Caffeine cache 3.1.8 · com.github.benmanes.caffeine.cache.Cache

Method Summary

Modifier and Type	Method and Description
public ConcurrentMap<K, V>	Returns: a thread-safe view of this cache supporting all of the optional `Map` operations asMap() Returns a view of the entries stored in this cache as a thread-safe map.
public void	cleanUp() Performs any pending maintenance operations needed by the cache.
public @NonNegative long	Returns: the estimated number of mappings estimatedSize() Returns the approximate number of entries in this cache.
public @PolyNull V	Returns: the current (existing or computed) value associated with the specified key, or null if the computed value is null get(K the key with which the specified value is to be associated key, Function<? super K, ? extends @PolyNull V> the function to compute a value mappingFunction) Returns the value associated with the `key` in this cache, obtaining that value from the `mappingFunction` if necessary.
public Map<K, V>	Returns: an unmodifiable mapping of keys to values for the specified keys in this cache getAll(Iterable<? extends K> the keys whose associated values are to be returned keys, Function<? super Set<? extends K>, ? extends Map<? extends K, ? extends V>> the function to compute the values mappingFunction) Returns a map of the values associated with the `keys`, creating or retrieving those values if necessary.
public Map<K, V>	Returns: an unmodifiable mapping of keys to values for the specified keys found in this cache getAllPresent(Iterable<? extends K> the keys whose associated values are to be returned keys) Returns a map of the values associated with the `keys` in this cache.
public @Nullable V	Returns: the value to which the specified key is mapped, or `null` if this cache does not contain a mapping for the key getIfPresent(K the key whose associated value is to be returned key) Returns the value associated with the `key` in this cache, or `null` if there is no cached value for the `key`.
public void	invalidate(K the key whose mapping is to be removed from the cache key) Discards any cached value for the `key`.
public void	invalidateAll(Iterable<? extends K> the keys whose associated values are to be removed keys) Discards any cached values for the `keys`.
public void	invalidateAll() Discards all entries in the cache.
public Policy<K, V>	Returns: access to inspect and perform advanced operations based on the cache's characteristics policy() Returns access to inspect and perform low-level operations on this cache based on its runtime characteristics.
public void	put(K the key with which the specified value is to be associated key, V value to be associated with the specified key value) Associates the `value` with the `key` in this cache.
public void	putAll(Map<? extends K, ? extends V> the mappings to be stored in this cache map) Copies all of the mappings from the specified map to the cache.
public CacheStats	Returns: the current snapshot of the statistics of this cache stats() Returns a current snapshot of this cache's cumulative statistics.

Method Detail

asMap back to summary

asMap	back to summary
public ConcurrentMap<K, V> asMap() Returns a view of the entries stored in this cache as a thread-safe map. Modifications made to the map directly affect the cache. A computation operation, such as `ConcurrentMap#compute`, performs the entire method invocation atomically, so the function is applied at most once per key. Some attempted update operations by other threads may be blocked while computation is in progress. The computation must not attempt to update any other mappings of this cache. Iterators from the returned map are at least weakly consistent: they are safe for concurrent use, but if the cache is modified (including by eviction) after the iterator is created, it is undefined which of the changes (if any) will be reflected in that iterator. Returns:ConcurrentMap<K, V> a thread-safe view of this cache supporting all of the optional `Map` operations

public ConcurrentMap<K, V> asMap()

Returns a view of the entries stored in this cache as a thread-safe map. Modifications made to the map directly affect the cache.

A computation operation, such as ConcurrentMap#compute, performs the entire method invocation atomically, so the function is applied at most once per key. Some attempted update operations by other threads may be blocked while computation is in progress. The computation must not attempt to update any other mappings of this cache.

Iterators from the returned map are at least weakly consistent: they are safe for concurrent use, but if the cache is modified (including by eviction) after the iterator is created, it is undefined which of the changes (if any) will be reflected in that iterator.

