Class Caffeine<K,V>
- java.lang.Object
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- com.github.benmanes.caffeine.cache.Caffeine<K,V>
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- Type Parameters:
K
- the base key type for all caches created by this builderV
- the base value type for all caches created by this builder
public final class Caffeine<K,V> extends java.lang.Object
A builder ofAsyncLoadingCache
,LoadingCache
, andCache
instances having a combination of the following features:- automatic loading of entries into the cache, optionally asynchronously
- size-based eviction when a maximum is exceeded based on frequency and recency
- time-based expiration of entries, measured since last access or last write
- asynchronously refresh when the first stale request for an entry occurs
- keys automatically wrapped in weak references
- values automatically wrapped in weak or soft references
- writes propagated to an external resource
- notification of evicted (or otherwise removed) entries
- accumulation of cache access statistics
These features are all optional; caches can be created using all or none of them. By default cache instances created by
Caffeine
will not perform any type of eviction.Usage example:
LoadingCache<Key, Graph> graphs = Caffeine.newBuilder() .maximumSize(10_000) .expireAfterWrite(10, TimeUnit.MINUTES) .removalListener((Key key, Graph graph, RemovalCause cause) -> System.out.printf("Key %s was removed (%s)%n", key, cause)) .build(key -> createExpensiveGraph(key));
The returned cache is implemented as a hash table with similar performance characteristics to
ConcurrentHashMap
. TheasMap
view (and its collection views) have weakly consistent iterators. This means that they are safe for concurrent use, but if other threads modify the cache after the iterator is created, it is undefined which of these changes, if any, are reflected in that iterator. These iterators never throwConcurrentModificationException
.Note: by default, the returned cache uses equality comparisons (the
equals
method) to determine equality for keys or values. However, ifweakKeys()
was specified, the cache uses identity (==
) comparisons instead for keys. Likewise, ifweakValues()
orsoftValues()
was specified, the cache uses identity comparisons for values.Entries are automatically evicted from the cache when any of maximumSize, maximumWeight, expireAfterWrite, expireAfterAccess, weakKeys, weakValues, or softValues are requested.
If maximumSize or maximumWeight is requested entries may be evicted on each cache modification.
If expireAfterWrite or expireAfterAccess is requested entries may be evicted on each cache modification, on occasional cache accesses, or on calls to
Cache.cleanUp()
. Expired entries may be counted byCache.estimatedSize()
, but will never be visible to read or write operations.If weakKeys, weakValues, or softValues are requested, it is possible for a key or value present in the cache to be reclaimed by the garbage collector. Entries with reclaimed keys or values may be removed from the cache on each cache modification, on occasional cache accesses, or on calls to
Cache.cleanUp()
; such entries may be counted inCache.estimatedSize()
, but will never be visible to read or write operations.Certain cache configurations will result in the accrual of periodic maintenance tasks which will be performed during write operations, or during occasional read operations in the absence of writes. The
Cache.cleanUp()
method of the returned cache will also perform maintenance, but calling it should not be necessary with a high throughput cache. Only caches built with maximumSize, maximumWeight, expireAfterWrite, expireAfterAccess, weakKeys, weakValues, or softValues perform periodic maintenance.The caches produced by
Caffeine
are serializable, and the deserialized caches retain all the configuration properties of the original cache. Note that the serialized form does not include cache contents, but only configuration.
