Package freemarker.cache
Class MruCacheStorage
- java.lang.Object
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- freemarker.cache.MruCacheStorage
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- All Implemented Interfaces:
CacheStorage
,CacheStorageWithGetSize
public class MruCacheStorage extends java.lang.Object implements CacheStorageWithGetSize
A cache storage that implements a two-level Most Recently Used cache. In the first level, items are strongly referenced up to the specified maximum. When the maximum is exceeded, the least recently used item is moved into the second level cache, where they are softly referenced, up to another specified maximum. When the second level maximum is also exceeded, the least recently used item is discarded altogether. This cache storage is a generalization of bothStrongCacheStorage
andSoftCacheStorage
- the effect of both of them can be achieved by setting one maximum to zero and the other to the largest positive integer. On the other hand, if you wish to use this storage in a strong-only mode, or in a soft-only mode, you might consider usingStrongCacheStorage
orSoftCacheStorage
instead, as they can be used byTemplateCache
concurrently without any synchronization on a 5.0 or later JRE.This class is NOT thread-safe. If it's accessed from multiple threads concurrently, proper synchronization must be provided by the callers. Note that
TemplateCache
, the natural user of this class provides the necessary synchronizations when it uses the class. Also you might consider whether you need this sort of a mixed storage at all in your solution, as in most cases SoftCacheStorage can also be sufficient. SoftCacheStorage will use Java soft references, and they already use access timestamps internally to bias the garbage collector against clearing recently used references, so you can get reasonably good (and memory-sensitive) most-recently-used caching throughSoftCacheStorage
as well.
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Constructor Summary
Constructors Constructor Description MruCacheStorage(int strongSizeLimit, int softSizeLimit)
Creates a new MRU cache storage with specified maximum cache sizes.
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description void
clear()
java.lang.Object
get(java.lang.Object key)
int
getSize()
Returns a close approximation of the current number of cache entries.int
getSoftSize()
Returns a close approximation of the current number of soft cache entries.int
getSoftSizeLimit()
Returns the configured upper limit of the number of soft cache entries.int
getStrongSize()
Returns the current number of strong cache entries.int
getStrongSizeLimit()
Returns the configured upper limit of the number of strong cache entries.void
put(java.lang.Object key, java.lang.Object value)
void
remove(java.lang.Object key)
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Constructor Detail
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MruCacheStorage
public MruCacheStorage(int strongSizeLimit, int softSizeLimit)
Creates a new MRU cache storage with specified maximum cache sizes. Each cache size can vary between 0 andInteger.MAX_VALUE
.- Parameters:
strongSizeLimit
- the maximum number of strongly referenced templates; when exceeded, the entry used the least recently will be moved into the soft cache.softSizeLimit
- the maximum number of softly referenced templates; when exceeded, the entry used the least recently will be discarded.
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Method Detail
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get
public java.lang.Object get(java.lang.Object key)
- Specified by:
get
in interfaceCacheStorage
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put
public void put(java.lang.Object key, java.lang.Object value)
- Specified by:
put
in interfaceCacheStorage
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remove
public void remove(java.lang.Object key)
- Specified by:
remove
in interfaceCacheStorage
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clear
public void clear()
- Specified by:
clear
in interfaceCacheStorage
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getStrongSizeLimit
public int getStrongSizeLimit()
Returns the configured upper limit of the number of strong cache entries.- Since:
- 2.3.21
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getSoftSizeLimit
public int getSoftSizeLimit()
Returns the configured upper limit of the number of soft cache entries.- Since:
- 2.3.21
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getStrongSize
public int getStrongSize()
Returns the current number of strong cache entries.- Since:
- 2.3.21
- See Also:
getStrongSizeLimit()
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getSoftSize
public int getSoftSize()
Returns a close approximation of the current number of soft cache entries.- Since:
- 2.3.21
- See Also:
getSoftSizeLimit()
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getSize
public int getSize()
Returns a close approximation of the current number of cache entries.- Specified by:
getSize
in interfaceCacheStorageWithGetSize
- Since:
- 2.3.21
- See Also:
getStrongSize()
,getSoftSize()
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