Returns:ConcurrentMap<K, V>: a thread-safe view of this cache supporting all of the optional Map operations

cleanUp	back to summary
public void cleanUp() Performs any pending maintenance operations needed by the cache. Exactly which activities are performed -- if any -- is implementation-dependent.

estimatedSize back to summary

estimatedSize	back to summary
public @NonNegative long estimatedSize() Returns the approximate number of entries in this cache. The value returned is an estimate; the actual count may differ if there are concurrent insertions or removals, or if some entries are pending removal due to expiration or weak/soft reference collection. In the case of stale entries this inaccuracy can be mitigated by performing a `cleanUp()` first. Returns:@NonNegative long the estimated number of mappings

public @NonNegative long estimatedSize()

Returns the approximate number of entries in this cache. The value returned is an estimate; the actual count may differ if there are concurrent insertions or removals, or if some entries are pending removal due to expiration or weak/soft reference collection. In the case of stale entries this inaccuracy can be mitigated by performing a cleanUp() first.

Returns:@NonNegative long: the estimated number of mappings

get back to summary

get	back to summary
public @PolyNull V get(K key, Function<? super K, ? extends @PolyNull V> mappingFunction) Returns the value associated with the `key` in this cache, obtaining that value from the `mappingFunction` if necessary. This method provides a simple substitute for the conventional "if cached, return; otherwise create, cache and return" pattern. If the specified key is not already associated with a value, attempts to compute its value using the given mapping function and enters it into this cache unless `null`. The entire method invocation is performed atomically, so the function is applied at most once per key. Some attempted update operations on this cache by other threads may be blocked while the computation is in progress, so the computation should be short and simple, and must not attempt to update any other mappings of this cache. Warning as with `CacheLoader#load`, `mappingFunction` must not attempt to update any other mappings of this cache. Parameters key:K the key with which the specified value is to be associated mappingFunction:Function<? super K, ? extends @PolyNull V> the function to compute a value Returns:@PolyNull V the current (existing or computed) value associated with the specified key, or null if the computed value is null Exceptions NullPointerException: if the specified key or mappingFunction is null IllegalStateException: if the computation detectably attempts a recursive update to this cache that would otherwise never complete RuntimeException: or Error if the mappingFunction does so, in which case the mapping is left unestablished

public @PolyNull V get(K key, Function<? super K, ? extends @PolyNull V> mappingFunction)

Returns the value associated with the key in this cache, obtaining that value from the mappingFunction if necessary. This method provides a simple substitute for the conventional "if cached, return; otherwise create, cache and return" pattern.

If the specified key is not already associated with a value, attempts to compute its value using the given mapping function and enters it into this cache unless null. The entire method invocation is performed atomically, so the function is applied at most once per key. Some attempted update operations on this cache by other threads may be blocked while the computation is in progress, so the computation should be short and simple, and must not attempt to update any other mappings of this cache.

Warning

as with CacheLoader#load, mappingFunction must not attempt to update any other mappings of this cache.

Parameters

key:K: the key with which the specified value is to be associated
mappingFunction:Function<? super K, ? extends @PolyNull V>: the function to compute a value

Returns:@PolyNull V

the current (existing or computed) value associated with the specified key, or null if the computed value is null

Exceptions

NullPointerException:: if the specified key or mappingFunction is null
IllegalStateException:: if the computation detectably attempts a recursive update to this cache that would otherwise never complete
RuntimeException:: or Error if the mappingFunction does so, in which case the mapping is left unestablished

getAll back to summary

getAll	back to summary
public Map<K, V> getAll(Iterable<? extends K> keys, Function<? super Set<? extends K>, ? extends Map<? extends K, ? extends V>> mappingFunction) Returns a map of the values associated with the `keys`, creating or retrieving those values if necessary. The returned map contains entries that were already cached, combined with the newly loaded entries; it will never contain null keys or values. A single request to the `mappingFunction` is performed for all keys which are not already present in the cache. All entries returned by `mappingFunction` will be stored in the cache, over-writing any previously cached values. If another call to `get` tries to load the value for a key in `keys`, implementations may either have that thread load the entry or simply wait for this thread to finish and return the loaded value. In the case of overlapping non-blocking loads, the last load to complete will replace the existing entry. Note that multiple threads can concurrently load values for distinct keys. Any loaded values for keys that were not specifically requested will not be returned, but will be stored in the cache. Note that duplicate elements in `keys`, as determined by `Object#equals`, will be ignored. Parameters keys:Iterable<? extends K> the keys whose associated values are to be returned mappingFunction:Function<? super Set<? extends K>, ? extends Map<? extends K, ? extends V>> the function to compute the values Returns:Map<K, V> an unmodifiable mapping of keys to values for the specified keys in this cache Exceptions NullPointerException: if the specified collection is null or contains a null element, or if the map returned by the mappingFunction is null RuntimeException: or Error if the mappingFunction does so, in which case the mapping is left unestablished

