mysql_thd_store_imp.h

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/* Copyright (c) 2022, 2023, 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 also distributed 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 included with MySQL.
 
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, version 2.0, for more details.
 
You should have received a copy of the GNU General Public License
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Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA */
 
#ifndef SQL_SERVER_COMPONENT_MYSQL_THD_STORE_IMP_H
#define SQL_SERVER_COMPONENT_MYSQL_THD_STORE_IMP_H
 
#include <unordered_map>
 
#include "mysql/components/service_implementation.h"
#include "mysql/components/services/mysql_thd_store_service.h"
 
void init_thd_store_service();
void deinit_thd_store_service();
bool free_thd_store_resource(THD *thd,
                             std::unordered_map<unsigned int, void *> &data);
 
class Mysql_thd_store_service_imp final {
 public:
  /**
    Register a slot to store data specific to a component
 
    The free_resource callback is used to free the stored pointer
    before thd is destroyed
 
    @param [in]  name Implementation name
    @param [in]  free_fn  Callback to free resource stored in the slot
    @param [out] slot Key used to identify the object handle
 
    @returns status of registration
      @retval false Success
      @retval true  Error. This typically means all slots are full
  */
  static DEFINE_BOOL_METHOD(register_slot,
                            (const char *name, free_resource_fn free_fn,
                             mysql_thd_store_slot *slot));
 
  /**
    Unregister a slot
 
    @param [in, out] slot Key allocated to component
 
    @returns status of operation
      @retval false Success
      @retval true  Error
  */
  static DEFINE_BOOL_METHOD(unregister_slot, (mysql_thd_store_slot slot));
 
  /**
    Adds an opaque pointer to the session object
 
    @param [in] thd     Session handle. If NULL, current session will be used.
    @param [in] slot    Key used to identify the object handle
    @param [in] object  Handle of the object being stored. If NULL, it will be
                        considered removal.
 
    @returns Status of the operation
      @retval false Success
      @retval true  Error
  */
  static DEFINE_BOOL_METHOD(set, (MYSQL_THD thd, mysql_thd_store_slot slot,
                                  void *object));
 
  /**
    Get handle to an already stored object without removing it
 
    @param [in]  thd     Session handle. If NULL, current session will be used.
    @param [in]  slot    Key used to identify the object handle
 
    @returns handle to the object if found, nullptr otherwise
  */
  static DEFINE_METHOD(void *, get, (MYSQL_THD thd, mysql_thd_store_slot slot));
};
 
#endif  // !SQL_SERVER_COMPONENT_MYSQL_THD_STORE_IMP_H