}

    /**
     * Get a send region from the pool or allocate a new one
     *
     * @param minSize minimum required size
     * @return memory region for sending
     * @throws IOException if allocation fails
     */
    public RdmaMemoryRegion getSendRegion(int minSize) throws IOException {
        if (minSize <= sendBufferSize) {
            RdmaMemoryRegion region = availableSendRegions.poll();

     * SetView}.
     */
    abstract int minSize();

    /**
     * Returns the {@link #minSize()} of {@code set} if it is a {@link SetView}, or the exact {@link
     * #size()} of {@code set} otherwise.
     */
    static int minSize(Set<?> set) {
      return set instanceof SetView ? ((SetView<?>) set).minSize() : set.size();
    }

    /**

  }

  /**
   * Returns a {@link SetView} with a {@link SetView#minSize()} of {@code min} and a {@link
   * SetView#maxSize()} of {@code max}.
   */
  private static SetView<Integer> setSizeRange(int min, int max) {
    checkArgument(min >= 0 && max >= min);
    SetView<Integer> set = difference(setSize(max), setSize(max - min));
    checkState(set.minSize() == min && set.maxSize() == max);
    return set;
  }

  /**

            } catch (IOException e) {
                log.warn("Failed to pre-allocate receive buffer", e);
            }
        }
    }
    
    public RdmaMemoryRegion getSendRegion(int minSize) throws IOException {
        if (minSize <= sendBufferSize) {
            RdmaMemoryRegion region = availableSendRegions.poll();
            if (region != null) {
                region.getBuffer().clear();
                return region;

            // Calculate relative timing differences
            double maxTime = Math.max(Math.max(timeStart, timeMiddle), timeEnd);
            double minTime = Math.min(Math.min(timeStart, timeMiddle), timeEnd);
            double timingRatio = (maxTime - minTime) / maxTime;

            // Timing differences should be minimal (within tolerance)
            assertTrue(timingRatio < TIMING_TOLERANCE,
                    String.format(

  @Override
  public int size() {
    return elements.length;
  }

  // We're careful to put only E instances into the array in the mainline.
  // (In the backport, we don't need this suppression, but we keep it to minimize diffs.)
  @SuppressWarnings("unchecked")
  @Override
  public UnmodifiableIterator<E> iterator() {
    return (UnmodifiableIterator<E>) Iterators.forArray(elements);
  }

  @Override

}

@AfterClass
public static void afterClass() {
    runner.close();
    runner.clean();
}
```

### Testing Best Practices

- Minimize `Thread.sleep()` - use only when absolutely necessary
- For timestamp tests: use minimal delays (50-100ms)
- Clean only test-specific indices (not `_all` unless needed)
- Use `runner.refresh()` after index operations

import java.util.concurrent.Callable;
import java.util.concurrent.ConcurrentMap;
import java.util.concurrent.ExecutionException;

/**
 * This class provides a skeletal implementation of the {@code Cache} interface to minimize the
 * effort required to implement this interface.
 *
 * <p>To implement a cache, the programmer needs only to extend this class and provide an

import java.util.concurrent.Callable;
import java.util.concurrent.ConcurrentMap;
import java.util.concurrent.ExecutionException;

/**
 * This class provides a skeletal implementation of the {@code Cache} interface to minimize the
 * effort required to implement this interface.
 *
 * <p>To implement a cache, the programmer needs only to extend this class and provide an

   *
   * <p>The corresponding root-mean-square error in {@code x} as a function of {@code y} is a
   * fraction {@code sqrt(1/(R*R) - 1)} of the population standard deviation of {@code x}. This fit
   * does not normally minimize that error: to do that, you should swap the roles of {@code x} and
   * {@code y}.
   *
   * <h3>Non-finite values</h3>
   *