org.apache.arrow.vector.ipc

Class ArrowStreamReader

java.lang.Object

org.apache.arrow.vector.ipc.ArrowReader

org.apache.arrow.vector.ipc.ArrowStreamReader

All Implemented Interfaces:

AutoCloseable, DictionaryProvider

public class ArrowStreamReader
extends ArrowReader

This classes reads from an input stream and produces ArrowRecordBatches.

Nested Class Summary

Nested classes/interfaces inherited from interface org.apache.arrow.vector.dictionary.DictionaryProvider

DictionaryProvider.MapDictionaryProvider

Field Summary

Fields inherited from class org.apache.arrow.vector.ipc.ArrowReader

allocator

Constructor Summary

Constructors

Constructor and Description
ArrowStreamReader(InputStream in, BufferAllocator allocator) Constructs a streaming reader from an InputStream.
ArrowStreamReader(MessageReader messageReader, BufferAllocator allocator) Constructs a streaming reader using the MessageReader interface.
ArrowStreamReader(ReadableByteChannel in, BufferAllocator allocator) Constructs a streaming reader from a ReadableByteChannel input.

Method Summary

Methods

Modifier and Type	Method and Description
long	bytesRead() Get the number of bytes read from the stream since constructing the reader.
protected void	closeReadSource() Closes the underlying read source.
boolean	loadNextBatch() Load the next ArrowRecordBatch to the vector schema root if available.
protected ArrowDictionaryBatch	readDictionary() Read a dictionary batch message, will be invoked after the schema and before normal record batches are read.
protected Schema	readSchema() Reads the schema message from the beginning of the stream.

Methods inherited from class org.apache.arrow.vector.ipc.ArrowReader

close, close, ensureInitialized, getDictionaryVectors, getVectorSchemaRoot, loadDictionary, loadRecordBatch, lookup, prepareLoadNextBatch

Methods inherited from class java.lang.Object

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

Constructor Detail

ArrowStreamReader

public ArrowStreamReader(MessageReader messageReader,
                 BufferAllocator allocator)

Constructs a streaming reader using the MessageReader interface. Non-blocking.

Parameters:

messageReader - interface to get read messages

allocator - to allocate new buffers

ArrowStreamReader

public ArrowStreamReader(ReadableByteChannel in,
                 BufferAllocator allocator)

Constructs a streaming reader from a ReadableByteChannel input. Non-blocking.

Parameters:

in - ReadableByteChannel to read messages from

allocator - to allocate new buffers

ArrowStreamReader

public ArrowStreamReader(InputStream in,
                 BufferAllocator allocator)

Constructs a streaming reader from an InputStream. Non-blocking.

Parameters:

in - InputStream to read messages from

allocator - to allocate new buffers

Method Detail

bytesRead

public long bytesRead()

Get the number of bytes read from the stream since constructing the reader.

Specified by:

bytesRead in class ArrowReader

Returns:

number of bytes

closeReadSource

protected void closeReadSource()
                        throws IOException

Closes the underlying read source.

Specified by:

closeReadSource in class ArrowReader

Throws:

IOException

loadNextBatch

public boolean loadNextBatch()
                      throws IOException

Load the next ArrowRecordBatch to the vector schema root if available.

Specified by:

loadNextBatch in class ArrowReader

Returns:

true if a batch was read, false on EOS

Throws:

IOException

readSchema

protected Schema readSchema()
                     throws IOException

Reads the schema message from the beginning of the stream.

Specified by:

readSchema in class ArrowReader

Returns:

the deserialized arrow schema

Throws:

IOException

readDictionary

protected ArrowDictionaryBatch readDictionary()
                                       throws IOException

Read a dictionary batch message, will be invoked after the schema and before normal record batches are read.

Specified by:

readDictionary in class ArrowReader

Returns:

the deserialized dictionary batch

Throws:

IOException