mysql_cache_manager.h

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/*
  Copyright (c) 2021, 2026, 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.
 
  This program is designed to work with certain software (including
  but not limited to OpenSSL) that is licensed under separate terms,
  as designated in a particular file or component or in included license
  documentation.  The authors of MySQL hereby grant you an additional
  permission to link the program and your derivative works with the
  separately licensed software that they have either included with
  the program or referenced in the documentation.
 
  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
  along with this program; if not, write to the Free Software
  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
*/
 
#ifndef ROUTER_SRC_REST_MRS_SRC_CONNECTION_CACHE_MANAGER_H_
#define ROUTER_SRC_REST_MRS_SRC_CONNECTION_CACHE_MANAGER_H_
 
#include <cassert>
 
#include "collector/cache_manager.h"
#include "mrs/configuration.h"
 
#include "collector/counted_mysql_session.h"
#include "collector/destination_provider.h"
 
#include "secure_string.h"  // NOLINT(build/include_subdir)
 
namespace collector {
 
enum MySQLConnection {
  kMySQLConnectionMetadataRO,
  kMySQLConnectionUserdataRO,
  kMySQLConnectionMetadataRW,
  kMySQLConnectionUserdataRW
};
 
bool is_rw_connection(MySQLConnection type);
CountedMySQLSession::Sqls build_mysql_cache_initial_sqls(MySQLConnection type);
 
class ConnectionConfiguration {
 public:
  ConnectionConfiguration() = default;
 
  ConnectionConfiguration(MySQLConnection type,
                          const mrs::Configuration &configuration)
      : type_{type},
        provider_{is_rw() ? configuration.provider_rw_.get()
                          : configuration.provider_ro_.get()} {
    switch (type) {
      case kMySQLConnectionMetadataRW:
      case kMySQLConnectionMetadataRO:
        mysql_user_ = configuration.mysql_user_;
        mysql_password_ = configuration.mysql_user_password_;
        break;
      case kMySQLConnectionUserdataRW:
      case kMySQLConnectionUserdataRO:
        mysql_user_ = configuration.mysql_user_data_access_;
        mysql_password_ = configuration.mysql_user_data_access_password_;
        break;
    }
  }
 
  bool is_rw() const { return is_rw_connection(type_); }
 
  MySQLConnection type_{kMySQLConnectionMetadataRO};
  DestinationProvider *provider_{nullptr};
  std::string mysql_user_;
  mysql_harness::SecureString mysql_password_;
};
 
class MysqlCacheManager {
 public:
  using MySQLSession = CountedMySQLSession;
  using ConnectionParameters = MySQLSession::ConnectionParameters;
  using MySqlCacheManager = CacheManager<CountedMySQLSession *>;
  using CachedObject = MySqlCacheManager::CachedObject;
  using Callbacks = MySqlCacheManager::Callbacks;
  using Object = MySqlCacheManager::Object;
 
  class MysqlCacheCallbacks : public Callbacks {
   public:
    MysqlCacheCallbacks(const ConnectionConfiguration &configuration =
                            ConnectionConfiguration{})
        : connection_configuration_{configuration} {}
 
    bool object_before_cache(Object, bool dirty) override;
    bool object_retrived_from_cache(Object) override;
    void object_remove(Object) override;
    Object object_allocate(bool wait) override;
    bool is_default_user(Object &) const;
 
    const ConnectionConfiguration &get_connection_configuration() const;
 
   private:
    void object_restore_defaults(Object &, bool dirty);
    bool is_default_server(Object &) const;
 
    ConnectionParameters new_connection_params(bool wait);
 
   private:
    ConnectionConfiguration connection_configuration_;
    int node_rount_robin_{0};
  };
 
 public:
  MysqlCacheManager(const mrs::Configuration &configuration)
      : default_mysql_cache_instances_{configuration
                                           .default_mysql_cache_instances_},
        callbacks_metadata_ro_{
            {collector::kMySQLConnectionMetadataRO, configuration}},
        callbacks_userdata_ro_{{
            collector::kMySQLConnectionUserdataRO,
            configuration,
        }},
        callbacks_metadata_rw_{
            {collector::kMySQLConnectionMetadataRW, configuration}},
        callbacks_userdata_rw_{{
            collector::kMySQLConnectionUserdataRW,
            configuration,
        }} {}
  MysqlCacheManager(Callbacks *callbacks_meta, Callbacks *callbacks_user)
      : default_mysql_cache_instances_{10},
        cache_manager_metadata_ro_{callbacks_meta},
        cache_manager_userdata_ro_{callbacks_user} {}
 
  virtual ~MysqlCacheManager() = default;
 
  virtual CachedObject get_empty(collector::MySQLConnection type, bool wait) {
    switch (type) {
      case collector::kMySQLConnectionMetadataRO:
        return CachedObject(&cache_manager_metadata_ro_, wait);
      case collector::kMySQLConnectionUserdataRO:
        return CachedObject(&cache_manager_userdata_ro_, wait);
      case collector::kMySQLConnectionMetadataRW:
        return CachedObject(&cache_manager_metadata_rw_, wait);
      case collector::kMySQLConnectionUserdataRW:
        return CachedObject(&cache_manager_userdata_rw_, wait);
      default:
        assert(nullptr && "Shouldn't happen");
        return {};
    }
  }
 
