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. 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).
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

Returns:

the entry computed

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