SettableFuture<Long> future1 = SettableFuture.create();
    SettableFuture<Long> future2 = SettableFuture.create();
    WeakReference<SettableFuture<Long>> future1Ref = new WeakReference<>(future1);
    WeakReference<SettableFuture<Long>> future2Ref = new WeakReference<>(future2);

    Callable<Long> combiner =
        () -> {
          throw new AssertionError();
        };

    SettableFuture<Long> future1 = SettableFuture.create();
    SettableFuture<Long> future2 = SettableFuture.create();
    WeakReference<SettableFuture<Long>> future1Ref = new WeakReference<>(future1);
    WeakReference<SettableFuture<Long>> future2Ref = new WeakReference<>(future2);

    Callable<Long> combiner =
        () -> {
          throw new AssertionError();
        };

              new EmptyServiceManagerWarning());
      copy = ImmutableList.of(new NoOpService());
    }
    this.state = new ServiceManagerState(copy);
    this.services = copy;
    WeakReference<ServiceManagerState> stateReference = new WeakReference<>(state);
    for (Service service : copy) {
      service.addListener(new ServiceListener(service, stateReference), directExecutor());

 *   <li>time-based expiration of entries, measured since last access or last write
 *   <li>keys automatically wrapped in {@linkplain WeakReference weak} references
 *   <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

      // TODO(cpovirk): Should we use a simpler (presumably cheaper) data structure?
      /*
       * Using weak references here could let us release exceptions earlier, but:
       *
       * 1. On Android, querying a WeakReference blocks if the GC is doing an otherwise-concurrent
       * pass.
       *
       * 2. We would probably choose to compare exceptions using == instead of equals() (for

 *   <li>time-based expiration of entries, measured since last access or last write
 *   <li>keys automatically wrapped in {@linkplain WeakReference weak} references
 *   <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

 * limitations under the License.
 */
package okhttp3.internal.connection

import java.io.IOException
import java.io.InterruptedIOException
import java.lang.ref.WeakReference
import java.net.Socket
import java.util.concurrent.CopyOnWriteArrayList
import java.util.concurrent.ExecutorService
import java.util.concurrent.RejectedExecutionException
import java.util.concurrent.TimeUnit.MILLISECONDS

    int iterations = 10;
    WeakReference<Object> ref = new WeakReference<>(null);
    int expectedComputations = 0;
    for (int i = 0; i < iterations; i++) {
      // The entry should get garbage collected and recomputed.
      Object oldValue = ref.get();
      if (oldValue == null) {
        expectedComputations++;
      }
      ref = new WeakReference<>(cache.getUnchecked(1));
      oldValue = null;

      clearReferenceQueue(queueForKeys);
    }
  }

  static final class CleanupMapTask implements Runnable {
    final WeakReference<MapMakerInternalMap<?, ?, ?, ?>> mapReference;

    public CleanupMapTask(MapMakerInternalMap<?, ?, ?, ?> map) {
      this.mapReference = new WeakReference<>(map);
    }

    @Override
    public void run() {
      MapMakerInternalMap<?, ?, ?, ?> map = mapReference.get();

    int iterations = 10;
    WeakReference<Object> ref = new WeakReference<>(null);
    int expectedComputations = 0;
    for (int i = 0; i < iterations; i++) {
      // The entry should get garbage collected and recomputed.
      Object oldValue = ref.get();
      if (oldValue == null) {
        expectedComputations++;
      }
      ref = new WeakReference<>(cache.getUnchecked(1));
      oldValue = null;