* {@link Multiset#entrySet()}, as do many methods acting on the set returned by {@link
 * #elementSet()}. Override those methods for better performance.
 *
 * @author Louis Wasserman
 */
@GwtCompatible(emulated = true)
@ElementTypesAreNonnullByDefault
abstract class AbstractSortedMultiset<E extends @Nullable Object> extends AbstractMultiset<E>

 *
 * <p>In order to allow proper garbage collection of unused locks, the edges of the lock graph are
 * weak references.
 *
 * <p><strong>Performance</strong>
 *
 * <p>The extra bookkeeping done by cycle detecting locks comes at some cost to performance.
 * Benchmarks (as of December 2011) show that:
 *
 * <ul>
 *   <li>for an unnested {@code lock()} and {@code unlock()}, a cycle detecting lock takes 38ns as

    long result = 0;
    // Due to the way we shift, we can stop iterating once we've run out of data, the rest
    // of the result already being filled with zeros.

    // This loop is critical to performance, so please check HashBenchmark if altering it.
    int limit = Math.min(length, 8);
    for (int i = 0; i < limit; i++) {
      // Shift value left while iterating logically through the array.

    } catch (ClassCastException e) {
      return false;
    }
  }

  @Override
  public boolean containsAll(Collection<?> targets) {
    // TODO(jlevy): For optimal performance, use a binary search when
    // targets.size() < size() / log(size())
    // TODO(kevinb): see if we can share code with OrderedIterator after it
    // graduates from labs.
    if (targets instanceof Multiset) {

 *
 * <p>The core interface used to represent caches is {@link Cache}. In-memory caches can be
 * configured and created using {@link CacheBuilder}, with cache entries being loaded by {@link
 * CacheLoader}. Statistics about cache performance are exposed using {@link CacheStats}.
 *
 * <p>See the Guava User Guide article on <a
 * href="https://github.com/google/guava/wiki/CachesExplained">caches</a>.
 *

 *
 * <p>The core interface used to represent caches is {@link Cache}. In-memory caches can be
 * configured and created using {@link CacheBuilder}, with cache entries being loaded by {@link
 * CacheLoader}. Statistics about cache performance are exposed using {@link CacheStats}.
 *
 * <p>See the Guava User Guide article on <a
 * href="https://github.com/google/guava/wiki/CachesExplained">caches</a>.
 *

 * <p>This class is intended as a replacement for {@link ReentrantLock}. Code using {@code Monitor}
 * is less error-prone and more readable than code using {@code ReentrantLock}, without significant
 * performance loss. {@code Monitor} even has the potential for performance gain by optimizing the
 * evaluation and signaling of conditions. Signaling is entirely <a
 * href="http://en.wikipedia.org/wiki/Monitor_(synchronization)#Implicit_signaling">implicit</a>. By

        return new DistinctKeyIterator();
      }

      @Override
      public boolean contains(@CheckForNull Object key) { // for performance
        return containsKey(key);
      }

      @Override
      public boolean remove(@CheckForNull Object o) { // for performance
        return !LinkedListMultimap.this.removeAll(o).isEmpty();
      }
    }
    return new KeySetImpl();
  }

  @Override

  /*
   * TODO(cpovirk): if we start to override indexOf/lastIndexOf under GWT, we'll want some way to
   * override subList to return an ImmutableSortedAsList for better performance. Right now, I'm not
   * sure there's any performance hit from our failure to override subListUnchecked under GWT
   */
  @Override
  ImmutableList<E> subListUnchecked(int fromIndex, int toIndex) {

        }
      }
      return changed;
    }

    @CheckForNull
    WrappedCollection getAncestor() {
      return ancestor;
    }

    // The following methods are provided for better performance.

    @Override
    public boolean addAll(Collection<? extends V> collection) {
      if (collection.isEmpty()) {
        return false;
      }
      int oldSize = size(); // calls refreshIfEmpty