Package com.helger.commons.cache

Class MappedCache<KEYTYPE,KEYSTORETYPE,VALUETYPE>

java.lang.Object

com.helger.commons.cache.MappedCache<KEYTYPE,KEYSTORETYPE,VALUETYPE>

Type Parameters:

KEYTYPE - The cache source type

KEYSTORETYPE - The internal storage key type

VALUETYPE - The cache value type

All Implemented Interfaces:

ICache<KEYTYPE,VALUETYPE>, IMutableCache<KEYTYPE,VALUETYPE>, IHasSize, IHasName

Direct Known Subclasses:

Cache

@ThreadSafe
public class MappedCache<KEYTYPE,KEYSTORETYPE,VALUETYPE>
extends Object
implements IMutableCache<KEYTYPE,VALUETYPE>

Base implementation of ICache and IMutableCache.

Since:

9.3.8 generalized from the existing Cache class.

Author:

Philip Helger

Field Summary

Fields

Modifier and Type	Field	Description
protected SimpleReadWriteLock	m_aRWLock
static int	NO_MAX_SIZE	A constant indicating, that a cache has no max size
static String	STATISTICS_PREFIX	The prefix to be used for statistics elements

Constructor Summary

Constructors

Constructor	Description
MappedCache(Function<KEYTYPE,KEYSTORETYPE> aCacheKeyProvider, Function<KEYTYPE,VALUETYPE> aValueProvider, int nMaxSize, String sCacheName, boolean bAllowNullValues)	Constructor

Method Summary

Modifier and Type	Method	Description
EChange	clearCache()	Remove all cached elements.
protected ICommonsMap<KEYSTORETYPE,Wrapper<VALUETYPE>>	createCache()	Create a new cache map.
protected Function<KEYTYPE,KEYSTORETYPE>	getCacheKeyProvider()
VALUETYPE	getFromCache(KEYTYPE aKey)	Get the cached value associated with the passed key.
protected Wrapper<VALUETYPE>	getFromCacheNoStats(KEYSTORETYPE aCacheKey)
protected Wrapper<VALUETYPE>	getFromCacheNoStatsNotLocked(KEYSTORETYPE aCacheKey)
int	getMaxSize()
String	getName()
protected Function<KEYTYPE,VALUETYPE>	getValueProvider()
boolean	hasMaxSize()
boolean	isAllowNullValues()
boolean	isEmpty()
boolean	isInCache(KEYTYPE aKey)	Check if the passed key is already in the cache or not.
boolean	isNotEmpty()
protected void	putInCache(KEYTYPE aKey, VALUETYPE aValue)	Put a new value into the cache.
protected void	putInCacheNotLocked(KEYSTORETYPE aCacheKey, Wrapper<VALUETYPE> aCacheValue)	Put a new value into the cache.
EChange	removeFromCache(KEYTYPE aKey)	Remove the given key from the cache.
int	size()
String	toString()

Methods inherited from class java.lang.Object

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

Field Detail

STATISTICS_PREFIX

public static final String STATISTICS_PREFIX

The prefix to be used for statistics elements

See Also:

Constant Field Values

NO_MAX_SIZE

public static final int NO_MAX_SIZE

A constant indicating, that a cache has no max size

See Also:

Constant Field Values

m_aRWLock

protected final SimpleReadWriteLock m_aRWLock

Constructor Detail

MappedCache

public MappedCache(@Nonnull
                   Function<KEYTYPE,KEYSTORETYPE> aCacheKeyProvider,
                   @Nonnull
                   Function<KEYTYPE,VALUETYPE> aValueProvider,
                   int nMaxSize,
                   @Nonnull @Nonempty
                   String sCacheName,
                   boolean bAllowNullValues)

Constructor

Parameters:

aCacheKeyProvider - The cache key provider, that takes any KEYTYPE and creates a non-null KEYSTORETYPE instance. May not be null.

aValueProvider - The cache value provider. The value to be cached may be null depending on the parameter bAllowNullValues. May not be null.

nMaxSize - The maximum size of the cache. All values ≤ 0 indicate an unlimited size.

sCacheName - The internal name of the cache. May neither be null nor empty. This name is NOT checked for uniqueness.

bAllowNullValues - true if null values are allowed to be in the cache, false if not.

Method Detail

getCacheKeyProvider

@Nonnull
protected final Function<KEYTYPE,KEYSTORETYPE> getCacheKeyProvider()

Returns:

The cache key provider from the constructor. Never null.

