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.api.core.connection;
  
  import com.datastax.oss.driver.api.core.metadata.Node;
  import edu.umd.cs.findbugs.annotations.NonNull;
  import java.time.Duration;
  
  /**
   * Decides how often the driver tries to re-establish lost connections.
   *
   * <p>When a reconnection starts, the driver invokes this policy to create a {@link
   * ReconnectionSchedule ReconnectionSchedule} instance. That schedule's {@link
   * ReconnectionSchedule#nextDelay() nextDelay()} method will get called each time the driver needs
   * to program the next connection attempt. When the reconnection succeeds, the schedule is
   * discarded; if the connection is lost again later, the next reconnection attempt will query the
   * policy again to obtain a new schedule.
   *
   * <p>There are two types of reconnection:
   *
   * <ul>
   *   <li>{@linkplain #newNodeSchedule(Node) for regular node connections}: when the connection pool
   *       for a node does not have its configured number of connections (see {@code
   *       advanced.connection.pool.*.size} in the configuration), a reconnection starts for that
   *       pool.
   *   <li>{@linkplain #newControlConnectionSchedule(boolean) for the control connection}: when the
   *       control node goes down, a reconnection starts to find another node to replace it. This is
   *       also used if the configuration option {@code advanced.reconnect-on-init} is set and the
   *       driver has to retry the initial connection.
   * </ul>
   *
   * This interface defines separate methods for those two cases, but implementations are free to
   * delegate to the same method internally if the same type of schedule can be used.
   */
  public interface ReconnectionPolicy extends AutoCloseable {
  
    /** Creates a new schedule for the given node. */
    @NonNull
    ReconnectionSchedule newNodeSchedule(@NonNull Node node);
  
    /**
     * Creates a new schedule for the control connection.
     *
     * @param isInitialConnection whether this schedule is generated for the driver's initial attempt
     *     to connect to the cluster.
     *     <ul>
     *       <li>{@code true} means that the configuration option {@code advanced.reconnect-on-init}
     *           is set, the driver failed to reach any contact point, and it is now scheduling
     *           reattempts.
     *       <li>{@code false} means that the driver was already initialized, lost connection to the
     *           control node, and is now scheduling attempts to connect to another node.
     *     </ul>
     */
    @NonNull
    ReconnectionSchedule newControlConnectionSchedule(boolean isInitialConnection);
  
    /** Called when the cluster that this policy is associated with closes. */
    @Override
    void close();
  
    /**
     * The reconnection schedule from the time a connection is lost, to the time all connections to
     * this node have been restored.
     */
    interface ReconnectionSchedule {
      /** How long to wait before the next reconnection attempt. */
      @NonNull
      Duration nextDelay();
    }
  }
  