|
|||||||||
| Home >> All >> com >> opencms >> flex >> [ util overview ] | PREV CLASS NEXT CLASS | ||||||||
SUMMARY:  JAVADOC |  SOURCE |  DOWNLOAD | NESTED | FIELD | CONSTR | METHOD |
DETAIL: FIELD | CONSTR | METHOD | ||||||||
com.opencms.flex.util
Class CmsFlexLruCache
java.lang.Objectcom.opencms.flex.util.CmsFlexLruCache
- public class CmsFlexLruCache
- extends java.lang.Object
Implements an LRU (last recently used) cache.
The idea of this cache to separate the caching policy from the data structure where the cached objects are stored. The advantage of doing so is, that the CmsFlexLruCache can identify the last-recently-used object in O(1), whereas you would need at least O(n) to traverse the data structure that stores the cached objects. Second, you can easily use the CmsFlexLruCache to get an LRU cache, no matter what data structure is used to store your objects.
The cache policy is affected by the "costs" of the objects being cached. Valuable cache costs might be the byte size of the cached objects for example.
To add/remove cached objects from the data structure that stores them, the objects have to implement the methods defined in the interface I_CmsFlexLruCacheObject to be notified when they are added/removed from the CmsFlexLruCache.
- Version:
- $Revision: 1.13 $
| Field Summary | |
private int |
m_AvgCacheCosts
The avg. |
private boolean |
m_ForceFinalization
Force a finalization after down-sizing the cache? |
private I_CmsFlexLruCacheObject |
m_ListHead
The head of the list of double linked LRU cache objects. |
private I_CmsFlexLruCacheObject |
m_ListTail
The tail of the list of double linked LRU cache objects. |
private int |
m_MaxCacheCosts
The max. |
private int |
m_MaxObjectCosts
The max. |
private int |
m_ObjectCosts
The costs of all cached objects. |
private int |
m_ObjectCount
The sum of all cached objects. |
| Constructor Summary | |
CmsFlexLruCache(int theMaxCacheCosts,
int theAvgCacheCosts)
Constructor for a LRU cache with forced garbage collection/finalization, the max. |
|
CmsFlexLruCache(int theMaxCacheCosts,
int theAvgCacheCosts,
boolean forceFinalization)
Constructor for a LRU cache where the max. |
|
CmsFlexLruCache(int theMaxCacheCosts,
int theAvgCacheCosts,
int theMaxObjectCosts)
Constructor for a LRU cache with forced garbage collection/finalization. |
|
CmsFlexLruCache(int theMaxCacheCosts,
int theAvgCacheCosts,
int theMaxObjectCosts,
boolean forceFinalization)
The constructor with all options. |
|
| Method Summary | |
boolean |
add(I_CmsFlexLruCacheObject theCacheObject)
Adds a new object to this cache. |
private void |
addHead(I_CmsFlexLruCacheObject theCacheObject)
Adds a cache object as the new haed to the list of all cached objects in this cache. |
void |
clear()
Removes all cached objects in this cache. |
private void |
decreaseCache(I_CmsFlexLruCacheObject theCacheObject)
Decrease this caches statistics and notify the cached object that it was removed from this cache. |
protected void |
finalize()
Clears this cache for finalization. |
private void |
gc()
Removes the last recently used objects from the list of all cached objects as long as the costs of all cached objects are higher than the allowed avg. |
int |
getAvgCacheCosts()
Returns the average costs of all cached objects. |
int |
getMaxCacheCosts()
Returns the max costs of all cached objects. |
int |
getMaxObjectCosts()
Returns the max allowed costs per cached object. |
int |
getObjectCosts()
Returns the current costs of all cached objects. |
private void |
increaseCache(I_CmsFlexLruCacheObject theCacheObject)
Increase this caches statistics and notify the cached object that it was added to this cache. |
private boolean |
isCached(I_CmsFlexLruCacheObject theCacheObject)
Test if a given object resides inside the cache. |
I_CmsFlexLruCacheObject |
remove(I_CmsFlexLruCacheObject theCacheObject)
Removes an object from the list of all cached objects in this cache, no matter what position it has inside the list. |
private void |
removeTail()
Removes the tailing object from the list of all cached objects. |
int |
size()
Returns the count of all cached objects. |
java.lang.String |
toString()
Returns a string representing the current state of the cache. |
boolean |
touch(I_CmsFlexLruCacheObject theCacheObject)
Touch an existing object in this cache, in the sense that it's "last-recently-used" state is updated. |
| Methods inherited from class java.lang.Object |
clone, equals, getClass, hashCode, notify, notifyAll, wait, wait, wait |
| Field Detail |
m_ListHead
private I_CmsFlexLruCacheObject m_ListHead
- The head of the list of double linked LRU cache objects.
