* 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>

 * 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

    // 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

 * test with reference to the same "lock-like object", and then their interactions with that object
 * are choreographed via the various methods on this class.
 *
 * <p>A "lock-like object" is really any object that may be used for concurrency control. If the
 * {@link #callAndAssertBlocks} method is ever called in a test, the lock-like object must have a

      }
    }
  }

  /**
   * Invokes {@code lock.}{@link Lock#tryLock(long, TimeUnit) tryLock(timeout, unit)}
   * uninterruptibly.
   *
   * @since 30.0
   */
  @J2ktIncompatible
  @GwtIncompatible // concurrency
  @SuppressWarnings("GoodTime") // should accept a java.time.Duration
  public static boolean tryLockUninterruptibly(Lock lock, long timeout, TimeUnit unit) {
    boolean interrupted = false;

     * by concurrently running mojo executions. To prevent race conditions, an aggregating execution will block
     * all other executions until finished.
     * We also lock on a given project to forbid a forked lifecycle to be executed concurrently with the project.
     * TODO: ideally, the builder should take care of the ordering in a smarter way

    valueRef.clear();
    assertNotSame(value, map.get(key, loader));
    assertEquals(1, loader.getCount());
    assertEquals(1, segment.count);
  }

  @AndroidIncompatible // Perhaps emulator clock does not update between the two get() calls?
  public void testComputeExpiredEntry() throws ExecutionException {
    CacheBuilder<Object, Object> builder =
        createCacheBuilder().expireAfterWrite(1, TimeUnit.NANOSECONDS);

    valueRef.clear();
    assertNotSame(value, map.get(key, loader));
    assertEquals(1, loader.getCount());
    assertEquals(1, segment.count);
  }

  @AndroidIncompatible // Perhaps emulator clock does not update between the two get() calls?
  public void testComputeExpiredEntry() throws ExecutionException {
    CacheBuilder<Object, Object> builder =
        createCacheBuilder().expireAfterWrite(1, TimeUnit.NANOSECONDS);

    final Lock lock;

    LockingThread(Lock lock) {
      this.lock = lock;
    }

    @Override
    public void run() {
      lock.lock();
      try {
        locked.countDown();
        finishLatch.await(1, TimeUnit.MINUTES);
      } catch (InterruptedException e) {
        fail(e.toString());
      } finally {
        lock.unlock();
      }
    }