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.harry.model;
  
  import java.util.ArrayList;
  import java.util.List;
  import java.util.concurrent.TimeUnit;
  
  import com.google.common.util.concurrent.Uninterruptibles;
  
  import org.apache.cassandra.distributed.api.ConsistencyLevel;
  import org.apache.cassandra.distributed.api.ICoordinator;
  
  import static org.apache.cassandra.harry.model.TokenPlacementModel.peerStateToNodes;
  
  public class TokenPlacementModelHelper
  {
      /**
       * Updates to the peers table is async, which can see partial state... to avoid this issue retry until the writes have become stable.
       */
      private static List<TokenPlacementModel.Node> retryWhenNotComplete(ICoordinator coordinator, String query)
      {
          TokenPlacementModel.IncompletePeersStateException last = null;
          // 20 retries with 500ms ~10s...
          for (int i = 0; i < 20; i++)
          {
              try
              {
                  return peerStateToNodes(coordinator.execute(query, ConsistencyLevel.ONE));
              }
              catch (TokenPlacementModel.IncompletePeersStateException e)
              {
                  last = e;
                  Uninterruptibles.sleepUninterruptibly(500, TimeUnit.MILLISECONDS);
              }
          }
          throw last;
      }
  
      public static TokenPlacementModel.ReplicatedRanges getRing(ICoordinator coordinator, TokenPlacementModel.ReplicationFactor rf)
      {
          List<TokenPlacementModel.Node> other = retryWhenNotComplete(coordinator, "select peer, tokens, data_center, rack from system.peers");
          List<TokenPlacementModel.Node> self = retryWhenNotComplete(coordinator, "select broadcast_address, tokens, data_center, rack from system.local");
          List<TokenPlacementModel.Node> all = new ArrayList<>();
          all.addAll(self);
          all.addAll(other);
          all.sort(TokenPlacementModel.Node::compareTo);
          return rf.replicate(all);
      }
  }