import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;
import java.util.concurrent.atomic.AtomicReferenceFieldUpdater;
import java.util.concurrent.locks.LockSupport;
import java.util.logging.Level;
import javax.annotation.CheckForNull;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * An abstract implementation of {@link ListenableFuture}, intended for advanced users only. More

    // way for it to return a false negative would be for the target value to jump around in the map
    // such that none of the subsequent iterations observed it, despite the fact that at every point
    // in time it was present somewhere int the map. This becomes increasingly unlikely as
    // CONTAINS_VALUE_RETRIES increases, though without locking it is theoretically possible.

   * the {@code call} implementation but forget to add it to the arguments of {@code
   * whenAllComplete}.
   *
   * <p>If you are looking for a method to determine whether a given {@code Future} is done, use the
   * instance method {@link Future#isDone()}.
   *
   * @throws ExecutionException if the {@code Future} failed with an exception