mariadb/storage/heap/hp_create.c
Davi Arnaut f56dd32bf7 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 18:20:08 -03:00

311 lines
9.3 KiB
C

/* Copyright (C) 2000-2006 MySQL AB, 2008-2009 Sun Microsystems, Inc
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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */
#include "heapdef.h"
static int keys_compare(heap_rb_param *param, uchar *key1, uchar *key2);
static void init_block(HP_BLOCK *block,uint reclength,ulong min_records,
ulong max_records);
/* Create a heap table */
int heap_create(const char *name, HP_CREATE_INFO *create_info,
HP_SHARE **res, my_bool *created_new_share)
{
uint i, j, key_segs, max_length, length;
HP_SHARE *share= 0;
HA_KEYSEG *keyseg;
HP_KEYDEF *keydef= create_info->keydef;
uint reclength= create_info->reclength;
uint keys= create_info->keys;
ulong min_records= create_info->min_records;
ulong max_records= create_info->max_records;
DBUG_ENTER("heap_create");
if (!create_info->internal_table)
{
mysql_mutex_lock(&THR_LOCK_heap);
share= hp_find_named_heap(name);
if (share && share->open_count == 0)
{
hp_free(share);
share= 0;
}
}
*created_new_share= (share == NULL);
if (!share)
{
HP_KEYDEF *keyinfo;
DBUG_PRINT("info",("Initializing new table"));
/*
We have to store sometimes uchar* del_link in records,
so the record length should be at least sizeof(uchar*)
*/
set_if_bigger(reclength, sizeof (uchar*));
for (i= key_segs= max_length= 0, keyinfo= keydef; i < keys; i++, keyinfo++)
{
bzero((char*) &keyinfo->block,sizeof(keyinfo->block));
bzero((char*) &keyinfo->rb_tree ,sizeof(keyinfo->rb_tree));
for (j= length= 0; j < keyinfo->keysegs; j++)
{
length+= keyinfo->seg[j].length;
if (keyinfo->seg[j].null_bit)
{
length++;
if (!(keyinfo->flag & HA_NULL_ARE_EQUAL))
keyinfo->flag|= HA_NULL_PART_KEY;
if (keyinfo->algorithm == HA_KEY_ALG_BTREE)
keyinfo->rb_tree.size_of_element++;
}
switch (keyinfo->seg[j].type) {
case HA_KEYTYPE_SHORT_INT:
case HA_KEYTYPE_LONG_INT:
case HA_KEYTYPE_FLOAT:
case HA_KEYTYPE_DOUBLE:
case HA_KEYTYPE_USHORT_INT:
case HA_KEYTYPE_ULONG_INT:
case HA_KEYTYPE_LONGLONG:
case HA_KEYTYPE_ULONGLONG:
case HA_KEYTYPE_INT24:
case HA_KEYTYPE_UINT24:
case HA_KEYTYPE_INT8:
keyinfo->seg[j].flag|= HA_SWAP_KEY;
break;
case HA_KEYTYPE_VARBINARY1:
/* Case-insensitiveness is handled in coll->hash_sort */
keyinfo->seg[j].type= HA_KEYTYPE_VARTEXT1;
/* fall_through */
case HA_KEYTYPE_VARTEXT1:
keyinfo->flag|= HA_VAR_LENGTH_KEY;
length+= 2;
/* Save number of bytes used to store length */
keyinfo->seg[j].bit_start= 1;
break;
case HA_KEYTYPE_VARBINARY2:
/* Case-insensitiveness is handled in coll->hash_sort */
/* fall_through */
case HA_KEYTYPE_VARTEXT2:
keyinfo->flag|= HA_VAR_LENGTH_KEY;
length+= 2;
/* Save number of bytes used to store length */
keyinfo->seg[j].bit_start= 2;
/*
Make future comparison simpler by only having to check for
one type
*/
keyinfo->seg[j].type= HA_KEYTYPE_VARTEXT1;
break;
default:
break;
}
}
keyinfo->length= length;
length+= keyinfo->rb_tree.size_of_element +
((keyinfo->algorithm == HA_KEY_ALG_BTREE) ? sizeof(uchar*) : 0);
if (length > max_length)
max_length= length;
key_segs+= keyinfo->keysegs;
if (keyinfo->algorithm == HA_KEY_ALG_BTREE)
{
key_segs++; /* additional HA_KEYTYPE_END segment */
if (keyinfo->flag & HA_VAR_LENGTH_KEY)
keyinfo->get_key_length= hp_rb_var_key_length;
else if (keyinfo->flag & HA_NULL_PART_KEY)
keyinfo->get_key_length= hp_rb_null_key_length;
else
keyinfo->get_key_length= hp_rb_key_length;
}
}
if (!(share= (HP_SHARE*) my_malloc((uint) sizeof(HP_SHARE)+
keys*sizeof(HP_KEYDEF)+
key_segs*sizeof(HA_KEYSEG),
MYF(MY_ZEROFILL))))
goto err;
share->keydef= (HP_KEYDEF*) (share + 1);
share->key_stat_version= 1;
keyseg= (HA_KEYSEG*) (share->keydef + keys);
init_block(&share->block, reclength + 1, min_records, max_records);
/* Fix keys */
memcpy(share->keydef, keydef, (size_t) (sizeof(keydef[0]) * keys));
for (i= 0, keyinfo= share->keydef; i < keys; i++, keyinfo++)
{
keyinfo->seg= keyseg;