  virtual collector::MySQLConnection get_type(const CachedObject &obj) {
    if (obj.parent_ == &cache_manager_metadata_ro_)
      return collector::kMySQLConnectionMetadataRO;
    else if (obj.parent_ == &cache_manager_metadata_ro_)
      return collector::kMySQLConnectionMetadataRW;
    else if (obj.parent_ == &cache_manager_metadata_rw_)
      return collector::kMySQLConnectionUserdataRO;
    else if (obj.parent_ == &cache_manager_userdata_rw_)
      return collector::kMySQLConnectionUserdataRW;
 
    return collector::kMySQLConnectionUserdataRO;
  }
 
  virtual CachedObject get_instance(collector::MySQLConnection type,
                                    bool wait) {
    switch (type) {
      case collector::kMySQLConnectionMetadataRO:
        return cache_manager_metadata_ro_.get_instance(wait);
      case collector::kMySQLConnectionUserdataRO:
        return cache_manager_userdata_ro_.get_instance(wait);
      case collector::kMySQLConnectionMetadataRW:
        return cache_manager_metadata_rw_.get_instance(wait);
      case collector::kMySQLConnectionUserdataRW:
        return cache_manager_userdata_rw_.get_instance(wait);
      default:
        assert(nullptr && "Shouldn't happen");
        return {};
    }
  }
 
  // Bootstrap and metadata monitoring only. Embedded implementations may
  // bypass max_connections while retaining the selected SQL identity.
  virtual CachedObject get_control_plane_instance(
      collector::MySQLConnection type) {
    return get_instance(type, true);
  }
 
  virtual std::unique_ptr<collector::CountedMySQLSession> clone_instance(
      const CountedMySQLSession::ConnectionParameters &params);
 
  virtual void change_instance(CachedObject &instance,
                               collector::MySQLConnection type) {
    switch (type) {
      case collector::kMySQLConnectionMetadataRO:
        change_to(instance, &cache_manager_metadata_ro_);
        break;
      case collector::kMySQLConnectionUserdataRO:
        change_to(instance, &cache_manager_userdata_ro_);
        break;
      case collector::kMySQLConnectionMetadataRW:
        change_to(instance, &cache_manager_metadata_rw_);
        break;
      case collector::kMySQLConnectionUserdataRW:
        change_to(instance, &cache_manager_userdata_rw_);
        break;
    }
  }
 
  const ConnectionConfiguration &get_connection_configuration(
      collector::MySQLConnection type) const {
    switch (type) {
      case collector::kMySQLConnectionMetadataRO:
        return callbacks_metadata_ro_.get_connection_configuration();
      case collector::kMySQLConnectionUserdataRO:
        return callbacks_userdata_ro_.get_connection_configuration();
      case collector::kMySQLConnectionMetadataRW:
        return callbacks_metadata_rw_.get_connection_configuration();
      case collector::kMySQLConnectionUserdataRW:
        return callbacks_userdata_rw_.get_connection_configuration();
      default:
        assert(nullptr && "Shouldn't happen");
        throw std::logic_error("internal error");
    }
  }
 
  virtual void return_instance(CachedObject &object) {
    if (object.parent_) object.parent_->return_instance(object);
  }
 
  virtual void change_cache_object_limit(uint32_t limit) {
    cache_manager_metadata_ro_.change_cache_object_limit(limit);
    cache_manager_userdata_ro_.change_cache_object_limit(limit);
    cache_manager_metadata_rw_.change_cache_object_limit(limit);
    cache_manager_userdata_rw_.change_cache_object_limit(limit);
  }
 
  void configure(const std::string &json_object);
 
 private:
  static void change_to(CachedObject &instance, MySqlCacheManager *m) {
    if (instance.parent_ != m) {
      instance.parent_ = m;
      if (instance.get()) {
        auto cb = dynamic_cast<MysqlCacheCallbacks *>(m->get_callbacks());
 
        instance.get()->change_user(
            cb->get_connection_configuration().mysql_user_,
            cb->get_connection_configuration().mysql_password_, "");
      }
    }
  }
 
  uint32_t default_mysql_cache_instances_;
  MysqlCacheCallbacks callbacks_metadata_ro_;
  MysqlCacheCallbacks callbacks_userdata_ro_;
  MysqlCacheCallbacks callbacks_metadata_rw_;
  MysqlCacheCallbacks callbacks_userdata_rw_;
  MySqlCacheManager cache_manager_metadata_ro_{&callbacks_metadata_ro_,
                                               default_mysql_cache_instances_};
  MySqlCacheManager cache_manager_userdata_ro_{&callbacks_userdata_ro_,
                                               default_mysql_cache_instances_};
  MySqlCacheManager cache_manager_metadata_rw_{&callbacks_metadata_rw_,
                                               default_mysql_cache_instances_};
  MySqlCacheManager cache_manager_userdata_rw_{&callbacks_userdata_rw_,
                                               default_mysql_cache_instances_};
};
 
}  // namespace collector
 
#endif  // ROUTER_SRC_REST_MRS_SRC_CONNECTION_CACHE_MANAGER_H_