ai.rapids.cudf

Class HostMemoryBuffer

java.lang.Object

ai.rapids.cudf.MemoryBuffer

ai.rapids.cudf.HostMemoryBuffer

All Implemented Interfaces:

AutoCloseable

public class HostMemoryBuffer
extends MemoryBuffer

This class holds an off-heap buffer in the host/CPU memory. Please note that instances must be explicitly closed or native memory will be leaked! Internally this class will try to use PinnedMemoryPool to allocate and free the memory it uses by default. To avoid using the pinned memory pool for allocations by default set the Java system property ai.rapids.cudf.prefer-pinned to false. Be aware that the off heap memory limits set by Java do not apply to these buffers.

Nested Class Summary

Nested classes/interfaces inherited from class ai.rapids.cudf.MemoryBuffer

MemoryBuffer.MemoryBufferCleaner

Field Summary

Fields inherited from class ai.rapids.cudf.MemoryBuffer

address, cleaner, closed, id, length, refCount

Method Summary

Modifier and Type	Method and Description
static HostMemoryBuffer	allocate(long bytes) Allocate memory, but be sure to close the returned buffer to avoid memory leaks.
static HostMemoryBuffer	allocate(long bytes, boolean preferPinned) Allocate memory, but be sure to close the returned buffer to avoid memory leaks.
ByteBuffer	asByteBuffer() Return a ByteBuffer that provides access to the underlying memory.
ByteBuffer	asByteBuffer(long offset, int length) Return a ByteBuffer that provides access to the underlying memory.
void	copyFromDeviceBuffer(BaseDeviceMemoryBuffer deviceMemoryBuffer) Synchronously copy from a DeviceMemoryBuffer to a HostMemoryBuffer
void	copyFromDeviceBuffer(BaseDeviceMemoryBuffer deviceMemoryBuffer, Cuda.Stream stream) Copy from a DeviceMemoryBuffer to a HostMemoryBuffer using the specified stream.
void	copyFromDeviceBufferAsync(BaseDeviceMemoryBuffer deviceMemoryBuffer, Cuda.Stream stream) Copy from a DeviceMemoryBuffer to a HostMemoryBuffer using the specified stream.
void	copyFromHostBuffer(long destOffset, HostMemoryBuffer srcData, long srcOffset, long length) Copy the contents of the given buffer to this buffer
byte	getByte(long offset) Returns the byte value at that offset
void	getBytes(byte[] dst, long dstOffset, long srcOffset, long len) Copy a set of bytes to an array from the buffer starting at offset.
static HostMemoryBuffer	mapFile(File path, FileChannel.MapMode mode, long offset, long length) Create a host buffer that is memory-mapped to a file.
void	setByte(long offset, byte value) Sets the byte value at that offset
void	setBytes(long offset, byte[] data, long srcOffset, long len) Copy a set of bytes from an array into the buffer at offset.
HostMemoryBuffer	slice(long offset, long len) Slice off a part of the host buffer.
HostMemoryBuffer	sliceWithCopy(long offset, long len) Slice off a part of the host buffer, actually making a copy of the data.

Methods inherited from class ai.rapids.cudf.MemoryBuffer

addressOutOfBoundsCheck, close, getAddress, getLength, noWarnLeakExpected, toString

Methods inherited from class java.lang.Object

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

Method Detail

allocate

public static HostMemoryBuffer allocate(long bytes,
                                        boolean preferPinned)

Allocate memory, but be sure to close the returned buffer to avoid memory leaks.

Parameters:

bytes - size in bytes to allocate

preferPinned - If set to true, the pinned memory pool will be used if possible with a fallback to off-heap memory. If set to false, the allocation will always be from off-heap memory.

Returns:

the newly created buffer

allocate

public static HostMemoryBuffer allocate(long bytes)

Allocate memory, but be sure to close the returned buffer to avoid memory leaks. Pinned memory will be preferred for allocations if the java system property ai.rapids.cudf.prefer-pinned is set to true.

