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.bifromq.base.util;
  
  import static com.google.common.hash.Hashing.murmur3_128;
  
  import com.google.common.hash.Funnel;
  import lombok.Builder;
  
  /**
   * A simple implementation of Rendezvous Hashing.
   *
   * @param <K> The type of the key.
   * @param <N> The type of the node.
   */
  @Builder
  public class RendezvousHash<K, N> {
      private final Funnel<K> keyFunnel;
      private final Funnel<N> nodeFunnel;
      private final Iterable<N> nodes;
  
      /**
       * Get the node that the key should be mapped to.
       *
       * @param key The key.
       * @return The node.
       */
      public N get(K key) {
          long bestScore = Long.MIN_VALUE;
          N bestNode = null;
          for (N node : nodes) {
              long currentScore = murmur3_128()
                  .newHasher()
                  .putObject(key, keyFunnel)
                  .putObject(node, nodeFunnel)
                  .hash()
                  .asLong();
              if (currentScore > bestScore) {
                  bestScore = currentScore;
                  bestNode = node;
              }
          }
          return bestNode;
      }
  }