* never be removed.
 *
 * <p>Durations are represented by an integer, followed by one of "d", "h", "m", or "s",
 * representing days, hours, minutes, or seconds respectively. (There is currently no syntax to
 * request expiration in milliseconds, microseconds, or nanoseconds.)
 *
 * <p>Whitespace before and after commas and equal signs is ignored. Keys may not be repeated; it is

    Cache<Integer, Integer> cache =
        CacheBuilder.newBuilder()
            .expireAfterAccess(1, TimeUnit.MINUTES)
            .removalListener(listener)
            .ticker(ticker)
            .build();
    cache.put(1, 1);
    ticker.advance(10, TimeUnit.MINUTES);
    cache.invalidateAll();

    assertThat(listener.poll().getCause()).isEqualTo(RemovalCause.EXPIRED);
  }

    Cache<Integer, Integer> cache =
        CacheBuilder.newBuilder()
            .expireAfterAccess(1, TimeUnit.MINUTES)
            .removalListener(listener)
            .ticker(ticker)
            .build();
    cache.put(1, 1);
    ticker.advance(10, TimeUnit.MINUTES);
    cache.invalidateAll();

    assertThat(listener.poll().getCause()).isEqualTo(RemovalCause.EXPIRED);
  }

    CacheBuilderSpec spec = parse("expireAfterWrite=10m");
    assertEquals(TimeUnit.MINUTES, spec.writeExpirationTimeUnit);
    assertEquals(10L, spec.writeExpirationDuration);
    assertCacheBuilderEquivalence(
        CacheBuilder.newBuilder().expireAfterWrite(10L, TimeUnit.MINUTES), CacheBuilder.from(spec));
  }

  public void testParse_writeExpirationSeconds() {

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

    void waitUntilHoldingLock() throws InterruptedException {
      locked.await(1, TimeUnit.MINUTES);
    }

    void releaseLockAndFinish() throws InterruptedException {

      }
    }
  }


  @J2ktIncompatible // slow enough to cause flakiness
  @GwtIncompatible // far too slow
  public void testSqrtOfPerfectSquareAsDoubleIsPerfect() {
    // This takes just over a minute on my machine.
    for (long n = 0; n <= LongMath.FLOOR_SQRT_MAX_LONG; n++) {
      long actual = (long) Math.sqrt(n * n);
      assertTrue(actual == n);
    }
  }

    CacheBuilderSpec spec = parse("expireAfterWrite=10m");
    assertEquals(TimeUnit.MINUTES, spec.writeExpirationTimeUnit);
    assertEquals(10L, spec.writeExpirationDuration);
    assertCacheBuilderEquivalence(
        CacheBuilder.newBuilder().expireAfterWrite(10L, TimeUnit.MINUTES), CacheBuilder.from(spec));
  }

  public void testParse_writeExpirationSeconds() {

        };

    future = service.schedule(runnable, 5, TimeUnit.MINUTES);
    future.cancel(true);
    assertTrue(future.isCancelled());
    delegateFuture = (ScheduledFuture<?>) delegateQueue.element();
    assertTrue(delegateFuture.isCancelled());

    delegateQueue.clear();

    future = service.scheduleAtFixedRate(runnable, 5, 5, TimeUnit.MINUTES);
    future.cancel(true);
    assertTrue(future.isCancelled());

 *
 * <p>Usage example:
 *
 * <pre>{@code
 * LoadingCache<Key, Graph> graphs = CacheBuilder.newBuilder()
 *     .maximumSize(10000)
 *     .expireAfterWrite(10, TimeUnit.MINUTES)
 *     .removalListener(MY_LISTENER)
 *     .build(
 *         new CacheLoader<Key, Graph>() {
 *           public Graph load(Key key) throws AnyException {
 *             return createExpensiveGraph(key);

        };

    future = service.schedule(runnable, 5, TimeUnit.MINUTES);
    future.cancel(true);
    assertTrue(future.isCancelled());
    delegateFuture = (ScheduledFuture<?>) delegateQueue.element();
    assertTrue(delegateFuture.isCancelled());

    delegateQueue.clear();

    future = service.scheduleAtFixedRate(runnable, 5, 5, TimeUnit.MINUTES);
    future.cancel(true);
    assertTrue(future.isCancelled());