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f56dd32bf7
Essentially, the problem is that safemalloc is excruciatingly slow as it checks all allocated blocks for overrun at each memory management primitive, yielding a almost exponential slowdown for the memory management functions (malloc, realloc, free). The overrun check basically consists of verifying some bytes of a block for certain magic keys, which catches some simple forms of overrun. Another minor problem is violation of aliasing rules and that its own internal list of blocks is prone to corruption. Another issue with safemalloc is rather the maintenance cost as the tool has a significant impact on the server code. Given the magnitude of memory debuggers available nowadays, especially those that are provided with the platform malloc implementation, maintenance of a in-house and largely obsolete memory debugger becomes a burden that is not worth the effort due to its slowness and lack of support for detecting more common forms of heap corruption. Since there are third-party tools that can provide the same functionality at a lower or comparable performance cost, the solution is to simply remove safemalloc. Third-party tools can provide the same functionality at a lower or comparable performance cost. The removal of safemalloc also allows a simplification of the malloc wrappers, removing quite a bit of kludge: redefinition of my_malloc, my_free and the removal of the unused second argument of my_free. Since free() always check whether the supplied pointer is null, redudant checks are also removed. Also, this patch adds unit testing for my_malloc and moves my_realloc implementation into the same file as the other memory allocation primitives. client/mysqldump.c: Pass my_free directly as its signature is compatible with the callback type -- which wasn't the case for free_table_ent.
108 lines
4.1 KiB
C
108 lines
4.1 KiB
C
/* Copyright 2000-2008 MySQL AB, 2008 Sun Microsystems, Inc.
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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 as published by
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the Free Software Foundation; version 2 of the License.
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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 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */
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/* Dynamic hashing of record with different key-length */
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#ifndef _hash_h
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#define _hash_h
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#include "my_global.h" /* uchar */
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#include "my_sys.h" /* DYNAMIC_ARRAY */
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/*
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This forward declaration is used from C files where the real
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definition is included before. Since C does not allow repeated
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typedef declarations, even when identical, the definition may not be
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repeated.
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*/
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#ifndef CHARSET_INFO_DEFINED
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#define CHARSET_INFO_DEFINED
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typedef struct charset_info_st CHARSET_INFO;
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#endif /* CHARSET_INFO_DEFINED */
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#ifdef __cplusplus
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extern "C" {
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#endif
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/*
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Overhead to store an element in hash
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Can be used to approximate memory consumption for a hash
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*/
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#define HASH_OVERHEAD (sizeof(char*)*2)
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/* flags for hash_init */
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#define HASH_UNIQUE 1 /* hash_insert fails on duplicate key */
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typedef uint my_hash_value_type;
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typedef uchar *(*my_hash_get_key)(const uchar *,size_t*,my_bool);
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typedef void (*my_hash_free_key)(void *);
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typedef struct st_hash {
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size_t key_offset,key_length; /* Length of key if const length */
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size_t blength;
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ulong records;
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uint flags;
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DYNAMIC_ARRAY array; /* Place for hash_keys */
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my_hash_get_key get_key;
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void (*free)(void *);
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CHARSET_INFO *charset;
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} HASH;
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/* A search iterator state */
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typedef uint HASH_SEARCH_STATE;
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#define my_hash_init(A,B,C,D,E,F,G,H) \
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_my_hash_init(A,0,B,C,D,E,F,G,H)
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#define my_hash_init2(A,B,C,D,E,F,G,H,I) \
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_my_hash_init(A,B,C,D,E,F,G,H,I)
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my_bool _my_hash_init(HASH *hash, uint growth_size, CHARSET_INFO *charset,
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ulong default_array_elements, size_t key_offset,
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size_t key_length, my_hash_get_key get_key,
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void (*free_element)(void*),
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uint flags);
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void my_hash_free(HASH *tree);
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void my_hash_reset(HASH *hash);
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uchar *my_hash_element(HASH *hash, ulong idx);
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uchar *my_hash_search(const HASH *info, const uchar *key, size_t length);
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uchar *my_hash_search_using_hash_value(const HASH *info,
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my_hash_value_type hash_value,
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const uchar *key, size_t length);
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my_hash_value_type my_calc_hash(const HASH *info,
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const uchar *key, size_t length);
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uchar *my_hash_first(const HASH *info, const uchar *key, size_t length,
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HASH_SEARCH_STATE *state);
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uchar *my_hash_first_from_hash_value(const HASH *info,
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my_hash_value_type hash_value,
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const uchar *key,
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size_t length,
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HASH_SEARCH_STATE *state);
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uchar *my_hash_next(const HASH *info, const uchar *key, size_t length,
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HASH_SEARCH_STATE *state);
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my_bool my_hash_insert(HASH *info, const uchar *data);
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my_bool my_hash_delete(HASH *hash, uchar *record);
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my_bool my_hash_update(HASH *hash, uchar *record, uchar *old_key,
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size_t old_key_length);
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void my_hash_replace(HASH *hash, HASH_SEARCH_STATE *state, uchar *new_row);
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my_bool my_hash_check(HASH *hash); /* Only in debug library */
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#define my_hash_clear(H) bzero((char*) (H), sizeof(*(H)))
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#define my_hash_inited(H) ((H)->blength != 0)
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#define my_hash_init_opt(A,B,C,D,E,F,G,H) \
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(!my_hash_inited(A) && _my_hash_init(A,0,B,C,D,E,F,G,H))
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#ifdef __cplusplus
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}
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#endif
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#endif
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