Explicit memory order for storing unique_type_id_ value

Author: Enmk

clickhouse/types/types.cpp

@@ -121,9 +121,9 @@ uint64_t Type::GetTypeUniqueId() const {
             //   1. going to be the same
             //   2. going to be stored atomically
 
-            if (type_unique_id_ == 0) {
+            if (type_unique_id_.load(std::memory_order::memory_order_relaxed) == 0) {
                 const auto name = GetName();
-                type_unique_id_ = CityHash64WithSeed(name.c_str(), name.size(), code_);
+                type_unique_id_.store(CityHash64WithSeed(name.c_str(), name.size(), code_), std::memory_order::memory_order_relaxed);
             }
 
             return type_unique_id_;

clickhouse/types/types.h

@@ -75,6 +75,7 @@ class Type {
 
     /// Is given type same as current one.
     bool IsEqual(const Type& other) const {
+        // Types are equal only if both code_ and type_unique_id_ are equal.
         return this == &other
                 // GetTypeUniqueId() is relatively heavy, so avoid calling it when comparing obviously different types.
                 || (this->GetCode() == other.GetCode() && this->GetTypeUniqueId() == other.GetTypeUniqueId());