Utility classes¶

These are various utility and helper classes available in the system.

class TableMaker¶

A convenience class for populating small tables. It is a wrapper around Arrow Flight’s DoPut functionality. Typical usage

TableMaker tm;
std::vector<T1> data1 = { ... };
std::vector<T2> data2 = { ... };
tm.AddColumn("col1", data1);
tm.AddColumn("col2", data2);
auto tableHandle = tm.MakeTable();

Public Functions

TableMaker()¶: Constructor

~TableMaker()¶: Destructor

template<typename T> void AddColumn(std::string name, const std::vector<T> &values)¶: Creates a column whose server type most closely matches type T, having the given name and values. Each call to this method adds a column. When there are multiple calls to this method, the sizes of the values arrays must be consistent.

TableHandle MakeTable(const TableHandleManager &manager)¶

Make the table. Call this after all your calls to AddColumn().

Parameters:: manager – The TableHandleManager
Returns:: The TableHandle referencing the newly-created table.

class FlightWrapper¶

This class provides an interface to Arrow Flight, which is the main way to push data into and get data out of the system.

Public Functions

explicit FlightWrapper(std::shared_ptr<impl::TableHandleManagerImpl> impl)¶: Constructor. Used internally.

~FlightWrapper()¶: Destructor

std::unique_ptr<arrow::flight::FlightStreamReader> GetFlightStreamReader(const TableHandle &table) const¶

Construct an Arrow FlightStreamReader that is set up to read the given TableHandle.

Parameters:: table – The table to read from.
Returns:: An Arrow FlightStreamReader

void AddHeaders(arrow::flight::FlightCallOptions *options) const¶

Add Deephaven authentication headers, and any other extra headers request at session creation, to Arrow FlightCallOptions.

This is a bit of a hack, and is used in the scenario Where the caller is rolling their own Arrow Flight DoPut operation. Example code might look like this:

// Get a FlightWrapper
auto wrapper = manager.CreateFlightWrapper();
// Get a
auto [result, fd] = manager.newTableHandleAndFlightDescriptor();
// Empty FlightCallOptions
arrow::flight::FlightCallOptions options;
// add Deephaven auth headers to the FlightCallOptions
wrapper.AddHeaders(&options);
std::unique_ptr<arrow::flight::FlightStreamWriter> fsw;
std::unique_ptr<arrow::flight::FlightMetadataReader> fmr;
auto status = wrapper.FlightClient()->DoPut(options, fd, Schema, &fsw, &fmr);

Parameters:: options – Destination object Where the authentication headers should be written.

arrow::flight::FlightClient *FlightClient() const¶

Gets the underlying FlightClient

Returns:: A pointer to the FlightClient.