code: /*
   * Copyright (c) 2016-present, RxJava Contributors.
   *
   * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in
   * compliance with the License. You may obtain a copy of the License at
   *
   * http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software distributed under the License is
   * distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See
   * the License for the specific language governing permissions and limitations under the License.
   */
  
  package io.reactivex.rxjava3.internal.subscriptions;
  
  import java.util.concurrent.atomic.AtomicLong;
  
  import io.reactivex.rxjava3.operators.QueueSubscription;
  
  /**
   * Base class extending AtomicLong (wip or request accounting) and QueueSubscription (fusion).
   *
   * @param <T> the value type
   */
  public abstract class BasicQueueSubscription<T> extends AtomicLong implements QueueSubscription<T> {
  
      private static final long serialVersionUID = -6671519529404341862L;
  
      @Override
      public final boolean offer(T e) {
          throw new UnsupportedOperationException("Should not be called!");
      }
  
      @Override
      public final boolean offer(T v1, T v2) {
          throw new UnsupportedOperationException("Should not be called!");
      }
  }
  