2011-06-30 17:46:53 +02:00
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/* Copyright (c) 2006, 2010, Oracle and/or its affiliates. All rights reserved.
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2009-11-18 03:31:40 +01:00
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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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2011-06-30 17:46:53 +02:00
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Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA */
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2009-11-18 03:31:40 +01:00
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/*
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Analog of DYNAMIC_ARRAY that never reallocs
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(so no pointer into the array may ever become invalid).
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Memory is allocated in non-contiguous chunks.
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This data structure is not space efficient for sparse arrays.
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Every element is aligned to sizeof(element) boundary
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(to avoid false sharing if element is big enough).
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LF_DYNARRAY is a recursive structure. On the zero level
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LF_DYNARRAY::level[0] it's an array of LF_DYNARRAY_LEVEL_LENGTH elements,
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on the first level it's an array of LF_DYNARRAY_LEVEL_LENGTH pointers
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to arrays of elements, on the second level it's an array of pointers
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to arrays of pointers to arrays of elements. And so on.
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With four levels the number of elements is limited to 4311810304
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(but as in all functions index is uint, the real limit is 2^32-1)
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Actually, it's wait-free, not lock-free ;-)
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*/
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#include <my_global.h>
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#include <m_string.h>
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#include <my_sys.h>
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#include <lf.h>
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void lf_dynarray_init(LF_DYNARRAY *array, uint element_size)
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{
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bzero(array, sizeof(*array));
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array->size_of_element= element_size;
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}
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static void recursive_free(void **alloc, int level)
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{
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if (!alloc)
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return;
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if (level)
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{
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int i;
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for (i= 0; i < LF_DYNARRAY_LEVEL_LENGTH; i++)
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recursive_free(alloc[i], level-1);
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Bug#34043: Server loops excessively in _checkchunk() when safemalloc is enabled
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.
2010-07-08 23:20:08 +02:00
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my_free(alloc);
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2009-11-18 03:31:40 +01:00
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}
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else
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Bug#34043: Server loops excessively in _checkchunk() when safemalloc is enabled
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.
2010-07-08 23:20:08 +02:00
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my_free(alloc[-1]);
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2009-11-18 03:31:40 +01:00
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}
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void lf_dynarray_destroy(LF_DYNARRAY *array)
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{
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int i;
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for (i= 0; i < LF_DYNARRAY_LEVELS; i++)
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recursive_free(array->level[i], i);
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}
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static const ulong dynarray_idxes_in_prev_levels[LF_DYNARRAY_LEVELS]=
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{
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0, /* +1 here to to avoid -1's below */
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LF_DYNARRAY_LEVEL_LENGTH,
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LF_DYNARRAY_LEVEL_LENGTH * LF_DYNARRAY_LEVEL_LENGTH +
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LF_DYNARRAY_LEVEL_LENGTH,
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LF_DYNARRAY_LEVEL_LENGTH * LF_DYNARRAY_LEVEL_LENGTH *
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LF_DYNARRAY_LEVEL_LENGTH + LF_DYNARRAY_LEVEL_LENGTH *
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LF_DYNARRAY_LEVEL_LENGTH + LF_DYNARRAY_LEVEL_LENGTH
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};
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static const ulong dynarray_idxes_in_prev_level[LF_DYNARRAY_LEVELS]=
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{
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0, /* +1 here to to avoid -1's below */
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LF_DYNARRAY_LEVEL_LENGTH,
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LF_DYNARRAY_LEVEL_LENGTH * LF_DYNARRAY_LEVEL_LENGTH,
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LF_DYNARRAY_LEVEL_LENGTH * LF_DYNARRAY_LEVEL_LENGTH *
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LF_DYNARRAY_LEVEL_LENGTH,
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};
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/*
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Returns a valid lvalue pointer to the element number 'idx'.
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Allocates memory if necessary.
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*/
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2015-01-12 17:03:45 +01:00
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void *lf_dynarray_lvalue(LF_DYNARRAY *array, uint idx)
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2009-11-18 03:31:40 +01:00
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{
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void * ptr, * volatile * ptr_ptr= 0;
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int i;
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for (i= LF_DYNARRAY_LEVELS-1; idx < dynarray_idxes_in_prev_levels[i]; i--)
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/* no-op */;
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ptr_ptr= &array->level[i];
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idx-= dynarray_idxes_in_prev_levels[i];
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for (; i > 0; i--)
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{
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if (!(ptr= *ptr_ptr))
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{
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void *alloc= my_malloc(LF_DYNARRAY_LEVEL_LENGTH * sizeof(void *),
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MYF(MY_WME|MY_ZEROFILL));
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if (unlikely(!alloc))
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return(NULL);
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if (my_atomic_casptr(ptr_ptr, &ptr, alloc))
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ptr= alloc;
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else
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Bug#34043: Server loops excessively in _checkchunk() when safemalloc is enabled
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.