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Nested Class Summary
Nested Classes Modifier and Type Class Description (package private) static class
Caffeine.Strength
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Field Summary
Fields Modifier and Type Field Description (package private) static int
DEFAULT_EXPIRATION_NANOS
(package private) static int
DEFAULT_INITIAL_CAPACITY
(package private) static int
DEFAULT_REFRESH_NANOS
(package private) static java.util.function.Supplier<StatsCounter>
ENABLED_STATS_COUNTER_SUPPLIER
(package private) java.util.concurrent.Executor
executor
(package private) long
expireAfterAccessNanos
(package private) long
expireAfterWriteNanos
(package private) int
initialCapacity
(package private) Caffeine.Strength
keyStrength
(package private) static java.util.logging.Logger
logger
(package private) long
maximumSize
(package private) long
maximumWeight
(package private) long
refreshNanos
(package private) RemovalListener<? super K,? super V>
removalListener
(package private) java.util.function.Supplier<StatsCounter>
statsCounterSupplier
(package private) boolean
strictParsing
(package private) Ticker
ticker
(package private) static int
UNSET_INT
(package private) Caffeine.Strength
valueStrength
(package private) Weigher<? super K,? super V>
weigher
(package private) CacheWriter<? super K,? super V>
writer
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Constructor Summary
Constructors Modifier Constructor Description private
Caffeine()
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Method Summary
All Methods Static Methods Instance Methods Concrete Methods Modifier and Type Method Description <K1 extends K,V1 extends V>
Cache<K1,V1>build()
Builds a cache which does not automatically load values when keys are requested.<K1 extends K,V1 extends V>
LoadingCache<K1,V1>build(CacheLoader<? super K1,V1> loader)
Builds a cache, which either returns an already-loaded value for a given key or atomically computes or retrieves it using the suppliedCacheLoader
.<K1 extends K,V1 extends V>
AsyncLoadingCache<K1,V1>buildAsync(AsyncCacheLoader<? super K1,V1> loader)
Builds a cache, which either returns aCompletableFuture
already loaded or currently computing the value for a given key, or atomically computes the value asynchronously through a supplied mapping function or the suppliedAsyncCacheLoader
.<K1 extends K,V1 extends V>
AsyncLoadingCache<K1,V1>buildAsync(CacheLoader<? super K1,V1> loader)
Builds a cache, which either returns aCompletableFuture
already loaded or currently computing the value for a given key, or atomically computes the value asynchronously through a supplied mapping function or the suppliedCacheLoader
.(package private) boolean
evicts()
Caffeine<K,V>
executor(java.util.concurrent.Executor executor)
Specifies the executor to use when running asynchronous tasks.Caffeine<K,V>
expireAfterAccess(long duration, java.util.concurrent.TimeUnit unit)
Specifies that each entry should be automatically removed from the cache once a fixed duration has elapsed after the entry's creation, the most recent replacement of its value, or its last read.Caffeine<K,V>
expireAfterWrite(long duration, java.util.concurrent.TimeUnit unit)
Specifies that each entry should be automatically removed from the cache once a fixed duration has elapsed after the entry's creation, or the most recent replacement of its value.(package private) boolean
expiresAfterAccess()
(package private) boolean
expiresAfterWrite()
static Caffeine<java.lang.Object,java.lang.Object>
from(CaffeineSpec spec)
Constructs a newCaffeine
instance with the settings specified inspec
.static Caffeine<java.lang.Object,java.lang.Object>
from(java.lang.String spec)
Constructs a newCaffeine
instance with the settings specified inspec
.(package private) <K1 extends K,V1 extends V>
CacheWriter<K1,V1>getCacheWriter()
(package private) java.util.concurrent.Executor
getExecutor()
(package private) long
getExpiresAfterAccessNanos()
(package private) long
getExpiresAfterWriteNanos()
(package private) int
getInitialCapacity()
(package private) long
getMaximum()
(package private) long
getRefreshAfterWriteNanos()
(package private) <K1 extends K,V1 extends V>
RemovalListener<K1,V1>getRemovalListener(boolean async)
(package private) java.util.function.Supplier<? extends StatsCounter>
getStatsCounterSupplier()
(package private) Ticker
getTicker()
(package private) <K1 extends K,V1 extends V>
Weigher<K1,V1>getWeigher(boolean isAsync)
(package private) boolean
hasInitialCapacity()
Caffeine<K,V>
initialCapacity(int initialCapacity)
Sets the minimum total size for the internal data structures.(package private) boolean
isBounded()
(package private) boolean
isRecordingStats()
(package private) boolean
isSoftValues()
(package private) boolean
isStrongKeys()
(package private) boolean
isStrongValues()
(package private) boolean
isWeakKeys()
(package private) boolean
isWeakValues()
(package private) boolean
isWeighted()
Caffeine<K,V>
maximumSize(long maximumSize)
Specifies the maximum number of entries the cache may contain.Caffeine<K,V>
maximumWeight(long maximumWeight)
Specifies the maximum weight of entries the cache may contain.static Caffeine<java.lang.Object,java.lang.Object>
