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	Fixing the code adding MySQL _0900_ collations as _uca1400_ aliases
not to perform deep initialization of the corresponding _uca1400_
collations.
Only basic initialization is now performed which allows to watch
these collations (both _0900_ and _uca1400_) in queries to
INFORMATION_SCHEMA tables COLLATIONS and
COLLATION_CHARACTER_SET_APPLICABILITY,
as well as in SHOW COLLATION statements.
Deep initialization is now performed only when a collation
(either the _0900_ alias or the corresponding  _uca1400_ collation)
is used for the very first time after the server startup.
Refactoring was done to maintain the code easier:
- most of the _uca1400_ code was moved from ctype-uca.c
  to a new file ctype-uca1400.c
- most of the _0900_ code was moved from type-uca.c
  to a new file ctype-uca0900.c
Change details:
- The original function add_alias_for_collation() added by the patch for
   "MDEV-20912 Add support for utf8mb4_0900_* collations in MariaDB Server"
  was removed from mysys/charset.c, as it had two two problems:
  a. it forced deep initialization of the _uca1400_ collations
     when adding _0900_ aliases for them at the server startup
     (the main reported problem)
  b. the collation initialization code in add_alias_for_collation()
     was related more to collations rather than to memory management,
     so /strings should be a better place for it than /mysys.
  The code from add_alias_for_collation() was split into separate functions.
  Cyclic dependency was removed. `#include <my_sys.h>` was removed
  from /strings/ctype-uca.c. Collations are now added using a callback
  function MY_CHARSET_LOADED::add_collation, like it is done for
  user collations defined in Index.xml. The code in /mysys sets
  MY_CHARSET_LOADED::add_collation to add_compiled_collation().
- The function compare_collations() was removed.
  A new virtual function was added into my_collation_handler_st instead:
    my_bool (*eq_collation)(CHARSET_INFO *self, CHARSET_INFO *other);
  because it is the collation handler who knows how to detect equal
  collations by comparing only some of CHARSET_INFO members without
  their deep initialization.
  Three implementations were added:
  - my_ci_eq_collation_uca() for UCA collations, it compares
    _0900_ collations as equal to their corresponding _uca1400_ collations.
  - my_ci_eq_collation_utf8mb4_bin(), it compares
    utf8mb4_nopad_bin and utf8mb4_0900_bin as equal.
  - my_ci_eq_collation_generic() - the default implementation,
    which compares all collations as not equal.
  A C++ wrapper CHARSET_INFO::eq_collations() was added.
  The code in /sql was changes to use the wrapper instead of
  the former calls for the removed function compare_collations().
- A part of add_alias_for_collation() was moved into a new function
  my_ci_alloc(). It allocates a memory for a new charset_info_st
  instance together with the collation name and the comment using a single
  MY_CHARSET_LOADER::once_alloc call, which points to my_once_alloc()
  in the server.
- A part of add_alias_for_collation() was moved into a new function
  my_ci_make_comment_for_alias(). It makes an "Alias for xxx" string,
  e.g. "Alias for utf8mb4_uca1400_swedish_ai_ci" in case of
  utf8mb4_sv_0900_ai_ci.
- A part of the code in create_tailoring() was moved to
  a new function my_uca1400_collation_get_initialized_shared_uca(),
  to reuse the code between _uca1400_ and _0900_ collations.
- A new function my_collation_id_is_mysql_uca0900() was added
  in addition to my_collation_id_is_mysql_uca1400().
- Functions to build collation names were added:
   my_uca0900_collation_build_name()
   my_uca1400_collation_build_name()
- A shared function function was added:
  my_bool
  my_uca1400_collation_alloc_and_init(MY_CHARSET_LOADER *loader,
                                      LEX_CSTRING name,
                                      LEX_CSTRING comment,
                                      const uca_collation_def_param_t *param,
                                      uint id)
  It's reused to add _uca1400_ and _0900_ collations, with basic
  initialization (without deep initialization).
- The function add_compiled_collation() changed its return type from
  void to int, to make it compatible with MY_CHARSET_LOADER::add_collation.
- Functions mysql_uca0900_collation_definition_add(),
  mysql_uca0900_utf8mb4_collation_definitions_add(),
  mysql_utf8mb4_0900_bin_add() were added into ctype-uca0900.c.
  They get MY_CHARSET_LOADER as a parameter.
- Functions my_uca1400_collation_definition_add(),
  my_uca1400_collation_definitions_add() were moved from
  charset-def.c to strings/ctype-uca1400.c.
  The latter now accepts MY_CHARSET_LOADER as the first parameter
  instead of initializing a MY_CHARSET_LOADER inside.
- init_compiled_charsets() now initializes a MY_CHARSET_LOADER
  variable and passes it to all functions adding collations:
  - mysql_utf8mb4_0900_collation_definitions_add()
  - mysql_uca0900_utf8mb4_collation_definitions_add()
  - mysql_utf8mb4_0900_bin_add()
- A new structure was added into ctype-uca.h:
  typedef struct uca_collation_def_param
  {
    my_cs_encoding_t cs_id;
    uint tailoring_id;
    uint nopad_flags;
    uint level_flags;
  } uca_collation_def_param_t;
  It simplifies reusing the code for _uca1400_ and _0900_ collations.
- The definition of MY_UCA1400_COLLATION_DEFINITION was
  moved from ctype-uca.c to ctype-uca1400.h, to reuse
  the code for _uca1400_ and _0900_ collations.
- The definitions of "MY_UCA_INFO my_uca_v1400" and
  "MY_UCA_INFO my_uca1400_info_tailored[][]" were moved from
  ctype-uca.c to ctype-uca1400.c.
- The definitions/declarations of:
  - mysql_0900_collation_start,
  - struct mysql_0900_to_mariadb_1400_mapping
  - mysql_0900_to_mariadb_1400_mapping
  - mysql_utf8mb4_0900_collation_definitions_add()
  were moved from ctype-uca.c to ctype-uca0900.c
- Functions
  my_uca1400_make_builtin_collation_id()
  my_uca1400_collation_definition_init()
  my_uca1400_collation_id_uca400_compat()
  my_ci_get_collation_name_uca1400_context()
  were moved from ctype-uca.c to ctype-uca1400.c and ctype-uca1400.h
- A part of my_uca1400_collation_definition_init()
  was moved into my_uca0520_builtin_collation_by_id(),
  to make functions smaller.
		
