allocated bigger blocks if it needed

include/my_sys.h:
  memory root structures definition put in one file
include/mysql.h:
  memory root structures definition put in one file

include/my_alloc.h

@@ -0,0 +1,39 @@
+/* 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