mysql_thd_store_service.h

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/* Copyright (c) 2022, 2024, 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
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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
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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, 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 COMPONENTS_SERVICES_MYSQL_THD_STORE_SERVICE_H
#define COMPONENTS_SERVICES_MYSQL_THD_STORE_SERVICE_H
 
#include <mysql/components/service.h>
#include <mysql/components/services/mysql_current_thread_reader.h>  // MYSQL_THD
 
DEFINE_SERVICE_HANDLE(mysql_thd_store_slot);
 
/**
  Callback to free resource stored in THD
 
  returns 0 for success, 1 otherwise.
*/
typedef int (*free_resource_fn)(void *);
 
/**
  @file mysql/components/services/mysql_thd_store_service.h
  Connection event tracking.
*/
 
/**
  @ingroup event_tracking_services_inventory
 
  A service to store an opaque pointer in MYSQL_THD
*/
 
BEGIN_SERVICE_DEFINITION(mysql_thd_store)
 
/**
  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
*/
DECLARE_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
*/
DECLARE_BOOL_METHOD(unregister_slot, (mysql_thd_store_slot slot));
 
/**
  Set/Reset an opaque pointer in thd store.
 
  @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
*/
DECLARE_BOOL_METHOD(set,
                    (MYSQL_THD thd, mysql_thd_store_slot slot, void *object));
 
/**
  Get handle to an already stored object
 
  @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
*/
DECLARE_METHOD(void *, get, (MYSQL_THD thd, mysql_thd_store_slot slot));
 
END_SERVICE_DEFINITION(mysql_thd_store)
 
#endif  // !COMPONENTS_SERVICES_MYSQL_THD_STORE_SERVICE_H