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, 46 insertions, 56 deletions

diff --git a/client/mysqltest.cc b/client/mysqltest.cc
index 75b23ea9af7..1d821c18111 100644
--- a/client/mysqltest.cc
+++ b/client/mysqltest.cc
@@ -84,10 +84,10 @@ static my_bool get_one_option(int optid, const struct my_option *,
 C_MODE_END
 
 enum {
-  OPT_SKIP_SAFEMALLOC=OPT_MAX_CLIENT_OPTION,
-  OPT_PS_PROTOCOL, OPT_SP_PROTOCOL, OPT_CURSOR_PROTOCOL, OPT_VIEW_PROTOCOL,
-  OPT_MAX_CONNECT_RETRIES, OPT_MAX_CONNECTIONS, OPT_MARK_PROGRESS,
-  OPT_LOG_DIR, OPT_TAIL_LINES, OPT_RESULT_FORMAT_VERSION
+  OPT_PS_PROTOCOL=OPT_MAX_CLIENT_OPTION, OPT_SP_PROTOCOL,
+  OPT_CURSOR_PROTOCOL, OPT_VIEW_PROTOCOL, OPT_MAX_CONNECT_RETRIES,
+  OPT_MAX_CONNECTIONS, OPT_MARK_PROGRESS, OPT_LOG_DIR,
+  OPT_TAIL_LINES, OPT_RESULT_FORMAT_VERSION
 };
 
 static int record= 0, opt_sleep= -1;
@@ -156,7 +156,7 @@ static struct st_block *cur_block, *block_stack_end;
 struct st_test_file
 {
   FILE* file;
-  const char *file_name;
+  char *file_name;
   uint lineno; /* Current line in file */
 };
 
@@ -1106,9 +1106,9 @@ void close_connections()
     mysql_close(&next_con->mysql);
     if (next_con->util_mysql)
       mysql_close(next_con->util_mysql);
-    my_free(next_con->name, MYF(MY_ALLOW_ZERO_PTR));
+    my_free(next_con->name);
   }
-  my_free(connections, MYF(MY_WME));
+  my_free(connections);
   DBUG_VOID_RETURN;
 }
 
@@ -1137,7 +1137,7 @@ void close_files()
       DBUG_PRINT("info", ("closing file: %s", cur_file->file_name));
       fclose(cur_file->file);
     }
-    my_free((uchar*) cur_file->file_name, MYF(MY_ALLOW_ZERO_PTR));
+    my_free(cur_file->file_name);
     cur_file->file_name= 0;
   }
   DBUG_VOID_RETURN;
@@ -1157,22 +1157,22 @@ void free_used_memory()
   for (i= 0 ; i < q_lines.elements ; i++)
   {
     struct st_command **q= dynamic_element(&q_lines, i, struct st_command**);
-    my_free((*q)->query_buf,MYF(MY_ALLOW_ZERO_PTR));
+    my_free((*q)->query_buf);
     if ((*q)->content.str)
       dynstr_free(&(*q)->content);
-    my_free((*q),MYF(0));
+    my_free((*q));
   }
   for (i= 0; i < 10; i++)
   {
     if (var_reg[i].alloced_len)
-      my_free(var_reg[i].str_val, MYF(MY_WME));
+      my_free(var_reg[i].str_val);
   }
   while (embedded_server_arg_count > 1)
-    my_free(embedded_server_args[--embedded_server_arg_count],MYF(0));
+    my_free(embedded_server_args[--embedded_server_arg_count]);
   delete_dynamic(&q_lines);
   dynstr_free(&ds_res);
   free_all_replace();
-  my_free(opt_pass,MYF(MY_ALLOW_ZERO_PTR));
+  my_free(opt_pass);
   free_defaults(default_argv);
   free_re();
 #ifdef __WIN__
@@ -1933,9 +1933,10 @@ static uchar *get_var_key(const uchar* var, size_t *len,
 
 static void var_free(void *v)
 {
-  my_free(((VAR*) v)->str_val, MYF(MY_WME));
-  if (((VAR*)v)->alloced)
-    my_free(v, MYF(MY_WME));
+  VAR *var= (VAR*) v;
+  my_free(var->str_val);
+  if (var->alloced)
+    my_free(var);
 }
 
 C_MODE_END
@@ -4824,7 +4825,7 @@ void do_close_connection(struct st_command *command)
   con->util_mysql= 0;
   con->pending= FALSE;
   
-  my_free(con->name, MYF(0));
+  my_free(con->name);
 
