checkMessage(expected, "LockC -> LockA", "LockB -> LockC", "LockA -> LockB");
  }

  public void testReentrancy_noDeadlock() {
    lockA.lock();
    lockB.lock();
    lockA.lock(); // Should not assert on lockB -> reentrant(lockA)
  }

  public void testExplicitOrdering_noViolations() {
    lock1.lock();
    lock3.lock();
    lock3.unlock();
    lock2.lock();
    lock3.lock();
  }

    checkMessage(expected, "LockC -> LockA", "LockB -> LockC", "LockA -> LockB");
  }

  public void testReentrancy_noDeadlock() {
    lockA.lock();
    lockB.lock();
    lockA.lock(); // Should not assert on lockB -> reentrant(lockA)
  }

  public void testExplicitOrdering_noViolations() {
    lock1.lock();
    lock3.lock();
    lock3.unlock();
    lock2.lock();
    lock3.lock();
  }

 * method equivalent to {@link
 * java.util.concurrent.locks.ReentrantLock#hasWaiters(java.util.concurrent.locks.Condition)},
 * except that the method parameter must accept whatever condition-like object is passed into {@code
 * callAndAssertWaits} by the test.
 *
 * @param <L> the type of the lock-like object to be used
 * @author Justin T. Sampson
 */

 * method equivalent to {@link
 * java.util.concurrent.locks.ReentrantLock#hasWaiters(java.util.concurrent.locks.Condition)},
 * except that the method parameter must accept whatever condition-like object is passed into {@code
 * callAndAssertWaits} by the test.
 *
 * @param <L> the type of the lock-like object to be used
 * @author Justin T. Sampson
 */

  @IgnoreJRERequirement // Users will use this only if they're already using Duration.
  public static boolean tryLockUninterruptibly(Lock lock, Duration timeout) {
    return tryLockUninterruptibly(lock, toNanosSaturated(timeout), TimeUnit.NANOSECONDS);
  }

  /**
   * Invokes {@code lock.}{@link Lock#tryLock(long, TimeUnit) tryLock(timeout, unit)}
   * uninterruptibly.
   *
   * @since 30.0
   */
  @J2ktIncompatible

     * always under a lock.
     */
    private static final class SupplantableFuture implements Cancellable {
      private final ReentrantLock lock;

      @GuardedBy("lock")
      private Future<@Nullable Void> currentFuture;

      SupplantableFuture(ReentrantLock lock, Future<@Nullable Void> currentFuture) {
        this.lock = lock;
        this.currentFuture = currentFuture;
      }

import com.google.common.annotations.VisibleForTesting;
import com.google.j2objc.annotations.ReflectionSupport;
import java.util.concurrent.atomic.AtomicReference;
import java.util.concurrent.locks.AbstractOwnableSynchronizer;
import java.util.concurrent.locks.LockSupport;
import javax.annotation.CheckForNull;
import org.checkerframework.checker.nullness.qual.Nullable;

@GwtCompatible(emulated = true)

import java.util.concurrent.ExecutionException;
import java.util.concurrent.Executor;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;
import java.util.concurrent.locks.AbstractQueuedSynchronizer;
import org.checkerframework.checker.nullness.qual.Nullable;

/** Utilities for the AbstractFutureBenchmarks */
final class AbstractFutureBenchmarks {
  private AbstractFutureBenchmarks() {}

import com.google.common.annotations.VisibleForTesting;
import com.google.j2objc.annotations.ReflectionSupport;
import java.util.concurrent.atomic.AtomicReference;
import java.util.concurrent.locks.AbstractOwnableSynchronizer;
import java.util.concurrent.locks.LockSupport;
import javax.annotation.CheckForNull;
import org.checkerframework.checker.nullness.qual.Nullable;

@GwtCompatible(emulated = true)

   */
  @GuardedBy("lock")
  private int runningTasks = 0;

  @GuardedBy("lock")
  private boolean shutdown = false;

  @Override
  public void execute(Runnable command) {
    startTask();
    try {
      command.run();
    } finally {
      endTask();
    }
  }

  @Override
  public boolean isShutdown() {
    synchronized (lock) {
      return shutdown;
    }
  }