destination_status_component.h

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/*
  Copyright (c) 2022, 2025, Oracle and/or its affiliates.
 
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  it under the terms of the GNU General Public License, version 2.0,
  as published by the Free Software Foundation.
 
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*/
 
#ifndef MYSQLROUTER_DESTINATION_STATUS_COMPONENT_INCLUDED
#define MYSQLROUTER_DESTINATION_STATUS_COMPONENT_INCLUDED
 
#include <chrono>
#include <memory>
 
#include "mysql/harness/destination.h"
#include "mysqlrouter/destination_status_export.h"
#include "mysqlrouter/destination_status_types.h"
 
class UnreachableDestinationsQuarantine;
 
/**
 * @class DestinationStatusComponent
 * @brief Shared component representing status of the routing destinations.
 *
 */
class DESTINATION_STATUS_EXPORT DestinationStatusComponent {
 public:
  /**
   * @brief Get the singleton instance object of our class.
   */
  static DestinationStatusComponent &get_instance();
 
  // disable copy, as we are a single-instance
  DestinationStatusComponent(DestinationStatusComponent const &) = delete;
  void operator=(DestinationStatusComponent const &) = delete;
 
  // no move either
  DestinationStatusComponent(DestinationStatusComponent &&) = delete;
  void operator=(DestinationStatusComponent &&) = delete;
 
  ~DestinationStatusComponent();
 
  /**
   * @brief Initialize the component with the configured options.
   *
   * @param quarantine_interval interval after which the quarantined
   * destinations are checked for availability
   * @param qurantine_threshold number of invalid connect attempts after which
   * the destination is added to the quarantine
   */
  void init(std::chrono::seconds quarantine_interval,
            uint32_t qurantine_threshold);
 
  /**
   * @brief Register callbacks requied by the quarantine mechanism (start/stop
   * acceptor etc.).
   *
   * @param routing_callbacks object defining the callbacks
   */
  void register_quarantine_callbacks(
      QuarantineRoutingCallbacks &&routing_callbacks);
  /**
   * @brief Unregister callbacks requied by the quarantine mechanism.
   */
  void unregister_quarantine_callbacks();
 
  /**
   * @brief Register routing instance in the quarantine mechanism.
   *
   * @param name name of the route
   */
  void register_route(const std::string &name);
 
  /**
   * Register the connection error or success to a given destination.
   *
   * If registering a success it will set the number of reported errors to a
   * given connection to 0.
   *
   * If registering a failure it will increment the number of reported failed
   * connections to the destination. If the number reached the
   * quarantine_threshold the destination will be added to the quarantine. If
   * the destination candidate is not quarantine yet it will starting the async
   * handler for it, otherwise it will just update the referencing plugins list.
   *
   * @param[in] dest Reported destination address.
   * @param[in] success Indicates if the reported connection result is success
   * of failure.
   *
   * @returns true if the destination got added to the quarantine, false
   * otherwise
   */
  bool report_connection_result(const mysql_harness::Destination &dest,
                                bool success);
 
  /**
   * Query the quarantined destination candidates set and check if the given
   * destination candidate is quarantined.
   *
   * @param[in] dest Destination candidate address.
   * @returns true if the destination candidate is quarantined, false otherwise.
   */
  bool is_destination_quarantined(const mysql_harness::Destination &dest);
 
  /**
   * Stop all async operations and clear the quarantine list.
   */
  void stop_unreachable_destinations_quarantine();
 
  /**
   * Refresh the quarantined destination candidates list on metadata refresh.
   *
   * 1) if the destination candidates list got updated we have to go through the
   * quarantined destinations and check if there are still routing plugins that
   * references them.
   * 2) for each destination returned in the metadata (which is available from
   * the md perspective) check if it is still unreachable and should be
   * quarantined.
   *
   * @param[in] instance_name Routing plugin instance name.
   * @param[in] nodes_changed_on_md_refresh Information if the destination
   *            candidates have been updated for the given routing plugin.
   * @param[in] new_destinations List of destination candidates that are
   *            available for the given routing plugin after metadata refresh.
   */
  void refresh_destinations_quarantine(const std::string &instance_name,
                                       const bool nodes_changed_on_md_refresh,
                                       const AllowedNodes &new_destinations);
 
 private:
  DestinationStatusComponent();
 
  std::unique_ptr<UnreachableDestinationsQuarantine>
      unreachable_destinations_quarantine_;
};
 
#endif  // MYSQLROUTER_DESTINATION_STATUS_COMPONENT_INCLUDED