org.apache.hadoop.hbase.io.hfile.bucket

Class BucketCache

java.lang.Object

org.apache.hadoop.hbase.io.hfile.bucket.BucketCache

All Implemented Interfaces:

Iterable<CachedBlock>, HeapSize, BlockCache

@InterfaceAudience.Private
public class BucketCache
extends Object
implements BlockCache, HeapSize

BucketCache uses BucketAllocator to allocate/free blocks, and uses BucketCache#ramCache and BucketCache#backingMap in order to determine if a given element is in the cache. The bucket cache can use on-heap or off-heap memory ByteBufferIOEngine or in a file FileIOEngine to store/read the block data.

Eviction is via a similar algorithm as used in LruBlockCache

BucketCache can be used as mainly a block cache (see CombinedBlockCache), combined with LruBlockCache to decrease CMS GC and heap fragmentation.

It also can be used as a secondary cache (e.g. using a file on ssd/fusionio to store blocks) to enlarge cache space via LruBlockCache.setVictimCache(org.apache.hadoop.hbase.io.hfile.BlockCache)

Field Summary

Fields

Modifier and Type	Field and Description
static int	DEFAULT_ERROR_TOLERATION_DURATION

Constructor Summary

Constructors

Constructor and Description
BucketCache(String ioEngineName, long capacity, int blockSize, int[] bucketSizes, int writerThreadNum, int writerQLen, String persistencePath)
BucketCache(String ioEngineName, long capacity, int blockSize, int[] bucketSizes, int writerThreadNum, int writerQLen, String persistencePath, int ioErrorsTolerationDuration, org.apache.hadoop.conf.Configuration conf)

Method Summary

Modifier and Type	Method and Description
void	cacheBlock(BlockCacheKey cacheKey, Cacheable buf) Cache the block with the specified name and buffer.
void	cacheBlock(BlockCacheKey cacheKey, Cacheable cachedItem, boolean inMemory) Cache the block with the specified name and buffer.
boolean	evictBlock(BlockCacheKey cacheKey) Evict block from cache.
boolean	evictBlock(BlockCacheKey cacheKey, boolean deletedBlock)
int	evictBlocksByHfileName(String hfileName) Evicts all blocks for a specific HFile.
BucketAllocator	getAllocator()
Cacheable	getBlock(BlockCacheKey key, boolean caching, boolean repeat, boolean updateCacheMetrics) Get the buffer of the block with the specified key.
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.
String	getIoEngine()
long	getMaxSize() Returns the Max size of the block cache, in bytes.
long	getRealCacheSize()
int	getRefCount(BlockCacheKey cacheKey)
CacheStats	getStats() Get the statistics for this block cache.
long	heapSize()
Iterator<CachedBlock>	iterator()
void	logStats()
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.
protected void	startWriterThreads() Called by the constructor to start the writer threads.

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.lang.Iterable

forEach, spliterator

Field Detail

DEFAULT_ERROR_TOLERATION_DURATION

public static final int DEFAULT_ERROR_TOLERATION_DURATION

See Also:

Constant Field Values

Constructor Detail

BucketCache

public BucketCache(String ioEngineName,
                   long capacity,
                   int blockSize,
                   int[] bucketSizes,
                   int writerThreadNum,
                   int writerQLen,
                   String persistencePath)
            throws FileNotFoundException,
                   IOException

Throws:

FileNotFoundException

IOException

BucketCache

public BucketCache(String ioEngineName,
                   long capacity,
                   int blockSize,
                   int[] bucketSizes,
                   int writerThreadNum,
                   int writerQLen,
                   String persistencePath,
                   int ioErrorsTolerationDuration,
                   org.apache.hadoop.conf.Configuration conf)
            throws FileNotFoundException,
                   IOException

Throws:

FileNotFoundException

IOException

Method Detail

startWriterThreads

protected void startWriterThreads()

Called by the constructor to start the writer threads. Used by tests that need to override starting the threads.

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

getIoEngine

public String getIoEngine()

cacheBlock

public void cacheBlock(BlockCacheKey cacheKey,
                       Cacheable buf)

Cache the block with the specified name and buffer.

Specified by:

cacheBlock in interface BlockCache

Parameters:

cacheKey - block's cache key

buf - block buffer

cacheBlock

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

Cache the block with the specified name and buffer.

Specified by:

cacheBlock in interface BlockCache

Parameters:

cacheKey - block's cache key

cachedItem - block buffer

inMemory - if block is in-memory

getBlock

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

Get the buffer of the block with the specified key.

Specified by:

getBlock in interface BlockCache

Parameters:

key - block's cache key

caching - true if the caller caches blocks on cache misses

repeat - Whether this is a repeat lookup for the same block

updateCacheMetrics - Whether we should update cache metrics or not

Returns:

buffer of specified cache key, or null if not in 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

evictBlock

public boolean evictBlock(BlockCacheKey cacheKey,
                          boolean deletedBlock)

logStats

public void logStats()

getRealCacheSize

public long getRealCacheSize()

shutdown

public void shutdown()

Description copied from interface: BlockCache

Shutdown the cache.

Specified by:

shutdown in interface BlockCache

getStats

public CacheStats getStats()

Description copied from interface: BlockCache

Get the statistics for this block cache.

Specified by:

getStats in interface BlockCache

Returns:

Stats

getAllocator

public BucketAllocator getAllocator()

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.

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

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

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

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

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

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

evictBlocksByHfileName

public int evictBlocksByHfileName(String hfileName)

Evicts all blocks for a specific HFile.

This is used for evict-on-close to remove all blocks of a specific HFile.

Specified by:

evictBlocksByHfileName in interface BlockCache

Returns:

the number of blocks evicted

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.

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.

returnBlock

public void returnBlock(BlockCacheKey cacheKey,
                        Cacheable block)

Description copied from interface: BlockCache

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.

Specified by:

returnBlock in interface BlockCache

Parameters:

cacheKey - the cache key of the block

block - the hfileblock to be returned

getRefCount

public int getRefCount(BlockCacheKey cacheKey)