long size();

  /**
   * Returns a current snapshot of this cache's cumulative statistics, or a set of default values if
   * the cache is not recording statistics. All statistics begin at zero and never decrease over the
   * lifetime of the cache.
   *
   * <p><b>Warning:</b> this cache may not be recording statistical data. For example, a cache

   * loaded entries; it will never contain null keys or values.
   *
   * <p>Caches loaded by a {@link CacheLoader} will issue a single request to {@link
   * CacheLoader#loadAll} for all keys which are not already present in the cache. All entries
   * returned by {@link CacheLoader#loadAll} will be stored in the cache, over-writing any

    for (LoadingCache<Key, String> cache : caches()) {
      Key key = new Key(1);
      String value = key.toString();
      assertThat(cache.getUnchecked(key)).isSameInstanceAs(value);
      assertThat(cache.asMap().isEmpty()).isFalse();
      cache.invalidateAll();
      assertThat(cache.size()).isEqualTo(0);
      assertThat(cache.asMap().isEmpty()).isTrue();
      assertThat(cache.asMap().containsKey(key)).isFalse();

    for (LoadingCache<Key, String> cache : caches()) {
      Key key = new Key(1);
      String value = key.toString();
      assertThat(cache.getUnchecked(key)).isSameInstanceAs(value);
      assertThat(cache.asMap().isEmpty()).isFalse();
      cache.invalidateAll();
      assertThat(cache.size()).isEqualTo(0);
      assertThat(cache.asMap().isEmpty()).isTrue();
      assertThat(cache.asMap().containsKey(key)).isFalse();

  }

  /**
   * Accumulates statistics during the operation of a {@link Cache} for presentation by {@link
   * Cache#stats}. This is solely intended for consumption by {@code Cache} implementors.
   *
   * @since 10.0
   */
  public interface StatsCounter {
    /**
     * Records cache hits. This should be called when a cache request returns a cached value.
     *
     * @param count the number of hits to record

 - ConnectionReleased
 - CallEnd
 
## Cache directory

The cache directory must be exclusively owned by a single instance.

Deleting the cache when it is no longer needed can be done.  However this may delete the purpose of the cache
which is designed to persist between app restarts.

```kotlin
cache.delete()
```
 
## Pruning the Cache

Pruning the entire Cache to clear space temporarily can be done using evictAll.

Shinsuke Sugaya <******@****.***> 1462510149 +0900

Shinsuke Sugaya <******@****.***> 1462510149 +0900

        }

        // Since cache cannot store, getBuffer must create a new buffer of configured size
        byte[] got = impl.getBuffer();
        assertNotNull(got);
        assertEquals(8, got.length, "Allocation uses configured maximum size when cache is empty");
        assertNotSame(supplied, got, "Zero-sized cache must not return the released instance");
    }

  }

  /**
   * Accumulates statistics during the operation of a {@link Cache} for presentation by {@link
   * Cache#stats}. This is solely intended for consumption by {@code Cache} implementors.
   *
   * @since 10.0
   */
  public interface StatsCounter {
    /**
     * Records cache hits. This should be called when a cache request returns a cached value.
     *
     * @param count the number of hits to record