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.sidecar.client.selection;
  
  import java.util.ArrayList;
  import java.util.Collections;
  import java.util.Iterator;
  import java.util.List;
  import java.util.concurrent.ThreadLocalRandom;
  
  import org.apache.cassandra.sidecar.client.SidecarInstance;
  import org.apache.cassandra.sidecar.client.SidecarInstancesProvider;
  import org.jetbrains.annotations.NotNull;
  
  /**
   * An instance selection policy that returns instances in random order, and does not necessarily return the instances
   * in the provided order from the underlying {@link Iterator} for the {@link SidecarInstancesProvider#instances()}.
   */
  public class RandomInstanceSelectionPolicy extends OrderedInstanceSelectionPolicy
  {
      /**
       * Constructs a new {@link RandomInstanceSelectionPolicy} with the provided list of instances
       *
       * @param instancesProvider the class that provides the sidecar instances
       */
      public RandomInstanceSelectionPolicy(SidecarInstancesProvider instancesProvider)
      {
          super(instancesProvider);
      }
  
      /**
       * Returns an iterator of {@link SidecarInstance instances} in random order. This is a non-deterministic operation
       * because the underlying list will be shuffled every time this iterator is called.
       *
       * @return an iterator of {@link SidecarInstance instances} in random order
       */
      @Override
      @NotNull
      public Iterator<SidecarInstance> iterator()
      {
          List<SidecarInstance> instances = new ArrayList<>(instancesProvider.instances());
          Collections.shuffle(instances, ThreadLocalRandom.current());
          return instances.iterator();
      }
  }
  