public AsyncUnaryCall <Schema> GetSchema(FlightDescriptor flightDescriptor, Metadata headers = null)
{
var schemaResult = _client.GetSchemaAsync(flightDescriptor.ToProtocol(), headers);
var schema = schemaResult
.ResponseAsync
.ContinueWith(async schema => FlightMessageSerializer.DecodeSchema((await schemaResult.ResponseAsync.ConfigureAwait(false)).Schema.Memory))
.Unwrap();
return(new AsyncUnaryCall <Schema>(
schema,
schemaResult.ResponseHeadersAsync,
schemaResult.GetStatus,
schemaResult.GetTrailers,
schemaResult.Dispose));
}
public async ValueTask <Schema> ReadSchema()
{
if (HasReadSchema)
{
return(Schema);
}
var moveNextResult = await _flightDataStream.MoveNext().ConfigureAwait(false);
if (!moveNextResult)
{
throw new Exception("No records or schema in this flight");
}
//AppMetadata will never be null, but length 0 if empty
//Those are skipped
if (_flightDataStream.Current.AppMetadata.Length > 0)
{
_applicationMetadatas.Add(_flightDataStream.Current.AppMetadata);
}
var header = _flightDataStream.Current.DataHeader.Memory;
Message message = Message.GetRootAsMessage(
ArrowReaderImplementation.CreateByteBuffer(header));
if (_flightDataStream.Current.FlightDescriptor != null)
{
_flightDescriptor = new FlightDescriptor(_flightDataStream.Current.FlightDescriptor);
}
switch (message.HeaderType)
{
case MessageHeader.Schema:
Schema = FlightMessageSerializer.DecodeSchema(message.ByteBuffer);
break;
default:
throw new Exception($"Expected schema as the first message, but got: {message.HeaderType.ToString()}");
}
return(Schema);
}