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.metadata;
  
  import com.datastax.oss.driver.api.core.session.Session;
  import com.datastax.oss.driver.internal.core.context.InternalDriverContext;
  import java.util.Collections;
  import java.util.List;
  
  /**
   * Any update to the driver's metadata. It produces a new metadata instance, and may also trigger
   * events.
   *
   * <p>This is modelled as a separate type for modularity, and because we can't send the events while
   * we are doing the refresh (by contract, the new copy of the metadata needs to be visible before
   * the events are sent). This also makes unit testing very easy.
   *
   * <p>This is only instantiated and called from {@link MetadataManager}'s admin thread, therefore
   * implementations don't need to be thread-safe.
   *
   * @see Session#getMetadata()
   */
  public interface MetadataRefresh {
  
    Result compute(
        DefaultMetadata oldMetadata, boolean tokenMapEnabled, InternalDriverContext context);
  
    class Result {
      public final DefaultMetadata newMetadata;
      public final List<Object> events;
  
      public Result(DefaultMetadata newMetadata, List<Object> events) {
        this.newMetadata = newMetadata;
        this.events = events;
      }
  
      public Result(DefaultMetadata newMetadata) {
        this(newMetadata, Collections.emptyList());
      }
    }
  }
  