builtin_plugins.h

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/*
  Copyright (c) 2018, 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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  permission to link the program and your derivative works with the
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  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
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  You should have received a copy of the GNU General Public License
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*/
 
#ifndef MYSQL_HARNESS_BUILTIN_PLUGINS_INCLUDED
#define MYSQL_HARNESS_BUILTIN_PLUGINS_INCLUDED
 
#include "mysql/harness/plugin.h"
 
#include "harness_export.h"
 
#include <map>
#include <string>
 
namespace mysql_harness {
 
/**
 * @brief Singleton class implementing registry of the built-in MySQLRouter
 * plugins.
 *
 * Built-in plugin is statically linked to the harness library (does not have
 * dedicated .so or .dll file) but implements the same API as the external
 * plugin (init(), start(), etc.) that is called by the Loader.
 */
class HARNESS_EXPORT BuiltinPlugins {
 public:
  /**
   * @brief Gets the singleton instance.
   */
  static BuiltinPlugins &instance();
 
  /**
   * It's a singleton so we disable copying.
   */
  BuiltinPlugins(const BuiltinPlugins &) = delete;
  BuiltinPlugins &operator=(const BuiltinPlugins &) = delete;
 
  /**
   * Stores the information about a single built-in plugin.
   */
  struct PluginInfo {
    /**
     * pointer to the plugin struct (used by the Loader to run init(),
     * start(), etc on the plugin)
     */
    Plugin *plugin;
 
    /** if true the plugin should ALWAYS be loaded even if it does not have
     * its section in the configuration
     */
    bool always_load;
  };
 
  using PluginsMap = std::map<std::string, PluginInfo>;
 
  /** @brief Checks if there is a built-in plugin with a specified name
   *
   * @param plugin_name plugin name to check
   * @return true if there is a built-in plugin with a given name in the
   * registry, false otherwise
   */
  bool has(const std::string &plugin_name) noexcept;
 
  /** @brief Returns the map containing information about all built-in plugins
   * in the registry
   *
   * @return map containing information about all built-in plugins in the
   * registry
   */
  const PluginsMap *get() noexcept { return &plugins_; }
 
  /** @brief Returns pointer to the Plugin struct for the plugin with
   * selected name
   *
   * @throw  std::out_of_range if there is no info about the plugin with a given
   * name.
   *
   * @param plugin_name name of the plugin queried for the Plugin struct
   * @return Plugin struct for the plugin with selected name
   */
  Plugin *get_plugin(const std::string &plugin_name) {
    return plugins_.at(plugin_name).plugin;
  }
 
  /**
   * add plugin to the built in plugins.
   */
  void add(std::string name, PluginInfo plugin_info);
 
 private:
  BuiltinPlugins();
  PluginsMap plugins_;
};
 
}  // namespace mysql_harness
 
#endif