org.apache.hadoop.hbase.io.hfile

Class TinyLfuBlockCache

java.lang.Object

org.apache.hadoop.hbase.io.hfile.TinyLfuBlockCache

All Implemented Interfaces:

Iterable<CachedBlock>, HeapSize, BlockCache, FirstLevelBlockCache, ResizableBlockCache

@InterfaceAudience.Private
public final class TinyLfuBlockCache
extends Object
implements FirstLevelBlockCache

A block cache that is memory-aware using HeapSize, memory bounded using the W-TinyLFU eviction algorithm, and concurrent. This implementation delegates to a Caffeine cache to provide O(1) read and write operations.

• W-TinyLFU: http://arxiv.org/pdf/1512.00727.pdf
• Caffeine: https://github.com/ben-manes/caffeine
• Cache design: http://highscalability.com/blog/2016/1/25/design-of-a-modern-cache.html

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
private static class	TinyLfuBlockCache.CachedBlockView
private class	TinyLfuBlockCache.EvictionListener A removal listener to asynchronously record evictions and populate the victim cache.

Field Summary

Fields

Modifier and Type	Field and Description
(package private) com.github.benmanes.caffeine.cache.Cache<BlockCacheKey,Cacheable>	cache
private static long	DEFAULT_MAX_BLOCK_SIZE
private static org.slf4j.Logger	LOG
private static String	MAX_BLOCK_SIZE
private long	maxBlockSize
private com.github.benmanes.caffeine.cache.Policy.Eviction<BlockCacheKey,Cacheable>	policy
private static int	STAT_THREAD_PERIOD_SECONDS
private CacheStats	stats
private ScheduledExecutorService	statsThreadPool
private BlockCache	victimCache

Constructor Summary

Constructors

Constructor and Description
TinyLfuBlockCache(long maximumSizeInBytes, long avgBlockSize, Executor executor, org.apache.hadoop.conf.Configuration conf) Creates a block cache.
TinyLfuBlockCache(long maximumSizeInBytes, long avgBlockSize, long maxBlockSize, Executor executor) Creates a block cache.

Method Summary

Modifier and Type	Method and Description
void	cacheBlock(BlockCacheKey key, Cacheable value) Add block to cache (defaults to not in-memory).
void	cacheBlock(BlockCacheKey cacheKey, Cacheable value, boolean inMemory) Add block to cache.
boolean	containsBlock(BlockCacheKey cacheKey) Whether the cache contains the block with specified cacheKey
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.
long	heapSize()
Iterator<CachedBlock>	iterator()
private void	logStats()
private void	recordEviction() Records an eviction.
void	setMaxSize(long size) Sets the max heap size that can be used by the BlockCache.
void	setVictimCache(BlockCache victimCache) Specifies the secondary cache.
void	shutdown() Shutdown the cache.
long	size() Returns the total size of the block cache, in bytes.
String	toString()

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Methods inherited from interface java.lang.Iterable

forEach, spliterator

Field Detail

LOG

private static final org.slf4j.Logger LOG

MAX_BLOCK_SIZE

private static final String MAX_BLOCK_SIZE

See Also:

Constant Field Values

DEFAULT_MAX_BLOCK_SIZE

private static final long DEFAULT_MAX_BLOCK_SIZE

See Also:

Constant Field Values

STAT_THREAD_PERIOD_SECONDS

private static final int STAT_THREAD_PERIOD_SECONDS

See Also:

Constant Field Values

policy

private final com.github.benmanes.caffeine.cache.Policy.Eviction<BlockCacheKey,Cacheable> policy

statsThreadPool

private final ScheduledExecutorService statsThreadPool

maxBlockSize

private final long maxBlockSize

stats

private final CacheStats stats

victimCache

private BlockCache victimCache

cache

final com.github.benmanes.caffeine.cache.Cache<BlockCacheKey,Cacheable> cache

Constructor Detail

TinyLfuBlockCache

public TinyLfuBlockCache(long maximumSizeInBytes,
                         long avgBlockSize,
                         Executor executor,
                         org.apache.hadoop.conf.Configuration conf)

Creates a block cache.

Parameters:

maximumSizeInBytes - maximum size of this cache, in bytes

avgBlockSize - expected average size of blocks, in bytes

executor - the cache's executor

conf - additional configuration

TinyLfuBlockCache

public TinyLfuBlockCache(long maximumSizeInBytes,
                         long avgBlockSize,
                         long maxBlockSize,
                         Executor executor)

Creates a block cache.

