// we try hard to make them robust in practice.  We could additionally try to add in a system
    // load timeout multiplier.  Or we could try to use a CPU time bound instead of wall clock time
    // bound.  But these ideas are harder to implement.  We do not try to detect or handle a
    // user-specified -XX:+DisableExplicitGC.
    //
    // TODO(user): Consider using

 * doing so does <i>not</i> give a reliable measurement of elapsed time, because wall time readings
 * are inherently approximate, routinely affected by periodic clock corrections. Because this class
 * (by default) uses {@link System#nanoTime}, it is unaffected by these changes.
 *
 * <p>Use this class instead of direct calls to {@link System#nanoTime} for two reasons:
 *
 * <ul>

beating.  Now, if you only kept on good terms with him, he'd do
almost anything you liked with the clock.  For instance, suppose
it were nine o'clock in the morning, just time to begin lessons:
you'd only have to whisper a hint to Time, and round goes the
clock in a twinkling!  Half-past one, time for dinner!'

  (`I only wish it was,' the March Hare said to itself in a
whisper.)

 * doing so does <i>not</i> give a reliable measurement of elapsed time, because wall time readings
 * are inherently approximate, routinely affected by periodic clock corrections. Because this class
 * (by default) uses {@link System#nanoTime}, it is unaffected by these changes.
 *
 * <p>Use this class instead of direct calls to {@link System#nanoTime} for two reasons:
 *
 * <ul>

    // we try hard to make them robust in practice.  We could additionally try to add in a system
    // load timeout multiplier.  Or we could try to use a CPU time bound instead of wall clock time
    // bound.  But these ideas are harder to implement.  We do not try to detect or handle a
    // user-specified -XX:+DisableExplicitGC.
    //
    // TODO(user): Consider using

    }

    static TestCondition create() {
      Lock lock = new ReentrantLock();
      Condition condition = lock.newCondition();
      return new TestCondition(lock, condition);
    }

    @Override
    public void await() throws InterruptedException {
      lock.lock();
      try {
        condition.await();
      } finally {
        lock.unlock();
      }
    }

    @Override

import java.util.Random;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;

/** A benchmark comparing the various striped implementations. */
@VmOptions({"-Xms12g", "-Xmx12g", "-d64"})
public class StripedBenchmark {
  private static final Supplier<Lock> LOCK_SUPPLIER =
      new Supplier<Lock>() {
        @Override
        public Lock get() {
          return new ReentrantLock();
        }

import java.util.Random;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;

/** A benchmark comparing the various striped implementations. */
@VmOptions({"-Xms12g", "-Xmx12g", "-d64"})
public class StripedBenchmark {
  private static final Supplier<Lock> LOCK_SUPPLIER =
      new Supplier<Lock>() {
        @Override
        public Lock get() {
          return new ReentrantLock();
        }

     * error-prone code like:
     *
     * Striped<Lock> stripedLock = Striped.lazyWeakXXX(...)'
     * Iterable<Lock> locks = stripedLock.bulkGet(keys);
     * for (Lock lock : locks) {
     *   lock.lock();
     * }
     * operation();
     * for (Lock lock : locks) {
     *   lock.unlock();
     * }
     *

     * 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;
      }