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.

1 files changed, 16 insertions, 66 deletions

diff --git a/include/my_sys.h b/include/my_sys.h
index 29c78289a1b..64b20753567 100644
--- a/include/my_sys.h
+++ b/include/my_sys.h
@@ -158,46 +158,15 @@ extern int NEAR my_errno;		/* Last error in mysys */
 #define GETDATE_FIXEDLENGTH	16
 
 	/* defines when allocating data */
-#ifdef SAFEMALLOC
-#define my_malloc(SZ,FLAG) _mymalloc((SZ), __FILE__, __LINE__, FLAG )
-#define my_malloc_ci(SZ,FLAG) _mymalloc((SZ), sFile, uLine, FLAG )
-#define my_realloc(PTR,SZ,FLAG) _myrealloc((PTR), (SZ), __FILE__, __LINE__, FLAG )
-#define my_checkmalloc() _sanity( __FILE__, __LINE__ )
-#define my_free(PTR,FLAG) _myfree((PTR), __FILE__, __LINE__,FLAG)
-#define my_memdup(A,B,C) _my_memdup((A),(B), __FILE__,__LINE__,C)
-#define my_strdup(A,C) _my_strdup((A), __FILE__,__LINE__,C)
-#define my_strndup(A,B,C) _my_strndup((A),(B),__FILE__,__LINE__,C)
-#define TRASH(A,B) do { bfill(A, B, 0x8F); MEM_UNDEFINED(A, B); } while (0)
-#define QUICK_SAFEMALLOC sf_malloc_quick=1
-#define NORMAL_SAFEMALLOC sf_malloc_quick=0
-extern uint sf_malloc_prehunc,sf_malloc_endhunc,sf_malloc_quick;
-extern ulonglong sf_malloc_mem_limit;
-
-#define CALLER_INFO_PROTO   , const char *sFile, uint uLine
-#define CALLER_INFO         , __FILE__, __LINE__
-#define ORIG_CALLER_INFO    , sFile, uLine
-#else
-#define my_checkmalloc()
-#undef TERMINATE
-#define TERMINATE(A,B) {}
-#define QUICK_SAFEMALLOC
-#define NORMAL_SAFEMALLOC
 extern void *my_malloc(size_t Size,myf MyFlags);
-#define my_malloc_ci(SZ,FLAG) my_malloc( SZ, FLAG )
+extern void *my_multi_malloc(myf MyFlags, ...);
 extern void *my_realloc(void *oldpoint, size_t Size, myf MyFlags);
-extern void my_no_flags_free(void *ptr);
+extern void my_free(void *ptr);
 extern void *my_memdup(const void *from,size_t length,myf MyFlags);
 extern char *my_strdup(const char *from,myf MyFlags);
 extern char *my_strndup(const char *from, size_t length,
 				   myf MyFlags);
-/* we do use FG (as a no-op) in below so that a typo on FG is caught */
-#define my_free(PTR,FG) ((void)FG,my_no_flags_free(PTR))
-#define CALLER_INFO_PROTO   /* nothing */
-#define CALLER_INFO         /* nothing */
-#define ORIG_CALLER_INFO    /* nothing */
 #define TRASH(A,B) do{MEM_CHECK_ADDRESSABLE(A,B);MEM_UNDEFINED(A,B);} while (0)
-#endif
-
 #if defined(ENABLED_DEBUG_SYNC)
 extern void (*debug_sync_C_callback_ptr)(const char *, size_t);
 #define DEBUG_SYNC_C(_sync_point_name_) do {                            \
@@ -211,11 +180,11 @@ extern void (*debug_sync_C_callback_ptr)(const char *, size_t);
 #ifdef HAVE_LARGE_PAGES
 extern uint my_get_large_page_size(void);
 extern uchar * my_large_malloc(size_t size, myf my_flags);
-extern void my_large_free(uchar * ptr, myf my_flags);
+extern void my_large_free(uchar *ptr);
 #else
 #define my_get_large_page_size() (0)
 #define my_large_malloc(A,B) my_malloc_lock((A),(B))
-#define my_large_free(A,B) my_free_lock((A),(B))
+#define my_large_free(A) my_free_lock((A))
 #endif /* HAVE_LARGE_PAGES */
 
 #ifdef HAVE_ALLOCA
@@ -233,7 +202,7 @@ extern void my_large_free(uchar * ptr, myf my_flags);
 #define my_afree(PTR) {}
 #else
 #define my_alloca(SZ) my_malloc(SZ,MYF(0))
-#define my_afree(PTR) my_free(PTR,MYF(MY_WME))
+#define my_afree(PTR) my_free(PTR)
 #endif /* HAVE_ALLOCA */
 
