collision resolving

include/my_alloc.h

+/* Copyright (C) 2000 MySQL AB
+
+   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; either version 2 of the License, or
+   (at your option) any later version.
+
+   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 */
+
+/* 
+   Data structures for mysys/my_alloc.c (root memory allocator)
+*/
+
+#ifndef ST_USED_MEM_DEFINED
+#define ST_USED_MEM_DEFINED
+typedef struct st_used_mem {	   /* struct for once_alloc (block) */
+  struct st_used_mem *next;	   /* Next block in use */
+  unsigned int	left;		   /* memory left in block  */
+  unsigned int	size;		   /* size of block */
+} USED_MEM;
+typedef struct st_mem_root {
+  USED_MEM *free;                  /* blocks with free memory in it */
+  USED_MEM *used;                  /* blocks almost without free memory */
+  USED_MEM *pre_alloc;             /* preallocated block */
+  /* if block have less memory it will be put in 'used' list*/
+  unsigned int	min_malloc;
+  unsigned int	block_size;        /* initial block size */
+  unsigned int	block_num;         /* allocated blocks counter */
+
+  void (*error_handler)(void);
+} MEM_ROOT;
+#endif

include/my_sys.h

@@ -464,26 +464,7 @@ typedef struct st_changeable_var {
 } CHANGEABLE_VAR;
 
 
-/* structs for alloc_root */
-
-#ifndef ST_USED_MEM_DEFINED
-#define ST_USED_MEM_DEFINED
-typedef struct st_used_mem {			/* struct for once_alloc */
-  struct st_used_mem *next;			/* Next block in use */
-  unsigned int left;				/* memory left in block  */
-  unsigned int size;				/* Size of block */
-} USED_MEM;
-
-typedef struct st_mem_root {
-  USED_MEM *free;
-  USED_MEM *used;
-  USED_MEM *pre_alloc;
-  unsigned int	min_malloc;
-  unsigned int	block_size;
-
-  void (*error_handler)(void);
-} MEM_ROOT;
-#endif
+#include "my_alloc.h"
 
 	/* Prototypes for mysys and my_func functions */
 

include/mysql.h

@@ -100,23 +100,7 @@ typedef struct st_mysql_rows {
 
 typedef MYSQL_ROWS *MYSQL_ROW_OFFSET;	/* offset to current row */
 
-#ifndef ST_USED_MEM_DEFINED
-#define ST_USED_MEM_DEFINED
-typedef struct st_used_mem {			/* struct for once_alloc */
-  struct st_used_mem *next;			/* Next block in use */
-  unsigned int	left;				/* memory left in block  */
-  unsigned int	size;				/* size of block */
-} USED_MEM;
-typedef struct st_mem_root {
-  USED_MEM *free;
-  USED_MEM *used;
-  USED_MEM *pre_alloc;
-  unsigned int	min_malloc;
-  unsigned int	block_size;
-
-  void (*error_handler)(void);
-} MEM_ROOT;
-#endif
+#include "my_alloc.h"
 
 typedef struct st_mysql_data {
   my_ulonglong rows;

mysys/my_alloc.c

@@ -29,6 +29,7 @@ void init_alloc_root(MEM_ROOT *mem_root, uint block_size,
   mem_root->min_malloc=32;
   mem_root->block_size=block_size-MALLOC_OVERHEAD-sizeof(USED_MEM)-8;
   mem_root->error_handler=0;
+  mem_root->block_num= 0;
 #if !(defined(HAVE_purify) && defined(EXTRA_DEBUG))
   if (pre_alloc_size)
   {
@@ -61,25 +62,20 @@ gptr alloc_root(MEM_ROOT *mem_root,unsigned int Size)
   mem_root->used=next;
   return (gptr) (((char*) next)+ALIGN_SIZE(sizeof(USED_MEM)));
 #else
-  uint get_size,max_left;
+  uint get_size, block_size;
   gptr point;
   reg1 USED_MEM *next;
   reg2 USED_MEM **prev;
 
   Size= ALIGN_SIZE(Size);
   prev= &mem_root->free;
-  max_left=0;
   for (next= *prev ; next && next->left < Size ; next= next->next)
-  {
-    if (next->left > max_left)
-      max_left=next->left;
     prev= &next->next;
-  }
   if (! next)
   {						/* Time to alloc new block */
+    block_size= mem_root->block_size*((mem_root->block_num>>2)+1);
     get_size= Size+ALIGN_SIZE(sizeof(USED_MEM));
-    if (max_left*4 < mem_root->block_size && get_size < mem_root->block_size)
-      get_size=mem_root->block_size;		/* Normal alloc */
+    get_size= max(get_size, block_size);
 
     if (!(next = (USED_MEM*) my_malloc(get_size,MYF(MY_WME))))
     {
@@ -87,6 +83,7 @@ gptr alloc_root(MEM_ROOT *mem_root,unsigned int Size)
 	(*mem_root->error_handler)();
       return((gptr) 0);				/* purecov: inspected */
     }
+    mem_root->block_num++;
     next->next= *prev;
     next->size= get_size;
     next->left= get_size-ALIGN_SIZE(sizeof(USED_MEM));
@@ -165,7 +162,10 @@ void free_root(MEM_ROOT *root, myf MyFlags)
     root->free=root->pre_alloc;
     root->free->left=root->pre_alloc->size-ALIGN_SIZE(sizeof(USED_MEM));
     root->free->next=0;
+    root->block_num= 1;
   }
+  else
+    root->block_num= 0;
   DBUG_VOID_RETURN;
 }