BlockCache (Apache HBase 1.2.12 API)

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

Methods
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, boolean cacheDataInL1)` 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`	`getCurrentSize()` Returns the occupied size of the block cache, in bytes.
`long`	`getFreeSize()` Returns the free size of the block cache, in bytes.
`CacheStats`	`getStats()` Get the statistics for this block cache.
`Iterator<CachedBlock>`	`iterator()`
`void`	`shutdown()` Shutdown the cache.
`long`	`size()` Returns the total size of the block cache, in bytes.

- Method Detail
  - cacheBlock
```
void cacheBlock(BlockCacheKey cacheKey,
              Cacheable buf,
              boolean inMemory,
              boolean cacheDataInL1)
```
    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
    cacheDataInL1 - If multi-tier block cache deploy -- i.e. has an L1 and L2 tier -- then if this flag is true, cache data blocks up in the L1 tier (meta blocks are probably being cached in L1 already).
  - 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
  - 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
  - getBlockCount
```
long getBlockCount()
```
    Returns the number of 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.

Interface BlockCache

Method Summary

Method Detail

cacheBlock

cacheBlock

getBlock

evictBlock

evictBlocksByHfileName

getStats

shutdown

size

getFreeSize

getCurrentSize

getBlockCount

iterator

getBlockCaches