// 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

    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 ReentrantLock lock = this.lock;
    lock.lock();

    boolean satisfied = false;
    try {
      return satisfied = guard.isSatisfied();
    } finally {
      if (!satisfied) {
        lock.unlock();
      }
    }
  }

  /**
   * Enters this monitor if the guard is satisfied. Blocks at most the given time acquiring the
   * lock, but does not wait for the guard to be satisfied.

    }

    /*
     * This is an unsynchronized read! After the read, the function returns immediately or acquires
     * the lock to check again. Since an IDLE state was observed inside the preceding synchronized
     * block, and reference field assignment is atomic, this may save reacquiring the lock when
     * another thread or the worker task has cleared the count and set the state.
     *

    MEDIUM_DELAY_MS = SHORT_DELAY_MS * 10;
    LONG_DELAY_MS = SHORT_DELAY_MS * 200;
  }

  /**
   * Returns a timeout in milliseconds to be used in tests that verify that operations block or time
   * out.
   */
  long timeoutMillis() {
    return SHORT_DELAY_MS / 4;
  }

  /** Returns a new Date instance representing a time delayMillis milliseconds in the future. */

    // is likely to be a bug anyway.

    // N.B. All writes to the list and the next pointers must have happened before the above
    // synchronized block, so we can iterate the list without the lock held here.
    RunnableExecutorPair reversedList = null;
    while (list != null) {
      RunnableExecutorPair tmp = list;
      list = list.next;
      tmp.next = reversedList;

    }
  }

  /** A reference to a value. */
  interface ValueReference<K, V> {
    /** Returns the value. Does not block or throw exceptions. */
    @CheckForNull
    V get();

    /**
     * Waits for a value that may still be loading. Unlike get(), this method can block (in the case
     * of FutureValueReference).
     *
     * @throws ExecutionException if the loading thread throws an exception

   * needed.
   *
   * A single spinlock ("busy") is used for initializing and
   * resizing the table, as well as populating slots with new Cells.
   * There is no need for a blocking lock; when the lock is not
   * available, threads try other slots (or the base).  During these
   * retries, there is increased contention and reduced locality,
   * which is still better than alternatives.
   *