Merge bk-internal.mysql.com:/home/bk/mysql-4.1

into mysql.com:/home/dlenev/src/mysql-4.1-memroot


sql/sql_class.cc:
  Auto merged
sql/sql_class.h:
  Auto merged

1 files changed, 32 insertions, 5 deletions

diff --git a/mysys/my_alloc.c b/mysys/my_alloc.c
index c9784ddc9a0..f0bc62b10a0 100644
--- a/mysys/my_alloc.c
+++ b/mysys/my_alloc.c
@@ -22,6 +22,27 @@
 #undef EXTRA_DEBUG
 #define EXTRA_DEBUG
 
+
+/*
+  Initialize memory root
+
+  SYNOPSIS
+    init_alloc_root()
+      mem_root       - memory root to initialize
+      block_size     - size of chunks (blocks) used for memory allocation
+                       (It is external size of chunk i.e. it should include
+                        memory required for internal structures, thus it
+                        should be no less than ALLOC_ROOT_MIN_BLOCK_SIZE)
+      pre_alloc_size - if non-0, then size of block that should be
+                       pre-allocated during memory root initialization.
+
+  DESCRIPTION
+    This function prepares memory root for further use, sets initial size of
+    chunk for memory allocation and pre-allocates first block if specified.
+    Altough error can happen during execution of this function if pre_alloc_size
+    is non-0 it won't be reported. Instead it will be reported as error in first
+    alloc_root() on this memory root.
+*/
 void init_alloc_root(MEM_ROOT *mem_root, uint block_size,
 		     uint pre_alloc_size __attribute__((unused)))
 {
@@ -29,7 +50,7 @@ void init_alloc_root(MEM_ROOT *mem_root, uint block_size,
   DBUG_PRINT("enter",("root: 0x%lx", mem_root));
   mem_root->free= mem_root->used= mem_root->pre_alloc= 0;
   mem_root->min_malloc= 32;
-  mem_root->block_size= block_size-MALLOC_OVERHEAD-sizeof(USED_MEM)-8;
+  mem_root->block_size= block_size - ALLOC_ROOT_MIN_BLOCK_SIZE;
   mem_root->error_handler= 0;
   mem_root->block_num= 4;			/* We shift this with >>2 */
   mem_root->first_block_usage= 0;
@@ -54,9 +75,9 @@ void init_alloc_root(MEM_ROOT *mem_root, uint block_size,
   SYNOPSIS
     reset_root_defaults()
     mem_root        memory root to change defaults of
-    block_size      new value of block size. Must be 
-                    greater than ~68 bytes (the exact value depends on
-                    platform and compilation flags)
+    block_size      new value of block size. Must be greater or equal
+                    than ALLOC_ROOT_MIN_BLOCK_SIZE (this value is about
+                    68 bytes and depends on platform and compilation flags)
     pre_alloc_size  new size of preallocated block. If not zero,
                     must be equal to or greater than block size,
                     otherwise means 'no prealloc'.
@@ -70,7 +91,9 @@ void init_alloc_root(MEM_ROOT *mem_root, uint block_size,
 void reset_root_defaults(MEM_ROOT *mem_root, uint block_size,
                          uint pre_alloc_size __attribute__((unused)))
 {
-  mem_root->block_size= block_size-MALLOC_OVERHEAD-sizeof(USED_MEM)-8;
+  DBUG_ASSERT(alloc_root_inited(mem_root));
+
+  mem_root->block_size= block_size - ALLOC_ROOT_MIN_BLOCK_SIZE;
 #if !(defined(HAVE_purify) && defined(EXTRA_DEBUG))
   if (pre_alloc_size)
   {
@@ -123,6 +146,8 @@ gptr alloc_root(MEM_ROOT *mem_root,unsigned int Size)
   DBUG_ENTER("alloc_root");
   DBUG_PRINT("enter",("root: 0x%lx", mem_root));
 
+  DBUG_ASSERT(alloc_root_inited(mem_root));
+
   Size+=ALIGN_SIZE(sizeof(USED_MEM));
   if (!(next = (USED_MEM*) my_malloc(Size,MYF(MY_WME))))
   {
@@ -140,6 +165,8 @@ gptr alloc_root(MEM_ROOT *mem_root,unsigned int Size)
   reg1 USED_MEM *next= 0;
   reg2 USED_MEM **prev;
 
+  DBUG_ASSERT(alloc_root_inited(mem_root));
+
   Size= ALIGN_SIZE(Size);
   if ((*(prev= &mem_root->free)) != NULL)
   {