Cache (SIRIUS kernel 12.0-rc9 API)

Type Parameters:

K - the key type determining the type of the lookup values in the cache

V - the value type determining the type of values stored in the cache
```
public interface Cache<K,V>
```
Provides a cache which can be used to store and access values.
In contrast to a simple Map, the cache has a maximum size. If the cache is full, old (least recently used) entries are evicted to make room for newer ones. Also this cache will be automatically evicted from time to time so that only values which are really used remain in the cache. Therefore system resources (most essentially heap storage) is released if no longer required.
A new Cache is created by invoking CacheManager.createCache(String). The maximal size as well as the time to live value for each entry is set via the cache.[cacheName] extension. Additionally CacheManager.createCache(String, ValueComputer, ValueVerifier) can be used to supply a ValueComputer as well as a ValueVerifier. Those classes are responsible for creating non- existent cache values or to verify that cached values are still up to date, before they are returned to a user of the cache.

See Also:

CacheManager, ValueComputer, ValueVerifier

Method Summary

All Methods Instance Methods Abstract Methods
Modifier and Type	Method and Description
`void`	`clear()` Clears the complete cache
`boolean`	`contains(K key)` Checks if there is a cached entry for the given key
`V`	`get(K key)` Returns the value associated with the given key.
`V`	`get(K key, ValueComputer<K,V> computer)` Returns the value associated with the given key.
`List<CacheEntry<K,V>>`	`getContents()` Provides access to the contents of this cache
`Long`	`getHitRate()` Returns the cache hit-rate (in percent)
`List<Long>`	`getHitRateHistory()` Returns the statistical values of "hit rate" for the last some eviction intervals.
`Date`	`getLastEvictionRun()` Returns the date of the last eviction run.
`int`	`getMaxSize()` Returns the max size of the cache
`String`	`getName()` Returns the name of the cache, which is also used to load the configuration.
`int`	`getSize()` Returns the number of entries in the cache
`List<Long>`	`getUseHistory()` Returns the statistical values of "uses" for the last some eviction intervals.
`long`	`getUses()` Returns the number of reads since the last eviction
`Iterator<K>`	`keySet()` Provides access to the keys stored in this cache
`Cache<K,V>`	`onRemove(Callback<Tuple<K,V>> onRemoveCallback)` Sets the remove callback which is invoked once a value is removed from the cache.
`void`	`put(K key, V value)` Stores the given key value mapping in the cache
`void`	`remove(K key)` Removes the given item from the cache
`void`	`removeIf(Predicate<CacheEntry<K,V>> predicate)` Removes all cached values for which the predicate returns true.

- Method Detail
  - getName
```
String getName()
```
    Returns the name of the cache, which is also used to load the configuration.
    
    Returns:
    
    the name of the cache
  - getMaxSize
```
int getMaxSize()
```
    Returns the max size of the cache
    
    Returns:
    
    the maximal number of cached entries
  - getSize
```
int getSize()
```
    Returns the number of entries in the cache
    
    Returns:
    
    the number of cached entries
  - getUses
```
long getUses()
```
    Returns the number of reads since the last eviction
    
    Returns:
    
    the number of uses of this cache since the last eviction run
  - getUseHistory
```
List<Long> getUseHistory()
```
    Returns the statistical values of "uses" for the last some eviction intervals.
    
    Returns:
    
    a list of uses for the last N eviction intervals
  - getHitRate
```
Long getHitRate()
```
    Returns the cache hit-rate (in percent)
    
    Returns:
    
    the cache hit-rate (successful gets) of this cache since the last eviction
  - getHitRateHistory
```
List<Long> getHitRateHistory()
```
    Returns the statistical values of "hit rate" for the last some eviction intervals.
    
    Returns:
    
    a list of hit-rates for the last N eviction intervals
  - getLastEvictionRun
```
Date getLastEvictionRun()
```
    Returns the date of the last eviction run.
    
    Returns:
    
    the timestamp of the last eviction
  - clear
```
void clear()
```
    Clears the complete cache
  - get
```
@Nullable
V get(@Nonnull
                K key)
```
    Returns the value associated with the given key.
    
    Parameters:
    
    key - the key used to retrieve the value in the cache
    
    Returns:
    
    the cached value or null if neither a valid value was found, nor one could be computed.
  - get
```
@Nullable
V get(@Nonnull
                K key,
                @Nullable
                ValueComputer<K,V> computer)
```
    Returns the value associated with the given key. If the value is not found, the ValueComputer is invoked.
    
    Parameters:
    
    key - the key used to retrieve the value in the cache
    
    computer - the computer used to generate a value if absent in the cache
    
    Returns:
    
    the cached value or null if neither a valid value was found, nor one could be computed.
  - put
```
void put(@Nonnull
         K key,
         @Nullable
         V value)
```
    Stores the given key value mapping in the cache
    
    Parameters:
    
    key - the key used to store this entry
    
    value - the value to be stored in the entry
  - remove
```
void remove(@Nonnull
            K key)
```
    Removes the given item from the cache
    
    Parameters:
    
    key - the key which should be removed from the cache
  - removeIf
```
void removeIf(@Nonnull
              Predicate<CacheEntry<K,V>> predicate)
```
    Removes all cached values for which the predicate returns true.
    
    Parameters:
    
    predicate - the predicate used to determine if a value should be removed from the cache.
  - contains
```
boolean contains(@Nonnull
                 K key)
```
    Checks if there is a cached entry for the given key
    
    Parameters:
    
    key - contains the key to check in the cache
    
    Returns:
    
    true if a value os present for the given key, false otherwise
  - keySet
```
Iterator<K> keySet()
```
    Provides access to the keys stored in this cache
    
    Returns:
    
    an Iterator for all keys in the cache
  - getContents
```
List<CacheEntry<K,V>> getContents()
```
    Provides access to the contents of this cache
    
    Returns:
    
    a list of entries which provide detailed information about each entry in the cache
  - onRemove
```
Cache<K,V> onRemove(Callback<Tuple<K,V>> onRemoveCallback)
```
    Sets the remove callback which is invoked once a value is removed from the cache.
    Only one handler can be set at a time.
    
    Parameters:
    
    onRemoveCallback - the callback to call when an element is removed from the cache. Can be null null to remove the last handler.
    
    Returns:
    
    the original instance of the cache.

Interface Cache<K,V>

Method Summary

Method Detail

getName

getMaxSize

getSize

getUses

getUseHistory

getHitRate

getHitRateHistory

getLastEvictionRun

clear

get

get

put

remove

removeIf

contains

keySet

getContents

onRemove