assertNotNull(ArbitraryInstances.get(Ticker.class));
    assertFreshInstanceReturned(Random.class);
    assertEquals(
        ArbitraryInstances.get(Random.class).nextInt(),
        ArbitraryInstances.get(Random.class).nextInt());
  }

  public void testGet_concurrent() {
    assertTrue(ArbitraryInstances.get(BlockingDeque.class).isEmpty());
    assertTrue(ArbitraryInstances.get(BlockingQueue.class).isEmpty());

    for (int i = 0; i < reps; i++) {
      dummy += cache.getUnchecked(nextRandomKey());
    }
    requests.addAndGet(reps);
    return dummy;
  }

  private int nextRandomKey() {
    int a = random.nextInt(max);

    /*
     * For example, if concentration=2.0, the following takes the square root of
     * the uniformly-distributed random integer, then truncates any fractional

      }
      // We need to ensure that at least 4 bytes have been put into the hasher or else
      // Hasher#hash will throw an ISE.
      int intToPut = random.nextInt();
      for (Hasher hasher : sinksAndControl) {
        hasher.putInt(intToPut);
      }
      for (Sink sink : sinks) {
        HashCode unused = sink.hash();
      }

      }
      // We need to ensure that at least 4 bytes have been put into the hasher or else
      // Hasher#hash will throw an ISE.
      int intToPut = random.nextInt();
      for (Hasher hasher : sinksAndControl) {
        hasher.putInt(intToPut);
      }
      for (Sink sink : sinks) {
        HashCode unused = sink.hash();
      }

   */
  final void retryUpdate(long x, int @Nullable [] hc, boolean wasUncontended) {
    int h;
    if (hc == null) {
      threadHashCode.set(hc = new int[1]); // Initialize randomly
      int r = rng.nextInt(); // Avoid zero to allow xorShift rehash
      h = hc[0] = (r == 0) ? 1 : r;
    } else h = hc[0];
    boolean collide = false; // True if last slot nonempty
    for (; ; ) {
      Cell[] as;
      Cell a;

      assertFalse(len4.matches(c));
    }

    Random rand = new Random(1234);
    for (int testCase = 0; testCase < 100; testCase++) {
      char[] chars = randomChars(rand, rand.nextInt(63) + 1);
      CharMatcher m = SmallCharMatcher.from(bitSet(chars), new String(chars));
      checkExactMatches(m, chars);
    }
  }

  static void checkExactMatches(CharMatcher m, char[] chars) {

    final int min;
    final int max;

    ListSizeDistribution(int min, int max) {
      this.min = min;
      this.max = max;
    }

    public int chooseSize(Random random) {
      return random.nextInt(max - min + 1) + min;
    }
  }

  private BenchmarkHelpers() {}

    CacheLoader<String, String> countingIdentityLoader =
        new CacheLoader<String, String>() {
          @Override
          public String load(String key) throws InterruptedException {
            int behavior = random.nextInt(4);
            if (behavior == 0) { // throw an exception
              exceptionCount.incrementAndGet();
              throw new RuntimeException("fake exception for test");

    assertNotNull(ArbitraryInstances.get(Ticker.class));
    assertFreshInstanceReturned(Random.class);
    assertEquals(
        ArbitraryInstances.get(Random.class).nextInt(),
        ArbitraryInstances.get(Random.class).nextInt());
  }

  public void testGet_concurrent() {
    assertTrue(ArbitraryInstances.get(BlockingDeque.class).isEmpty());
    assertTrue(ArbitraryInstances.get(BlockingQueue.class).isEmpty());

    CacheLoader<String, String> countingIdentityLoader =
        new CacheLoader<String, String>() {
          @Override
          public String load(String key) throws InterruptedException {
            int behavior = random.nextInt(4);
            if (behavior == 0) { // throw an exception
              exceptionCount.incrementAndGet();
              throw new RuntimeException("fake exception for test");