ai.rapids.cudf

Class GatherMap

java.lang.Object

ai.rapids.cudf.GatherMap

All Implemented Interfaces:

AutoCloseable

public class GatherMap
extends Object
implements AutoCloseable

This class tracks the data associated with a gather map, a buffer of INT32 elements that index a source table and can be passed to a table gather operation.

Constructor Summary

Constructors

Constructor and Description
GatherMap(DeviceMemoryBuffer buffer) Construct a gather map instance from a device buffer.

Method Summary

Modifier and Type	Method and Description
void	close() Close the device buffer backing the gather map data.
long	getRowCount() Return the number of rows in the gather map
DeviceMemoryBuffer	releaseBuffer() Release the underlying device buffer instance.
ColumnView	toColumnView(long startRow, int numRows) Create a column view that can be used to perform a gather operation.

Methods inherited from class java.lang.Object

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

Constructor Detail

GatherMap

public GatherMap(DeviceMemoryBuffer buffer)

Construct a gather map instance from a device buffer. The buffer length must be a multiple of the DType.INT32 size, as each row of the gather map is an INT32.

Parameters:

buffer - device buffer backing the gather map data

Method Detail

getRowCount

public long getRowCount()

Return the number of rows in the gather map

toColumnView

public ColumnView toColumnView(long startRow,
                               int numRows)

Create a column view that can be used to perform a gather operation. Note that the resulting column view MUST NOT outlive the underlying device buffer within this instance!

Parameters:

startRow - row offset where the resulting gather map will start

numRows - number of rows in the resulting gather map

Returns:

column view of gather map data

releaseBuffer

public DeviceMemoryBuffer releaseBuffer()

Release the underlying device buffer instance. After this is called, closing this instance will not close the underlying device buffer. It is the responsibility of the caller to close the returned device buffer.

Returns:

device buffer backing gather map data or null if the buffer has already been released

close

public void close()

Close the device buffer backing the gather map data.

Specified by:

close in interface AutoCloseable