Module com.github.benmanes.caffeine
Package com.github.benmanes.caffeine.cache

Interface Policy<K,V>

Type Parameters:
K - the type of keys
V - the type of values
@NullMarked public interface Policy<K,V>
An access point for inspecting and performing low-level operations based on the cache's runtime characteristics. These operations are optional and dependent on how the cache was constructed and what abilities the implementation exposes.

  • Method Details

    • isRecordingStats

      boolean isRecordingStats()
      Returns whether the cache statistics are being accumulated.
      Returns:
      if cache statistics are being recorded

    • getIfPresentQuietly

      @Nullable V getIfPresentQuietly(K key)
      Returns the value associated with the key in this cache, or null if there is no cached value for the key. Unlike Cache.getIfPresent(Object), this method does not produce any side effects such as updating statistics, the eviction policy, resetting the expiration time, or triggering a refresh.
      Parameters:
      key - the key whose associated value is to be returned
      Returns:
      the value to which the specified key is mapped, or null if this cache contains no mapping for the key
      Throws:
      NullPointerException - if the specified key is null

    • getEntryIfPresentQuietly

      default @Nullable Policy.CacheEntry<K,V> getEntryIfPresentQuietly(K key)
      Returns the cache entry associated with the key in this cache, or null if there is no cached value for the key. Unlike Cache.getIfPresent(Object), this method does not produce any side effects such as updating statistics, the eviction policy, resetting the expiration time, or triggering a refresh.
      Parameters:
      key - the key whose associated value is to be returned
      Returns:
      the entry mapping for the specified key, or null if this cache contains no mapping for the key
      Throws:
      NullPointerException - if the specified key is null

    • refreshes

      Map<K,CompletableFuture<V>> refreshes()
      Returns an unmodifiable snapshot Map view of the in-flight refresh operations.
      Returns:
      a snapshot view of the in-flight refresh operations

    • eviction

      Optional<Policy.Eviction<K,V>> eviction()
      Returns access to perform operations based on the maximum size or maximum weight eviction policy. If the cache was not constructed with a size-based bound or the implementation does not support these operations, an empty Optional is returned.
      Returns:
      access to low-level operations for this cache if an eviction policy is used

    • expireAfterAccess

      Optional<Policy.FixedExpiration<K,V>> expireAfterAccess()
      Returns access to perform operations based on the time-to-idle expiration policy. This policy determines that an 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 access. Access time is reset by all cache read and write operations (including Cache.asMap().get(Object) and Cache.asMap().put(K, V)), but not by operations on the collection-views of Cache.asMap().

      If the cache was not constructed with access-based expiration or the implementation does not support these operations, an empty Optional is returned.

      Returns:
      access to low-level operations for this cache if a time-to-idle expiration policy is used

    • expireAfterWrite

      Optional<Policy.FixedExpiration<K,V>> expireAfterWrite()
      Returns access to perform operations based on the time-to-live expiration policy. This policy determines that an 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.

      If the cache was not constructed with write-based expiration or the implementation does not support these operations, an empty Optional is returned.

      Returns:
      access to low-level operations for this cache if a time-to-live expiration policy is used

    • expireVariably

      Optional<Policy.VarExpiration<K,V>> expireVariably()
      Returns access to perform operations based on the variable expiration policy. This policy determines that an entry should be automatically removed from the cache once a per-entry duration has elapsed.

      If the cache was not constructed with variable expiration or the implementation does not support these operations, an empty Optional is returned.

      Returns:
      access to low-level operations for this cache if a variable expiration policy is used

    • refreshAfterWrite

      Optional<Policy.FixedRefresh<K,V>> refreshAfterWrite()
      Returns access to perform operations based on the time-to-live refresh policy. This policy determines that an entry should be automatically reloaded once a fixed duration has elapsed after the entry's creation, or the most recent replacement of its value.

      If the cache was not constructed with write-based refresh or the implementation does not support these operations, an empty Optional is returned.

      Returns:
      access to low-level operations for this cache if a time-to-live refresh policy is used