org.apache.jackrabbit.core.cache

Class AbstractCache

java.lang.Object

org.apache.jackrabbit.core.cache.AbstractCache

All Implemented Interfaces:

Cache

Direct Known Subclasses:

ConcurrentCache

public abstract class AbstractCache
extends Object
implements Cache

Abstract base class for managed Caches. This class uses atomic variables to track the current and maximum size of the cache, the cache access count and a possible CacheAccessListener instance.

A subclass should call the protected recordCacheAccess() method whenever the cache is accessed (even cache misses should be reported). The subclass should also use the recordSizeChange(long) method to record all changes in the cache size, and automatically evict excess items when the isTooBig() method returns true.

Constructor Summary

Constructors

Constructor and Description
AbstractCache()

Method Summary

Modifier and Type	Method and Description
void	dispose()
long	getAccessCount() Get the number of accesses (get or set) until resetAccessCount was called.
String	getCacheInfoAsString() Gathers the stats of the cache for logging.
long	getMaxMemorySize() Get the current limit.
long	getMemoryUsed() Get the amount of used memory.
long	getMissCount() Get the number of cache misses.
long	getTotalAccessCount() Get the total number of cache accesses.
protected boolean	isTooBig() Checks whether the current estimate of the amount of memory used by this cache exceeds the allocated maximum amount of memory.
protected void	recordCacheAccess() Records a single cache access and calls the configured CacheAccessListener (if any) whenever the constant access interval has passed since the previous listener call.
protected void	recordCacheMiss()
protected void	recordSizeChange(long delta) Updates the current memory use estimate of this cache.
void	resetAccessCount() Reset the access counter.
void	resetMissCount() Reset the cache miss counter.
void	setAccessListener(CacheAccessListener listener) Set the cache access listener.
void	setMaxMemorySize(long size) Set the new memory limit.

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.apache.jackrabbit.core.cache.Cache

getElementCount

Constructor Detail

AbstractCache

public AbstractCache()

Method Detail

isTooBig

protected boolean isTooBig()

Checks whether the current estimate of the amount of memory used by this cache exceeds the allocated maximum amount of memory.

Returns:

true if the cache size is too big, false otherwise

recordSizeChange

protected void recordSizeChange(long delta)

Updates the current memory use estimate of this cache.

Parameters:

delta - number of bytes added or removed

recordCacheAccess

protected void recordCacheAccess()

Records a single cache access and calls the configured CacheAccessListener (if any) whenever the constant access interval has passed since the previous listener call.

recordCacheMiss

protected void recordCacheMiss()

getAccessCount

public long getAccessCount()

Description copied from interface: Cache

Get the number of accesses (get or set) until resetAccessCount was called.

Specified by:

getAccessCount in interface Cache

Returns:

the count

resetAccessCount

public void resetAccessCount()

Description copied from interface: Cache

Reset the access counter.

Specified by:

resetAccessCount in interface Cache

getTotalAccessCount

public long getTotalAccessCount()

Description copied from interface: Cache

Get the total number of cache accesses.

Specified by:

getTotalAccessCount in interface Cache

Returns:

the number of hits

getMissCount

public long getMissCount()

Description copied from interface: Cache

Get the number of cache misses.

Specified by:

getMissCount in interface Cache

Returns:

the number of misses

resetMissCount

public void resetMissCount()

Description copied from interface: Cache

Reset the cache miss counter.

Specified by:

resetMissCount in interface Cache

getMemoryUsed

public long getMemoryUsed()

Description copied from interface: Cache

Get the amount of used memory.

Specified by:

getMemoryUsed in interface Cache

Returns:

the size in bytes

getMaxMemorySize

public long getMaxMemorySize()

Description copied from interface: Cache

Get the current limit.

Specified by:

getMaxMemorySize in interface Cache

Returns:

the size in bytes

setMaxMemorySize

public void setMaxMemorySize(long size)

Description copied from interface: Cache

Set the new memory limit.

Specified by:

setMaxMemorySize in interface Cache

Parameters:

size - the size in bytes

setAccessListener

public void setAccessListener(CacheAccessListener listener)

Set the cache access listener. Only one listener per cache is supported.

Specified by:

setAccessListener in interface Cache

Parameters:

listener - the new listener

dispose

public void dispose()

getCacheInfoAsString

public String getCacheInfoAsString()

Gathers the stats of the cache for logging.

Specified by:

getCacheInfoAsString in interface Cache