org.apache.hadoop.hbase.io.hfile

Interface Cacheable

All Superinterfaces:

HBaseReferenceCounted, HeapSize, org.apache.hbase.thirdparty.io.netty.util.ReferenceCounted

All Known Implementing Classes:

ExclusiveMemHFileBlock, HFileBlock, SharedMemHFileBlock

@InterfaceAudience.Private
public interface Cacheable
extends HeapSize, HBaseReferenceCounted

Cacheable is an interface that allows for an object to be cached. If using an on heap cache, just use heapsize. If using an off heap cache, Cacheable provides methods for serialization of the object. Some objects cannot be moved off heap, those objects will return a getSerializedLength() of 0.

Method Summary

Modifier and Type	Method and Description
BlockType	getBlockType() Returns the block type of this cached HFile block
CacheableDeserializer<Cacheable>	getDeserializer() Returns CacheableDeserializer instance which reconstructs original object from ByteBuffer.
int	getSerializedLength() Returns the length of the ByteBuffer required to serialized the object.
default int	refCnt() Reference count of this Cacheable.
default boolean	release() Decrease its reference count, and if no reference then free the memory of this object, its backend is usually a ByteBuff, and we will put its NIO ByteBuffers back to ByteBuffAllocator
default Cacheable	retain() Increase its reference count, and only when no reference we can free the object's memory.
void	serialize(ByteBuffer destination, boolean includeNextBlockMetadata) Serializes its data into destination.

Methods inherited from interface org.apache.hadoop.hbase.io.HeapSize

heapSize

Methods inherited from interface org.apache.hadoop.hbase.nio.HBaseReferenceCounted

release, retain, touch, touch

Method Detail

getSerializedLength

int getSerializedLength()

Returns the length of the ByteBuffer required to serialized the object. If the object cannot be serialized, it should return 0.

Returns:

int length in bytes of the serialized form or 0 if the object cannot be cached.

serialize

void serialize(ByteBuffer destination,
               boolean includeNextBlockMetadata)

Serializes its data into destination.

Parameters:

destination - Where to serialize to

includeNextBlockMetadata - Whether to include nextBlockMetadata in the Cache block.

getDeserializer

CacheableDeserializer<Cacheable> getDeserializer()

Returns CacheableDeserializer instance which reconstructs original object from ByteBuffer.

Returns:

CacheableDeserialzer instance.

getBlockType

BlockType getBlockType()

Returns the block type of this cached HFile block

retain

default Cacheable retain()

Increase its reference count, and only when no reference we can free the object's memory.

Specified by:

retain in interface org.apache.hbase.thirdparty.io.netty.util.ReferenceCounted

refCnt

default int refCnt()

Reference count of this Cacheable.

Specified by:

refCnt in interface org.apache.hbase.thirdparty.io.netty.util.ReferenceCounted

release

default boolean release()

Decrease its reference count, and if no reference then free the memory of this object, its backend is usually a ByteBuff, and we will put its NIO ByteBuffers back to ByteBuffAllocator

Specified by:

release in interface org.apache.hbase.thirdparty.io.netty.util.ReferenceCounted