*   <li>values automatically wrapped in {@linkplain WeakReference weak} or {@linkplain
 *       SoftReference soft} references
 *   <li>notification of evicted (or otherwise removed) entries
 *   <li>accumulation of cache access statistics
 * </ul>
 *
 * <p>These features are all optional; caches can be created using all or none of them. By default,
 * cache instances created by {@code CacheBuilder} will not perform any type of eviction.
 *

        
        // Wait for all reconnections
        CompletableFuture.allOf(futures.toArray(new CompletableFuture[0])).join();
    }
}
```

## 11. Monitoring and Metrics

### 11.1 Handle Statistics
```java
public class HandleStatistics {
    private final AtomicLong handlesRequested = new AtomicLong();
    private final AtomicLong handlesGranted = new AtomicLong();

        }
        
        // Fall back to direct server query
        return directory.performDirectEnumeration();
    }
}
```

## 10. Monitoring and Metrics

### 10.1 Directory Cache Statistics
```java
public class DirectoryCacheStatistics {
    private final AtomicLong cacheHits = new AtomicLong();
    private final AtomicLong cacheMisses = new AtomicLong();

@NullUnmarked
@J2ktIncompatible
@GwtIncompatible
class StatsTesting {
  // TODO(cpovirk): Convince myself that this larger error makes sense.
  static final double ALLOWED_ERROR = isAndroid() ? .25 : 1e-10;

  // Inputs and their statistics:

  static final double ONE_VALUE = 12.34;

  static final double OTHER_ONE_VALUE = -56.78;

  static final ImmutableList<Double> TWO_VALUES = ImmutableList.of(12.34, -56.78);

@NullUnmarked
@J2ktIncompatible
@GwtIncompatible
class StatsTesting {
  // TODO(cpovirk): Convince myself that this larger error makes sense.
  static final double ALLOWED_ERROR = isAndroid() ? .25 : 1e-10;

  // Inputs and their statistics:

  static final double ONE_VALUE = 12.34;

  static final double OTHER_ONE_VALUE = -56.78;

  static final ImmutableList<Double> TWO_VALUES = ImmutableList.of(12.34, -56.78);

    }

    /**
     * Get key rotation metrics
     *
     * @return metrics map containing rotation statistics
     */
    public java.util.Map<String, Long> getKeyRotationMetrics() {
        java.util.Map<String, Long> metrics = new java.util.HashMap<>();
        metrics.put("totalRotations", totalKeyRotations.get());

    
    // Multi-channel should be faster
    assertTrue(multiChannelTime < singleChannelTime * 0.7);  // At least 30% improvement
}
```

## 8. Performance Metrics

### 8.1 Channel Statistics
```java
public class MultiChannelStatistics {
    private final Map<String, ChannelStatistics> channelStats;
    
    public class ChannelStatistics {

    private final AtomicInteger consecutiveFailures = new AtomicInteger(0);
    private final AtomicInteger consecutiveSuccesses = new AtomicInteger(0);

    // Hystrix-style windowed statistics
    private final RollingWindow rollingWindow = new RollingWindow(10, 1000); // 10 buckets, 1 second each

    /**
     * Create a circuit breaker with default settings
     *

 * described by <a
 * href="http://en.wikipedia.org/wiki/Quantile#Estimating_the_quantiles_of_a_population">
 * wikipedia</a> as providing "Linear interpolation of the modes for the order statistics for the
 * uniform distribution on [0,1]."
 *
 * <h3>Handling of non-finite values</h3>
 *
 * <p>If any values in the input are {@link Double#NaN NaN} then all values returned are {@link

    // Currently, this is going into /dev/null, but I'll fix that
    System.out.println("hit rate: " + hit / req);
  }

  // for proper distributions later:
  // import JSci.maths.statistics.ProbabilityDistribution;
  // int key = (int) dist.inverse(random.nextDouble());