cluster_metadata_ar.h

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/*
  Copyright (c) 2019, 2025, Oracle and/or its affiliates.
 
  This program is free software; you can redistribute it and/or modify
  it under the terms of the GNU General Public License, version 2.0,
  as published by the Free Software Foundation.
 
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  as designated in a particular file or component or in included license
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  permission to link the program and your derivative works with the
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  This program is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  GNU General Public License for more details.
 
  You should have received a copy of the GNU General Public License
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*/
 
#ifndef METADATA_CACHE_CLUSTER_METADATA_AR_INCLUDED
#define METADATA_CACHE_CLUSTER_METADATA_AR_INCLUDED
 
#include "mysqlrouter/metadata_cache_export.h"
 
#include "cluster_metadata.h"
#include "gr_notifications_listener.h"
 
/** @class ARClusterMetadata
 *
 * The `ARClusterMetadata` class encapsulates a connection to the ReplicaSet
 * Cluster metadata server.
 *
 */
class METADATA_CACHE_EXPORT ARClusterMetadata : public ClusterMetadata {
 public:
  /** @brief Constructor
   *
   * @param session_config Metadata MySQL session configuration
   * @param ssl_options SSL related options to use for MySQL connections
   * @param view_id last known view_id of the cluster metadata
   */
  ARClusterMetadata(
      const metadata_cache::MetadataCacheMySQLSessionConfig &session_config,
      const mysqlrouter::SSLOptions &ssl_options, uint64_t view_id)
      : ClusterMetadata(session_config, ssl_options), view_id_(view_id) {}
 
  explicit ARClusterMetadata(const ARClusterMetadata &) = delete;
  ARClusterMetadata &operator=(const ARClusterMetadata &) = delete;
 
  /** @brief Destructor
   *
   * Disconnect and release the connection to the metadata node.
   */
  ~ARClusterMetadata() override;
 
  /** @brief Returns cluster defined in the metadata given set of the
   *         metadata servers (cluster members)
   *
   * @param terminated flag indicating that the process is cterminating,
   * allowing the function to leave earlier if possible
   * @param [in,out] target_cluster object identifying the Cluster this
   * operation refers to
   * @param router_id id of the router in the cluster metadata
   * @param metadata_servers  set of the metadata servers to use to fetch the
   * metadata
   * @param needs_writable_node flag indicating if the caller needs us to query
   * for writable node
   * @param [out] instance_id id of the server the metadata was fetched from
   * @return object containing cluster topology information in case of success,
   * or error code in case of failure
   * @throws metadata_cache::metadata_error
   */
  stdx::expected<metadata_cache::ClusterTopology, std::error_code>
  fetch_cluster_topology(
      const std::atomic<bool> &terminated,
      mysqlrouter::TargetCluster &target_cluster, const unsigned router_id,
      const metadata_cache::metadata_servers_list_t &metadata_servers,
      bool needs_writable_node, const std::string & /*clusterset_id*/,
      bool /*whole_topology*/, std::size_t &instance_id) override;
 
  /** @brief Returns cluster type this object is suppsed to handle
   */
  mysqlrouter::ClusterType get_cluster_type() override {
    return mysqlrouter::ClusterType::RS_V2;
  }
 
  void setup_notifications_listener(
      const metadata_cache::ClusterTopology & /*cluster_topology*/,
      const GRNotificationListener::NotificationClb & /*callback*/) override {}
 
  /** @brief Deinitializes the notifications listener thread
   */
  void shutdown_notifications_listener() override {}
 
 private:
  /** @brief Returns the current cluster topology according to the metadata of
   * the given metadata server.
   *
   * @param session active connection to the member that is checked for the
   * metadata
   * @param view_id last known view_id of the cluster metadata
   * @param cluster_id ID of the cluster this operation refers to
   * @return vector of the cluster members
   */
  metadata_cache::ClusterTopology fetch_topology_from_member(
      mysqlrouter::MySQLSession &session, unsigned view_id,
      const std::string &cluster_id = "");
 
  /** @brief Returns metadata view id the given member holds
   *
   * @param session active connection to the member that is checked for the view
   * id
   * @param cluster_id ID of the cluster this operation refers to
   * @param[out] result  member's metadata view_id
   * @retval true on success
   * @retval false otherwise.
   */
  bool get_member_view_id(mysqlrouter::MySQLSession &session,
                          const std::string &cluster_id, uint64_t &result);
 
  uint64_t view_id_;
};
 
#endif  // METADATA_CACHE_CLUSTER_METADATA_AR_INCLUDED