newBuilder()
Constructs a newCaffeine
instance with default settings, including strong keys, strong values, and no automatic eviction of any kind.Caffeine<K,V>
recordStats()
Enables the accumulation ofCacheStats
during the operation of the cache.Caffeine<K,V>
recordStats(java.util.function.Supplier<? extends StatsCounter> statsCounterSupplier)
Enables the accumulation ofCacheStats
during the operation of the cache.Caffeine<K,V>
refreshAfterWrite(long duration, java.util.concurrent.TimeUnit unit)
Specifies that active entries are eligible for automatic refresh once a fixed duration has elapsed after the entry's creation, or the most recent replacement of its value.(package private) boolean
refreshes()
<K1 extends K,V1 extends V>
Caffeine<K1,V1>removalListener(RemovalListener<? super K1,? super V1> removalListener)
Specifies a listener instance that caches should notify each time an entry is removed for any reason.(package private) static void
requireArgument(boolean expression)
Ensures that the argument expression is true.(package private) static void
requireArgument(boolean expression, java.lang.String template, java.lang.Object... args)
Ensures that the argument expression is true.(package private) void
requireNonLoadingCache()
(package private) static void
requireState(boolean expression)
Ensures that the state expression is true.(package private) static void
requireState(boolean expression, java.lang.String template, java.lang.Object... args)
Ensures that the state expression is true.(package private) void
requireWeightWithWeigher()
Caffeine<K,V>
softValues()
Specifies that each value (not key) stored in the cache should be wrapped in aSoftReference
(by default, strong references are used).Caffeine<K,V>
ticker(Ticker ticker)
Specifies a nanosecond-precision time source for use in determining when entries should be expired or refreshed.java.lang.String
toString()
Returns a string representation for this Caffeine instance.Caffeine<K,V>
weakKeys()
Specifies that each key (not value) stored in the cache should be wrapped in aWeakReference
(by default, strong references are used).Caffeine<K,V>
weakValues()
Specifies that each value (not key) stored in the cache should be wrapped in aWeakReference
(by default, strong references are used).<K1 extends K,V1 extends V>
Caffeine<K1,V1>weigher(Weigher<? super K1,? super V1> weigher)
Specifies the weigher to use in determining the weight of entries.<K1 extends K,V1 extends V>
Caffeine<K1,V1>writer(CacheWriter<? super K1,? super V1> writer)
Specifies a writer instance that caches should notify each time an entry is explicitly created or modified, or removed for any reason.
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Field Detail
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logger
static final java.util.logging.Logger logger
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ENABLED_STATS_COUNTER_SUPPLIER
static final java.util.function.Supplier<StatsCounter> ENABLED_STATS_COUNTER_SUPPLIER
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UNSET_INT
static final int UNSET_INT
- See Also:
- Constant Field Values
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DEFAULT_INITIAL_CAPACITY
static final int DEFAULT_INITIAL_CAPACITY
- See Also:
- Constant Field Values
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DEFAULT_EXPIRATION_NANOS
static final int DEFAULT_EXPIRATION_NANOS
- See Also:
- Constant Field Values
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DEFAULT_REFRESH_NANOS
static final int DEFAULT_REFRESH_NANOS
- See Also:
- Constant Field Values
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strictParsing
boolean strictParsing
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maximumSize
long maximumSize
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maximumWeight
long maximumWeight
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initialCapacity
int initialCapacity
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refreshNanos
long refreshNanos
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expireAfterWriteNanos
long expireAfterWriteNanos
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expireAfterAccessNanos
long expireAfterAccessNanos
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removalListener
RemovalListener<? super K,? super V> removalListener
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statsCounterSupplier
java.util.function.Supplier<StatsCounter> statsCounterSupplier
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writer
CacheWriter<? super K,? super V> writer
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executor
java.util.concurrent.Executor executor
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ticker
Ticker ticker
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keyStrength
Caffeine.Strength keyStrength
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valueStrength
Caffeine.Strength valueStrength
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Method Detail
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requireArgument
static void requireArgument(boolean expression, java.lang.String template, java.lang.Object... args)
Ensures that the argument expression is true.
