F grpc select

Summary

Implementation of the handling of Responses to SELECT queries.

Server implementation in caosdb-server!72 (merged)

Focus

The new code mainly wraps the protobuf "SelectQueryResult" message and it's members. The pattern used for the new ResultTable class is a delegator pattern which makes it possible to hide third-party headers from our public API.

Test Environment

No Tests here, just integration tests in caosdb-cppinttest!27 (merged)

Unit tests would not help a lot anyways because we have mainly wrapper classes around the protobuf messages.

Check List for the Author

Please, prepare your MR for a review. Be sure to write a summary and a focus and create gitlab comments for the reviewer. They should guide the reviewer through the changes, explain your changes and also point out open questions. For further good practices have a look at our review guidelines

• All automated tests pass (failures in downstream libraries - julia and octave - are not caused by these changes. They also happen in the dev branch)
• Reference related issues
• Up-to-date CHANGELOG.md (or not necessary)
• 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 (or not necessary)
• 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/transaction.h

@@ -342,10 +342,6 @@ public:
       CAOSDB_LOG_ERROR(logger_name)
         << "GetResultTable was called before the transaction has terminated. This is a programming "
            "error of the code which uses the transaction.";
-      // TODO(tf) This is a really bad SegFault factory. When the transaction
-      // terminates and the result_set is being overriden, the unique_ptr
-      // created here will be deleted and any client of the return ResultTable
-      // will have a SegFault.
     } else if (this->GetStatus().GetCode() == StatusCode::SPOILED) {
       CAOSDB_LOG_ERROR(logger_name)
         << "GetResultTable was called on a \"spoiled\" transaction. That means "