content: /*
   * Licensed to the Apache Software Foundation (ASF) under one
   * or more contributor license agreements.  See the NOTICE file
   * distributed with this work for additional information
   * regarding copyright ownership.  The ASF licenses this file
   * to you 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 org.apache.cassandra.utils.concurrent;
  
  import java.util.concurrent.atomic.AtomicReferenceFieldUpdater;
  import java.util.function.BiConsumer;
  import java.util.function.Consumer;
  
  public class ConcurrentLinkedStack<T>
  {
      static final class Node<T> extends IntrusiveStack<Node<T>>
      {
          final T value;
          Node(T value)
          {
              this.value = value;
          }
      }
  
      private volatile Node<T> head;
      private static final AtomicReferenceFieldUpdater<ConcurrentLinkedStack, Node> headUpdater = AtomicReferenceFieldUpdater.newUpdater(ConcurrentLinkedStack.class, Node.class, "head");
  
      public void push(T value)
      {
          IntrusiveStack.getAndPush(headUpdater, this, (Node)new Node<>(value));
      }
  
      public boolean isEmpty()
      {
          return head == null;
      }
  
      public void drain(Consumer<T> forEach, boolean reverse)
      {
          if (isEmpty())
              return;
  
          Node<T> head = headUpdater.getAndSet(this, null);
          if (reverse) head = IntrusiveStack.reverse(head);
          IntrusiveStack.forEach(head, n -> n.value, forEach);
      }
  
      public <P> void drain(BiConsumer<P, T> forEach, P param, boolean reverse)
      {
          if (isEmpty())
              return;
  
          Node<T> head = headUpdater.getAndSet(this, null);
          if (reverse) head = IntrusiveStack.reverse(head);
          IntrusiveStack.forEach(head, n -> n.value, forEach, param);
      }
  }
  