Package org.apache.datasketches.memory

Class DefaultMemoryRequestServer

java.lang.Object

org.apache.datasketches.memory.DefaultMemoryRequestServer

All Implemented Interfaces:

MemoryRequestServer

public final class DefaultMemoryRequestServer
extends Object
implements MemoryRequestServer

DefaultMemoryRequestServer relies on preview features of the Java platform:

• DefaultMemoryRequestServer refers to one or more preview APIs: Arena.

Programs can only use DefaultMemoryRequestServer when preview features are enabled.

Preview features may be removed in a future release, or upgraded to permanent features of the Java platform.

This example MemoryRequestServer is simple but demonstrates one of many ways to manage continuous requests for larger memory. This capability is only available for writable, non-file-memory-mapping resources.

Author:

Lee Rhodes

Constructor Summary

Constructors

Constructor	Description
DefaultMemoryRequestServer()	Default constructor.
DefaultMemoryRequestServer(boolean offHeap, boolean copyOldToNew)	Constructor with parameters

Method Summary

Modifier and Type	Method	Description
WritableMemory	request(WritableMemory currentWmem, long newCapacityBytes, ArenaPREVIEW arena)	Request new WritableMemory with the given newCapacityBytes.
void	requestClose(WritableMemory memToClose, WritableMemory newMemory)	Request to close the resource, if applicable.

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.apache.datasketches.memory.MemoryRequestServer

request, requestClose

Constructor Details

DefaultMemoryRequestServer

public DefaultMemoryRequestServer()

Default constructor. Create new memory on-heap and do not copy old contents to new memory.

DefaultMemoryRequestServer

public DefaultMemoryRequestServer(boolean offHeap,
 boolean copyOldToNew)

Constructor with parameters

Parameters:

offHeap - if true, the returned new memory will be off heap

copyOldToNew - if true, the data from the current memory will be copied to the new memory, starting at address 0, and through the currentMemory capacity.

Method Details

request

public WritableMemory request(WritableMemory currentWmem,
 long newCapacityBytes,
 ArenaPREVIEW arena)

Description copied from interface: MemoryRequestServer

Request new WritableMemory with the given newCapacityBytes. The current Writable Memory can be used to determine the byte order of the returned WritableMemory and other properties.

Specified by:

request in interface MemoryRequestServer

Parameters:

currentWmem - the current writableMemory of the client. It must be non-null.

newCapacityBytes - The capacity being requested. It must be > the capacity of the currentWritableMemory.

arena - the Arena to be used for the newly allocated memory. It must be non-null. Warning: This class is not thread-safe. Specifying an Arena that allows multiple threads is not recommended.

Returns:

new WritableMemory with the requested capacity.

requestClose

public void requestClose(WritableMemory memToClose,
 WritableMemory newMemory)

Description copied from interface: MemoryRequestServer

Request to close the resource, if applicable.

Specified by:

requestClose in interface MemoryRequestServer

Parameters:

memToClose - the relevant WritableMemory to be considered for closing. It must be non-null.

newMemory - the newly allocated WritableMemory. The newMemory reference is returned from the client for the convenience of the system that owns the responsibility of memory allocation. It may be null.