 #ifndef errno				/* did we already get it? */
@@ -642,20 +611,6 @@ extern size_t my_fwrite(FILE *stream,const uchar *Buffer,size_t Count,
 		      myf MyFlags);
 extern my_off_t my_fseek(FILE *stream,my_off_t pos,int whence,myf MyFlags);
 extern my_off_t my_ftell(FILE *stream,myf MyFlags);
-extern void *_mymalloc(size_t uSize,const char *sFile,
-                       uint uLine, myf MyFlag);
-extern void *_myrealloc(void *pPtr,size_t uSize,const char *sFile,
-		       uint uLine, myf MyFlag);
-extern void * my_multi_malloc _VARARGS((myf MyFlags, ...));
-extern void _myfree(void *pPtr,const char *sFile,uint uLine, myf MyFlag);
-extern int _sanity(const char *sFile, uint uLine);
-extern void *_my_memdup(const void *from, size_t length,
-                        const char *sFile, uint uLine,myf MyFlag);
-extern char * _my_strdup(const char *from, const char *sFile, uint uLine,
-                         myf MyFlag);
-extern char *_my_strndup(const char *from, size_t length,
-                         const char *sFile, uint uLine,
-                         myf MyFlag);
 
 /* implemented in my_memmem.c */
 extern void *my_memmem(const void *haystack, size_t haystacklen,
@@ -684,9 +639,6 @@ extern HANDLE   my_get_osfhandle(File fd);
 extern void     my_osmaperr(unsigned long last_error);
 #endif
 
-#ifndef TERMINATE
-extern void TERMINATE(FILE *file, uint flag);
-#endif
 extern void init_glob_errs(void);
 extern const char** get_global_errmsgs();
 extern void wait_for_free_space(const char *filename, int errors);
@@ -835,18 +787,16 @@ extern my_bool real_open_cached_file(IO_CACHE *cache);
 extern void close_cached_file(IO_CACHE *cache);
 File create_temp_file(char *to, const char *dir, const char *pfx,
 		      int mode, myf MyFlags);
-#define my_init_dynamic_array(A,B,C,D) init_dynamic_array2(A,B,NULL,C,D CALLER_INFO)
-#define my_init_dynamic_array_ci(A,B,C,D) init_dynamic_array2(A,B,NULL,C,D ORIG_CALLER_INFO)
-#define my_init_dynamic_array2(A,B,C,D,E) init_dynamic_array2(A,B,C,D,E CALLER_INFO)
-#define my_init_dynamic_array2_ci(A,B,C,D,E) init_dynamic_array2(A,B,C,D,E ORIG_CALLER_INFO)
-extern my_bool init_dynamic_array2(DYNAMIC_ARRAY *array,uint element_size,
-                                   void *init_buffer, uint init_alloc, 
-                                   uint alloc_increment
-                                   CALLER_INFO_PROTO);
+#define my_init_dynamic_array(A,B,C,D) init_dynamic_array2(A,B,NULL,C,D)
+#define my_init_dynamic_array_ci(A,B,C,D) init_dynamic_array2(A,B,NULL,C,D)
+#define my_init_dynamic_array2(A,B,C,D,E) init_dynamic_array2(A,B,C,D,E)
+#define my_init_dynamic_array2_ci(A,B,C,D,E) init_dynamic_array2(A,B,C,D,E)
+extern my_bool init_dynamic_array2(DYNAMIC_ARRAY *array, uint element_size,
+                                   void *init_buffer, uint init_alloc,
+                                   uint alloc_increment);
 /* init_dynamic_array() function is deprecated */
-extern my_bool init_dynamic_array(DYNAMIC_ARRAY *array,uint element_size,
-                                  uint init_alloc,uint alloc_increment
-                                  CALLER_INFO_PROTO);
+extern my_bool init_dynamic_array(DYNAMIC_ARRAY *array, uint element_size,
+                                  uint init_alloc, uint alloc_increment);
 extern my_bool insert_dynamic(DYNAMIC_ARRAY *array,uchar * element);
 extern uchar *alloc_dynamic(DYNAMIC_ARRAY *array);
 extern uchar *pop_dynamic(DYNAMIC_ARRAY*);
@@ -876,10 +826,10 @@ extern my_bool dynstr_trunc(DYNAMIC_STRING *str, size_t n);
 extern void dynstr_free(DYNAMIC_STRING *str);
 #ifdef HAVE_MLOCK
 extern void *my_malloc_lock(size_t length,myf flags);
-extern void my_free_lock(void *ptr,myf flags);
+extern void my_free_lock(void *ptr);
 #else
 #define my_malloc_lock(A,B) my_malloc((A),(B))
-#define my_free_lock(A,B) my_free((A),(B))
+#define my_free_lock(A) my_free((A))
 #endif
 #define alloc_root_inited(A) ((A)->min_malloc != 0)
 #define ALLOC_ROOT_MIN_BLOCK_SIZE (MALLOC_OVERHEAD + sizeof(USED_MEM) + 8)