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requireArgument
static void requireArgument(boolean expression)
Ensures that the argument expression is true.
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requireState
static void requireState(boolean expression)
Ensures that the state expression is true.
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requireState
static void requireState(boolean expression, java.lang.String template, java.lang.Object... args)
Ensures that the state expression is true.
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newBuilder
@Nonnull public static Caffeine<java.lang.Object,java.lang.Object> newBuilder()
Constructs a newCaffeine
instance with default settings, including strong keys, strong values, and no automatic eviction of any kind.- Returns:
- a new instance with default settings
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from
@Nonnull public static Caffeine<java.lang.Object,java.lang.Object> from(CaffeineSpec spec)
Constructs a newCaffeine
instance with the settings specified inspec
.- Parameters:
spec
- the specification to build from- Returns:
- a new instance with the specification's settings
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from
@Nonnull public static Caffeine<java.lang.Object,java.lang.Object> from(java.lang.String spec)
Constructs a newCaffeine
instance with the settings specified inspec
.- Parameters:
spec
- a String in the format specified byCaffeineSpec
- Returns:
- a new instance with the specification's settings
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initialCapacity
@Nonnull public Caffeine<K,V> initialCapacity(@Nonnegative int initialCapacity)
Sets the minimum total size for the internal data structures. Providing a large enough estimate at construction time avoids the need for expensive resizing operations later, but setting this value unnecessarily high wastes memory.- Parameters:
initialCapacity
- minimum total size for the internal data structures- Returns:
- this builder instance
- Throws:
java.lang.IllegalArgumentException
- ifinitialCapacity
is negativejava.lang.IllegalStateException
- if an initial capacity was already set
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hasInitialCapacity
boolean hasInitialCapacity()
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getInitialCapacity
int getInitialCapacity()
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executor
@Nonnull public Caffeine<K,V> executor(@Nonnull java.util.concurrent.Executor executor)
Specifies the executor to use when running asynchronous tasks. The executor is delegated to when sending removal notifications, when asynchronous computations are performed byAsyncLoadingCache
orLoadingCache.refresh(K)
orrefreshAfterWrite(long, java.util.concurrent.TimeUnit)
, or when performing periodic maintenance. By default,ForkJoinPool.commonPool()
is used.The primary intent of this method is to facilitate testing of caches which have been configured with
removalListener
or utilize asynchronous computations. A test may instead prefer to configure the cache to execute tasks directly on the same thread.Beware that configuring a cache with an executor that throws
RejectedExecutionException
may experience non-deterministic behavior.- Parameters:
executor
- the executor to use for asynchronous execution- Returns:
- this builder instance
- Throws:
java.lang.NullPointerException
- if the specified executor is null
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getExecutor
@Nonnull java.util.concurrent.Executor getExecutor()
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maximumSize
@Nonnull public Caffeine<K,V> maximumSize(@Nonnegative long maximumSize)
Specifies the maximum number of entries the cache may contain. Note that the cache may evict an entry before this limit is exceeded or temporarily exceed the threshold while evicting. As the cache size grows close to the maximum, the cache evicts entries that are less likely to be used again. For example, the cache may evict an entry because it hasn't been used recently or very often.When
size
is zero, elements will be evicted immediately after being loaded into the cache. This can be useful in testing, or to disable caching temporarily without a code change.This feature cannot be used in conjunction with
maximumWeight
.- Parameters:
maximumSize
- the maximum size of the cache- Returns:
- this builder instance
- Throws:
java.lang.IllegalArgumentException
- ifsize
is negativejava.lang.IllegalStateException
- if a maximum size or weight was already set
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maximumWeight
@Nonnull public Caffeine<K,V> maximumWeight(@Nonnegative long maximumWeight)
Specifies the maximum weight of entries the cache may contain. Weight is determined using theWeigher
specified withweigher
, and use of this method requires a corresponding call toweigher
prior to callingbuild()
.Note that the cache may evict an entry before this limit is exceeded or temporarily exceed the threshold while evicting. As the cache size grows close to the maximum, the cache evicts entries that are less likely to be used again. For example, the cache may evict an entry because it hasn't been used recently or very often.
