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Filename :
rpl_tblmap.h
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/* Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved. This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; version 2 of the License. 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 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 02110-1335 USA */ #ifndef TABLE_MAPPING_H #define TABLE_MAPPING_H /* Forward declarations */ #ifndef MYSQL_CLIENT struct TABLE; #else class Table_map_log_event; typedef Table_map_log_event TABLE; void free_table_map_log_event(TABLE *table); #endif /* CLASS table_mapping RESPONSIBILITIES The table mapping is used to map table id's to table pointers COLLABORATION RELAY_LOG For mapping table id:s to tables when receiving events. */ /* Guilhem to Mats: in the table_mapping class, the memory is allocated and never freed (until destruction). So this is a good candidate for allocating inside a MEM_ROOT: it gives the efficient allocation in chunks (like in expand()). So I have introduced a MEM_ROOT. Note that inheriting from Sql_alloc had no effect: it has effects only when "ptr= new table_mapping" is called, and this is never called. And it would then allocate from thd->mem_root which is a highly volatile object (reset from example after executing each query, see dispatch_command(), it has a free_root() at end); as the table_mapping object is supposed to live longer than a query, it was dangerous. A dedicated MEM_ROOT needs to be used, see below. */ #include "hash.h" /* HASH */ class table_mapping { private: MEM_ROOT m_mem_root; public: enum enum_error { ERR_NO_ERROR = 0, ERR_LIMIT_EXCEEDED, ERR_MEMORY_ALLOCATION }; table_mapping(); ~table_mapping(); TABLE* get_table(ulonglong table_id); int set_table(ulonglong table_id, TABLE* table); int remove_table(ulonglong table_id); void clear_tables(); ulong count() const { return m_table_ids.records; } private: /* This is a POD (Plain Old Data). Keep it that way (we apply offsetof() to it, which only works for PODs) */ struct entry { ulonglong table_id; union { TABLE *table; entry *next; }; }; entry *find_entry(ulonglong table_id) { return (entry *) my_hash_search(&m_table_ids, (uchar*)&table_id, sizeof(table_id)); } int expand(); /* Head of the list of free entries; "free" in the sense that it's an allocated entry free for use, NOT in the sense that it's freed memory. */ entry *m_free; /* Correspondance between an id (a number) and a TABLE object */ HASH m_table_ids; }; #endif