Package se.liu.ida.hefquin.base.datastructures.impl.cache

Class GenericCacheImpl<IdType,ObjectType,EntryType extends CacheEntry<ObjectType>>

java.lang.Object

se.liu.ida.hefquin.base.datastructures.impl.cache.GenericCacheImpl<IdType,ObjectType,EntryType>

All Implemented Interfaces:

Cache<IdType,ObjectType>

public class GenericCacheImpl<IdType,ObjectType,EntryType extends CacheEntry<ObjectType>>
extends Object
implements Cache<IdType,ObjectType>

A generic, thread-safe implementation of Cache.

Field Summary

Fields

Modifier and Type	Field	Description
protected Queue<Integer>	availableSlotIndexes	Indexes of empty/unused slots; will be used have the initial cache population phase.
protected final Map<IdType,Integer>	index	Maps keys to slot indexes.
protected boolean	initialPhaseCompleted	Indicates that we have completed the initial cache population phase during which the cache has not yet reached its capacity.
protected final CachePolicies<IdType,ObjectType,EntryType>	policies
protected final CacheReplacementPolicy<IdType,ObjectType,EntryType>	replacementPolicy
protected final List<EntryType>	slots	The slots of this cache.

Constructor Summary

Constructors

Constructor	Description
GenericCacheImpl(int capacity, CachePolicies<IdType,ObjectType,EntryType> policies)

Method Summary

Modifier and Type	Method	Description
void	clear()	Removes all objects from this cache.
boolean	evict(IdType id)	If the cache contains an object that is associated with the given ID, then this object is evicted from the cache and the method returns true.
boolean	evict(IdType id, ObjectType obj)	If an object equivalent to the given one is associated with the given ID in this cache, then this object is evicted from the cache and the method returns true.
ObjectType	get(IdType id)	Returns the object associated with the given ID in this cache, or null if there is no such object in the cache.
boolean	isEmpty()	Returns true if the cache does not contain any objects at the moment, and false otherwise.
void	put(IdType id, ObjectType obj)	Adds the given object to this cache, associated with the given ID.

Methods inherited from class java.lang.Object

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

Field Details

policies

protected final CachePolicies<IdType,ObjectType,EntryType extends CacheEntry<ObjectType>> policies

replacementPolicy

protected final CacheReplacementPolicy<IdType,ObjectType,EntryType extends CacheEntry<ObjectType>> replacementPolicy

slots

protected final List<EntryType extends CacheEntry<ObjectType>> slots

The slots of this cache.

index

protected final Map<IdType,Integer> index

Maps keys to slot indexes.

initialPhaseCompleted

protected boolean initialPhaseCompleted

Indicates that we have completed the initial cache population phase during which the cache has not yet reached its capacity.

availableSlotIndexes

protected Queue<Integer> availableSlotIndexes

Indexes of empty/unused slots; will be used have the initial cache population phase.

Constructor Details

GenericCacheImpl

public GenericCacheImpl(int capacity,
 CachePolicies<IdType,ObjectType,EntryType> policies)

Method Details

put

public void put(IdType id,
 ObjectType obj)

Description copied from interface: Cache

Adds the given object to this cache, associated with the given ID. If there is another object currently associated with the given ID, that object will be replaced by the given one. Updating the cache may also lead to the eviction of other cached objects, depending on whether the cache has reached its capacity. In such a case, the object(s) that are evicted are determined based on the cache replacement policy of this cache.

Specified by:

put in interface Cache<IdType,ObjectType>

get

public ObjectType get(IdType id)

Description copied from interface: Cache

Returns the object associated with the given ID in this cache, or null if there is no such object in the cache. Implementations may also return null even if there is such an object but that object is not valid anymore, according to a cache invalidation policy employed by the cache. In such a case, the object may also be evicted altogether from the cache.

Specified by:

get in interface Cache<IdType,ObjectType>

evict

public boolean evict(IdType id)

Description copied from interface: Cache

If the cache contains an object that is associated with the given ID, then this object is evicted from the cache and the method returns true. If there is no such cached object, the method returns false. Calling this method may also have the side effect that other objects are evicted from the cache, depending on the invalidation policy of this cache.

Specified by:

evict in interface Cache<IdType,ObjectType>

evict

public boolean evict(IdType id,
 ObjectType obj)

Description copied from interface: Cache

If an object equivalent to the given one is associated with the given ID in this cache, then this object is evicted from the cache and the method returns true. If there is another object associated with the ID, or none at all, the method returns false. Calling this method may also have the side effect that other objects are evicted from the cache, depending on the invalidation policy of this cache.

Specified by:

evict in interface Cache<IdType,ObjectType>

isEmpty

public boolean isEmpty()

Description copied from interface: Cache

Returns true if the cache does not contain any objects at the moment, and false otherwise.

Specified by:

isEmpty in interface Cache<IdType,ObjectType>

clear

public void clear()

Description copied from interface: Cache

Removes all objects from this cache.

Specified by:

clear in interface Cache<IdType,ObjectType>