ha_example.h
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上传日期:2022-05-23
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- /* Copyright (C) 2003 MySQL AB
- 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; either version 2 of the License, or
- (at your option) any later version.
- 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */
- /*
- Please read ha_exmple.cc before reading this file.
- Please keep in mind that the example storage engine implements all methods
- that are required to be implemented. handler.h has a full list of methods
- that you can implement.
- */
- #ifdef USE_PRAGMA_INTERFACE
- #pragma interface /* gcc class implementation */
- #endif
- /*
- EXAMPLE_SHARE is a structure that will be shared amoung all open handlers
- The example implements the minimum of what you will probably need.
- */
- typedef struct st_example_share {
- char *table_name;
- uint table_name_length,use_count;
- pthread_mutex_t mutex;
- THR_LOCK lock;
- } EXAMPLE_SHARE;
- /*
- Class definition for the storage engine
- */
- class ha_example: public handler
- {
- THR_LOCK_DATA lock; /* MySQL lock */
- EXAMPLE_SHARE *share; /* Shared lock info */
- public:
- ha_example(TABLE *table): handler(table)
- {
- }
- ~ha_example()
- {
- }
- /* The name that will be used for display purposes */
- const char *table_type() const { return "EXAMPLE"; }
- /*
- The name of the index type that will be used for display
- don't implement this method unless you really have indexes
- */
- const char *index_type(uint inx) { return "HASH"; }
- const char **bas_ext() const;
- /*
- This is a list of flags that says what the storage engine
- implements. The current table flags are documented in
- handler.h
- */
- ulong table_flags() const
- {
- return 0;
- }
- /*
- This is a bitmap of flags that says how the storage engine
- implements indexes. The current index flags are documented in
- handler.h. If you do not implement indexes, just return zero
- here.
- part is the key part to check. First key part is 0
- If all_parts it's set, MySQL want to know the flags for the combined
- index up to and including 'part'.
- */
- ulong index_flags(uint inx, uint part, bool all_parts) const
- {
- return 0;
- }
- /*
- unireg.cc will call the following to make sure that the storage engine can
- handle the data it is about to send.
- Return *real* limits of your storage engine here. MySQL will do
- min(your_limits, MySQL_limits) automatically
- There is no need to implement ..._key_... methods if you don't suport
- indexes.
- */
- uint max_supported_record_length() const { return HA_MAX_REC_LENGTH; }
- uint max_supported_keys() const { return 0; }
- uint max_supported_key_parts() const { return 0; }
- uint max_supported_key_length() const { return 0; }
- /*
- Called in test_quick_select to determine if indexes should be used.
- */
- virtual double scan_time() { return (double) (records+deleted) / 20.0+10; }
- /*
- The next method will never be called if you do not implement indexes.
- */
- virtual double read_time(ha_rows rows) { return (double) rows / 20.0+1; }
- /*
- Everything below are methods that we implment in ha_example.cc.
- Most of these methods are not obligatory, skip them and
- MySQL will treat them as not implemented
- */
- int open(const char *name, int mode, uint test_if_locked); // required
- int close(void); // required
- int write_row(byte * buf);
- int update_row(const byte * old_data, byte * new_data);
- int delete_row(const byte * buf);
- int index_read(byte * buf, const byte * key,
- uint key_len, enum ha_rkey_function find_flag);
- int index_read_idx(byte * buf, uint idx, const byte * key,
- uint key_len, enum ha_rkey_function find_flag);
- int index_next(byte * buf);
- int index_prev(byte * buf);
- int index_first(byte * buf);
- int index_last(byte * buf);
- /*
- unlike index_init(), rnd_init() can be called two times
- without rnd_end() in between (it only makes sense if scan=1).
- then the second call should prepare for the new table scan
- (e.g if rnd_init allocates the cursor, second call should
- position it to the start of the table, no need to deallocate
- and allocate it again
- */
- int rnd_init(bool scan); //required
- int rnd_end();
- int rnd_next(byte *buf); //required
- int rnd_pos(byte * buf, byte *pos); //required
- void position(const byte *record); //required
- void info(uint); //required
- int extra(enum ha_extra_function operation);
- int reset(void);
- int external_lock(THD *thd, int lock_type); //required
- int delete_all_rows(void);
- ha_rows records_in_range(uint inx, key_range *min_key,
- key_range *max_key);
- int delete_table(const char *from);
- int rename_table(const char * from, const char * to);
- int create(const char *name, TABLE *form,
- HA_CREATE_INFO *create_info); //required
- THR_LOCK_DATA **store_lock(THD *thd, THR_LOCK_DATA **to,
- enum thr_lock_type lock_type); //required
- };