Since:

9.3.8

getValueProvider

@Nonnull
protected final Function<KEYTYPE,VALUETYPE> getValueProvider()

Returns:

The cache value provider from the constructor. Never null.

Since:

9.3.8

getMaxSize

public final int getMaxSize()

Returns:

The maximum number of entries allowed in this cache. Values ≤ 0 indicate that the cache size is not limited at all.

See Also:

hasMaxSize()

hasMaxSize

public final boolean hasMaxSize()

Returns:

true if this cache has a size limit, false if not.

See Also:

getMaxSize()

getName

@Nonnull
@Nonempty
public final String getName()

Specified by:

getName in interface IHasName

Returns:

The name of the object. May not be null.

isAllowNullValues

public final boolean isAllowNullValues()

Returns:

true if null can be in the cache, false if not.

Since:

9.3.8

createCache

@Nonnull
@ReturnsMutableCopy
@OverrideOnDemand
@CodingStyleguideUnaware
protected ICommonsMap<KEYSTORETYPE,Wrapper<VALUETYPE>> createCache()

Create a new cache map. This is the internal map that is used to store the items.

Returns:

Never null.

putInCacheNotLocked

@MustBeLocked(WRITE)
protected final void putInCacheNotLocked(@Nonnull
                                         KEYSTORETYPE aCacheKey,
                                         @Nonnull
                                         Wrapper<VALUETYPE> aCacheValue)

Put a new value into the cache.

Parameters:

aCacheKey - The cache key. May not be null.

aCacheValue - The cache value. May not be null.

putInCache

@IsLocked(WRITE)
protected final void putInCache(KEYTYPE aKey,
                                VALUETYPE aValue)

Put a new value into the cache. Use this in derived classes to e.g. prefill the cache with existing values.

Parameters:

aKey - The cache key. May be null depending on the cache key provider.

aValue - The cache value. May be null depending on the settings.

getFromCacheNoStatsNotLocked

@Nullable
@MustBeLocked(READ)
protected final Wrapper<VALUETYPE> getFromCacheNoStatsNotLocked(@Nullable
                                                                KEYSTORETYPE aCacheKey)

getFromCacheNoStats

@Nullable
@IsLocked(READ)
protected final Wrapper<VALUETYPE> getFromCacheNoStats(@Nullable
                                                       KEYSTORETYPE aCacheKey)

isInCache

public final boolean isInCache(KEYTYPE aKey)

Check if the passed key is already in the cache or not.

Parameters:

aKey - The key to check. May be null.

Returns:

true if the value is already in the cache, false if not.

Since:

9.3.8

getFromCache

public VALUETYPE getFromCache(KEYTYPE aKey)

Description copied from interface: ICache

Get the cached value associated with the passed key. If the value is not in the cache, it might be automatically retrieved from a respective provider.

Specified by:

getFromCache in interface ICache<KEYTYPE,KEYSTORETYPE>

Parameters:

aKey - The key to be looked up. May be nullable or not - depends upon the implementation.

Returns:

null if no such value is in the cache.

removeFromCache

@Nonnull
@OverridingMethodsMustInvokeSuper
public EChange removeFromCache(KEYTYPE aKey)

Description copied from interface: IMutableCache

Remove the given key from the cache.

Specified by:

removeFromCache in interface IMutableCache<KEYTYPE,KEYSTORETYPE>

Parameters:

aKey - The key to be removed. May be nullable or not - depends upon the implementation.

Returns:

EChange.CHANGED upon success, EChange.UNCHANGED if the key was not within the cache,

clearCache

@Nonnull
@OverridingMethodsMustInvokeSuper
public EChange clearCache()

Description copied from interface: IMutableCache

Remove all cached elements.

Specified by:

clearCache in interface IMutableCache<KEYTYPE,KEYSTORETYPE>

Returns:

EChange.

size

@Nonnegative
public int size()

Specified by:

size in interface IHasSize

Returns:

The number of contained elements. Always ≥ 0.

isEmpty

public boolean isEmpty()

Specified by:

isEmpty in interface IHasSize

Returns:

true if no items are present, false if at least a single item is present.

See Also:

IHasSize.size(), IHasSize.isNotEmpty()

isNotEmpty

public boolean isNotEmpty()

Specified by:

isNotEmpty in interface IHasSize

Returns:

true if at least one item is present, false if no item is present.

See Also:

IHasSize.size(), IHasSize.isEmpty()

toString

public String toString()

Overrides:

toString in class Object