/** Discards all entries in the cache. */
  void invalidateAll();

  /** Returns the approximate number of entries in this cache. */
  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.
   *

    cache.put(654, 2675);
    cache.put(2456, 56);
    cache.put(2, 15);

    cache.invalidateAll();
    assertFalse(cache.asMap().containsKey(654));
    assertFalse(cache.asMap().containsKey(2456));
    assertFalse(cache.asMap().containsKey(2));

    cache.put(654, 2675);
    cache.put(2456, 56);
    cache.put(2, 15);
    cache.put(1, 3);

    cache.invalidateAll(ImmutableSet.of(1, 2));

 * the License.
 */

package com.google.common.cache;

import static com.google.common.cache.TestingCacheLoaders.identityLoader;
import static com.google.common.cache.TestingRemovalListeners.countingRemovalListener;
import static com.google.common.cache.TestingWeighers.constantWeigher;
import static com.google.common.cache.TestingWeighers.intKeyWeigher;
import static com.google.common.cache.TestingWeighers.intValueWeigher;

    for (LoadingCache<Object, Object> cache : caches()) {
      checkEmpty(cache);
    }
  }


  public void testInvalidate_empty() {
    for (LoadingCache<Object, Object> cache : caches()) {
      cache.getUnchecked("a");
      cache.getUnchecked("b");
      cache.invalidate("a");
      cache.invalidate("b");
      cache.invalidate(0);
      checkEmpty(cache);
    }
  }

    assertFalse(cache.asMap().containsKey(two));
    assertFalse(cache.asMap().containsValue(one));

    cache.put(one, two);

    assertSame(two, cache.getIfPresent(one));
    stats = cache.stats();
    assertEquals(2, stats.missCount());
    assertEquals(0, stats.loadSuccessCount());
    assertEquals(0, stats.loadExceptionCount());
    assertEquals(1, stats.hitCount());

    assertFalse(cache.asMap().containsKey(two));
    assertFalse(cache.asMap().containsValue(one));

    cache.put(one, two);

    assertSame(two, cache.getIfPresent(one));
    stats = cache.stats();
    assertEquals(2, stats.missCount());
    assertEquals(0, stats.loadSuccessCount());
    assertEquals(0, stats.loadExceptionCount());
    assertEquals(1, stats.hitCount());

        assertTrue(cache.asMap().remove(key, value));
        assertFalse(cache.asMap().remove(key, -1));
        assertFalse(cache.asMap().containsKey(key));
      }
      checkEmpty(cache);
    }
  }


  public void testKeySet_populated() {
    for (LoadingCache<Object, Object> cache : caches()) {
      Set<Object> keys = cache.asMap().keySet();

    return Math.max(accessQueueSize(cache), writeQueueSize(cache));
  }

  static void processPendingNotifications(Cache<?, ?> cache) {
    if (hasLocalCache(cache)) {
      LocalCache<?, ?> cchm = toLocalCache(cache);
      cchm.processPendingNotifications();
    }
  }

  interface Receiver<T> {
    void accept(@Nullable T object);
  }

  /**

    LocalLoadingCache<Object, Object> cache = makeCache(builder, identityLoader());
    assertEquals(0, cache.stats().hitCount());
    assertEquals(0, cache.stats().missCount());

    Object one = new Object();
    cache.getUnchecked(one);
    assertEquals(0, cache.stats().hitCount());
    assertEquals(1, cache.stats().missCount());

    cache.getUnchecked(one);
    assertEquals(1, cache.stats().hitCount());

 * 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 {@link Cache#cleanUp}; such
 * entries may be counted in {@link Cache#size}, but will never be visible to read or write
 * operations.
 *