* CacheLoader#reload}.
   *
   * <p>As the default implementation of {@link CacheLoader#reload} is synchronous, it is
   * recommended that users of this method override {@link CacheLoader#reload} with an asynchronous
   * implementation; otherwise refreshes will be performed during unrelated cache read and write
   * operations.
   *

   * CacheLoader#reload}.
   *
   * <p>As the default implementation of {@link CacheLoader#reload} is synchronous, it is
   * recommended that users of this method override {@link CacheLoader#reload} with an asynchronous
   * implementation; otherwise refreshes will be performed during unrelated cache read and write
   * operations.
   *

    }

    /**
     * Returns the final value of the associated {@link ClosingFuture}, or throws an exception as
     * {@link Future#get()} would.
     *
     * <p>Because the asynchronous operation has already completed, this method is synchronous and
     * returns immediately.
     *
     * @throws CancellationException if the computation was cancelled
     * @throws ExecutionException if the computation threw an exception

     * another thread or the worker task has cleared the count and set the state.
     *
     * <p>When {@link #executor} is a directExecutor(), the value written to
     * {@code workerRunningState} will be available synchronously, and behaviour will be
     * deterministic.
     */
    @SuppressWarnings("GuardedBy")
    boolean alreadyMarkedQueued = workerRunningState != QUEUING;
    if (alreadyMarkedQueued) {
      return;
    }

   * {@code delegate} has begun to reject execution, the previously submitted tasks may never run,
   * despite not throwing a RejectedExecutionException synchronously with the call to {@code
   * execute}. If this behaviour is problematic, use an Executor with a single thread (e.g. {@link
   * Executors#newSingleThreadExecutor}).
   *

import java.util.concurrent.atomic.AtomicReference;
import javax.annotation.CheckForNull;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * Serializes execution of tasks, somewhat like an "asynchronous {@code synchronized} block." Each
 * {@linkplain #submit enqueued} callable will not be submitted to its associated executor until the

 * article on <a href="https://github.com/google/guava/wiki/ListenableFutureExplained">{@code
 * ListenableFuture}</a>.
 *
 * <p>The main purpose of {@code ListenableFuture} is to help you chain together a graph of
 * asynchronous operations. You can chain them together manually with calls to methods like {@link
 * Futures#transform(ListenableFuture, Function, Executor) Futures.transform}, but you will often