BucketCache (Apache HBase 1.4.11 API)

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 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

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

Methods
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, boolean cacheDataInL1)` Cache the block with the specified name and buffer.
`void`	`cacheBlockWithWait(BlockCacheKey cacheKey, Cacheable cachedItem, boolean inMemory, boolean cacheDataInL1, boolean wait)` Cache the block to ramCache
`boolean`	`evictBlock(BlockCacheKey cacheKey)` Evict block from cache.
`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.
`UniqueIndexMap<Integer>`	`getDeserialiserMap()`
`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()`
`CacheStats`	`getStats()` Get the statistics for this block cache.
`long`	`heapSize()`
`Iterator<CachedBlock>`	`iterator()`
`void`	`logStats()`
`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

- 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 IOException
```
    Throws:
    
    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,
              boolean cacheDataInL1)
```
    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
    cacheDataInL1 -
  - cacheBlockWithWait
```
public void cacheBlockWithWait(BlockCacheKey cacheKey,
                      Cacheable cachedItem,
                      boolean inMemory,
                      boolean cacheDataInL1,
                      boolean wait)
```
    Cache the block to ramCache
    
    Parameters:
    cacheKey - block's cache key
    cachedItem - block buffer
    inMemory - if block is in-memory
    wait - if true, blocking wait when queue is full
  - 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
  - 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.
  - getDeserialiserMap
```
public UniqueIndexMap<Integer> getDeserialiserMap()
```

Class BucketCache

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

DEFAULT_ERROR_TOLERATION_DURATION

Constructor Detail

BucketCache

BucketCache

Method Detail

startWriterThreads

getMaxSize

getIoEngine

cacheBlock

cacheBlock

cacheBlockWithWait

getBlock

evictBlock

logStats

getRealCacheSize

shutdown

getStats

getAllocator

heapSize

size

getCurrentDataSize

getFreeSize

getBlockCount

getDataBlockCount

getCurrentSize

evictBlocksByHfileName

iterator

getBlockCaches

getDeserialiserMap