sys_vars_shared.h

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#ifndef SYS_VARS_SHARED_INCLUDED
#define SYS_VARS_SHARED_INCLUDED
 
/* Copyright (c) 2002, 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
   along with this program; if not, write to the Free Software
   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA */
 
/**
  @file
  "protected" interface to sys_var - server configuration variables.
 
  This header is included by files implementing support and utility
  functions of sys_var's (set_var.cc) and files implementing
  classes in the sys_var hierarchy (sql_plugin.cc)
*/
 
#include "mysql/psi/mysql_mutex.h"
#include "mysql/psi/mysql_thread.h"  // mysql_mutex_t
#include "sql/sql_table.h"
 
class THD;
class sys_var;
 
extern bool throw_bounds_warning(THD *thd, const char *name, bool fixed,
                                 bool is_unsigned, longlong v);
extern bool throw_bounds_warning(THD *thd, const char *name, bool fixed,
                                 double v);
extern sys_var *find_static_system_variable(const std::string &name);
extern sys_var *find_dynamic_system_variable(const std::string &name);
extern sys_var *intern_find_sys_var(const char *str, size_t length);
 
/** wrapper to hide a mutex and an rwlock under a common interface */
class PolyLock {
 public:
  virtual void rdlock() = 0;
  virtual void wrlock() = 0;
  virtual void unlock() = 0;
  virtual ~PolyLock() = default;
};
 
class PolyLock_mutex : public PolyLock {
  mysql_mutex_t *mutex;
 
 public:
  PolyLock_mutex(mysql_mutex_t *arg) : mutex(arg) {}
  void rdlock() override { mysql_mutex_lock(mutex); }
  void wrlock() override { mysql_mutex_lock(mutex); }
  void unlock() override { mysql_mutex_unlock(mutex); }
};
 
class PolyLock_rwlock : public PolyLock {
  mysql_rwlock_t *rwlock;
 
 public:
  PolyLock_rwlock(mysql_rwlock_t *arg) : rwlock(arg) {}
  void rdlock() override { mysql_rwlock_rdlock(rwlock); }
  void wrlock() override { mysql_rwlock_wrlock(rwlock); }
  void unlock() override { mysql_rwlock_unlock(rwlock); }
};
 
class PolyLock_lock_log : public PolyLock {
 public:
  void rdlock() override;
  void wrlock() override;
  void unlock() override;
};
 
class AutoWLock {
  PolyLock *lock;
 
 public:
  AutoWLock(PolyLock *l) : lock(l) {
    if (lock) lock->wrlock();
  }
  ~AutoWLock() {
    if (lock) lock->unlock();
  }
};
 
class AutoRLock {
  PolyLock *lock;
 
 public:
  AutoRLock(PolyLock *l) : lock(l) {
    if (lock) lock->rdlock();
  }
  ~AutoRLock() {
    if (lock) lock->unlock();
  }
};
 
#endif /* SYS_VARS_SHARED_INCLUDED */