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https://issues.apache.org/jira/browse/ARROW-18320?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
David Li reassigned ARROW-18320:
--------------------------------
Assignee: David Li
> [C++] Flight client may crash due to improper Result/Status conversion
> ----------------------------------------------------------------------
>
> Key: ARROW-18320
> URL: https://issues.apache.org/jira/browse/ARROW-18320
> Project: Apache Arrow
> Issue Type: Bug
> Components: C++, FlightRPC
> Affects Versions: 6.0.0
> Reporter: David Li
> Assignee: David Li
> Priority: Major
>
> Reported on user@
> https://lists.apache.org/thread/84z329t1djhnbr5bq936v4hr8cyngj2l
> {noformat}
> I have an issue on my project, we have a query execution engine that
> returns result data as a flight stream and c++ client that receives the
> stream. In case a query has no results but the result schema implies
> dictionary encoded fields in results we have client app crushed.
> The cause is in cpp/src/arrow/flight/client.cc:461:
> ::arrow::Result<std::unique_ptr<ipc::Message>> ReadNextMessage() override {
> if (stream_finished_) {
> return nullptr;
> }
> internal::FlightData* data;
> {
> auto guard = read_mutex_ ? std::unique_lock<std::mutex>(*read_mutex_)
> : std::unique_lock<std::mutex>();
> peekable_reader_->Next(&data);
> }
> if (!data) {
> stream_finished_ = true;
> return stream_->Finish(Status::OK()); // Here the issue
> }
> // Validate IPC message
> auto result = data->OpenMessage();
> if (!result.ok()) {
> return stream_->Finish(std::move(result).status());
> }
> *app_metadata_ = std::move(data->app_metadata);
> return result;
> }
> The method returns Result object while stream_Finish(..) returns a Status.
> So there is an implicit conversion from Status to Result that causes
> Result(Status) constructor to be called, but the constructor expects only
> error statuses which in turn causes the app to be failed:
> /// Constructs a Result object with the given non-OK Status object. All
> /// calls to ValueOrDie() on this object will abort. The given `status` must
> /// not be an OK status, otherwise this constructor will abort.
> ///
> /// This constructor is not declared explicit so that a function with a
> return
> /// type of `Result<T>` can return a Status object, and the status will be
> /// implicitly converted to the appropriate return type as a matter of
> /// convenience.
> ///
> /// \param status The non-OK Status object to initialize to.
> Result(const Status& status) noexcept // NOLINT(runtime/explicit)
> : status_(status) {
> if (ARROW_PREDICT_FALSE(status.ok())) {
> internal::DieWithMessage(std::string("Constructed with a non-error status: ")
> +
> status.ToString());
> }
> }
> Is there a way to workaround or fix it? We use Arrow 6.0.0, but it seems
> that the issue exists in all future versions.
> {noformat}
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