m_ListTail
private I_CmsFlexLruCacheObject m_ListTail
- The tail of the list of double linked LRU cache objects.
m_ForceFinalization
private boolean m_ForceFinalization
- Force a finalization after down-sizing the cache?
m_MaxCacheCosts
private int m_MaxCacheCosts
- The max. sum of costs the cached objects might reach.
m_AvgCacheCosts
private int m_AvgCacheCosts
- The avg. sum of costs the cached objects.
m_MaxObjectCosts
private int m_MaxObjectCosts
- The max. costs of cacheable objects.
m_ObjectCosts
private int m_ObjectCosts
- The costs of all cached objects.
m_ObjectCount
private int m_ObjectCount
- The sum of all cached objects.
| Constructor Detail |
CmsFlexLruCache
public CmsFlexLruCache(int theMaxCacheCosts,
int theAvgCacheCosts,
int theMaxObjectCosts,
boolean forceFinalization)
- The constructor with all options.
CmsFlexLruCache
public CmsFlexLruCache(int theMaxCacheCosts,
int theAvgCacheCosts,
int theMaxObjectCosts)
- Constructor for a LRU cache with forced garbage collection/finalization.
CmsFlexLruCache
public CmsFlexLruCache(int theMaxCacheCosts,
int theAvgCacheCosts)
- Constructor for a LRU cache with forced garbage collection/finalization, the max. allowed costs of cacheable
objects is 1/4 of the max. costs of all cached objects.
CmsFlexLruCache
public CmsFlexLruCache(int theMaxCacheCosts,
int theAvgCacheCosts,
boolean forceFinalization)
- Constructor for a LRU cache where the max. allowed costs of cacheable objects is 1/4 of the max. costs of all cached objects.
| Method Detail |
toString
public java.lang.String toString()
- Returns a string representing the current state of the cache.
add
public boolean add(I_CmsFlexLruCacheObject theCacheObject)
- Adds a new object to this cache.
If add the same object more than once, the object is touched instead.
isCached
private boolean isCached(I_CmsFlexLruCacheObject theCacheObject)
- Test if a given object resides inside the cache.
touch
public boolean touch(I_CmsFlexLruCacheObject theCacheObject)
- Touch an existing object in this cache, in the sense that it's "last-recently-used" state
is updated.
addHead
private void addHead(I_CmsFlexLruCacheObject theCacheObject)
- Adds a cache object as the new haed to the list of all cached objects in this cache.
remove
public I_CmsFlexLruCacheObject remove(I_CmsFlexLruCacheObject theCacheObject)
- Removes an object from the list of all cached objects in this cache,
no matter what position it has inside the list.
removeTail
private void removeTail()
- Removes the tailing object from the list of all cached objects.
decreaseCache
private void decreaseCache(I_CmsFlexLruCacheObject theCacheObject)
- Decrease this caches statistics
and notify the cached object that it was removed from this cache.
increaseCache
private void increaseCache(I_CmsFlexLruCacheObject theCacheObject)
- Increase this caches statistics
and notify the cached object that it was added to this cache.
gc
private void gc()
- Removes the last recently used objects from the list of all cached objects as long
as the costs of all cached objects are higher than the allowed avg. costs of the cache.
size
public int size()
- Returns the count of all cached objects.
finalize
protected void finalize()
throws java.lang.Throwable
- Clears this cache for finalization.
clear
public void clear()
- Removes all cached objects in this cache.
getAvgCacheCosts
public int getAvgCacheCosts()
- Returns the average costs of all cached objects.
getMaxCacheCosts
public int getMaxCacheCosts()
- Returns the max costs of all cached objects.
getMaxObjectCosts
public int getMaxObjectCosts()
- Returns the max allowed costs per cached object.
getObjectCosts
public int getObjectCosts()
- Returns the current costs of all cached objects.
|
|||||||||
| Home >> All >> com >> opencms >> flex >> [ util overview ] | PREV CLASS NEXT CLASS | ||||||||
|
SUMMARY: JAVADOC | SOURCE | DOWNLOAD | NESTED | FIELD | CONSTR | METHOD |
DETAIL: FIELD | CONSTR | METHOD | ||||||||