com.github.benmanes.caffeine.cache

Interface Policy.Eviction<K,V>

Enclosing interface:

Policy<K,V>

public static interface Policy.Eviction<K,V>

The low-level operations for a cache with a size-based eviction policy.

Method Summary

Modifier and Type	Method and Description
Map<K,V>	coldest(int limit) Returns an unmodifiable snapshot Map view of the cache with ordered traversal.
long	getMaximum() Returns the maximum total weighted or unweighted size of this cache, depending on how the cache was constructed.
Map<K,V>	hottest(int limit) Returns an unmodifiable snapshot Map view of the cache with ordered traversal.
boolean	isWeighted() Returns whether the cache is bounded by a maximum size or maximum weight.
void	setMaximum(long maximum) Specifies the maximum total size of this cache.
OptionalLong	weightedSize() Returns the approximate accumulated weight of entries in this cache.
default OptionalInt	weightOf(K key) Returns the weight of the entry.

Method Detail

isWeighted

boolean isWeighted()

Returns whether the cache is bounded by a maximum size or maximum weight.

Returns:

if the size bounding takes into account the entry's weight

weightOf

@Nonnull
default OptionalInt weightOf(@Nonnull
                                      K key)

Returns the weight of the entry. If this cache does not use a weighted size bound or does not support querying for the entry's weight, then the OptionalInt will be empty.

Parameters:

key - the key for the entry being queried

Returns:

the weight if the entry is present in the cache

weightedSize

@Nonnull
OptionalLong weightedSize()

Returns the approximate accumulated weight of entries in this cache. If this cache does not use a weighted size bound, then the OptionalLong will be empty.

Returns:

the combined weight of the values in this cache

getMaximum

@Nonnegative
long getMaximum()

Returns the maximum total weighted or unweighted size of this cache, depending on how the cache was constructed. This value can be best understood by inspecting isWeighted().

Returns:

the maximum size bounding, which may be either weighted or unweighted

setMaximum

void setMaximum(@Nonnegative
                long maximum)

Specifies the maximum total size of this cache. This value may be interpreted as the weighted or unweighted threshold size based on how this cache was constructed. If the cache currently exceeds the new maximum size this operation eagerly evict entries until the cache shrinks to the appropriate size.

Note that some implementations may have an internal inherent bound on the maximum total size. If the value specified exceeds that bound, then the value is set to the internal maximum.

Parameters:

maximum - the maximum, interpreted as weighted or unweighted size depending on how this cache was constructed

Throws:

IllegalArgumentException - if the maximum size specified is negative

coldest

@Nonnull
Map<K,V> coldest(@Nonnegative
                          int limit)

Returns an unmodifiable snapshot Map view of the cache with ordered traversal. The order of iteration is from the entries least likely to be retained (coldest) to the entries most likely to be retained (hottest). This order is determined by the eviction policy's best guess at the time of creating this snapshot view.

Beware that obtaining the mappings is NOT a constant-time operation. Because of the asynchronous nature of the page replacement policy, determining the retention ordering requires a traversal of the entries.

Parameters:

limit - the maximum size of the returned map (use Integer.MAX_VALUE to disregard the limit)

Returns:

a snapshot view of the cache from coldest entry to the hottest

hottest

@Nonnull
Map<K,V> hottest(@Nonnegative
                          int limit)

Returns an unmodifiable snapshot Map view of the cache with ordered traversal. The order of iteration is from the entries most likely to be retained (hottest) to the entries least likely to be retained (coldest). This order is determined by the eviction policy's best guess at the time of creating this snapshot view.

Beware that obtaining the mappings is NOT a constant-time operation. Because of the asynchronous nature of the page replacement policy, determining the retention ordering requires a traversal of the entries.

Parameters:

limit - the maximum size of the returned map (use Integer.MAX_VALUE to disregard the limit)

Returns:

a snapshot view of the cache from hottest entry to the coldest