public Map<K, V> getAll(Iterable<? extends K> keys, Function<? super Set<? extends K>, ? extends Map<? extends K, ? extends V>> mappingFunction)

Returns a map of the values associated with the keys, creating or retrieving those values if necessary. The returned map contains entries that were already cached, combined with the newly loaded entries; it will never contain null keys or values.

A single request to the mappingFunction is performed for all keys which are not already present in the cache. All entries returned by mappingFunction will be stored in the cache, over-writing any previously cached values. If another call to get tries to load the value for a key in keys, implementations may either have that thread load the entry or simply wait for this thread to finish and return the loaded value. In the case of overlapping non-blocking loads, the last load to complete will replace the existing entry. Note that multiple threads can concurrently load values for distinct keys. Any loaded values for keys that were not specifically requested will not be returned, but will be stored in the cache.

Note that duplicate elements in keys, as determined by Object#equals, will be ignored.

Parameters

keys:Iterable<? extends K>: the keys whose associated values are to be returned
mappingFunction:Function<? super Set<? extends K>, ? extends Map<? extends K, ? extends V>>: the function to compute the values

Returns:Map<K, V>

an unmodifiable mapping of keys to values for the specified keys in this cache

Exceptions

NullPointerException:: if the specified collection is null or contains a null element, or if the map returned by the mappingFunction is null
RuntimeException:: or Error if the mappingFunction does so, in which case the mapping is left unestablished

getAllPresent back to summary

getAllPresent	back to summary
public Map<K, V> getAllPresent(Iterable<? extends K> keys) Returns a map of the values associated with the `keys` in this cache. The returned map will only contain entries which are already present in the cache. Note that duplicate elements in `keys`, as determined by `Object#equals`, will be ignored. Parameters keys:Iterable<? extends K> the keys whose associated values are to be returned Returns:Map<K, V> an unmodifiable mapping of keys to values for the specified keys found in this cache Exceptions NullPointerException: if the specified collection is null or contains a null element

public Map<K, V> getAllPresent(Iterable<? extends K> keys)

Returns a map of the values associated with the keys in this cache. The returned map will only contain entries which are already present in the cache.

Note that duplicate elements in keys, as determined by Object#equals, will be ignored.

Parameters

keys:Iterable<? extends K>: the keys whose associated values are to be returned

Returns:Map<K, V>

an unmodifiable mapping of keys to values for the specified keys found in this cache

Exceptions

NullPointerException:: if the specified collection is null or contains a null element

getIfPresent back to summary

getIfPresent	back to summary
public @Nullable V getIfPresent(K key) Returns the value associated with the `key` in this cache, or `null` if there is no cached value for the `key`. Parameters key:K the key whose associated value is to be returned Returns:@Nullable V the value to which the specified key is mapped, or `null` if this cache does not contain a mapping for the key Exceptions NullPointerException: if the specified key is null

public @Nullable V getIfPresent(K key)

Returns the value associated with the key in this cache, or null if there is no cached value for the key.

Parameters

key:K: the key whose associated value is to be returned

Returns:@Nullable V

the value to which the specified key is mapped, or null if this cache does not contain a mapping for the key

Exceptions

NullPointerException:: if the specified key is null

invalidate back to summary

invalidate	back to summary
public void invalidate(K key) Discards any cached value for the `key`. The behavior of this operation is undefined for an entry that is being loaded (or reloaded) and is otherwise not present. Parameters key:K the key whose mapping is to be removed from the cache Exceptions NullPointerException: if the specified key is null

public void invalidate(K key)

Discards any cached value for the key. The behavior of this operation is undefined for an entry that is being loaded (or reloaded) and is otherwise not present.