When
maximumWeight
is zero, elements will be evicted immediately after being loaded into cache. This can be useful in testing, or to disable caching temporarily without a code change.Note that weight is only used to determine whether the cache is over capacity; it has no effect on selecting which entry should be evicted next.
This feature cannot be used in conjunction with
maximumSize
.- Parameters:
maximumWeight
- the maximum total weight of entries the cache may contain- Returns:
- this builder instance
- Throws:
java.lang.IllegalArgumentException
- ifmaximumWeight
is negativejava.lang.IllegalStateException
- if a maximum weight or size was already set
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weigher
@Nonnull public <K1 extends K,V1 extends V> Caffeine<K1,V1> weigher(@Nonnull Weigher<? super K1,? super V1> weigher)
Specifies the weigher to use in determining the weight of entries. Entry weight is taken into consideration bymaximumWeight(long)
when determining which entries to evict, and use of this method requires a corresponding call tomaximumWeight(long)
prior to callingbuild()
. Weights are measured and recorded when entries are inserted into the cache, and are thus effectively static during the lifetime of a cache entry.When the weight of an entry is zero it will not be considered for size-based eviction (though it still may be evicted by other means).
Important note: Instead of returning this as a
Caffeine
instance, this method returnsCaffeine<K1, V1>
. From this point on, either the original reference or the returned reference may be used to complete configuration and build the cache, but only the "generic" one is type-safe. That is, it will properly prevent you from building caches whose key or value types are incompatible with the types accepted by the weigher already provided; theCaffeine
type cannot do this. For best results, simply use the standard method-chaining idiom, as illustrated in the documentation at top, configuring aCaffeine
and building yourCache
all in a single statement.Warning: if you ignore the above advice, and use this
Caffeine
to build a cache whose key or value type is incompatible with the weigher, you will likely experience aClassCastException
at some undefined point in the future.- Type Parameters:
K1
- key type of the weigherV1
- value type of the weigher- Parameters:
weigher
- the weigher to use in calculating the weight of cache entries- Returns:
- the cache builder reference that should be used instead of
this
for any remaining configuration and cache building - Throws:
java.lang.IllegalArgumentException
- ifsize
is negativejava.lang.IllegalStateException
- if a maximum size was already set
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evicts
boolean evicts()
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isWeighted
boolean isWeighted()
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getMaximum
@Nonnegative long getMaximum()
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weakKeys
@Nonnull public Caffeine<K,V> weakKeys()
Specifies that each key (not value) stored in the cache should be wrapped in aWeakReference
(by default, strong references are used).Warning: when this method is used, the resulting cache will use identity (
==
) comparison to determine equality of keys.Entries with keys that have been garbage collected may be counted in
Cache.estimatedSize()
, but will never be visible to read or write operations; such entries are cleaned up as part of the routine maintenance described in the class javadoc.This feature cannot be used in conjunction with
writer
.- Returns:
- this builder instance
- Throws:
java.lang.IllegalStateException
- if the key strength was already set or the writer was set
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isStrongKeys
boolean isStrongKeys()
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isWeakKeys
boolean isWeakKeys()
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weakValues
@Nonnull public Caffeine<K,V> weakValues()
Specifies that each value (not key) stored in the cache should be wrapped in aWeakReference
(by default, strong references are used).Weak values will be garbage collected once they are weakly reachable. This makes them a poor candidate for caching; consider
softValues()
instead.Note: when this method is used, the resulting cache will use identity (
==
) comparison to determine equality of values.Entries with values that have been garbage collected may be counted in
Cache.estimatedSize()
, but will never be visible to read or write operations; such entries are cleaned up as part of the routine maintenance described in the class javadoc.This feature cannot be used in conjunction with
buildAsync(com.github.benmanes.caffeine.cache.CacheLoader<? super K1, V1>)
.- Returns:
- this builder instance
- Throws:
java.lang.IllegalStateException
- if the value strength was already set
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isStrongValues
boolean isStrongValues()
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isWeakValues
boolean isWeakValues()
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isSoftValues
boolean isSoftValues()
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softValues
@Nonnull public Caffeine<K,V> softValues()
Specifies that each value (not key) stored in the cache should be wrapped in aSoftReference
(by default, strong references are used). Softly-referenced objects will be garbage-collected in a globally least-recently-used manner, in response to memory demand.Warning: in most circumstances it is better to set a per-cache maximum size instead of using soft references. You should only use this method if you are very familiar with the practical consequences of soft references.