memcpy(keyseg, keydef[i].seg,
(size_t) (sizeof(keyseg[0]) * keydef[i].keysegs));
keyseg+= keydef[i].keysegs;
if (keydef[i].algorithm == HA_KEY_ALG_BTREE)
{
/* additional HA_KEYTYPE_END keyseg */
keyseg->type= HA_KEYTYPE_END;
keyseg->length= sizeof(uchar*);
keyseg->flag= 0;
keyseg->null_bit= 0;
keyseg++;
init_tree(&keyinfo->rb_tree, 0, 0, sizeof(uchar*),
(qsort_cmp2)keys_compare, 1, NULL, NULL);
keyinfo->delete_key= hp_rb_delete_key;
keyinfo->write_key= hp_rb_write_key;
}
else
{
init_block(&keyinfo->block, sizeof(HASH_INFO), min_records,
max_records);
keyinfo->delete_key= hp_delete_key;
keyinfo->write_key= hp_write_key;
keyinfo->hash_buckets= 0;
}
if ((keyinfo->flag & HA_AUTO_KEY) && create_info->with_auto_increment)
share->auto_key= i + 1;
}
share->min_records= min_records;
share->max_records= max_records;
share->max_table_size= create_info->max_table_size;
share->data_length= share->index_length= 0;
share->reclength= reclength;
share->blength= 1;
share->keys= keys;
share->max_key_length= max_length;
share->changed= 0;
share->auto_key= create_info->auto_key;
share->auto_key_type= create_info->auto_key_type;
share->auto_increment= create_info->auto_increment;
/* Must be allocated separately for rename to work */
if (!(share->name= my_strdup(name,MYF(0))))
{
my_free(share);
goto err;
}
#ifdef THREAD
thr_lock_init(&share->lock);
mysql_mutex_init(hp_key_mutex_HP_SHARE_intern_lock,
&share->intern_lock, MY_MUTEX_INIT_FAST);
#endif
if (!create_info->internal_table)
{
share->open_list.data= (void*) share;
heap_share_list= list_add(heap_share_list,&share->open_list);
}
else
share->delete_on_close= 1;
}
if (!create_info->internal_table)
{
if (create_info->pin_share)
++share->open_count;
mysql_mutex_unlock(&THR_LOCK_heap);
}
*res= share;
DBUG_RETURN(0);
err:
if (!create_info->internal_table)
mysql_mutex_unlock(&THR_LOCK_heap);
DBUG_RETURN(1);
} /* heap_create */
static int keys_compare(heap_rb_param *param, uchar *key1, uchar *key2)
{
uint not_used[2];
return ha_key_cmp(param->keyseg, key1, key2, param->key_length,
param->search_flag, not_used);
}
static void init_block(HP_BLOCK *block, uint reclength, ulong min_records,
ulong max_records)
{
uint i,recbuffer,records_in_block;
max_records= max(min_records,max_records);
if (!max_records)
max_records= 1000; /* As good as quess as anything */
recbuffer= (uint) (reclength + sizeof(uchar**) - 1) & ~(sizeof(uchar**) - 1);
records_in_block= max_records / 10;
if (records_in_block < 10 && max_records)
records_in_block= 10;
if (!records_in_block || records_in_block*recbuffer >
(my_default_record_cache_size-sizeof(HP_PTRS)*HP_MAX_LEVELS))
records_in_block= (my_default_record_cache_size - sizeof(HP_PTRS) *
HP_MAX_LEVELS) / recbuffer + 1;
block->records_in_block= records_in_block;
block->recbuffer= recbuffer;
block->last_allocated= 0L;
for (i= 0; i <= HP_MAX_LEVELS; i++)
block->level_info[i].records_under_level=
(!i ? 1 : i == 1 ? records_in_block :
HP_PTRS_IN_NOD * block->level_info[i - 1].records_under_level);
}
static inline void heap_try_free(HP_SHARE *share)
{
if (share->open_count == 0)
hp_free(share);
else
share->delete_on_close= 1;
}
int heap_delete_table(const char *name)
{
int result;
reg1 HP_SHARE *share;
DBUG_ENTER("heap_delete_table");
mysql_mutex_lock(&THR_LOCK_heap);
if ((share= hp_find_named_heap(name)))
{
heap_try_free(share);
result= 0;
}
else
{
result= my_errno=ENOENT;
}
mysql_mutex_unlock(&THR_LOCK_heap);
DBUG_RETURN(result);
}
void heap_drop_table(HP_INFO *info)
{
DBUG_ENTER("heap_drop_table");
mysql_mutex_lock(&THR_LOCK_heap);
heap_try_free(info->s);
mysql_mutex_unlock(&THR_LOCK_heap);
DBUG_VOID_RETURN;
}
void hp_free(HP_SHARE *share)
{
if (share->open_list.data) /* If not internal table */
heap_share_list= list_delete(heap_share_list, &share->open_list);
hp_clear(share); /* Remove blocks from memory */
#ifdef THREAD
thr_lock_delete(&share->lock);
mysql_mutex_destroy(&share->intern_lock);
#endif
my_free(share->name);
my_free(share);
return;
}