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Diffstat (limited to 'storage/example/ha_example.h')
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diff --git a/storage/example/ha_example.h b/storage/example/ha_example.h new file mode 100644 index 00000000..5d067f7c --- /dev/null +++ b/storage/example/ha_example.h @@ -0,0 +1,254 @@ +/* + Copyright (c) 2004, 2010, 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 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 */ + +/** @file ha_example.h + + @brief + The ha_example engine is a stubbed storage engine for example purposes only; + it does nothing at this point. Its purpose is to provide a source + code illustration of how to begin writing new storage engines; see also + /storage/example/ha_example.cc. + + @note + Please read ha_example.cc before reading this file. + Reminder: The example storage engine implements all methods that are *required* + to be implemented. For a full list of all methods that you can implement, see + handler.h. + + @see + /sql/handler.h and /storage/example/ha_example.cc +*/ + +#ifdef USE_PRAGMA_INTERFACE +#pragma interface /* gcc class implementation */ +#endif + +#include "my_global.h" /* ulonglong */ +#include "thr_lock.h" /* THR_LOCK, THR_LOCK_DATA */ +#include "handler.h" /* handler */ +#include "my_base.h" /* ha_rows */ + +/** @brief + Example_share is a class that will be shared among all open handlers. + This example implements the minimum of what you will probably need. +*/ +class Example_share : public Handler_share { +public: + mysql_mutex_t mutex; + THR_LOCK lock; + Example_share(); + ~Example_share() + { + thr_lock_delete(&lock); + mysql_mutex_destroy(&mutex); + } +}; + +/** @brief + Class definition for the storage engine +*/ +class ha_example: public handler +{ + THR_LOCK_DATA lock; ///< MySQL lock + Example_share *share; ///< Shared lock info + Example_share *get_share(); ///< Get the share + +public: + ha_example(handlerton *hton, TABLE_SHARE *table_arg); + ~ha_example() = default; + + /** @brief + 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"; } + + /** @brief + This is a list of flags that indicate what functionality the storage engine + implements. The current table flags are documented in handler.h + */ + ulonglong table_flags() const + { + /* + We are saying that this engine is just statement capable to have + an engine that can only handle statement-based logging. This is + used in testing. + */ + return HA_BINLOG_STMT_CAPABLE; + } + + /** @brief + This is a bitmap of flags that indicates 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. + + @details + part is the key part to check. First key part is 0. + If all_parts is set, MySQL wants 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; + } + + /** @brief + unireg.cc will call max_supported_record_length(), max_supported_keys(), + max_supported_key_parts(), uint max_supported_key_length() + 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. + */ + uint max_supported_record_length() const { return HA_MAX_REC_LENGTH; } + + /** @brief + unireg.cc will call this 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. + + @details + There is no need to implement ..._key_... methods if your engine doesn't + support indexes. + */ + uint max_supported_keys() const { return 0; } + + /** @brief + unireg.cc will call this 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. + + @details + There is no need to implement ..._key_... methods if your engine doesn't + support indexes. + */ + uint max_supported_key_parts() const { return 0; } + + /** @brief + unireg.cc will call this 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. + + @details + There is no need to implement ..._key_... methods if your engine doesn't + support indexes. + */ + uint max_supported_key_length() const { return 0; } + + /** @brief + Called in test_quick_select to determine if indexes should be used. + */ + virtual double scan_time() { return (double) (stats.records+stats.deleted) / 20.0+10; } + + /** @brief + This method will never be called if you do not implement indexes. + */ + virtual double read_time(uint, uint, ha_rows rows) + { return (double) rows / 20.0+1; } + + /* + Everything below are methods that we implement in ha_example.cc. + + Most of these methods are not obligatory, skip them and + MySQL will treat them as not implemented + */ + /** @brief + We implement this in ha_example.cc; it's a required method. + */ + int open(const char *name, int mode, uint test_if_locked); // required + + /** @brief + We implement this in ha_example.cc; it's a required method. + */ + int close(void); // required + + /** @brief + We implement this in ha_example.cc. It's not an obligatory method; + skip it and and MySQL will treat it as not implemented. + */ + int write_row(const uchar *buf); + + /** @brief + We implement this in ha_example.cc. It's not an obligatory method; + skip it and and MySQL will treat it as not implemented. + */ + int update_row(const uchar *old_data, const uchar *new_data); + + /** @brief + We implement this in ha_example.cc. It's not an obligatory method; + skip it and and MySQL will treat it as not implemented. + */ + int delete_row(const uchar *buf); + + /** @brief + We implement this in ha_example.cc. It's not an obligatory method; + skip it and and MySQL will treat it as not implemented. + */ + int index_read_map(uchar *buf, const uchar *key, + key_part_map keypart_map, enum ha_rkey_function find_flag); + + /** @brief + We implement this in ha_example.cc. It's not an obligatory method; + skip it and and MySQL will treat it as not implemented. + */ + int index_next(uchar *buf); + + /** @brief + We implement this in ha_example.cc. It's not an obligatory method; + skip it and and MySQL will treat it as not implemented. + */ + int index_prev(uchar *buf); + + /** @brief + We implement this in ha_example.cc. It's not an obligatory method; + skip it and and MySQL will treat it as not implemented. + */ + int index_first(uchar *buf); + + /** @brief + We implement this in ha_example.cc. It's not an obligatory method; + skip it and and MySQL will treat it as not implemented. + */ + int index_last(uchar *buf); + + /** @brief + Unlike index_init(), rnd_init() can be called two consecutive times + without rnd_end() in between (it only makes sense if scan=1). In this + case, the second call should prepare for the new table scan (e.g if + rnd_init() allocates the cursor, the second call should position the + cursor to the start of the table; no need to deallocate and allocate + it again. This is a required method. + */ + int rnd_init(bool scan); //required + int rnd_end(); + int rnd_next(uchar *buf); ///< required + int rnd_pos(uchar *buf, uchar *pos); ///< required + void position(const uchar *record); ///< required + int info(uint); ///< required + int extra(enum ha_extra_function operation); + int external_lock(THD *thd, int lock_type); ///< required + int delete_all_rows(void); + ha_rows records_in_range(uint inx, const key_range *min_key, + const key_range *max_key, page_range *pages); + int delete_table(const char *from); + int create(const char *name, TABLE *form, + HA_CREATE_INFO *create_info); ///< required + enum_alter_inplace_result + check_if_supported_inplace_alter(TABLE* altered_table, + Alter_inplace_info* ha_alter_info); + + THR_LOCK_DATA **store_lock(THD *thd, THR_LOCK_DATA **to, + enum thr_lock_type lock_type); ///< required +}; |