org.enhydra.dods.cache.complete
Class DODSHashMapCache

java.lang.Object
  java.util.AbstractMap<K,V>
      java.util.HashMap
          org.enhydra.dods.cache.complete.DODSHashMapCache

All Implemented Interfaces:

java.io.Serializable, java.lang.Cloneable, java.util.Map, DODSCache, CacheStatistics

public class DODSHashMapCache
extends java.util.HashMap
implements DODSCache

DODSHashMapCache class implements HashMap cache (for storing data objects (or DataStruct objects), or simple queries, or complex queries), and provides query statistics about the cache (query number, cache hits number, their get/set/increment methods, percents of used cache, cache hits,...).

Version:

1.0 11.06.2006.

Author:

Tanja Jovanovic

See Also:

Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from class java.util.AbstractMap

java.util.AbstractMap.SimpleEntry<K,V>, java.util.AbstractMap.SimpleImmutableEntry<K,V>

Nested classes/interfaces inherited from interface java.util.Map

java.util.Map.Entry<K,V>

Field Summary

protected int	cacheAccessNum Total number of times the cache was accessed.
protected int	cacheHitsNum Number of queries performed on the cache successfully.

Method Summary

java.lang.Object	add(java.lang.Object key, java.lang.Object value) Adds a pair (key, value) to the cache.
void	clearStatistics() Clears statistics.
int	getCacheAccessNum() Returns total number of times the cache was accessed.
int	getCacheHitsNum() Returns number of queries performed on the cache successfully.
double	getCacheHitsPercents() Returns how much queries performed on the cache were successful.
int	getMaxEntries() Returns maximal number of objects in DODSHashMapCache.
double	getUsedPercents() Returns how much cache is currently used.
void	incrementCacheAccessNum(int num) Increases total number of times the cache was accessed.
void	incrementCacheHitsNum(int num) Increases number of queries performed on the cache successfully for one.
boolean	isNeedToSynchronize()
void	setCacheAccessNum(int num) Sets total number of times the cache was accessed.
void	setCacheHitsNum(int cacheHitsNum) Sets number of queries performed on the cache successfully.
void	setMaxEntries(int max) Sets maximal number of objects in DODSHashMapCache (if the number is negative).

Methods inherited from class java.util.HashMap

clear, clone, containsKey, containsValue, entrySet, get, isEmpty, keySet, put, putAll, remove, size, values

Methods inherited from class java.util.AbstractMap

equals, hashCode, toString

Methods inherited from class java.lang.Object

finalize, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface java.util.Map

clear, containsKey, containsValue, entrySet, equals, get, hashCode, isEmpty, keySet, put, putAll, remove, size, values

Field Detail

cacheAccessNum

protected int cacheAccessNum

Total number of times the cache was accessed.

cacheHitsNum

protected int cacheHitsNum

Number of queries performed on the cache successfully.

Method Detail

add

public java.lang.Object add(java.lang.Object key,
                            java.lang.Object value)

Adds a pair (key, value) to the cache. If key already exists, the method returns previous value asociated with this key. If maximum number of objects is achieved, the eldest entry will be removed and returned (this cache is unbounded, so the maximum number is never achieved).

Specified by:

add in interface DODSCache

Parameters:

key - Key asociated with the value.

value - Value that will be added to the cache.

Returns:

Previous value asociated with this key, if the key already exists, otherwise null.

getMaxEntries

public int getMaxEntries()

Returns maximal number of objects in DODSHashMapCache. Since this cache is always unbounded, the method always returns negative value.

Specified by:

getMaxEntries in interface DODSCache

Returns:

maximal number of objects in DODSHashMapCache.

setMaxEntries

public void setMaxEntries(int max)

Sets maximal number of objects in DODSHashMapCache (if the number is negative).

Specified by:

setMaxEntries in interface DODSCache

Parameters:

max - New value of maximal number of objects in DODSHashMapCache.

isNeedToSynchronize

public boolean isNeedToSynchronize()

Specified by:

isNeedToSynchronize in interface DODSCache

getCacheAccessNum

public int getCacheAccessNum()

Returns total number of times the cache was accessed.

Specified by:

getCacheAccessNum in interface CacheStatistics

Returns:

total number of times the cache was accessed.

setCacheAccessNum

public void setCacheAccessNum(int num)

Sets total number of times the cache was accessed.

Specified by:

setCacheAccessNum in interface CacheStatistics

Parameters:

num - Total number of times the cache was accessed.

incrementCacheAccessNum

public void incrementCacheAccessNum(int num)

Increases total number of times the cache was accessed.

Specified by:

incrementCacheAccessNum in interface CacheStatistics

getCacheHitsNum

public int getCacheHitsNum()

Returns number of queries performed on the cache successfully.

Specified by:

getCacheHitsNum in interface CacheStatistics

Returns:

Number of queries performed on the cache successfully.

setCacheHitsNum

public void setCacheHitsNum(int cacheHitsNum)

Sets number of queries performed on the cache successfully.

Specified by:

setCacheHitsNum in interface CacheStatistics

Parameters:

cacheHitsNum - Number of queries performed on the cache successfully.

incrementCacheHitsNum

public void incrementCacheHitsNum(int num)

Increases number of queries performed on the cache successfully for one.

Specified by:

incrementCacheHitsNum in interface CacheStatistics

getUsedPercents

public double getUsedPercents()

Returns how much cache is currently used. This value is given in percents. Since this cache is always unbounded, the method always returns 100%.

Specified by:

getUsedPercents in interface CacheStatistics

Returns:

Percents - how much cache is currently used.

getCacheHitsPercents

public double getCacheHitsPercents()

Returns how much queries performed on the cache were successful. This value is given in percents.

Specified by:

getCacheHitsPercents in interface CacheStatistics

Returns:

Percents - how much queries performed on the cache were successful.

clearStatistics

public void clearStatistics()

Clears statistics.

Specified by:

clearStatistics in interface CacheStatistics