org.apache.hadoop.hbase.io.hfile

Interface Cacheable

All Superinterfaces:

HeapSize

All Known Implementing Classes:

HFileBlock

@InterfaceAudience.Private
public interface Cacheable
extends HeapSize

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.

Nested Class Summary

Nested Classes

Modifier and Type	Interface and Description
static class	Cacheable.MemoryType SHARED means when this Cacheable is read back from cache it refers to the same memory area as used by the cache for caching it.

Method Summary

Modifier and Type	Method and Description
BlockType	getBlockType()
CacheableDeserializer<Cacheable>	getDeserializer() Returns CacheableDeserializer instance which reconstructs original object from ByteBuffer.
Cacheable.MemoryType	getMemoryType()
int	getSerializedLength() Returns the length of the ByteBuffer required to serialized the object.
void	serialize(ByteBuffer destination, boolean includeNextBlockMetadata) Serializes its data into destination.

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

heapSize

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

getMemoryType

Cacheable.MemoryType getMemoryType()

Returns:

the MemoryType of this Cacheable