Package org.apache.flink.core.memory

Class MemorySegmentFactory

java.lang.Object

org.apache.flink.core.memory.MemorySegmentFactory

@Internal
public final class MemorySegmentFactory
extends Object

A factory for memory segments (MemorySegment).

Constructor Summary

Constructors

Constructor	Description
MemorySegmentFactory()

Method Summary

Modifier and Type	Method	Description
static MemorySegment	allocateOffHeapUnsafeMemory(int size)
static MemorySegment	allocateOffHeapUnsafeMemory(int size, Object owner, Runnable customCleanupAction)	Allocates an off-heap unsafe memory and creates a new memory segment to represent that memory.
static MemorySegment	allocateUnpooledOffHeapMemory(int size)	Allocates some unpooled off-heap memory and creates a new memory segment that represents that memory.
static MemorySegment	allocateUnpooledOffHeapMemory(int size, Object owner)	Allocates some unpooled off-heap memory and creates a new memory segment that represents that memory.
static MemorySegment	allocateUnpooledSegment(int size)	Allocates some unpooled memory and creates a new memory segment that represents that memory.
static MemorySegment	allocateUnpooledSegment(int size, Object owner)	Allocates some unpooled memory and creates a new memory segment that represents that memory.
static MemorySegment	wrap(byte[] buffer)	Creates a new memory segment that targets the given heap memory region.
static MemorySegment	wrapCopy(byte[] bytes, int start, int end)	Copies the given heap memory region and creates a new memory segment wrapping it.
static MemorySegment	wrapInt(int value)	Wraps the four bytes representing the given number with a MemorySegment.
static MemorySegment	wrapOffHeapMemory(ByteBuffer memory)	Creates a memory segment that wraps the off-heap memory backing the given ByteBuffer.

Methods inherited from class java.lang.Object

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

Constructor Detail

MemorySegmentFactory

public MemorySegmentFactory()

Method Detail

wrap

public static MemorySegment wrap(byte[] buffer)

Creates a new memory segment that targets the given heap memory region.

This method should be used to turn short lived byte arrays into memory segments.

Parameters:

buffer - The heap memory region.

Returns:

A new memory segment that targets the given heap memory region.

wrapCopy

public static MemorySegment wrapCopy(byte[] bytes,
                                     int start,
                                     int end)
                              throws IllegalArgumentException

Copies the given heap memory region and creates a new memory segment wrapping it.

Parameters:

bytes - The heap memory region.

start - starting position, inclusive

end - end position, exclusive

Returns:

A new memory segment that targets a copy of the given heap memory region.

Throws:

IllegalArgumentException - if start > end or end > bytes.length

wrapInt

public static MemorySegment wrapInt(int value)

Wraps the four bytes representing the given number with a MemorySegment.

See Also:

ByteBuffer.putInt(int)

allocateUnpooledSegment

public static MemorySegment allocateUnpooledSegment(int size)

Allocates some unpooled memory and creates a new memory segment that represents that memory.

This method is similar to allocateUnpooledSegment(int, Object), but the memory segment will have null as the owner.

Parameters:

size - The size of the memory segment to allocate.

Returns:

A new memory segment, backed by unpooled heap memory.

allocateUnpooledSegment

public static MemorySegment allocateUnpooledSegment(int size,
                                                    Object owner)

Allocates some unpooled memory and creates a new memory segment that represents that memory.

This method is similar to allocateUnpooledSegment(int), but additionally sets the owner of the memory segment.

Parameters:

size - The size of the memory segment to allocate.

owner - The owner to associate with the memory segment.

Returns:

A new memory segment, backed by unpooled heap memory.

allocateUnpooledOffHeapMemory

public static MemorySegment allocateUnpooledOffHeapMemory(int size)

Allocates some unpooled off-heap memory and creates a new memory segment that represents that memory.

Parameters:

size - The size of the off-heap memory segment to allocate.

Returns:

A new memory segment, backed by unpooled off-heap memory.

allocateUnpooledOffHeapMemory

public static MemorySegment allocateUnpooledOffHeapMemory(int size,
                                                          Object owner)

Allocates some unpooled off-heap memory and creates a new memory segment that represents that memory.

Parameters:

size - The size of the off-heap memory segment to allocate.

owner - The owner to associate with the off-heap memory segment.

Returns:

A new memory segment, backed by unpooled off-heap memory.

allocateOffHeapUnsafeMemory

@VisibleForTesting
public static MemorySegment allocateOffHeapUnsafeMemory(int size)

allocateOffHeapUnsafeMemory

public static MemorySegment allocateOffHeapUnsafeMemory(int size,
                                                        Object owner,
                                                        Runnable customCleanupAction)

Allocates an off-heap unsafe memory and creates a new memory segment to represent that memory.

Creation of this segment schedules its memory freeing operation when its java wrapping object is about to be garbage collected, similar to DirectByteBuffer(int). The difference is that this memory allocation is out of option -XX:MaxDirectMemorySize limitation.

Parameters:

size - The size of the off-heap unsafe memory segment to allocate.

owner - The owner to associate with the off-heap unsafe memory segment.

customCleanupAction - A custom action to run upon calling GC cleaner.

Returns:

A new memory segment, backed by off-heap unsafe memory.

wrapOffHeapMemory

public static MemorySegment wrapOffHeapMemory(ByteBuffer memory)

Creates a memory segment that wraps the off-heap memory backing the given ByteBuffer. Note that the ByteBuffer needs to be a direct ByteBuffer.

This method is intended to be used for components which pool memory and create memory segments around long-lived memory regions.

Parameters:

memory - The byte buffer with the off-heap memory to be represented by the memory segment.

Returns:

A new memory segment representing the given off-heap memory.