MemcachedBlockCache (Apache HBase 1.2.12 API)

java.lang.Object
- org.apache.hadoop.hbase.io.hfile.MemcachedBlockCache

All Implemented Interfaces:

Iterable<CachedBlock>, BlockCache
```
@InterfaceAudience.Private
public class MemcachedBlockCache
extends Object
implements BlockCache
```
Class to store blocks into memcached. This should only be used on a cluster of Memcached daemons that are tuned well and have a good network connection to the HBase regionservers. Any other use will likely slow down HBase greatly.

Nested Class Summary

Nested Classes
Modifier and Type	Class and Description
`private static class`	`MemcachedBlockCache.HFileBlockTranscoder` Class to encode and decode an HFileBlock to and from memecached's resulting byte arrays.

Field Summary

Fields
Modifier and Type	Field and Description
`private CacheStats`	`cacheStats`
`private net.spy.memcached.MemcachedClient`	`client`
`private static org.apache.commons.logging.Log`	`LOG`
`static int`	`MAX_SIZE`
`static String`	`MEMCACHED_CONFIG_KEY`
`static long`	`MEMCACHED_DEFAULT_TIMEOUT`
`static String`	`MEMCACHED_OPTIMEOUT_KEY`
`static boolean`	`MEMCACHED_OPTIMIZE_DEFAULT`
`static String`	`MEMCACHED_OPTIMIZE_KEY`
`static String`	`MEMCACHED_TIMEOUT_KEY`
`private MemcachedBlockCache.HFileBlockTranscoder`	`tc`

Constructor Summary

Constructors
Constructor and Description

MemcachedBlockCache(org.apache.hadoop.conf.Configuration c)

Constructors
Constructor and Description
`MemcachedBlockCache(org.apache.hadoop.conf.Configuration c)`

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)` This method does nothing so that memcached can handle all evictions.
`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.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - LOG
```
private static final org.apache.commons.logging.Log LOG
```
  - MAX_SIZE
```
public static final int MAX_SIZE
```
    See Also:
    Constant Field Values
  - MEMCACHED_CONFIG_KEY
```
public static final String MEMCACHED_CONFIG_KEY
```
    See Also:
    Constant Field Values
  - MEMCACHED_TIMEOUT_KEY
```
public static final String MEMCACHED_TIMEOUT_KEY
```
    See Also:
    Constant Field Values
  - MEMCACHED_OPTIMEOUT_KEY
```
public static final String MEMCACHED_OPTIMEOUT_KEY
```
    See Also:
    Constant Field Values
  - MEMCACHED_OPTIMIZE_KEY
```
public static final String MEMCACHED_OPTIMIZE_KEY
```
    See Also:
    Constant Field Values
  - MEMCACHED_DEFAULT_TIMEOUT
```
public static final long MEMCACHED_DEFAULT_TIMEOUT
```
    See Also:
    Constant Field Values
  - MEMCACHED_OPTIMIZE_DEFAULT
```
public static final boolean MEMCACHED_OPTIMIZE_DEFAULT
```
    See Also:
    Constant Field Values
  - client
```
private final net.spy.memcached.MemcachedClient client
```
  - tc
```
private final MemcachedBlockCache.HFileBlockTranscoder tc
```
  - cacheStats
```
private final CacheStats cacheStats
```
- Constructor Detail
  - MemcachedBlockCache
```
public MemcachedBlockCache(org.apache.hadoop.conf.Configuration c)
                    throws IOException
```
    Throws:
    
    IOException
- Method Detail
  - cacheBlock
```
public void cacheBlock(BlockCacheKey cacheKey,
              Cacheable buf,
              boolean inMemory,
              boolean cacheDataInL1)
```
    Description copied from interface: BlockCache
    
    Add block to cache.
    
    Specified by:
    
    cacheBlock in interface BlockCache
    
    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
```
public void cacheBlock(BlockCacheKey cacheKey,
              Cacheable buf)
```
    Description copied from interface: BlockCache
    
    Add block to cache (defaults to not in-memory).
    
    Specified by:
    
    cacheBlock in interface BlockCache
    
    Parameters:
    cacheKey - The block's cache key.
    buf - The object to cache.
  - 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.
  - 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)
```
    This method does nothing so that memcached can handle all evictions.
    
    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
  - 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
  - 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.

Class MemcachedBlockCache

Nested Class Summary

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

LOG

MAX_SIZE

MEMCACHED_CONFIG_KEY

MEMCACHED_TIMEOUT_KEY

MEMCACHED_OPTIMEOUT_KEY

MEMCACHED_OPTIMIZE_KEY

MEMCACHED_DEFAULT_TIMEOUT

MEMCACHED_OPTIMIZE_DEFAULT

client

tc

cacheStats

Constructor Detail

MemcachedBlockCache

Method Detail

cacheBlock

cacheBlock

getBlock

evictBlock

evictBlocksByHfileName

getStats

shutdown

size

getFreeSize

getCurrentSize

getBlockCount

iterator

getBlockCaches