Parameters

key:K: the key whose mapping is to be removed from the cache

Exceptions

NullPointerException:: if the specified key is null

invalidateAll back to summary

invalidateAll	back to summary
public void invalidateAll(Iterable<? extends K> keys) Discards any cached values for the `keys`. The behavior of this operation is undefined for an entry that is being loaded (or reloaded) and is otherwise not present. Parameters keys:Iterable<? extends K> the keys whose associated values are to be removed Exceptions NullPointerException: if the specified collection is null or contains a null element

public void invalidateAll(Iterable<? extends K> keys)

Discards any cached values for the keys. The behavior of this operation is undefined for an entry that is being loaded (or reloaded) and is otherwise not present.

Parameters

keys:Iterable<? extends K>: the keys whose associated values are to be removed

Exceptions

NullPointerException:: if the specified collection is null or contains a null element

invalidateAll	back to summary
public void invalidateAll() Discards all entries in the cache. The behavior of this operation is undefined for an entry that is being loaded (or reloaded) and is otherwise not present.

policy	back to summary
public Policy<K, V> policy() Returns access to inspect and perform low-level operations on this cache based on its runtime characteristics. These operations are optional and dependent on how the cache was constructed and what abilities the implementation exposes. Warning policy operations must not be performed from within an atomic scope of another cache operation. Returns:Policy<K, V> access to inspect and perform advanced operations based on the cache's characteristics

policy

back to summary

public Policy<K, V> policy()

Returns access to inspect and perform low-level operations on this cache based on its runtime characteristics. These operations are optional and dependent on how the cache was constructed and what abilities the implementation exposes.

Warning

policy operations must not be performed from within an atomic scope of another cache operation.

Returns:Policy<K, V>: access to inspect and perform advanced operations based on the cache's characteristics

put back to summary

put	back to summary
public void put(K key, V value) Associates the `value` with the `key` in this cache. If the cache previously contained a value associated with the `key`, the old value is replaced by the new `value`. Prefer `get(Object, Function)` when using the conventional "if cached, return; otherwise create, cache and return" pattern. Parameters key:K the key with which the specified value is to be associated value:V value to be associated with the specified key Exceptions NullPointerException: if the specified key or value is null

public void put(K key, V value)

Associates the value with the key in this cache. If the cache previously contained a value associated with the key, the old value is replaced by the new value.

Prefer get(Object, Function) when using the conventional "if cached, return; otherwise create, cache and return" pattern.

Parameters

key:K: the key with which the specified value is to be associated
value:V: value to be associated with the specified key

Exceptions

NullPointerException:: if the specified key or value is null

putAll back to summary

putAll	back to summary
public void putAll(Map<? extends K, ? extends V> map) Copies all of the mappings from the specified map to the cache. The effect of this call is equivalent to that of calling `put(k, v)` on this map once for each mapping from key `k` to value `v` in the specified map. The behavior of this operation is undefined if the specified map is modified while the operation is in progress. Parameters map:Map<? extends K, ? extends V> the mappings to be stored in this cache Exceptions NullPointerException: if the specified map is null or the specified map contains null keys or values

public void putAll(Map<? extends K, ? extends V> map)

Copies all of the mappings from the specified map to the cache. The effect of this call is equivalent to that of calling put(k, v) on this map once for each mapping from key k to value v in the specified map. The behavior of this operation is undefined if the specified map is modified while the operation is in progress.

Parameters

map:Map<? extends K, ? extends V>: the mappings to be stored in this cache

Exceptions

NullPointerException:: if the specified map is null or the specified map contains null keys or values

stats	back to summary
public CacheStats stats() Returns a current snapshot of this cache's cumulative statistics. All statistics are initialized to zero and are monotonically increasing over the lifetime of the cache. Due to the performance penalty of maintaining statistics, some implementations may not record the usage history immediately or at all. Returns:CacheStats the current snapshot of the statistics of this cache

public Interface Cache<K, V>

Method Summary

Method Detail