160 lines
4.8 KiB
C++
160 lines
4.8 KiB
C++
/* Copyright (c) 2017, 2024, Oracle and/or its affiliates.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License, version 2.0,
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as published by the Free Software Foundation.
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This program is designed to work with certain software (including
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but not limited to OpenSSL) that is licensed under separate terms,
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as designated in a particular file or component or in included license
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documentation. The authors of MySQL hereby grant you an additional
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permission to link the program and your derivative works with the
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separately licensed software that they have either included with
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the program or referenced in the documentation.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License, version 2.0, for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA */
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#ifndef SQL_LOCK_INCLUDED
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#define SQL_LOCK_INCLUDED
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#include <sys/types.h>
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#include "my_sqlcommand.h" // SQLCOM_LOCK_INSTANCE, SQLCOM_UNLOCK_INSTANCE
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#include "sql/sql_cmd.h" // Sql_cmd
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class THD;
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/**
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Sql_cmd_lock_instance represents statement LOCK INSTANCE FOR BACKUP.
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*/
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class Sql_cmd_lock_instance : public Sql_cmd {
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public:
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/**
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Execute LOCK INSTANCE statement once.
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@param thd Thread handler
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@returns false on success, true on error
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*/
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bool execute(THD *thd) override;
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enum_sql_command sql_command_code() const override {
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return SQLCOM_LOCK_INSTANCE;
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}
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};
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/**
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Sql_cmd_unlock_instance represents statement UNLOCK INSTANCE.
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*/
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class Sql_cmd_unlock_instance : public Sql_cmd {
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public:
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/**
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Execute UNLOCK INSTANCE statement once.
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@param thd Thread handler
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@returns false on success, true on error
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*/
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bool execute(THD *thd) override;
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enum_sql_command sql_command_code() const override {
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return SQLCOM_UNLOCK_INSTANCE;
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}
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};
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/**
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MDL_key::BACKUP_LOCK RAII.
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*/
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class Shared_backup_lock_guard {
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public:
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/**
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There are three possible results while checking if the instance is locked
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for backup.
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*/
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enum class Lock_result { not_locked = 0, locked = 1, oom = 2 };
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Shared_backup_lock_guard(THD *thd);
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Shared_backup_lock_guard(const Shared_backup_lock_guard &o) = delete;
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Shared_backup_lock_guard(Shared_backup_lock_guard &&o) = default;
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Shared_backup_lock_guard &operator=(const Shared_backup_lock_guard &o) =
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delete;
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Shared_backup_lock_guard &operator=(Shared_backup_lock_guard &&o) = default;
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~Shared_backup_lock_guard();
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operator Lock_result() const;
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private:
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/**
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Try to acquire shared backup lock.
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@param[in] thd Current thread context
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@param[in] for_trx true if MDL duration is MDL_TRANSACTION
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false if MDL duration is MDL_EXPLICIT
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@return Operation status.
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@retval Shared_backup_lock_guard::Lock_result::locked Locked shared
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BACKUP lock.
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@retval Shared_backup_lock_guard::Lock_result::not_locked Could not lock
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shared BACKUP lock. Conflicting lock exists.
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@retval Shared_backup_lock_guard::Lock_result::oom Error. Could
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not lock shared BACKUP lock.
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*/
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Shared_backup_lock_guard::Lock_result try_acquire_shared_backup_lock(
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THD *thd, bool for_trx);
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Shared_backup_lock_guard::Lock_result m_lock_state;
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THD *m_thd;
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};
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/**
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Acquire exclusive Backup Lock.
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@param[in] thd Current thread context
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@param[in] lock_wait_timeout How many seconds to wait before timeout.
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@param[in] for_trx true if MDL duration is MDL_TRANSACTION
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false if MDL duration is MDL_EXPLICIT
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@return Operation status.
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@retval false Success
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@retval true Failure
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*/
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bool acquire_exclusive_backup_lock(THD *thd, unsigned long lock_wait_timeout,
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bool for_trx);
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/**
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Acquire shared Backup Lock.
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@param[in] thd Current thread context
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@param[in] lock_wait_timeout How many seconds to wait before timeout.
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@param[in] for_trx true if MDL duration is MDL_TRANSACTION
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false if MDL duration is MDL_EXPLICIT
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@return Operation status.
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@retval false Success
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@retval true Failure
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*/
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bool acquire_shared_backup_lock(THD *thd, unsigned long lock_wait_timeout,
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bool for_trx = true);
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/**
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Release Backup Lock if it was acquired.
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@param[in] thd Current thread context
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*/
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void release_backup_lock(THD *thd);
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#endif /* SQL_LOCK_INCLUDED */
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