Parameters:

bytes - size in bytes to allocate

Returns:

the newly created buffer

mapFile

public static HostMemoryBuffer mapFile(File path,
                                       FileChannel.MapMode mode,
                                       long offset,
                                       long length)
                                throws IOException

Create a host buffer that is memory-mapped to a file.

Parameters:

path - path to the file to map into host memory

mode - mapping type

offset - file offset where the map will start

length - the number of bytes to map

Returns:

file-mapped buffer

Throws:

IOException

asByteBuffer

public final ByteBuffer asByteBuffer()

Return a ByteBuffer that provides access to the underlying memory. Please note: if the buffer is larger than a ByteBuffer can handle (2GB) an exception will be thrown. Also be aware that the ByteBuffer will be in native endian order, which is different from regular ByteBuffers that are big endian by default.

asByteBuffer

public final ByteBuffer asByteBuffer(long offset,
                                     int length)

Return a ByteBuffer that provides access to the underlying memory. Be aware that the ByteBuffer will be in native endian order, which is different from regular ByteBuffers that are big endian by default.

Parameters:

offset - the offset to start at

length - how many bytes to include.

copyFromHostBuffer

public final void copyFromHostBuffer(long destOffset,
                                     HostMemoryBuffer srcData,
                                     long srcOffset,
                                     long length)

Copy the contents of the given buffer to this buffer

Parameters:

destOffset - offset in bytes in this buffer to start copying to

srcData - Buffer to be copied from

srcOffset - offset in bytes to start copying from in srcData

length - number of bytes to copy

getByte

public final byte getByte(long offset)

Returns the byte value at that offset

Parameters:

offset - - offset from the address

Returns:

- value

setByte

public final void setByte(long offset,
                          byte value)

Sets the byte value at that offset

Parameters:

offset - - offset from the address

value - - value to be set

getBytes

public final void getBytes(byte[] dst,
                           long dstOffset,
                           long srcOffset,
                           long len)

Copy a set of bytes to an array from the buffer starting at offset.

Parameters:

dstOffset - the offset from the address to start copying to

dst - the data to be copied.

setBytes

public final void setBytes(long offset,
                           byte[] data,
                           long srcOffset,
                           long len)

Copy a set of bytes from an array into the buffer at offset.

Parameters:

offset - the offset from the address to start copying to

data - the data to be copied.

copyFromDeviceBuffer

public final void copyFromDeviceBuffer(BaseDeviceMemoryBuffer deviceMemoryBuffer)

Synchronously copy from a DeviceMemoryBuffer to a HostMemoryBuffer

Parameters:

deviceMemoryBuffer - buffer to copy data from

copyFromDeviceBuffer

public final void copyFromDeviceBuffer(BaseDeviceMemoryBuffer deviceMemoryBuffer,
                                       Cuda.Stream stream)

Copy from a DeviceMemoryBuffer to a HostMemoryBuffer using the specified stream. The copy has completed when this returns, but the memory copy could overlap with operations occurring on other streams.

Parameters:

deviceMemoryBuffer - buffer to copy data from

stream - CUDA stream to use

copyFromDeviceBufferAsync

public final void copyFromDeviceBufferAsync(BaseDeviceMemoryBuffer deviceMemoryBuffer,
                                            Cuda.Stream stream)

Copy from a DeviceMemoryBuffer to a HostMemoryBuffer using the specified stream. The copy is async and may not have completed when this returns.

Parameters:

deviceMemoryBuffer - buffer to copy data from

stream - CUDA stream to use

slice

public final HostMemoryBuffer slice(long offset,
                                    long len)

Slice off a part of the host buffer.

Specified by:

slice in class MemoryBuffer

Parameters:

offset - where to start the slice at.

len - how many bytes to slice

Returns:

a host buffer that will need to be closed independently from this buffer.

sliceWithCopy

public final HostMemoryBuffer sliceWithCopy(long offset,
                                            long len)

Slice off a part of the host buffer, actually making a copy of the data.

Parameters:

offset - where to start the slice at.

len - how many bytes to slice

Returns:

a host buffer that will need to be closed independently from this buffer.