import static com.google.common.base.Preconditions.checkNotNull;
import static com.google.common.base.Preconditions.checkState;
import static com.google.common.util.concurrent.AggregateFuture.ReleaseResourcesReason.ALL_INPUT_FUTURES_PROCESSED;
import static com.google.common.util.concurrent.AggregateFuture.ReleaseResourcesReason.OUTPUT_FUTURE_DONE;
import static com.google.common.util.concurrent.Futures.getDone;

 * the License.
 */

package com.google.common.util.concurrent;

import static com.google.common.base.Preconditions.checkNotNull;
import static com.google.common.util.concurrent.AggregateFuture.ReleaseResourcesReason.OUTPUT_FUTURE_DONE;

import com.google.common.annotations.GwtCompatible;
import com.google.common.collect.ImmutableCollection;
import com.google.errorprone.annotations.concurrent.LazyInit;

@GwtCompatible(emulated = true)
@ElementTypesAreNonnullByDefault
abstract class CollectionFuture<V extends @Nullable Object, C extends @Nullable Object>
    extends AggregateFuture<V, C> {
  /*
   * We access this field racily but safely. For discussion of a similar situation, see the comments
   * on the fields of TimeoutFuture. This field is slightly different from the fields discussed

# Real cycle, but the runningState field is null'ed on completion of the future.
FIELD com.google.common.util.concurrent.AggregateFuture.runningState
FIELD java.util.AbstractMap.keySet com.google.common.collect.AbstractMapBasedMultimap.NavigableKeySet
FIELD java.util.AbstractMap.keySet com.google.common.collect.Maps.FilteredEntryNavigableMap.navigableKeySet.$

          @Override
          public void run() {
            /*
             * firstFuture just completed, but AggregateFuture hasn't yet had time to record the
             * exception in seenExceptions. When we complete secondFuture with the same exception,
             * we want for AggregateFuture to still detect that it's been previously seen.
             */
            secondFuture.setException(sameInstance);
          }

          @Override
          public void run() {
            /*
             * firstFuture just completed, but AggregateFuture hasn't yet had time to record the
             * exception in seenExceptions. When we complete secondFuture with the same exception,
             * we want for AggregateFuture to still detect that it's been previously seen.
             */
            secondFuture.setException(sameInstance);
          }