Interface Policy.Expiration<K,V>

All Known Implementing Classes:
BoundedLocalCache.BoundedPolicy.BoundedExpireAfterAccess, BoundedLocalCache.BoundedPolicy.BoundedExpireAfterWrite, BoundedLocalCache.BoundedPolicy.BoundedRefreshAfterWrite
Enclosing interface:
Policy<K,V>

public static interface Policy.Expiration<K,V>
The low-level operations for a cache with a expiration policy.
  • Method Summary

    Modifier and Type
    Method
    Description
    ageOf(K key, TimeUnit unit)
    Returns the age of the entry based on the expiration policy.
    long
    Returns the fixed duration used to determine if an entry should be automatically removed due to elapsing this time bound.
    oldest(int limit)
    Returns an unmodifiable snapshot Map view of the cache with ordered traversal.
    void
    setExpiresAfter(long duration, TimeUnit unit)
    Specifies that each entry should be automatically removed from the cache once a fixed duration has elapsed based.
    youngest(int limit)
    Returns an unmodifiable snapshot Map view of the cache with ordered traversal.
  • Method Details

    • ageOf

      @Nonnull OptionalLong ageOf(@Nonnull K key, @Nonnull TimeUnit unit)
      Returns the age of the entry based on the expiration policy. The entry's age is the cache's estimate of the amount of time since the entry's expiration was last reset.

      An expiration policy uses the age to determine if an entry is fresh or stale by comparing it to the freshness lifetime. This is calculated as fresh = freshnessLifetime > age where freshnessLifetime = expires - currentTime.

      Parameters:
      key - the key for the entry being queried
      unit - the unit that age is expressed in
      Returns:
      the age if the entry is present in the cache
    • getExpiresAfter

      @Nonnegative long getExpiresAfter(@Nonnull TimeUnit unit)
      Returns the fixed duration used to determine if an entry should be automatically removed due to elapsing this time bound. An entry is considered fresh if its age is less than this duration, and stale otherwise. The expiration policy determines when the entry's age is reset.
      Parameters:
      unit - the unit that duration is expressed in
      Returns:
      the length of time after which an entry should be automatically removed
    • setExpiresAfter

      void setExpiresAfter(@Nonnegative long duration, @Nonnull TimeUnit unit)
      Specifies that each entry should be automatically removed from the cache once a fixed duration has elapsed based. The expiration policy determines when the entry's age is reset.
      Parameters:
      duration - the length of time after which an entry should be automatically removed
      unit - the unit that duration is expressed in
      Throws:
      IllegalArgumentException - if duration is negative
    • oldest

      @Nonnull Map<K,V> oldest(@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 expire (oldest) to the entries least likely to expire (youngest). This order is determined by the expiration 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 oldest entry to the youngest
    • youngest

      @Nonnull Map<K,V> youngest(@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 expire (youngest) to the entries most likely to expire (oldest). This order is determined by the expiration 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 youngest entry to the oldest