org.opendaylight.infrautils.caches.baseimpl

Class DelegatingNullSafeCache<K,V>

java.lang.Object

org.opendaylight.infrautils.caches.baseimpl.DelegatingNullSafeCache<K,V>

All Implemented Interfaces:

AutoCloseable, BaseCache<K,V>, Cache<K,V>

public final class DelegatingNullSafeCache<K,V>
extends Object
implements Cache<K,V>

Cache with null handling, useful for API implementors (not users).

Author:

Michael Vorburger.ch

Constructor Summary

Constructors

Constructor and Description
DelegatingNullSafeCache(Cache<K,V> delegate)

Method Summary

Modifier and Type	Method and Description
void	close()
void	evict(K key) Evict an entry from the cache.
com.google.common.collect.ImmutableMap<K,V>	get(Iterable<? extends K> keys) Get several cache entries, in one go.
V	get(K key) Get cache entry.
CacheManager	getManager()
void	put(K key, V value) Puts a new entry into the Cache, replacing any existing one.
String	toString()

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Methods inherited from interface org.opendaylight.infrautils.caches.Cache

get

Constructor Detail

DelegatingNullSafeCache

public DelegatingNullSafeCache(Cache<K,V> delegate)

Method Detail

get

public V get(K key)
      throws BadCacheFunctionRuntimeException

Description copied from interface: Cache

Get cache entry. If the cache does not currently contain an entry under this key, then one is created, using the CacheFunction given when the cache was created.

Specified by:

get in interface Cache<K,V>

Parameters:

key - key of cache entry

Returns:

value, never null (but may be an Optional)

Throws:

BadCacheFunctionRuntimeException - if the cache's function returned null value

get

public com.google.common.collect.ImmutableMap<K,V> get(Iterable<? extends K> keys)
                                                throws BadCacheFunctionRuntimeException

Description copied from interface: Cache

Get several cache entries, in one go.

Specified by:

get in interface Cache<K,V>

Parameters:

keys - list of keys of cache entries

Returns:

Map of cache keys and values (neither ever null, but may be an Optional)

Throws:

BadCacheFunctionRuntimeException - if the cache's function returned null value

put

public void put(K key,
                V value)

Description copied from interface: BaseCache

Puts a new entry into the Cache, replacing any existing one.

Normally, you often never need to call this method, as in regular usage scenarios a cache API client just invokes Cache.get(Object) (or CheckedCache.get(Object), which then internally (may) use the CacheFunction (or CheckedCacheFunction) - without you ever having had to explicitly put something into the Cache.

This method is ONLY (!) intended for "optimizations". It is useful if the code using a cache already has a key and value (e.g. following an external update notification event kind of thing) and wants to "save time" on an expected subsequent Cache.get(Object) (or CheckedCache.get(Object) invoking the CacheFunction (or CheckedCacheFunction) unnecessarily, using this "hint" to "propose" an entry to the cache.

Any code using this must expect key/value pairs that have been put into a cache to disappear at any time (e.g. when the cache is full and this key/value hasn't been used, or after a programmatic or end-user operator initiated eviction), and be able to obtain THE SAME value from the CacheFunction (or CheckedCacheFunction), for the given key.

Failure to implement calls to this put method consistent with the implementation of the cache's get function WILL lead to weird cache inconsistencies!

Some Cache implementations may IGNORE this "hint" method.

Specified by:

put in interface BaseCache<K,V>

Parameters:

key - the key of the proposed new cache entry

value - the value of the proposed new cache entry

evict

public void evict(K key)

Description copied from interface: BaseCache

Evict an entry from the cache. If the cache does not currently contain an entry under this key, then this is ignored. If it does, that entry is evicted, to be re-calculated on the next get.

Use CacheManager.evictAll() to evict all entries of the entire cache.

Specified by:

evict in interface BaseCache<K,V>

getManager

public CacheManager getManager()

Specified by:

getManager in interface BaseCache<K,V>

close

public void close()
           throws Exception

Specified by:

close in interface AutoCloseable

Throws:

Exception

toString

public String toString()

Overrides:

toString in class Object