fr.cnes.sirius.patrius.tools.cache

Class FIFOThreadSafeCache<K,V>

java.lang.Object

fr.cnes.sirius.patrius.tools.cache.FIFOThreadSafeCache<K,V>

Type Parameters:

K - The key, usually used to identify if the computation has already been performed

V - The value, usually representing the result of the computation associated to the key

All Implemented Interfaces:

Serializable

public class FIFOThreadSafeCache<K,V>
extends Object
implements Serializable

This class implements a thread safe cache.
It is based on a FirstInFirstOut (FIFO) structure. As soon as the structure reaches it's maximum size, adding a new entry removes the oldest entry.

The tread-safety is handled by the use of the ConcurrentLinkedDeque implementation (which is a lock-free implementation).

Author:

veuillh

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
static int	DEFAULT_MAX_SIZE Default max size for the cache: trade-off between the duration for look-up in the cache versus reuse of already computed values.
static int	PERCENT Percent conversion value.

Constructor Summary

Constructors

Constructor and Description
FIFOThreadSafeCache() Constructor with default max size DEFAULT_MAX_SIZE.
FIFOThreadSafeCache(int listMaxSize) Standard constructor.

Method Summary

Modifier and Type	Method and Description
void	clear() Clears the cache.
CacheEntry<K,V>	computeIf(Predicate<CacheEntry<K,V>> cacheAvailabilityPredicate, Supplier<CacheEntry<K,V>> entrySupplier) Computes and add a new entry in the cache, if necessary.
CacheEntry<K,V>	computeIfAbsent(K key, Supplier<CacheEntry<K,V>> entrySupplier) Computes and add a new entry in the cache, if necessary.
int	getMaxSize() Getter for the maximum size of the cache.
double	getReusabilityRatio() Provides the ratio of reusability of this cache.
String	toString() Returns a string representation of the cache structure.

Methods inherited from class java.lang.Object

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

Field Detail

DEFAULT_MAX_SIZE

public static final int DEFAULT_MAX_SIZE

Default max size for the cache: trade-off between the duration for look-up in the cache versus reuse of already computed values.

See Also:

Constant Field Values

PERCENT

public static final int PERCENT

Percent conversion value.

See Also:

Constant Field Values

Constructor Detail

FIFOThreadSafeCache

public FIFOThreadSafeCache()

Constructor with default max size DEFAULT_MAX_SIZE.

FIFOThreadSafeCache

public FIFOThreadSafeCache(int listMaxSize)

Standard constructor.

Parameters:

listMaxSize - The max size of the cache. 0 is a legitimate value emulating the absence of cache.

Throws:

NotPositiveException - if listMaxSize < 0

Method Detail

computeIf

public CacheEntry<K,V> computeIf(Predicate<CacheEntry<K,V>> cacheAvailabilityPredicate,
                                 Supplier<CacheEntry<K,V>> entrySupplier)

Computes and add a new entry in the cache, if necessary.

Parameters:

cacheAvailabilityPredicate - The predicate that test if one of the entries of the cache matches the requirement

entrySupplier - The supplier that will build the entry if required. If it returns null, the entry will be returned normally but not added into the cache.

Returns:

the entry computed. Can be null if the supplier provided such a value.

computeIfAbsent

public CacheEntry<K,V> computeIfAbsent(K key,
                                       Supplier<CacheEntry<K,V>> entrySupplier)

Computes and add a new entry in the cache, if necessary.

Parameters:

key - The key to assess if the computation is required

entrySupplier - The supplier that will build the entry if required

Returns:

the entry computed

clear

public void clear()

Clears the cache.
Note that this method might have non desired effects if it is called in concurrency with computeIf(java.util.function.Predicate<fr.cnes.sirius.patrius.tools.cache.CacheEntry<K, V>>, java.util.function.Supplier<fr.cnes.sirius.patrius.tools.cache.CacheEntry<K, V>>) (more precisely with addEntry internal method).

getMaxSize

public int getMaxSize()

Getter for the maximum size of the cache.

Returns:

the maximum size of the cache

getReusabilityRatio

public double getReusabilityRatio()

Provides the ratio of reusability of this cache.

This method can help to chose the size of the cache.

Returns:

the reusability ratio (0 means no reusability at all, 0.5 means that the supplier is called only half time compared to the computeIf(Predicate, Supplier) method)

toString

public String toString()

Returns a string representation of the cache structure.

Overrides:

toString in class Object

Returns:

a string representation of the cache structure