Parameters:

maximumSizeInBytes - maximum size of this cache, in bytes

avgBlockSize - expected average size of blocks, in bytes

maxBlockSize - maximum size of a block, in bytes

executor - the cache's executor

Method Detail

setVictimCache

public void setVictimCache(BlockCache victimCache)

Description copied from interface: FirstLevelBlockCache

Specifies the secondary cache. An entry that is evicted from this cache due to a size constraint will be inserted into the victim cache.

Specified by:

setVictimCache in interface FirstLevelBlockCache

Parameters:

victimCache - the second level cache

size

public long size()

Description copied from interface: BlockCache

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

Specified by:

size in interface BlockCache

Returns:

size of cache, in bytes

getFreeSize

public long getFreeSize()

Description copied from interface: BlockCache

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

Specified by:

getFreeSize in interface BlockCache

Returns:

free space in cache, in bytes

getCurrentSize

public long getCurrentSize()

Description copied from interface: BlockCache

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

Specified by:

getCurrentSize in interface BlockCache

Returns:

occupied space in cache, in bytes

getBlockCount

public long getBlockCount()

Description copied from interface: BlockCache

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

Specified by:

getBlockCount in interface BlockCache

Returns:

number of blocks in the cache

heapSize

public long heapSize()

Specified by:

heapSize in interface HeapSize

Returns:

Approximate 'exclusive deep size' of implementing object. Includes count of payload and hosting object sizings.

setMaxSize

public void setMaxSize(long size)

Description copied from interface: ResizableBlockCache

Sets the max heap size that can be used by the BlockCache.

Specified by:

setMaxSize in interface ResizableBlockCache

Parameters:

size - The max heap size.

containsBlock

public boolean containsBlock(BlockCacheKey cacheKey)

Description copied from interface: FirstLevelBlockCache

Whether the cache contains the block with specified cacheKey

Specified by:

containsBlock in interface FirstLevelBlockCache

Parameters:

cacheKey - cache key for the block

Returns:

true if it contains the block

getBlock

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

Description copied from interface: BlockCache

Fetch block from cache.

Specified by:

getBlock in interface BlockCache

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.

cacheBlock

public void cacheBlock(BlockCacheKey cacheKey,
                       Cacheable value,
                       boolean inMemory)

Description copied from interface: BlockCache

Add block to cache.

Specified by:

cacheBlock in interface BlockCache

Parameters:

cacheKey - The block's cache key.

value - The block contents wrapped in a ByteBuffer.

inMemory - Whether block should be treated as in-memory

cacheBlock

public void cacheBlock(BlockCacheKey key,
                       Cacheable value)

Description copied from interface: BlockCache

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

Specified by:

cacheBlock in interface BlockCache

Parameters:

key - The block's cache key.

value - The object to cache.

evictBlock

public boolean evictBlock(BlockCacheKey cacheKey)

Description copied from interface: BlockCache

Evict block from cache.

Specified by:

evictBlock in interface BlockCache

Parameters:

cacheKey - Block to evict

Returns:

true if block existed and was evicted, false if not

evictBlocksByHfileName

public int evictBlocksByHfileName(String hfileName)

Description copied from interface: BlockCache

Evicts all blocks for the given HFile.

Specified by:

evictBlocksByHfileName in interface BlockCache

Returns:

the number of blocks evicted

getStats

public CacheStats getStats()

Description copied from interface: BlockCache

Get the statistics for this block cache.

Specified by:

getStats in interface BlockCache

Returns:

Stats

shutdown

public void shutdown()

Description copied from interface: BlockCache

Shutdown the cache.

Specified by:

shutdown in interface BlockCache

getBlockCaches

public BlockCache[] getBlockCaches()

Specified by:

getBlockCaches in interface BlockCache

Returns:

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

iterator

public Iterator<CachedBlock> iterator()

Specified by:

iterator in interface Iterable<CachedBlock>

Specified by:

iterator in interface BlockCache

Returns:

Iterator over the blocks in the cache.

logStats

private void logStats()

toString

public String toString()

Overrides:

toString in class Object

recordEviction

private void recordEviction()

Records an eviction. The number of eviction operations and evicted blocks are identical, as an eviction is triggered immediately when the capacity has been exceeded. An eviction is performed asynchronously. See the library's documentation for details on write buffers, batching, and maintenance behavior.

getMaxSize

public long getMaxSize()

Description copied from interface: BlockCache

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

Specified by:

getMaxSize in interface BlockCache

Returns:

size of cache, in bytes

getCurrentDataSize

public long getCurrentDataSize()

Description copied from interface: BlockCache

Returns the occupied size of data blocks, in bytes.

Specified by:

getCurrentDataSize in interface BlockCache

Returns:

occupied space in cache, in bytes

getDataBlockCount

public long getDataBlockCount()

Description copied from interface: BlockCache

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

Specified by:

getDataBlockCount in interface BlockCache

Returns:

number of blocks in the cache