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a10ae35328
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.
52 lines
1.5 KiB
C
52 lines
1.5 KiB
C
/* Copyright (C) 2000 MySQL AB
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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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/*
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Header to remove use of my_functions in functions where we need speed and
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where calls to posix functions should work
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*/
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#ifndef _my_nosys_h
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#define _my_nosys_h
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#ifdef __cplusplus
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extern "C" {
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#endif
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#ifndef __MY_NOSYS__
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#define __MY_NOSYS__
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#ifndef HAVE_STDLIB_H
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#include <malloc.h>
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#endif
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#undef my_read /* Can be predefined in raid.h */
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#undef my_write
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#undef my_seek
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#define my_read(a,b,c,d) my_quick_read(a,b,c,d)
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#define my_write(a,b,c,d) my_quick_write(a,b,c)
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extern size_t my_quick_read(File Filedes,uchar *Buffer,size_t Count,
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myf myFlags);
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extern size_t my_quick_write(File Filedes,const uchar *Buffer,size_t Count);
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#if defined(USE_HALLOC)
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#define my_malloc(a,b) halloc(a,1)
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#define my_no_flags_free(a) hfree(a)
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#endif
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#endif /* __MY_NOSYS__ */
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#ifdef __cplusplus
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}
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#endif
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#endif
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