Package io.deephaven.extensions.barrage.chunk

Class SingleElementListHeaderWriter

java.lang.Object

java.io.InputStream

io.deephaven.extensions.barrage.util.DefensiveDrainable

io.deephaven.extensions.barrage.chunk.ChunkWriter.DrainableColumn

io.deephaven.extensions.barrage.chunk.SingleElementListHeaderWriter

All Implemented Interfaces:

io.grpc.Drainable, Closeable, AutoCloseable

public class SingleElementListHeaderWriter
extends ChunkWriter.DrainableColumn

The SingleElementListHeaderWriter is a specialized ChunkWriter.DrainableColumn implementation that writes the header for singleton list-wrapped columns in Apache Arrow record batches.

This writer ensures compatibility with Apache Arrow's format by providing the necessary metadata and offsets for a single-element list, while omitting unnecessary buffers such as validity buffers. It is designed to write the header information for a column where all rows are represented as a singleton list, with no null values.

See Also:

• SingleElementListHeaderReader

Constructor Summary

Constructors

Constructor	Description
SingleElementListHeaderWriter(int numElements)

Method Summary

Modifier and Type	Method	Description
int	available()	A defensive drainable needs to override available.
int	drainTo(OutputStream outputStream)
int	nullCount()	Count the number of null elements in the outer-most layer of this column (i.e.
void	visitBuffers(ChunkWriter.BufferListener listener)	Append the buffer boundaries to the flatbuffer payload via the supplied listener.
void	visitFieldNodes(ChunkWriter.FieldNodeListener listener)	Append the field node to the flatbuffer payload via the supplied listener.

Methods inherited from class io.deephaven.extensions.barrage.util.DefensiveDrainable

capture, read, read, read, skip

Methods inherited from class java.io.InputStream

close, mark, markSupported, nullInputStream, readAllBytes, readNBytes, readNBytes, reset, skipNBytes, transferTo

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

SingleElementListHeaderWriter

public SingleElementListHeaderWriter(int numElements)

Method Details

visitFieldNodes

public void visitFieldNodes(ChunkWriter.FieldNodeListener listener)

Description copied from class: ChunkWriter.DrainableColumn

Append the field node to the flatbuffer payload via the supplied listener.

Specified by:

visitFieldNodes in class ChunkWriter.DrainableColumn

Parameters:

listener - the listener to notify for each logical field node in this payload

visitBuffers

public void visitBuffers(ChunkWriter.BufferListener listener)

Description copied from class: ChunkWriter.DrainableColumn

Append the buffer boundaries to the flatbuffer payload via the supplied listener.

Specified by:

visitBuffers in class ChunkWriter.DrainableColumn

Parameters:

listener - the listener to notify for each sub-buffer in this payload

nullCount

public int nullCount()

Description copied from class: ChunkWriter.DrainableColumn

Count the number of null elements in the outer-most layer of this column (i.e. does not count nested nulls inside of arrays)

Specified by:

nullCount in class ChunkWriter.DrainableColumn

Returns:

the number of null elements -- 'useDeephavenNulls' counts are always 0 so that we may omit the validity buffer

drainTo

public int drainTo(OutputStream outputStream)
            throws IOException

Throws:

IOException

available

public int available()
              throws IOException

Description copied from class: DefensiveDrainable

A defensive drainable needs to override available. As opposed to the generic InputStream, this method must return the exact amount available.

Overrides:

available in class DefensiveDrainable

Returns:

the exact amount available

Throws:

IOException - if an I/O exception occurs