Note: when this method is used, the resulting cache will use identity (
==
) comparison to determine equality of values.Entries with values that have been garbage collected may be counted in
Cache.estimatedSize()
, but will never be visible to read or write operations; such entries are cleaned up as part of the routine maintenance described in the class javadoc.This feature cannot be used in conjunction with
buildAsync(com.github.benmanes.caffeine.cache.CacheLoader<? super K1, V1>)
.- Returns:
- this builder instance
- Throws:
java.lang.IllegalStateException
- if the value strength was already set
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expireAfterWrite
@Nonnull public Caffeine<K,V> expireAfterWrite(@Nonnegative long duration, @Nonnull java.util.concurrent.TimeUnit unit)
Specifies that each entry should be automatically removed from the cache once a fixed duration has elapsed after the entry's creation, or the most recent replacement of its value.Expired entries may be counted in
Cache.estimatedSize()
, but will never be visible to read or write operations. Expired entries are cleaned up as part of the routine maintenance described in the class javadoc.- Parameters:
duration
- the length of time after an entry is created that it should be automatically removedunit
- the unit thatduration
is expressed in- Returns:
- this builder instance
- Throws:
java.lang.IllegalArgumentException
- ifduration
is negativejava.lang.IllegalStateException
- if the time to live or time to idle was already set
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getExpiresAfterWriteNanos
@Nonnegative long getExpiresAfterWriteNanos()
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expiresAfterWrite
boolean expiresAfterWrite()
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expireAfterAccess
@Nonnull public Caffeine<K,V> expireAfterAccess(@Nonnegative long duration, @Nonnull java.util.concurrent.TimeUnit unit)
Specifies that each entry should be automatically removed from the cache once a fixed duration has elapsed after the entry's creation, the most recent replacement of its value, or its last read. Access time is reset by all cache read and write operations (includingCache.asMap().get(Object)
andCache.asMap().put(K, V)
), but not by operations on the collection-views ofCache.asMap()
.Expired entries may be counted in
Cache.estimatedSize()
, but will never be visible to read or write operations. Expired entries are cleaned up as part of the routine maintenance described in the class javadoc.- Parameters:
duration
- the length of time after an entry is last accessed that it should be automatically removedunit
- the unit thatduration
is expressed in- Returns:
- this builder instance
- Throws:
java.lang.IllegalArgumentException
- ifduration
is negativejava.lang.IllegalStateException
- if the time to idle or time to live was already set
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getExpiresAfterAccessNanos
@Nonnegative long getExpiresAfterAccessNanos()
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expiresAfterAccess
boolean expiresAfterAccess()
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refreshAfterWrite
@Nonnull public Caffeine<K,V> refreshAfterWrite(@Nonnegative long duration, @Nonnull java.util.concurrent.TimeUnit unit)
Specifies that active entries are eligible for automatic refresh once a fixed duration has elapsed after the entry's creation, or the most recent replacement of its value. The semantics of refreshes are specified inLoadingCache.refresh(K)
, and are performed by callingCacheLoader.reload(K, V)
.Automatic refreshes are performed when the first stale request for an entry occurs. The request triggering refresh will make an asynchronous call to
CacheLoader.reload(K, V)
and immediately return the old value.Note: all exceptions thrown during refresh will be logged and then swallowed.
