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.

3 files changed, 24 insertions, 24 deletions

diff --git a/extra/comp_err.c b/extra/comp_err.c
index 53d8c18262b..c85aef7bcc5 100644
--- a/extra/comp_err.c
+++ b/extra/comp_err.c
@@ -387,15 +387,15 @@ static void clean_up(struct languages *lang_head, struct errors *error_head)
   struct errors *tmp_error, *next_error;
   uint count, i;
 
-  my_free((uchar*) default_language, MYF(0));
+  my_free((void*) default_language);
 
   for (tmp_lang= lang_head; tmp_lang; tmp_lang= next_language)
   {
     next_language= tmp_lang->next_lang;
-    my_free(tmp_lang->lang_short_name, MYF(0));
-    my_free(tmp_lang->lang_long_name, MYF(0));
-    my_free(tmp_lang->charset, MYF(0));
-    my_free((uchar*) tmp_lang, MYF(0));
+    my_free(tmp_lang->lang_short_name);
+    my_free(tmp_lang->lang_long_name);
+    my_free(tmp_lang->charset);
+    my_free(tmp_lang);
   }
 
   for (tmp_error= error_head; tmp_error; tmp_error= next_error)
@@ -406,17 +406,17 @@ static void clean_up(struct languages *lang_head, struct errors *error_head)
     {
       struct message *tmp;
       tmp= dynamic_element(&tmp_error->msg, i, struct message*);
-      my_free((uchar*) tmp->lang_short_name, MYF(0));
-      my_free((uchar*) tmp->text, MYF(0));
+      my_free(tmp->lang_short_name);
+      my_free(tmp->text);
     }
 
     delete_dynamic(&tmp_error->msg);
     if (tmp_error->sql_code1[0])
-      my_free((uchar*) tmp_error->sql_code1, MYF(0));
+      my_free((void*) tmp_error->sql_code1);
     if (tmp_error->sql_code2[0])
-      my_free((uchar*) tmp_error->sql_code2, MYF(0));
-    my_free((uchar*) tmp_error->er_name, MYF(0));
-    my_free((uchar*) tmp_error, MYF(0));
+      my_free((void*) tmp_error->sql_code2);
+    my_free((void*) tmp_error->er_name);
+    my_free(tmp_error);
   }
 }
 
@@ -559,7 +559,7 @@ static uint parse_error_offset(char *str)
 
   end= 0;
   ioffset= (uint) my_strtoll10(soffset, &end, &error);
-  my_free((uchar*) soffset, MYF(0));
+  my_free(soffset);
   DBUG_RETURN(ioffset);
 }
 
diff --git a/extra/my_print_defaults.c b/extra/my_print_defaults.c
index 9595e1b2df8..81416df2922 100644
--- a/extra/my_print_defaults.c
+++ b/extra/my_print_defaults.c
@@ -200,7 +200,7 @@ int main(int argc, char **argv)
   for (argument= arguments+1 ; *argument ; argument++)
     if (*argument != args_separator)           /* skip arguments separator */
       puts(*argument);
-  my_free((char*) load_default_groups,MYF(0));
+  my_free(load_default_groups);
   free_defaults(arguments);
 
   exit(0);
diff --git a/extra/replace.c b/extra/replace.c
index 3f07183807c..1a887ac3e21 100644
--- a/extra/replace.c
+++ b/extra/replace.c
@@ -262,7 +262,7 @@ static int insert_pointer_name(reg1 POINTER_ARRAY *pa,char * name)
     if (!(pa->str= (uchar*) my_malloc((uint) (PS_MALLOC-MALLOC_OVERHEAD),
 				     MYF(MY_WME))))
     {
-      my_free((uchar*) pa->typelib.type_names,MYF(0));
+      my_free(pa->typelib.type_names);
       DBUG_RETURN (-1);
     }
     pa->max_count=(PC_MALLOC-MALLOC_OVERHEAD)/(sizeof(uchar*)+
@@ -324,9 +324,9 @@ static void free_pointer_array(reg1 POINTER_ARRAY *pa)
   if (pa->typelib.count)
   {
     pa->typelib.count=0;
-    my_free((uchar*) pa->typelib.type_names,MYF(0));
+    my_free(pa->typelib.type_names);
     pa->typelib.type_names=0;
-    my_free((uchar*) pa->str,MYF(0));
+    my_free(pa->str);
   }
   return;
 } /* free_pointer_array */
@@ -441,7 +441,7 @@ static REPLACE *init_replace(char * *from, char * *to,uint count,
   if (!(follow=(FOLLOWS*) my_malloc((states+2)*sizeof(FOLLOWS),MYF(MY_WME))))
   {
     free_sets(&sets);
-    my_free((uchar*) found_set,MYF(0));
+    my_free(found_set);
     DBUG_RETURN(0);
   }
 
@@ -663,9 +663,9 @@ static REPLACE *init_replace(char * *from, char * *to,uint count,
 	  replace[i].next[j]=(REPLACE*) (rep_str+(-sets.set[i].next[j]-1));
     }
   }
-  my_free((uchar*) follow,MYF(0));
+  my_free(follow);
   free_sets(&sets);
-  my_free((uchar*) found_set,MYF(0));
+  my_free(found_set);
   DBUG_PRINT("exit",("Replace table has %d states",sets.count));
   DBUG_RETURN(replace);
 }
@@ -681,7 +681,7 @@ static int init_sets(REP_SETS *sets,uint states)
   if (!(sets->bit_buffer=(uint*) my_malloc(sizeof(uint)*sets->size_of_bits*
 					   SET_MALLOC_HUNC,MYF(MY_WME))))
   {
-    my_free((uchar*) sets->set,MYF(0));
+    my_free(sets->set);
     return 1;
   }
   return 0;
@@ -742,8 +742,8 @@ static void free_last_set(REP_SETS *sets)
 
 static void free_sets(REP_SETS *sets)
 {
-  my_free((uchar*)sets->set_buffer,MYF(0));
-  my_free((uchar*)sets->bit_buffer,MYF(0));
+  my_free(sets->set_buffer);
+  my_free(sets->bit_buffer);
   return;
 }
 
@@ -950,8 +950,8 @@ static void reset_buffer()
 
 static void free_buffer()
 {
-  my_free(buffer,MYF(MY_WME));
-  my_free(out_buff,MYF(MY_WME));
+  my_free(buffer);
+  my_free(out_buff);
 }