Interface ReplacementPolicy

All Known Implementing Classes:

ClockPolicy

interface ReplacementPolicy

Interface that must be implemented by classes that provide a replacement algorithm for ConcurrentCache.

Nested Class Summary

Nested Classes

Modifier and Type	Interface	Description
static interface	ReplacementPolicy.Callback	The interface for the callback objects that ConcurrentCache uses to notify the replacement algorithm about events such as look-ups and removals.

Method Summary

Modifier and Type	Method	Description
void	doShrink()	Try to shrink the cache if it has exceeded its maximum size.
void	insertEntry(CacheEntry entry)	Insert an entry into the ReplacementPolicy's data structure, possibly evicting another entry.
int	size()	Get the number of entries allocated in the data structure that holds cached objects.

Method Details

insertEntry

void insertEntry(CacheEntry entry)
          throws StandardException

Insert an entry into the ReplacementPolicy's data structure, possibly evicting another entry. The entry should be uninitialized when the method is called (that is, its Cacheable should be null), and it should be locked. When the method returns, the entry may have been initialized with a Cacheable which is ready to be reused. It is also possible that the Cacheable is still null when the method returns, in which case the caller must allocate one itself. The entry will be associated with a Callback object that it can use to communicate back to the replacement policy events (for instance, that it has been accessed or become invalid).

Parameters:

entry - the entry to insert

Throws:

StandardException - if an error occurs while inserting the entry

See Also:

• CacheEntry.setCallback(ReplacementPolicy.Callback)

doShrink

void doShrink()

Try to shrink the cache if it has exceeded its maximum size. It is not guaranteed that the cache will actually shrink.

size

int size()

Get the number of entries allocated in the data structure that holds cached objects. This number could include empty entries for objects that have been removed from the cache, if those entries are still kept in the data structure for reuse.

Returns:

the number of entries allocated in the cache