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.

1 files changed, 6 insertions, 8 deletions

diff --git a/sql/sql_plugin.h b/sql/sql_plugin.h
index e7ecca029b9..079dc4e6dca 100644
--- a/sql/sql_plugin.h
+++ b/sql/sql_plugin.h
@@ -30,8 +30,6 @@
 #include "m_string.h"                       /* LEX_STRING */
 #include "my_alloc.h"                       /* MEM_ROOT */
 
-#include "my_sys.h"                         /* CALLER_INFO_PROTO */
-
 class sys_var;
 enum SHOW_COMP_OPTION { SHOW_OPTION_YES, SHOW_OPTION_NO, SHOW_OPTION_DISABLED};
 
@@ -134,13 +132,13 @@ extern int plugin_init(int *argc, char **argv, int init_flags);
 extern void plugin_shutdown(void);
 void add_plugin_options(DYNAMIC_ARRAY *options, MEM_ROOT *mem_root);
 extern bool plugin_is_ready(const LEX_STRING *name, int type);
-#define my_plugin_lock_by_name(A,B,C) plugin_lock_by_name(A,B,C CALLER_INFO)
-#define my_plugin_lock_by_name_ci(A,B,C) plugin_lock_by_name(A,B,C ORIG_CALLER_INFO)
-#define my_plugin_lock(A,B) plugin_lock(A,B CALLER_INFO)
-#define my_plugin_lock_ci(A,B) plugin_lock(A,B ORIG_CALLER_INFO)
-extern plugin_ref plugin_lock(THD *thd, plugin_ref *ptr CALLER_INFO_PROTO);
+#define my_plugin_lock_by_name(A,B,C) plugin_lock_by_name(A,B,C)
+#define my_plugin_lock_by_name_ci(A,B,C) plugin_lock_by_name(A,B,C)
+#define my_plugin_lock(A,B) plugin_lock(A,B)
+#define my_plugin_lock_ci(A,B) plugin_lock(A,B)
+extern plugin_ref plugin_lock(THD *thd, plugin_ref *ptr);
 extern plugin_ref plugin_lock_by_name(THD *thd, const LEX_STRING *name,
-                                      int type CALLER_INFO_PROTO);
+                                      int type);
 extern void plugin_unlock(THD *thd, plugin_ref plugin);
 extern void plugin_unlock_list(THD *thd, plugin_ref *list, uint count);
 extern bool mysql_install_plugin(THD *thd, const LEX_STRING *name,