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124 lines
4.4 KiB
124 lines
4.4 KiB
5 months ago
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/* Copyright (c) 2014, 2019, Oracle and/or its affiliates. All rights reserved.
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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 also distributed 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 included with MySQL.
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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 RPL_TABLE_ACCESS_H_
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#define RPL_TABLE_ACCESS_H_
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#include <sys/types.h>
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#include "lex_string.h"
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#include "thr_lock.h" // thr_lock_type
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class Open_tables_backup;
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class THD;
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struct TABLE;
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/**
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A base class for accessing a system table.
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*/
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class System_table_access {
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public:
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virtual ~System_table_access() {}
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/**
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Opens and locks a system table.
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It's assumed that the caller knows what they are doing:
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- whether it was necessary to reset-and-backup the open tables state
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- whether the requested lock does not lead to a deadlock
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- whether this open mode would work under LOCK TABLES, or inside a
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stored function or trigger.
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Note that if the table can't be locked successfully this operation will
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close it. Therefore it provides guarantee that it either opens and locks
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table or fails without leaving any tables open.
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@param[in] thd Thread requesting to open the table
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@param[in] dbstr Database where the table resides
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@param[in] tbstr Table to be openned
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@param[in] max_num_field Maximum number of fields
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@param[in] lock_type How to lock the table
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@param[out] table We will store the open table here
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@param[out] backup Save the lock info. here
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@return
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@retval true open and lock failed - an error message is pushed into the
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stack
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@retval false success
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*/
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bool open_table(THD *thd, const LEX_CSTRING dbstr, const LEX_CSTRING tbstr,
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uint max_num_field, enum thr_lock_type lock_type,
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TABLE **table, Open_tables_backup *backup);
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/**
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Prepares before opening table.
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@param[in] thd Thread requesting to open the table
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*/
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virtual void before_open(THD *thd) = 0;
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/**
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Commits the changes, unlocks the table and closes it. This method
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needs to be called even if the open_table fails, in order to ensure
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the lock info is properly restored.
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@param[in] thd Thread requesting to close the table
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@param[in] table Table to be closed
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@param[in] backup Restore the lock info from here
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@param[in] error If there was an error while updating
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the table
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@param[in] need_commit Need to commit current transaction
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if it is true.
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@return
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@retval true failed
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@retval false success
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If there is an error, rolls back the current statement. Otherwise,
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commits it. However, if a new thread was created and there is an
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error, the transaction must be rolled back. Otherwise, it must be
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committed. In this case, the changes were not done on behalf of
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any user transaction and if not finished, there would be pending
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changes.
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*/
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bool close_table(THD *thd, TABLE *table, Open_tables_backup *backup,
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bool error, bool need_commit);
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/**
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Creates a new thread in the bootstrap process or in the mysqld startup,
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a thread is created in order to be able to access a table.
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@return
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@retval THD* Pointer to thread structure
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*/
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THD *create_thd();
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/**
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Destroys the created thread and restores the
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system_thread information.
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@param thd Thread requesting to be destroyed
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*/
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void drop_thd(THD *thd);
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/* Flags for opening table */
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uint m_flags;
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};
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#endif /* RPL_TABLE_ACCESS_H_ */
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