Package io.deephaven.extensions.barrage.chunk

Class SingleElementListHeaderReader<READ_CHUNK_TYPE extends WritableChunk<Values>>

java.lang.Object

io.deephaven.extensions.barrage.chunk.BaseChunkReader<READ_CHUNK_TYPE>

io.deephaven.extensions.barrage.chunk.SingleElementListHeaderReader<READ_CHUNK_TYPE>

Type Parameters:

READ_CHUNK_TYPE - The type of chunk being read, extending WritableChunk with Values.

All Implemented Interfaces:

ChunkReader<READ_CHUNK_TYPE>

public class SingleElementListHeaderReader<READ_CHUNK_TYPE extends WritableChunk<Values>>
extends BaseChunkReader<READ_CHUNK_TYPE>

The SingleElementListHeaderReader is a specialized BaseChunkReader used to handle singleton list-wrapped columns in Apache Arrow record batches. This implementation ensures compatibility with Apache Arrow's requirement that top-level column vectors must have the same number of rows, even when some columns in a record batch contain varying numbers of modified rows.

This reader works by skipping the validity and offset buffers for the singleton list and delegating the reading of the underlying data to a ChunkReader for the wrapped component type. This approach ensures that Arrow payloads remain compatible with official Arrow implementations while supporting Deephaven's semantics for record batches with varying column modifications.

This is used only when BarrageOptions.columnsAsList() is enabled.

Nested Class Summary

Nested classes/interfaces inherited from class io.deephaven.extensions.barrage.chunk.BaseChunkReader

BaseChunkReader.ChunkTransformer<READ_CHUNK_TYPE extends Chunk<Values>,DEST_CHUNK_TYPE extends WritableChunk<Values>>

Nested classes/interfaces inherited from interface io.deephaven.extensions.barrage.chunk.ChunkReader

ChunkReader.Factory

Constructor Summary

Constructors

Constructor	Description
SingleElementListHeaderReader(ChunkReader<READ_CHUNK_TYPE> componentReader)

Method Summary

Modifier and Type	Method	Description
READ_CHUNK_TYPE	readChunk(@NotNull Iterator<ChunkWriter.FieldNodeInfo> fieldNodeIter, PrimitiveIterator.OfLong bufferInfoIter, @NotNull DataInput is, @Nullable WritableChunk<Values> outChunk, int outOffset, int totalRows)	Reads the given DataInput to extract the next Arrow buffer as a Deephaven Chunk.

Methods inherited from class io.deephaven.extensions.barrage.chunk.BaseChunkReader

castOrCreateChunk, getChunkTypeFor, readValidityBuffer

Methods inherited from class java.lang.Object

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

Methods inherited from interface io.deephaven.extensions.barrage.chunk.ChunkReader

readChunk

Constructor Details

SingleElementListHeaderReader

public SingleElementListHeaderReader(ChunkReader<READ_CHUNK_TYPE> componentReader)

Method Details

readChunk

public READ_CHUNK_TYPE readChunk(@NotNull
 @NotNull Iterator<ChunkWriter.FieldNodeInfo> fieldNodeIter,
 @NotNull
 PrimitiveIterator.OfLong bufferInfoIter,
 @NotNull
 @NotNull DataInput is,
 @Nullable
 @Nullable WritableChunk<Values> outChunk,
 int outOffset,
 int totalRows)
                          throws IOException

Description copied from interface: ChunkReader

Reads the given DataInput to extract the next Arrow buffer as a Deephaven Chunk.

Parameters:

fieldNodeIter - iterator to read fields from the stream

bufferInfoIter - iterator to read buffers from the stream

is - input stream containing buffers to be read

outChunk - chunk to write to

outOffset - offset within the outChunk to begin writing

totalRows - total rows to write to the outChunk

Returns:

a Chunk containing the data from the stream

Throws:

IOException - if an error occurred while reading the stream