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;
  
  import org.apache.cassandra.concurrent.ExecutorPlus;
  
  import static org.apache.cassandra.utils.Shared.Scope.SIMULATION;
  
  /**
   * A generic interface for encapsulating a Runnable task with related work before and after execution,
   * using the built-in try-with-resources functionality offered by {@link Closeable}.
   *
   * See {@link ExecutorPlus#execute(WithResources, Runnable)}
   */
  @Shared(scope = SIMULATION)
  public interface WithResources
  {
      static class None implements WithResources
      {
          static final None INSTANCE = new None();
          private None() {}
          @Override
          public Closeable get()
          {
              return () -> {};
          }
  
          @Override
          public boolean isNoOp()
          {
              return true;
          }
      }
  
      /**
       * Instantiate any necessary resources
       * @return an object that closes any instantiated resources
       */
      public Closeable get();
  
      /**
       * A convenience method to avoid unnecessary work.
       * @return true iff this object performs no work when {@link #get()} is invoked, nor when {@link Closeable#close()}
       *         is invoked on the object it returns.
       */
      default public boolean isNoOp() { return false; }
      default public WithResources and(WithResources withResources)
      {
          return and(this, withResources);
      }
      static WithResources none() { return None.INSTANCE; }
  
      public static WithResources and(WithResources first, WithResources second)
      {
          if (second.isNoOp()) return first;
          if (first.isNoOp()) return second;
          return () -> {
              Closeable a = first.get();
              try
              {
                  Closeable b = second.get();
                  return () -> {
                      try { a.close(); }
                      finally { b.close(); }
                  };
              }
              catch (Throwable t)
              {
                  try { a.close(); } catch (Throwable t2) { t.addSuppressed(t2); }
                  throw t;
              }
          };
      }
  }
  