	
			
		
			
				
	
	
		
			69 lines
		
	
	
	
		
			2.7 KiB
		
	
	
	
		
			C
		
	
	
	
	
	
			
		
		
	
	
			69 lines
		
	
	
	
		
			2.7 KiB
		
	
	
	
		
			C
		
	
	
	
	
	
#ifndef CTYPE_UCA_0520_H
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#define CTYPE_UCA_0520_H
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/* Copyright (c) 2025, MariaDB Corporation
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   This library is free software; you can redistribute it and/or
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   modify it under the terms of the GNU Library General Public
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   License as published by the Free Software Foundation; version 2
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   of the License.
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   This library 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 GNU
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   Library General Public License for more details.
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   You should have received a copy of the GNU Library General Public
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   License along with this library; if not, write to the Free
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   Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
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   MA 02110-1335  USA */
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extern struct charset_info_st my_charset_utf8mb3_unicode_520_nopad_ci;
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extern struct charset_info_st my_charset_utf8mb3_unicode_520_ci;
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extern struct charset_info_st my_charset_utf8mb4_unicode_520_nopad_ci;
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extern struct charset_info_st my_charset_utf8mb4_unicode_520_ci;
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extern struct charset_info_st my_charset_ucs2_unicode_520_nopad_ci;
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extern struct charset_info_st my_charset_ucs2_unicode_520_ci;
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extern struct charset_info_st my_charset_utf16_unicode_520_nopad_ci;
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extern struct charset_info_st my_charset_utf16_unicode_520_ci;
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extern struct charset_info_st my_charset_utf32_unicode_520_nopad_ci;
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extern struct charset_info_st my_charset_utf32_unicode_520_ci;
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extern struct charset_info_st my_charset_utf8mb4_turkish_uca_ci;
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/*
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  Get a UCA-5.2.0 CHARSET_INFO using its character set ID and PAD flags.
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  Used to initialize UCA-14.0.0 collations.
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*/
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static inline
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CHARSET_INFO *my_uca0520_builtin_collation_by_id(my_cs_encoding_t cs_id,
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                                                 uint nopad_flags)
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{
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  switch (cs_id) {
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  case MY_CS_ENCODING_UTF8MB3:
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    return nopad_flags ? &my_charset_utf8mb3_unicode_520_nopad_ci :
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                         &my_charset_utf8mb3_unicode_520_ci;
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  case MY_CS_ENCODING_UTF8MB4:
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    return nopad_flags ? &my_charset_utf8mb4_unicode_520_nopad_ci :
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                         &my_charset_utf8mb4_unicode_520_ci;
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#ifdef HAVE_CHARSET_ucs2
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  case MY_CS_ENCODING_UCS2:
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    return nopad_flags ? &my_charset_ucs2_unicode_520_nopad_ci :
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                         &my_charset_ucs2_unicode_520_ci;
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#endif
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#ifdef HAVE_CHARSET_utf16
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  case MY_CS_ENCODING_UTF16:
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    return nopad_flags ? &my_charset_utf16_unicode_520_nopad_ci :
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                         &my_charset_utf16_unicode_520_ci;
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#endif
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#ifdef HAVE_CHARSET_utf32
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  case MY_CS_ENCODING_UTF32:
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    return nopad_flags ? &my_charset_utf32_unicode_520_nopad_ci :
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                         &my_charset_utf32_unicode_520_ci;
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#endif
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  }
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  return NULL;
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}
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#endif /* CTYPE_UCA_0520_H */
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