DirectBufferAllocator (GemFire XD Java API Documentation)

java.lang.Object
- com.gemstone.gemfire.internal.shared.BufferAllocator
- - com.gemstone.gemfire.internal.shared.unsafe.DirectBufferAllocator

All Implemented Interfaces:

Closeable, AutoCloseable
```
public class DirectBufferAllocator
extends BufferAllocator
```
Generic implementation of BufferAllocator for direct ByteBuffers using Java NIO API.

Field Summary

Fields
Modifier and Type	Field and Description
`static int`	`DIRECT_OBJECT_OVERHEAD` Overhead of allocation on off-heap memory is kept fixed at 8 even though actual overhead will be dependent on the malloc implementation.
`static String`	`DIRECT_STORE_DATA_FRAME_OUTPUT`
`static String`	`DIRECT_STORE_OBJECT_OWNER` The owner of direct buffers that are stored in Regions and tracked in UMM.

Fields inherited from class com.gemstone.gemfire.internal.shared.BufferAllocator
STORE_DATA_FRAME_OUTPUT

Constructor Summary

Constructors
Modifier Constructor and Description

protected DirectBufferAllocator()

Constructors
Modifier	Constructor and Description
`protected`	`DirectBufferAllocator()`

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`ByteBuffer`	`allocate(int size, String owner)` Allocate a new ByteBuffer of given size.
`ByteBuffer`	`allocateForStorage(int size)` Allocate a new ByteBuffer of given size for storage in a Region.
`Object`	`baseObject(ByteBuffer buffer)` Get the base object of the ByteBuffer for raw reads/writes by Unsafe API.
`long`	`baseOffset(ByteBuffer buffer)` Get the base offset of the ByteBuffer for raw reads/writes by Unsafe API.
`void`	`changeOwnerToStorage(ByteBuffer buffer, int capacity, java.util.function.Consumer<String> changeOwner)`
`void`	`clearPostAllocate(ByteBuffer buffer)` Clears the memory to be zeros immediately after allocation.
`void`	`close()` Any cleanup required at system close.
`ByteBuffer`	`expand(ByteBuffer buffer, int required, String owner)` Expand given ByteBuffer to new capacity.
`ByteBuffer`	`fromBytesToStorage(byte[] bytes, int offset, int length)` Return a ByteBuffer either copying from, or sharing the given heap bytes.
`DirectBufferAllocator`	`initialize()`
`static DirectBufferAllocator`	`instance()`
`boolean`	`isDirect()` Indicates if this allocator will produce direct ByteBuffers.
`RuntimeException`	`lowMemoryException(String op, int required)`
`void`	`release(ByteBuffer buffer)` For direct ByteBuffers the release method is preferred to eagerly release the memory instead of depending on heap GC which can be delayed.
`static void`	`resetInstance()`
`static void`	`setInstance(DirectBufferAllocator allocator)`
`ByteBuffer`	`transfer(ByteBuffer buffer, String owner)` Return a ByteBuffer either sharing data of given ByteBuffer if its type matches, or else copying from the given ByteBuffer.

Methods inherited from class com.gemstone.gemfire.internal.shared.BufferAllocator
clearBuffer, expandedSize, toBytes

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - DIRECT_OBJECT_OVERHEAD
```
public static final int DIRECT_OBJECT_OVERHEAD
```
    Overhead of allocation on off-heap memory is kept fixed at 8 even though actual overhead will be dependent on the malloc implementation.
    
    See Also:
    
    Constant Field Values
  - DIRECT_STORE_OBJECT_OWNER
```
public static final String DIRECT_STORE_OBJECT_OWNER
```
    The owner of direct buffers that are stored in Regions and tracked in UMM.
    
    See Also:
    
    Constant Field Values
  - DIRECT_STORE_DATA_FRAME_OUTPUT
```
public static final String DIRECT_STORE_DATA_FRAME_OUTPUT
```
    See Also:
    
    Constant Field Values
- Constructor Detail
  - DirectBufferAllocator
```
protected DirectBufferAllocator()
```
- Method Detail
  - instance
```
public static DirectBufferAllocator instance()
```
  - initialize
```
public DirectBufferAllocator initialize()
```
  - setInstance
```
public static void setInstance(DirectBufferAllocator allocator)
```
  - resetInstance
```
public static void resetInstance()
```
  - lowMemoryException
```
public RuntimeException lowMemoryException(String op,
                                           int required)
```
  - changeOwnerToStorage
```
public void changeOwnerToStorage(ByteBuffer buffer,
                                 int capacity,
                                 java.util.function.Consumer<String> changeOwner)
```
  - allocate
```
public ByteBuffer allocate(int size,
                           String owner)
```
    Description copied from class: BufferAllocator
    
    Allocate a new ByteBuffer of given size.
    
