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 com.datastax.oss.driver.internal.core.loadbalancing.nodeset;
  
  import com.datastax.oss.driver.api.core.metadata.Node;
  import edu.umd.cs.findbugs.annotations.NonNull;
  import edu.umd.cs.findbugs.annotations.Nullable;
  import java.util.Set;
  import net.jcip.annotations.ThreadSafe;
  
  /**
   * A thread-safe abstraction around a map of nodes per datacenter, to facilitate node management by
   * load balancing policies.
   */
  @ThreadSafe
  public interface NodeSet {
  
    /**
     * Adds the given node to this set.
     *
     * <p>If this set was initialized with datacenter awareness, the node will be added to its
     * datacenter's specific set; otherwise, the node is added to a general set containing all nodes
     * in the cluster.
     *
     * @param node The node to add.
     * @return true if the node was added, false otherwise (because it was already present).
     */
    boolean add(@NonNull Node node);
  
    /**
     * Removes the node from the set.
     *
     * @param node The node to remove.
     * @return true if the node was removed, false otherwise (because it was not present).
     */
    boolean remove(@NonNull Node node);
  
    /**
     * Returns the current nodes in the given datacenter.
     *
     * <p>If this set was initialized with datacenter awareness, the returned set will contain only
     * nodes pertaining to the given datacenter; otherwise, the given datacenter name is ignored and
     * the returned set will contain all nodes in the cluster.
     *
     * @param dc The datacenter name, or null if the datacenter name is not known, or irrelevant.
     * @return the current nodes in the given datacenter.
     */
    @NonNull
    Set<Node> dc(@Nullable String dc);
  
    /**
     * Returns the current datacenter names known to this set. If datacenter awareness has been
     * disabled, this method returns an empty set.
     */
    Set<String> dcs();
  }
  