content: /*
   * Copyright 1999-2018 Alibaba Group Holding Ltd.
   *
   * Licensed 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.alibaba.nacos.core.cluster;
  
  import com.alibaba.nacos.common.notify.Event;
  
  import java.util.Collection;
  import java.util.Collections;
  import java.util.HashSet;
  
  /**
   * Publish this event when the node list changes，All interested in the node list change event can listen to this event.
   *
   * <ul>
   *     <li>{@link com.alibaba.nacos.core.distributed.ProtocolManager}</li>
   *     <li>{@link com.alibaba.nacos.naming.core.DistroMapper}</li>
   *     <li>{@link com.alibaba.nacos.naming.consistency.persistent.raft.RaftPeerSet}</li>
   * </ul>
   *
   * @author <a href="mailto:liaochuntao@live.com">liaochuntao</a>
   */
  public class MembersChangeEvent extends Event {
      
      private static final long serialVersionUID = 7308126651076668976L;
      
      private final Collection<Member> members;
      
      private final Collection<Member> triggers;
      
      private MembersChangeEvent(Collection<Member> members, Collection<Member> triggers) {
          this.members = members;
          this.triggers = new HashSet<>();
          if (triggers != null) {
              this.triggers.addAll(triggers);
          }
      }
      
      public static MemberChangeEventBuilder builder() {
          return new MemberChangeEventBuilder();
      }
      
      public Collection<Member> getMembers() {
          return members;
      }
      
      public boolean hasTriggers() {
          return !triggers.isEmpty();
      }
      
      public Collection<Member> getTriggers() {
          return triggers;
      }
      
      @Override
      public String toString() {
          return "MembersChangeEvent{" + "members=" + members + ", triggers=" + triggers + ", no=" + sequence() + '}';
      }
      
      public static final class MemberChangeEventBuilder {
          
          private Collection<Member> allMembers;
          
          private Collection<Member> triggers;
      
          private MemberChangeEventBuilder() {
          }
          
          public MemberChangeEventBuilder members(Collection<Member> allMembers) {
              this.allMembers = allMembers;
              return this;
          }
          
          public MemberChangeEventBuilder triggers(Collection<Member> triggers) {
              this.triggers = triggers;
              return this;
          }
          
          public MemberChangeEventBuilder trigger(Member trigger) {
              this.triggers = Collections.singleton(trigger);
              return this;
          }
      
          /**
           * build MemberChangeEvent.
           *
           * @return {@link MembersChangeEvent}
           */
          public MembersChangeEvent build() {
              return new MembersChangeEvent(allMembers, triggers);
          }
      }
  }
  