org.opengts.extra.util
Class MemCache<KEY,VAL>

java.lang.Object
  org.opengts.extra.util.MemCache<KEY,VAL>

All Implemented Interfaces:

MemCacheAPI<KEY,VAL>

public class MemCache<KEY,VAL>
extends java.lang.Object
implements MemCacheAPI<KEY,VAL>

A simple memory cache handler

Nested Class Summary

class	MemCache.MemCacheMap<KEY,VAL> Class MemCachMap
static class	MemCache.MemEntry<KEY,VAL> Class MemEntry
static class	MemCache.MemEntryComparator<KEY,VAL> Class MemEntryComparator (used for debugging only)

Field Summary

static int	DEFAULT_CACHE_SIZE
static double	DEFAULT_TRIM_PERCENT
static int	DEFAULT_TRIM_SIZE
static double	MAX_MEMORY_UTILIZATION
static long	MAXIMUM_CACHE_AGE_MS
static int	MINIMUM_CACHE_SIZE

Constructor Summary

MemCache()
Constructor

MemCache(int maxSize)
Constructor

Method Summary

void	addValue(KEY key, VAL val) Add entry to cache
boolean	exceedsMaximumCacheSize(double maxGain) Returns true if the current size exceeds the maximum cache size
int	getMaximumCacheSize() Gets the maximum cache size
int	getMaximumCacheSizeCutbackCount() Returns the number of size cutbacks performed on the cache which were caused by excessive memory usage.
long	getMaximumEntryAgeMS() Gets the maximum age of a cached entry (in milliseconds)
int	getSize() Gets the current size of the memory-cache
boolean	getTrimOnAdd() Gets the trim-on-add state
VAL	getValue(KEY key) Get entry from cache
VAL	getValue(KEY key, VAL dft) Get entry from cache
boolean	hasValue(KEY key) Returns true if the specified key exists in the cache
static void	main(java.lang.String[] argv)
int	setMaximumCacheSize(int maxSize) Sets the maximum cache size
long	setMaximumEntryAgeMS(long maxAgeMS) Sets the maximum age of a cached entry (in milliseconds)
void	setTrimOnAdd(boolean toa) Sets the trim-on-add state
java.lang.String	toString() Gets a String representation of the contents of this MemCache.
void	trimCache() Remove old/excessive entries in cache
void	trimCache(java.lang.String msg) Remove old/excessive entries in cache
static int	TrimSize(int size)

Methods inherited from class java.lang.Object

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

Field Detail

MINIMUM_CACHE_SIZE

public static final int MINIMUM_CACHE_SIZE

See Also:

Constant Field Values

DEFAULT_CACHE_SIZE

public static final int DEFAULT_CACHE_SIZE

See Also:

Constant Field Values

MAXIMUM_CACHE_AGE_MS

public static final long MAXIMUM_CACHE_AGE_MS

See Also:

Constant Field Values

DEFAULT_TRIM_PERCENT

public static final double DEFAULT_TRIM_PERCENT

See Also:

Constant Field Values

DEFAULT_TRIM_SIZE

public static final int DEFAULT_TRIM_SIZE

MAX_MEMORY_UTILIZATION

public static final double MAX_MEMORY_UTILIZATION

See Also:

Constant Field Values

Constructor Detail

MemCache

public MemCache()

Constructor

MemCache

public MemCache(int maxSize)

Constructor

Method Detail

TrimSize

public static int TrimSize(int size)

getSize

public int getSize()

Gets the current size of the memory-cache

Returns:

The current size of the memory-cache

setMaximumCacheSize

public int setMaximumCacheSize(int maxSize)

Sets the maximum cache size

Specified by:

setMaximumCacheSize in interface MemCacheAPI<KEY,VAL>

Parameters:

maxSize - The maximum cache size

Returns:

The maximum cache size that was successfully set, or -1 if unable to set the size.

getMaximumCacheSize

public int getMaximumCacheSize()

Gets the maximum cache size

Specified by:

getMaximumCacheSize in interface MemCacheAPI<KEY,VAL>

Returns:

The maximum cache size, or -1 if unable to retrieve the size.

exceedsMaximumCacheSize

public boolean exceedsMaximumCacheSize(double maxGain)

Returns true if the current size exceeds the maximum cache size

Parameters:

maxGain - The gain/percentage to apply to the max cache size

Returns:

True if the current size exceeds the maximum size, multiplied by the maxGain.

setMaximumEntryAgeMS

public long setMaximumEntryAgeMS(long maxAgeMS)

Sets the maximum age of a cached entry (in milliseconds)

Parameters:

maxAgeMS - The maximum age of a cached entry (in milliseconds)

Returns:

The maximum age that was successfully set.

getMaximumEntryAgeMS

public long getMaximumEntryAgeMS()

Gets the maximum age of a cached entry (in milliseconds)

Returns:

The maximum age of a cached entry.

getMaximumCacheSizeCutbackCount

public int getMaximumCacheSizeCutbackCount()

Returns the number of size cutbacks performed on the cache which were caused by excessive memory usage.

setTrimOnAdd

public void setTrimOnAdd(boolean toa)

Sets the trim-on-add state

getTrimOnAdd

public boolean getTrimOnAdd()

Gets the trim-on-add state

trimCache

public void trimCache(java.lang.String msg)

Remove old/excessive entries in cache

trimCache

public void trimCache()

Remove old/excessive entries in cache

addValue

public void addValue(KEY key,
                     VAL val)

Add entry to cache

Specified by:

addValue in interface MemCacheAPI<KEY,VAL>

Parameters:

key - The key to add

val - The value to associate with the specified key

hasValue

public boolean hasValue(KEY key)

Returns true if the specified key exists in the cache

Specified by:

hasValue in interface MemCacheAPI<KEY,VAL>

Parameters:

key - The key to check for existence

Returns:

True if the specified key exists in the cache, false otherwise

getValue

public VAL getValue(KEY key)

Get entry from cache

Parameters:

key - The key of the value to retrieve

Returns:

The value for the specified key, or null if the key does not exist

getValue

public VAL getValue(KEY key,
                    VAL dft)

Get entry from cache

Specified by:

getValue in interface MemCacheAPI<KEY,VAL>

Parameters:

key - The key of the value to retrieve

dft - The default value if the key does not exist

Returns:

The value for the specified key, or specified default if the key does not exist

toString

public java.lang.String toString()

Gets a String representation of the contents of this MemCache. (used for debugging only)

Overrides:

toString in class java.lang.Object

main

public static void main(java.lang.String[] argv)