- Parameters:
duration
- the length of time after an entry is created that it should be considered stale, and thus eligible for refreshunit
- the unit thatduration
is expressed in- Returns:
- this builder instance
- Throws:
java.lang.IllegalArgumentException
- ifduration
is negativejava.lang.IllegalStateException
- if the refresh interval was already set
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getRefreshAfterWriteNanos
@Nonnegative long getRefreshAfterWriteNanos()
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refreshes
boolean refreshes()
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ticker
@Nonnull public Caffeine<K,V> ticker(@Nonnull Ticker ticker)
Specifies a nanosecond-precision time source for use in determining when entries should be expired or refreshed. By default,System.nanoTime()
is used.The primary intent of this method is to facilitate testing of caches which have been configured with
expireAfterWrite(long, java.util.concurrent.TimeUnit)
,expireAfterAccess(long, java.util.concurrent.TimeUnit)
, orrefreshAfterWrite(long, java.util.concurrent.TimeUnit)
.- Parameters:
ticker
- a nanosecond-precision time source- Returns:
- this builder instance
- Throws:
java.lang.IllegalStateException
- if a ticker was already setjava.lang.NullPointerException
- if the specified ticker is null
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getTicker
@Nonnull Ticker getTicker()
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removalListener
@Nonnull public <K1 extends K,V1 extends V> Caffeine<K1,V1> removalListener(@Nonnull RemovalListener<? super K1,? super V1> removalListener)
Specifies a listener instance that caches should notify each time an entry is removed for any reason. Each cache created by this builder will invoke this listener as part of the routine maintenance described in the class documentation above.Warning: after invoking this method, do not continue to use this cache builder reference; instead use the reference this method returns. At runtime, these point to the same instance, but only the returned reference has the correct generic type information so as to ensure type safety. For best results, use the standard method-chaining idiom illustrated in the class documentation above, configuring a builder and building your cache in a single statement. Failure to heed this advice can result in a
ClassCastException
being thrown by a cache operation at some undefined point in the future.Warning: any exception thrown by
listener
will not be propagated to theCache
user, only logged via aLogger
.- Type Parameters:
K1
- the key type of the listenerV1
- the value type of the listener- Parameters:
removalListener
- a listener instance that caches should notify each time an entry is removed- Returns:
- the cache builder reference that should be used instead of
this
for any remaining configuration and cache building - Throws:
java.lang.IllegalStateException
- if a removal listener was already setjava.lang.NullPointerException
- if the specified removal listener is null
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getRemovalListener
<K1 extends K,V1 extends V> RemovalListener<K1,V1> getRemovalListener(boolean async)
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writer
@Nonnull public <K1 extends K,V1 extends V> Caffeine<K1,V1> writer(@Nonnull CacheWriter<? super K1,? super V1> writer)
Specifies a writer instance that caches should notify each time an entry is explicitly created or modified, or removed for any reason. The writer is not notified when an entry is loaded or computed. Each cache created by this builder will invoke this writer as part of the atomic operation that modifies the cache.Warning: after invoking this method, do not continue to use this cache builder reference; instead use the reference this method returns. At runtime, these point to the same instance, but only the returned reference has the correct generic type information so as to ensure type safety. For best results, use the standard method-chaining idiom illustrated in the class documentation above, configuring a builder and building your cache in a single statement. Failure to heed this advice can result in a
ClassCastException
being thrown by a cache operation at some undefined point in the future.Warning: any exception thrown by
writer
will be propagated to theCache
user.This feature cannot be used in conjunction with
weakKeys()
orbuildAsync(com.github.benmanes.caffeine.cache.CacheLoader<? super K1, V1>)
.- Type Parameters:
K1
- the key type of the writerV1
- the value type of the writer- Parameters:
writer
- a writer instance that caches should notify each time an entry is explicitly created or modified, or removed for any reason- Returns:
- the cache builder reference that should be used instead of
this
for any remaining configuration and cache building - Throws:
java.lang.IllegalStateException
- if a writer was already set or if the key strength is weakjava.lang.NullPointerException
- if the specified writer is null
-
getCacheWriter