    Specified by:
    
    allocate in class BufferAllocator
  - allocateForStorage
```
public ByteBuffer allocateForStorage(int size)
```
    Description copied from class: BufferAllocator
    
    Allocate a new ByteBuffer of given size for storage in a Region.
    
    Specified by:
    
    allocateForStorage in class BufferAllocator
  - clearPostAllocate
```
public void clearPostAllocate(ByteBuffer buffer)
```
    Description copied from class: BufferAllocator
    
    Clears the memory to be zeros immediately after allocation.
    
    Specified by:
    
    clearPostAllocate in class BufferAllocator
  - baseObject
```
public Object baseObject(ByteBuffer buffer)
```
    Description copied from class: BufferAllocator
    
    Get the base object of the ByteBuffer for raw reads/writes by Unsafe API.
    
    Specified by:
    
    baseObject in class BufferAllocator
  - baseOffset
```
public long baseOffset(ByteBuffer buffer)
```
    Description copied from class: BufferAllocator
    
    Get the base offset of the ByteBuffer for raw reads/writes by Unsafe API.
    
    Specified by:
    
    baseOffset in class BufferAllocator
  - expand
```
public ByteBuffer expand(ByteBuffer buffer,
                         int required,
                         String owner)
```
    Description copied from class: BufferAllocator
    
    Expand given ByteBuffer to new capacity. The new buffer is positioned at the start and caller has to reposition if required.
    
    Specified by:
    
    expand in class BufferAllocator
    
    Returns:
    
    the new expanded ByteBuffer
  - fromBytesToStorage
```
public ByteBuffer fromBytesToStorage(byte[] bytes,
                                     int offset,
                                     int length)
```
    Description copied from class: BufferAllocator
    
    Return a ByteBuffer either copying from, or sharing the given heap bytes.
    
    Specified by:
    
    fromBytesToStorage in class BufferAllocator
  - transfer
```
public ByteBuffer transfer(ByteBuffer buffer,
                           String owner)
```
    Description copied from class: BufferAllocator
    
    Return a ByteBuffer either sharing data of given ByteBuffer if its type matches, or else copying from the given ByteBuffer.
    
    Overrides:
    
    transfer in class BufferAllocator
  - release
```
public void release(ByteBuffer buffer)
```
    Description copied from class: BufferAllocator
    
    For direct ByteBuffers the release method is preferred to eagerly release the memory instead of depending on heap GC which can be delayed.
    
    Specified by:
    
    release in class BufferAllocator
  - isDirect
```
public boolean isDirect()
```
    Description copied from class: BufferAllocator
    
    Indicates if this allocator will produce direct ByteBuffers.
    
    Specified by:
    
    isDirect in class BufferAllocator
  - close
```
public void close()
```
    Description copied from class: BufferAllocator
    
    Any cleanup required at system close.
    
    Specified by:
    
    close in interface Closeable
    
    Specified by:
    
    close in interface AutoCloseable
    
    Specified by:
    
    close in class BufferAllocator

Class DirectBufferAllocator

Field Summary

Fields inherited from class com.gemstone.gemfire.internal.shared.BufferAllocator

Constructor Summary

Method Summary

Methods inherited from class com.gemstone.gemfire.internal.shared.BufferAllocator

Methods inherited from class java.lang.Object

Field Detail

DIRECT_OBJECT_OVERHEAD

DIRECT_STORE_OBJECT_OWNER

DIRECT_STORE_DATA_FRAME_OUTPUT

Constructor Detail

DirectBufferAllocator

Method Detail

instance

initialize

setInstance

resetInstance

lowMemoryException

changeOwnerToStorage

allocate

allocateForStorage

clearPostAllocate

baseObject

baseOffset

expand

fromBytesToStorage

transfer

release

isDirect

close