Package org.apache.hadoop.hbase.mob

Class MobFileCache

java.lang.Object

org.apache.hadoop.hbase.mob.MobFileCache

@Private
public class MobFileCache
extends Object

The cache for mob files. This cache doesn't cache the mob file blocks. It only caches the references of mob files. We are doing this to avoid opening and closing mob files all the time. We just keep references open.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
(package private) static class	MobFileCache.EvictionThread

Field Summary

Fields

Modifier and Type	Field	Description
private final org.apache.hadoop.conf.Configuration	conf
private final AtomicLong	count
private final LongAdder	evictedFileCount
private final ReentrantLock	evictionLock
private float	evictRemainRatio
private final boolean	isCacheEnabled
private final IdLock	keyLock
private long	lastAccess
private long	lastEvictedFileCount
private long	lastMiss
private static final org.slf4j.Logger	LOG
private Map<String,CachedMobFile>	map
private final LongAdder	miss
private final int	mobFileMaxCacheSize
private final ScheduledExecutorService	scheduleThreadPool

Constructor Summary

Constructors

Constructor	Description
MobFileCache(org.apache.hadoop.conf.Configuration conf)

Method Summary

Modifier and Type	Method	Description
void	closeFile(MobFile file)	Closes a mob file.
void	evict()	Evicts the lru cached mob files when the count of the cached files is larger than the threshold.
void	evictFile(String fileName)	Evicts the cached file by the name.
long	getAccessCount()	Gets the count of accesses to the mob file cache.
int	getCacheSize()	Gets the count of cached mob files.
long	getEvictedFileCount()	Gets the number of items evicted from the mob file cache.
double	getHitRatio()	Gets the hit ratio to the mob file cache.
long	getMissCount()	Gets the count of misses to the mob file cache.
private long	hashFileName(String fileName)	Use murmurhash to reduce the conflicts of hashed file names.
MobFile	openFile(org.apache.hadoop.fs.FileSystem fs, org.apache.hadoop.fs.Path path, CacheConfig cacheConf)	Opens a mob file.
void	printStatistics()	Prints the statistics.
void	shutdown()

Methods inherited from class java.lang.Object

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

Field Details

LOG

private static final org.slf4j.Logger LOG

map

private Map<String,CachedMobFile> map

count

private final AtomicLong count

lastAccess

private long lastAccess

miss

private final LongAdder miss

lastMiss

private long lastMiss

evictedFileCount

private final LongAdder evictedFileCount

lastEvictedFileCount

private long lastEvictedFileCount

evictionLock

private final ReentrantLock evictionLock

keyLock

private final IdLock keyLock

scheduleThreadPool

private final ScheduledExecutorService scheduleThreadPool

conf

private final org.apache.hadoop.conf.Configuration conf

mobFileMaxCacheSize

private final int mobFileMaxCacheSize

isCacheEnabled

private final boolean isCacheEnabled

evictRemainRatio

private float evictRemainRatio

Constructor Details

MobFileCache

public MobFileCache(org.apache.hadoop.conf.Configuration conf)

Method Details

evict

public void evict()

Evicts the lru cached mob files when the count of the cached files is larger than the threshold.

evictFile

public void evictFile(String fileName)

Evicts the cached file by the name.

Parameters:

fileName - The name of a cached file.

openFile

public MobFile openFile(org.apache.hadoop.fs.FileSystem fs,
 org.apache.hadoop.fs.Path path,
 CacheConfig cacheConf)
                 throws IOException

Opens a mob file.

Parameters:

fs - The current file system.

path - The file path.

cacheConf - The current MobCacheConfig

Returns:

A opened mob file.

Throws:

IOException

closeFile

public void closeFile(MobFile file)

Closes a mob file.

Parameters:

file - The mob file that needs to be closed.

shutdown

public void shutdown()

getCacheSize

public int getCacheSize()

Gets the count of cached mob files.

Returns:

The count of the cached mob files.

getAccessCount

public long getAccessCount()

Gets the count of accesses to the mob file cache.

Returns:

The count of accesses to the mob file cache.

getMissCount

public long getMissCount()

Gets the count of misses to the mob file cache.

Returns:

The count of misses to the mob file cache.

getEvictedFileCount

public long getEvictedFileCount()

Gets the number of items evicted from the mob file cache.

Returns:

The number of items evicted from the mob file cache.

getHitRatio

public double getHitRatio()

Gets the hit ratio to the mob file cache.

Returns:

The hit ratio to the mob file cache.

printStatistics

public void printStatistics()

Prints the statistics.

hashFileName

private long hashFileName(String fileName)

Use murmurhash to reduce the conflicts of hashed file names. We should notice that the hash conflicts may bring deadlocks, when opening mob files with evicting some other files, as described in HBASE-28047.