Module udf_impl 

Remote UDF implementation via Arrow Flight.

RemoteUdf implements DataFusion’s AsyncScalarUDFImpl, turning a scalar call into an Arrow Flight DoExchange round-trip:

1. Materialise the arguments into one input RecordBatch.
2. Bridge it from DataFusion’s arrow-58 to arrow-59 and send it with a per-call timeout, collecting the response under a streaming byte ceiling.
3. Bridge the response back, validate schema/row-count containment, and return column 0.

A per-service CircuitBreaker fails fast when a worker is unhealthy, and every invocation records metrics (by reason) and an audit-log entry — never payload data.

Structs

RemoteUdf

Remote UDF that calls an external worker via Arrow Flight.