<K1 extends K,V1 extends V> CacheWriter<K1,V1> getCacheWriter()
-
recordStats
@Nonnull public Caffeine<K,V> recordStats()
Enables the accumulation ofCacheStats
during the operation of the cache. Without thisCache.stats()
will return zero for all statistics. Note that recording statistics requires bookkeeping to be performed with each operation, and thus imposes a performance penalty on cache operation.- Returns:
- this builder instance
-
recordStats
@Nonnull public Caffeine<K,V> recordStats(@Nonnull java.util.function.Supplier<? extends StatsCounter> statsCounterSupplier)
Enables the accumulation ofCacheStats
during the operation of the cache. Without thisCache.stats()
will return zero for all statistics. Note that recording statistics requires bookkeeping to be performed with each operation, and thus imposes a performance penalty on cache operation. Any exception thrown by the suppliedStatsCounter
will be suppressed and logged.- Parameters:
statsCounterSupplier
- a supplier instance that returns a newStatsCounter
- Returns:
- this builder instance
-
isRecordingStats
boolean isRecordingStats()
-
getStatsCounterSupplier
@Nonnull java.util.function.Supplier<? extends StatsCounter> getStatsCounterSupplier()
-
isBounded
boolean isBounded()
-
build
@Nonnull public <K1 extends K,V1 extends V> Cache<K1,V1> build()
Builds a cache which does not automatically load values when keys are requested.Consider
build(CacheLoader)
instead, if it is feasible to implement aCacheLoader
.This method does not alter the state of this
Caffeine
instance, so it can be invoked again to create multiple independent caches.- Type Parameters:
K1
- the key type of the cacheV1
- the value type of the cache- Returns:
- a cache having the requested features
-
build
@Nonnull public <K1 extends K,V1 extends V> LoadingCache<K1,V1> build(@Nonnull CacheLoader<? super K1,V1> loader)
Builds a cache, which either returns an already-loaded value for a given key or atomically computes or retrieves it using the suppliedCacheLoader
. If another thread is currently loading the value for this key, simply waits for that thread to finish and returns its loaded value. Note that multiple threads can concurrently load values for distinct keys.This method does not alter the state of this
Caffeine
instance, so it can be invoked again to create multiple independent caches.- Type Parameters:
K1
- the key type of the loaderV1
- the value type of the loader- Parameters:
loader
- the cache loader used to obtain new values- Returns:
- a cache having the requested features
- Throws:
java.lang.NullPointerException
- if the specified cache loader is null
-
buildAsync
@Nonnull public <K1 extends K,V1 extends V> AsyncLoadingCache<K1,V1> buildAsync(@Nonnull CacheLoader<? super K1,V1> loader)
Builds a cache, which either returns aCompletableFuture
already loaded or currently computing the value for a given key, or atomically computes the value asynchronously through a supplied mapping function or the suppliedCacheLoader
. If the asynchronous computation fails or computes anull
value then the entry will be automatically removed. Note that multiple threads can concurrently load values for distinct keys.This method does not alter the state of this
Caffeine
instance, so it can be invoked again to create multiple independent caches.- Type Parameters:
K1
- the key type of the loaderV1
- the value type of the loader- Parameters:
loader
- the cache loader used to obtain new values- Returns:
- a cache having the requested features
- Throws:
java.lang.IllegalStateException
- if the value strength is weak or softjava.lang.NullPointerException
- if the specified cache loader is null
-
buildAsync
@Nonnull public <K1 extends K,V1 extends V> AsyncLoadingCache<K1,V1> buildAsync(@Nonnull AsyncCacheLoader<? super K1,V1> loader)
Builds a cache, which either returns aCompletableFuture
already loaded or currently computing the value for a given key, or atomically computes the value asynchronously through a supplied mapping function or the suppliedAsyncCacheLoader
. If the asynchronous computation fails or computes anull
value then the entry will be automatically removed. Note that multiple threads can concurrently load values for distinct keys.This method does not alter the state of this
Caffeine
instance, so it can be invoked again to create multiple independent caches.- Type Parameters:
K1
- the key type of the loaderV1
- the value type of the loader- Parameters:
loader
- the cache loader used to obtain new values- Returns:
- a cache having the requested features
- Throws:
java.lang.IllegalStateException
- if the value strength is weak or softjava.lang.NullPointerException
- if the specified cache loader is null
-
requireNonLoadingCache
void requireNonLoadingCache()
-
requireWeightWithWeigher
void requireWeightWithWeigher()
-
toString
public java.lang.String toString()
Returns a string representation for this Caffeine instance. The exact form of the returned string is not specified.- Overrides:
toString
in classjava.lang.Object
-
-