org.apache.hadoop.hbase.io.hfile

Interface BlockCache

All Superinterfaces:

Iterable<CachedBlock>

All Known Subinterfaces:

ResizableBlockCache

All Known Implementing Classes:

BucketCache, CombinedBlockCache, InclusiveCombinedBlockCache, LruBlockCache, MemcachedBlockCache

@InterfaceAudience.Private
public interface BlockCache
extends Iterable<CachedBlock>

Block cache interface. Anything that implements the Cacheable interface can be put in the cache.

Method Summary

Modifier and Type	Method and Description
void	cacheBlock(BlockCacheKey cacheKey, Cacheable buf) Add block to cache (defaults to not in-memory).
void	cacheBlock(BlockCacheKey cacheKey, Cacheable buf, boolean inMemory) Add block to cache.
boolean	evictBlock(BlockCacheKey cacheKey) Evict block from cache.
int	evictBlocksByHfileName(String hfileName) Evicts all blocks for the given HFile.
Cacheable	getBlock(BlockCacheKey cacheKey, boolean caching, boolean repeat, boolean updateCacheMetrics) Fetch block from cache.
BlockCache[]	getBlockCaches()
long	getBlockCount() Returns the number of blocks currently cached in the block cache.
long	getCurrentDataSize() Returns the occupied size of data blocks, in bytes.
long	getCurrentSize() Returns the occupied size of the block cache, in bytes.
long	getDataBlockCount() Returns the number of data blocks currently cached in the block cache.
long	getFreeSize() Returns the free size of the block cache, in bytes.
long	getMaxSize() Returns the Max size of the block cache, in bytes.
CacheStats	getStats() Get the statistics for this block cache.
Iterator<CachedBlock>	iterator()
default void	returnBlock(BlockCacheKey cacheKey, Cacheable block) Called when the scanner using the block decides to return the block once its usage is over.
void	shutdown() Shutdown the cache.
long	size() Returns the total size of the block cache, in bytes.

Methods inherited from interface java.lang.Iterable

forEach, spliterator

Method Detail

cacheBlock

void cacheBlock(BlockCacheKey cacheKey,
                Cacheable buf,
                boolean inMemory)

Add block to cache.

Parameters:

cacheKey - The block's cache key.

buf - The block contents wrapped in a ByteBuffer.

inMemory - Whether block should be treated as in-memory

cacheBlock

void cacheBlock(BlockCacheKey cacheKey,
                Cacheable buf)

Add block to cache (defaults to not in-memory).

Parameters:

cacheKey - The block's cache key.

buf - The object to cache.

getBlock

Cacheable getBlock(BlockCacheKey cacheKey,
                   boolean caching,
                   boolean repeat,
                   boolean updateCacheMetrics)

Fetch block from cache.

Parameters:

cacheKey - Block to fetch.

caching - Whether this request has caching enabled (used for stats)

repeat - Whether this is a repeat lookup for the same block (used to avoid double counting cache misses when doing double-check locking)

updateCacheMetrics - Whether to update cache metrics or not

Returns:

Block or null if block is not in 2 cache.

evictBlock

boolean evictBlock(BlockCacheKey cacheKey)

Evict block from cache.

Parameters:

cacheKey - Block to evict

Returns:

true if block existed and was evicted, false if not

evictBlocksByHfileName

int evictBlocksByHfileName(String hfileName)

Evicts all blocks for the given HFile.

Returns:

the number of blocks evicted

getStats

CacheStats getStats()

Get the statistics for this block cache.

Returns:

Stats

shutdown

void shutdown()

Shutdown the cache.

size

long size()

Returns the total size of the block cache, in bytes.

Returns:

size of cache, in bytes

getMaxSize

long getMaxSize()

Returns the Max size of the block cache, in bytes.

Returns:

size of cache, in bytes

getFreeSize

long getFreeSize()

Returns the free size of the block cache, in bytes.

Returns:

free space in cache, in bytes

getCurrentSize

long getCurrentSize()

Returns the occupied size of the block cache, in bytes.

Returns:

occupied space in cache, in bytes

getCurrentDataSize

long getCurrentDataSize()

Returns the occupied size of data blocks, in bytes.

Returns:

occupied space in cache, in bytes

getBlockCount

long getBlockCount()

Returns the number of blocks currently cached in the block cache.

Returns:

number of blocks in the cache

getDataBlockCount

long getDataBlockCount()

Returns the number of data blocks currently cached in the block cache.

Returns:

number of blocks in the cache

iterator

Iterator<CachedBlock> iterator()

Specified by:

iterator in interface Iterable<CachedBlock>

Returns:

Iterator over the blocks in the cache.

getBlockCaches

BlockCache[] getBlockCaches()

Returns:

The list of sub blockcaches that make up this one; returns null if no sub caches.

returnBlock

default void returnBlock(BlockCacheKey cacheKey,
                         Cacheable block)

Called when the scanner using the block decides to return the block once its usage is over. This API should be called after the block is used, failing to do so may have adverse effects by preventing the blocks from being evicted because of which it will prevent new hot blocks from getting added to the block cache. The implementation of the BlockCache will decide on what to be done with the block based on the memory type of the block's Cacheable.MemoryType.

Parameters:

cacheKey - the cache key of the block

block - the hfileblock to be returned