org.apache.hadoop.hbase.io.hfile

Class MemcachedBlockCache

java.lang.Object

org.apache.hadoop.hbase.io.hfile.MemcachedBlockCache

All Implemented Interfaces:

java.lang.Iterable<CachedBlock>, BlockCache

@InterfaceAudience.Private
public class MemcachedBlockCache
extends java.lang.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.

Field Summary

Fields

Modifier and Type	Field and Description
static int	MAX_SIZE
static java.lang.String	MEMCACHED_CONFIG_KEY
static long	MEMCACHED_DEFAULT_TIMEOUT
static java.lang.String	MEMCACHED_OPTIMEOUT_KEY
static java.lang.String	MEMCACHED_TIMEOUT_KEY

Constructor Summary

Constructors

Constructor and Description
MemcachedBlockCache(Configuration c)

Method Summary

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(java.lang.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.
java.util.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

Methods inherited from interface java.lang.Iterable

forEach, spliterator

Field Detail

MAX_SIZE

public static final int MAX_SIZE

See Also:

Constant Field Values

MEMCACHED_CONFIG_KEY

public static final java.lang.String MEMCACHED_CONFIG_KEY

See Also:

Constant Field Values

MEMCACHED_TIMEOUT_KEY

public static final java.lang.String MEMCACHED_TIMEOUT_KEY

See Also:

Constant Field Values

MEMCACHED_OPTIMEOUT_KEY

public static final java.lang.String MEMCACHED_OPTIMEOUT_KEY

See Also:

Constant Field Values

MEMCACHED_DEFAULT_TIMEOUT

public static final long MEMCACHED_DEFAULT_TIMEOUT

See Also:

Constant Field Values

Constructor Detail

MemcachedBlockCache

public MemcachedBlockCache(Configuration c)
                    throws java.io.IOException

Throws:

java.io.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(java.lang.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 java.util.Iterator<CachedBlock> iterator()

Specified by:

iterator in interface java.lang.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.