}

	compactors[key].refs++

	return func() {
		compactorsMu.Lock()
		defer compactorsMu.Unlock()

		compactor := compactors[key]
		compactor.refs--
		if compactor.refs == 0 {
			compactor.cancel()
			compactor.client.Close()
			delete(compactors, key)
		}
	}, nil
}

 * the JDK.
 *
 * @since 21.0
 * @author Louis Wasserman
 */
@GwtCompatible
@ElementTypesAreNonnullByDefault
public final class Comparators {
  private Comparators() {}

  /**
   * Returns a new comparator which sorts iterables by comparing corresponding elements pairwise
   * until a nonzero result is found; imposes "dictionary order." If the end of one iterable is

 * the JDK.
 *
 * @since 21.0
 * @author Louis Wasserman
 */
@GwtCompatible
@ElementTypesAreNonnullByDefault
public final class Comparators {
  private Comparators() {}

  /**
   * Returns a new comparator which sorts iterables by comparing corresponding elements pairwise
   * until a nonzero result is found; imposes "dictionary order." If the end of one iterable is

   * to {@code reduce}).
   *
   * @param comparators the comparators to try in order
   */
  @GwtCompatible(serializable = true)
  public static <T extends @Nullable Object> Ordering<T> compound(
      Iterable<? extends Comparator<? super T>> comparators) {
    return new CompoundOrdering<>(comparators);
  }

  /**

import javax.annotation.CheckForNull;

/**
 * Implementation of {@code Table} whose row keys and column keys are ordered by their natural
 * ordering or by supplied comparators. When constructing a {@code TreeBasedTable}, you may provide
 * comparators for the row keys and the column keys, or you may use natural ordering for both.
 *
 * <p>The {@link #rowKeySet} method returns a {@link SortedSet} and the {@link #rowMap} method

   * to {@code reduce}).
   *
   * @param comparators the comparators to try in order
   */
  @GwtCompatible(serializable = true)
  public static <T extends @Nullable Object> Ordering<T> compound(
      Iterable<? extends Comparator<? super T>> comparators) {
    return new CompoundOrdering<>(comparators);
  }

  /**

import javax.annotation.CheckForNull;

/**
 * Implementation of {@code Table} whose row keys and column keys are ordered by their natural
 * ordering or by supplied comparators. When constructing a {@code TreeBasedTable}, you may provide
 * comparators for the row keys and the column keys, or you may use natural ordering for both.
 *
 * <p>The {@link #rowKeySet} method returns a {@link SortedSet} and the {@link #rowMap} method

 * create the {@code TopKSelector} instance.
 *
 * <p>If your input data is available as a {@link Stream}, prefer passing {@link
 * Comparators#least(int)} to {@link Stream#collect(java.util.stream.Collector)}. If it is available
 * as an {@link Iterable} or {@link Iterator}, prefer {@link Ordering#leastOf(Iterable, int)}.
 *

  private static final Comparator<Double> VALUE_COMPARATOR =
      Ordering.<Double>natural().reverse().nullsFirst();

  /**
   * Test that creating one TreeMultimap from another does not copy the comparators from the source
   * TreeMultimap.
   */
  public void testCreateFromTreeMultimap() {
    Multimap<Double, Double> tree = TreeMultimap.create(KEY_COMPARATOR, VALUE_COMPARATOR);
    tree.put(1.0, 2.0);

   * Table#cellSet()} iteration order. However, if {@link #orderRowsBy} or {@link #orderColumnsBy}
   * is called, the views are sorted by the supplied comparators.
   *
   * <p>For empty or single-cell immutable tables, {@link #of()} and {@link #of(Object, Object,
   * Object)} are even more convenient.
   *