2010-07-08 23:20:08 +02:00
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my_free(alloc);
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2009-11-18 03:31:40 +01:00
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}
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ptr_ptr= ((void **)ptr) + idx / dynarray_idxes_in_prev_level[i];
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idx%= dynarray_idxes_in_prev_level[i];
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}
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if (!(ptr= *ptr_ptr))
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{
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uchar *alloc, *data;
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alloc= my_malloc(LF_DYNARRAY_LEVEL_LENGTH * array->size_of_element +
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2013-03-25 23:03:13 +01:00
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MY_MAX(array->size_of_element, sizeof(void *)),
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2009-11-18 03:31:40 +01:00
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MYF(MY_WME|MY_ZEROFILL));
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if (unlikely(!alloc))
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return(NULL);
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/* reserve the space for free() address */
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data= alloc + sizeof(void *);
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{ /* alignment */
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intptr mod= ((intptr)data) % array->size_of_element;
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if (mod)
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data+= array->size_of_element - mod;
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}
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((void **)data)[-1]= alloc; /* free() will need the original pointer */
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if (my_atomic_casptr(ptr_ptr, &ptr, data))
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ptr= data;
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else
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Bug#34043: Server loops excessively in _checkchunk() when safemalloc is enabled
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.
2010-07-08 23:20:08 +02:00
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my_free(alloc);
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2009-11-18 03:31:40 +01:00
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}
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return ((uchar*)ptr) + array->size_of_element * idx;
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}
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/*
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Returns a pointer to the element number 'idx'
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or NULL if an element does not exists
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*/
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2015-01-12 17:03:45 +01:00
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void *lf_dynarray_value(LF_DYNARRAY *array, uint idx)
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2009-11-18 03:31:40 +01:00
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{
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void * ptr, * volatile * ptr_ptr= 0;
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int i;
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for (i= LF_DYNARRAY_LEVELS-1; idx < dynarray_idxes_in_prev_levels[i]; i--)
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/* no-op */;
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ptr_ptr= &array->level[i];
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idx-= dynarray_idxes_in_prev_levels[i];
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for (; i > 0; i--)
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{
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if (!(ptr= *ptr_ptr))
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return(NULL);
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ptr_ptr= ((void **)ptr) + idx / dynarray_idxes_in_prev_level[i];
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idx %= dynarray_idxes_in_prev_level[i];
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}
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if (!(ptr= *ptr_ptr))
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return(NULL);
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return ((uchar*)ptr) + array->size_of_element * idx;
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}
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static int recursive_iterate(LF_DYNARRAY *array, void *ptr, int level,
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lf_dynarray_func func, void *arg)
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{
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int res, i;
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if (!ptr)
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return 0;
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if (!level)
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return func(ptr, arg);
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for (i= 0; i < LF_DYNARRAY_LEVEL_LENGTH; i++)
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if ((res= recursive_iterate(array, ((void **)ptr)[i], level-1, func, arg)))
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return res;
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return 0;
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}
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/*
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Calls func(array, arg) on every array of LF_DYNARRAY_LEVEL_LENGTH elements
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in lf_dynarray.
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DESCRIPTION
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lf_dynarray consists of a set of arrays, LF_DYNARRAY_LEVEL_LENGTH elements
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2015-01-12 17:03:45 +01:00
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each. lf_dynarray_iterate() calls user-supplied function on every array
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2009-11-18 03:31:40 +01:00
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from the set. It is the fastest way to scan the array, faster than
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2015-01-12 17:03:45 +01:00
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for (i=0; i < N; i++) { func(lf_dynarray_value(dynarray, i)); }
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2009-11-18 03:31:40 +01:00
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NOTE
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if func() returns non-zero, the scan is aborted
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*/
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2015-01-12 17:03:45 +01:00
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int lf_dynarray_iterate(LF_DYNARRAY *array, lf_dynarray_func func, void *arg)
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2009-11-18 03:31:40 +01:00
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{
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int i, res;
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for (i= 0; i < LF_DYNARRAY_LEVELS; i++)
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if ((res= recursive_iterate(array, array->level[i], i, func, arg)))
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return res;
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return 0;
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}
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