status::SemanticError("Get null plan from sequential validator");
+    }
+    qctx->plan()->setRoot(root);
+    // reset maxStatements
+    maxStatements_ = 0;
+  } catch (const std::exception& error) {
+    maxStatements_ = 0;
+    return Status::SemanticError(std::string(error.what()));
   }
-  qctx->plan()->setRoot(root);
   return Status::OK();
 }
 

src/graph/validator/Validator.h

@@ -203,6 +203,7 @@ class Validator {
   std::set<std::string> userDefinedVarNameList_;
   // vid's Type
   Value::Type vidType_;
+  static thread_local uint32_t maxStatements_;
 };
 
 }  // namespace graph