Copy constructor for result set and entity

Summary

These changes support a better handling of the ResultSet and Entity objects when their owners are to be deleted (e.g. in clients which delete transansaction due to end of the scope of a function while they return an entity or the resultset of said transaction)

These changes are needed for caosdb-julialib!12 (merged)

The server is just being updated for version-compatibility reasons: caosdb-server!31 (merged)

Focus

• Refactoring of the ResultSet and Entity class' copy constructors (amd a general clean-up of the Entity constructor)
• Additional Transaction::ReleaseResultSet and ResultSet::release_at methods which release the unique_ptr from their owning objects.

Test Environment

• CPP Integration tests in caosdb-cppinttest!15 (merged)
• Julia integration tests in

Check List for the Author

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• All automated tests pass
• Reference related Issues
• [ ] Up-to-date CHANGELOG.md
• Annotations in code (Gitlab comments)
  • Intent of new code
  • Problems with old code
  • Why this implementation?

Check List for the Reviewer

• I understand the intent of this MR
• All automated tests pass
• [ ] Up-to-date CHANGELOG.md
• The test environment setup works and the intended behavior is reproducible in the test environment
• In-code documentation and comments are up-to-date.
• Check: Are there specifications? Are they satisfied?

For further good practices have a look at our review guidelines.

include/caosdb/entity.h

@@ -33,6 +33,7 @@
 #include "caosdb/entity/v1alpha1/main.pb.h"            // for RepeatedPtrField
 #include "caosdb/logging.h"                            // for CAOSDB_LOG_WARN
 #include "caosdb/message_code.h"                       // for get_message_code
+#include "caosdb/protobuf_helper.h"                    // for get_arena
 #include "caosdb/status_code.h"                        // for StatusCode
 #include "caosdb/value.h"                              // for Value
 #include <boost/filesystem/operations.hpp>             // for exists, is_di...
@@ -67,6 +68,7 @@ using ProtoImportance = caosdb::entity::v1alpha1::Importance;
 using caosdb::StatusCode;
 using caosdb::entity::v1alpha1::EntityResponse;
 using caosdb::entity::v1alpha1::FileTransmissionId;
+using caosdb::utility::get_arena;
 using ::google::protobuf::RepeatedPtrField;
 using google::protobuf::RepeatedPtrField;
 
@@ -202,6 +204,8 @@ protected:
     }
   }
 
+  inline auto Clear() noexcept -> void { this->wrapped->Clear(); }
+
   ::google::protobuf::RepeatedPtrField<P> *wrapped;
   mutable std::map<int, T> cache;
 
@@ -323,7 +327,6 @@ public:
   // friend class Parent;
   // friend class Property;
 
-private:
   inline Messages() : RepeatedPtrFieldWrapper(){};
 };
 
@@ -588,25 +591,30 @@ private:
 };
 
 /**
- * @brief Wrapper for the Protobuf entity.
+ * Entity is the central and basic data object of CaosDB.
+ *
+ * This class is a wrapper of the Entity class auto-generated by protobuf
+ * (henceforth "ProtoEntity").
+ *
+ * Overview of the Constructors:
+ *
+ * <li> Entity() - Calls Entity(ProtoEntity *) with a fresh ProtoEntity
+ * <li> Entity(Entity) - Copy constructor, calls Entity(ProtoEntity *) after copying wrapped
+ * ProtoEntity of the original, then also copies all Messages. <li> Entity(ProtoEntity *) - The
+ * workhorse of the constructors. Initializes everything and does not call other Entity
+ * constructors. <li> Entity(EntityResponse *) - Constructor which is used by the Transaction class
+ * to create an Entity from the server's response, calls Entity(ProtoEntity). <li> Entity(IdResponse
+ * *) - Constructor which is used by the Transaction class to create an Entity from the servers's
+ * response. calls Entity(), then moves the data to the wrapped ProtoEntity.
+ *
  */
 class Entity {
 public:
-  Entity();
-  inline Entity(const Entity &original)
-    : wrapped(original.wrapped), value(Value(original.wrapped->mutable_value())),
-      data_type(DataType(original.wrapped->mutable_data_type())) {
-    this->wrapped->CopyFrom(*original.wrapped);
-    data_type.wrapped = this->wrapped->mutable_data_type();
-    value.wrapped = this->wrapped->mutable_value();
-    properties.wrapped = this->wrapped->mutable_properties();
-    parents.wrapped = this->wrapped->mutable_parents();
-    // FIXME(dh) copy messages?
-    errors.wrapped = CreateMessagesField();
-    warnings.wrapped = CreateMessagesField();
-    infos.wrapped = CreateMessagesField();
+  inline Entity(const Entity &original) : Entity(Copy(*original.wrapped)) {
+    this->errors.wrapped->CopyFrom(*original.errors.wrapped);
+    this->warnings.wrapped->CopyFrom(*original.warnings.wrapped);
+    this->infos.wrapped->CopyFrom(*original.infos.wrapped);
   };
-  explicit Entity(IdResponse *id_response);
   explicit Entity(ProtoEntity *other)
     : wrapped(other), value(Value(other->mutable_value())),
       data_type(DataType(other->mutable_data_type())) {
@@ -614,17 +622,26 @@ public:
     value.wrapped = this->wrapped->mutable_value();
     properties.wrapped = this->wrapped->mutable_properties();
     parents.wrapped = this->wrapped->mutable_parents();
-    // FIXME(dh) copy messages?
     errors.wrapped = CreateMessagesField();
     warnings.wrapped = CreateMessagesField();
     infos.wrapped = CreateMessagesField();
   };
   explicit inline Entity(EntityResponse *response) : Entity(response->release_entity()) {
-    errors.wrapped->Swap(response->mutable_errors());
-    warnings.wrapped->Swap(response->mutable_warnings());
-    infos.wrapped->Swap(response->mutable_infos());
+    this->errors.wrapped->Swap(response->mutable_errors());
+    this->warnings.wrapped->Swap(response->mutable_warnings());
+    this->infos.wrapped->Swap(response->mutable_infos());
+  };
+
+  explicit inline Entity(IdResponse *id_response) : Entity() {
+    this->wrapped->set_id(id_response->id());
+    this->wrapped->mutable_version()->Swap(id_response->mutable_version());
+    this->errors.wrapped->Swap(id_response->mutable_errors());
+    this->warnings.wrapped->Swap(id_response->mutable_warnings());
+    this->infos.wrapped->Swap(id_response->mutable_infos());
   };
 
+  explicit inline Entity() : Entity(Entity::CreateProtoEntity()){};
+
   [[nodiscard]] inline auto GetId() const noexcept -> const std::string & { return wrapped->id(); };
   [[nodiscard]] inline auto HasId() const noexcept -> bool { return !wrapped->id().empty(); }
   [[nodiscard]] inline auto GetVersionId() const -> const std::string & {
@@ -734,7 +751,18 @@ public:
     return StatusCode::SUCCESS;
   }
 
+  inline auto ClearMessages() noexcept -> void {
+    errors.Clear();
+    warnings.Clear();
+    infos.Clear();
+  }
+
 private:
+  static inline auto Copy(const ProtoEntity &from) -> ProtoEntity * {
+    auto to = from.New();
+    to->CopyFrom(from);
+    return to;
+  }
   inline auto GetNextFileId() -> std::string {
     std::string str = "0123456789abcdef";
     std::mt19937 generator(std::random_device{}());