   /*
     When the connection is closed set name to "-closed_connection-"
@@ -5491,7 +5492,7 @@ int read_line(char *buf, int size)
 	fclose(cur_file->file);
         cur_file->file= 0;
       }
-      my_free((uchar*) cur_file->file_name, MYF(MY_ALLOW_ZERO_PTR));
+      my_free(cur_file->file_name);
       cur_file->file_name= 0;
       if (cur_file == file_stack)
       {
@@ -5967,9 +5968,6 @@ static struct my_option my_long_options[] =
    0, 0, 0},
   {"silent", 's', "Suppress all normal output. Synonym for --quiet.",
    &silent, &silent, 0, GET_BOOL, NO_ARG, 0, 0, 0, 0, 0, 0},
-  {"skip-safemalloc", OPT_SKIP_SAFEMALLOC,
-   "Don't use the memory allocation checking.", 0, 0, 0, GET_NO_ARG, NO_ARG,
-   0, 0, 0, 0, 0, 0},
   {"sleep", 'T', "Always sleep this many seconds on sleep commands.",
    &opt_sleep, &opt_sleep, 0, GET_INT, REQUIRED_ARG, -1, -1, 0,
    0, 0, 0},
@@ -6125,7 +6123,7 @@ get_one_option(int optid, const struct my_option *, char *argument)
       argument= (char*) "";			// Don't require password
     if (argument)
     {
-      my_free(opt_pass, MYF(MY_ALLOW_ZERO_PTR));
+      my_free(opt_pass);
       opt_pass= my_strdup(argument, MYF(MY_FAE));
       while (*argument) *argument++= 'x';		/* Destroy argument */
       tty_password= 0;
@@ -6158,11 +6156,6 @@ get_one_option(int optid, const struct my_option *, char *argument)
   case 'F':
     read_embedded_server_arguments(argument);
     break;
-  case OPT_SKIP_SAFEMALLOC:
-#ifdef SAFEMALLOC
-    sf_malloc_quick=1;
-#endif
-    break;
   case OPT_RESULT_FORMAT_VERSION:
     set_result_format_version(opt_result_format_version);
     break;
@@ -6321,7 +6314,7 @@ void init_win_path_patterns()
     /* Don't insert zero length strings in patterns array */
     if (strlen(p) == 0)
     {
-      my_free(p, MYF(0));
+      my_free(p);
       continue;
     }
 
@@ -6345,7 +6338,7 @@ void free_win_path_patterns()
   for (i=0 ; i < patterns.elements ; i++)
   {
     const char** pattern= dynamic_element(&patterns, i, const char**);
-    my_free((char*) *pattern, MYF(0));
+    my_free(*pattern);
   }
   delete_dynamic(&patterns);
 }
@@ -6538,12 +6531,12 @@ void append_stmt_result(DYNAMIC_STRING *ds, MYSQL_STMT *stmt,
   for (i= 0; i < num_fields; i++)
   {
     /* Free data for output */
-    my_free(my_bind[i].buffer, MYF(MY_WME | MY_FAE));
+    my_free(my_bind[i].buffer);
   }
   /* Free array with bind structs, lengths and NULL flags */
-  my_free(my_bind    , MYF(MY_WME | MY_FAE));
-  my_free(length  , MYF(MY_WME | MY_FAE));
-  my_free(is_null , MYF(MY_WME | MY_FAE));
+  my_free(my_bind);
+  my_free(length);
+  my_free(is_null);
 }
 
 
@@ -8489,11 +8482,11 @@ void do_get_replace_column(struct st_command *command)
     if (!*from)
       die("Wrong number of arguments to replace_column in '%s'", command->query);
     to= get_string(&buff, &from, command);
-    my_free(replace_column[column_number-1], MY_ALLOW_ZERO_PTR);
+    my_free(replace_column[column_number-1]);
     replace_column[column_number-1]= my_strdup(to, MYF(MY_WME | MY_FAE));
     set_if_bigger(max_replace_column, column_number);
   }
-  my_free(start, MYF(0));
+  my_free(start);
   command->last_argument= command->end;
 
   DBUG_VOID_RETURN;
@@ -8507,7 +8500,7 @@ void free_replace_column()
   {
     if (replace_column[i])
     {
-      my_free(replace_column[i], 0);
+      my_free(replace_column[i]);
       replace_column[i]= 0;
     }
   }
@@ -8588,7 +8581,7 @@ void do_get_replace(struct st_command *command)
     die("Can't initialize replace from '%s'", command->query);
   free_pointer_array(&from_array);
   free_pointer_array(&to_array);
-  my_free(start, MYF(0));
+  my_free(start);
   command->last_argument= command->end;
   DBUG_VOID_RETURN;
 }
@@ -8597,11 +8590,8 @@ void do_get_replace(struct st_command *command)
 void free_replace()
 {
   DBUG_ENTER("free_replace");
-  if (glob_replace)
-  {
-    my_free(glob_replace,MYF(0));
-    glob_replace=0;
-  }
+  my_free(glob_replace);
+  glob_replace= NULL;
   DBUG_VOID_RETURN;
 }
 
@@ -8821,7 +8811,7 @@ struct st_replace_regex* init_replace_regex(char* expr)
   return res;
 
 err:
-  my_free(res,0);
+  my_free(res);
   die("Error parsing replace_regex \"%s\"", expr);
   return 0;
 }
@@ -8913,9 +8903,9 @@ void free_replace_regex()
   if (glob_replace_regex)
   {
     delete_dynamic(&glob_replace_regex->regex_arr);
-    my_free(glob_replace_regex->even_buf,MYF(MY_ALLOW_ZERO_PTR));
-    my_free(glob_replace_regex->odd_buf,MYF(MY_ALLOW_ZERO_PTR));
-    my_free(glob_replace_regex,MYF(0));
+    my_free(glob_replace_regex->even_buf);
+    my_free(glob_replace_regex->odd_buf);
+    my_free(glob_replace_regex);
     glob_replace_regex=0;
   }
 }
@@ -9110,7 +9100,7 @@ int reg_replace(char** buf_p, int* buf_len_p, char *pattern,
       str_p= str_end;
     }
   }
-  my_free(subs, MYF(0));
+  my_free(subs);
   my_regfree(&r);
   *res_p= 0;
   *buf_p= buf;
@@ -9242,7 +9232,7 @@ 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(found_set,MYF(0));
+    my_free(found_set);
     DBUG_RETURN(0);
   }
 
@@ -9437,9 +9427,9 @@ REPLACE *init_replace(char * *from, char * *to,uint count,
 	  replace[i].next[j]=(REPLACE*) (rep_str+(-sets.set[i].next[j]-1));
     }
   }
-  my_free(follow,MYF(0));
+  my_free(follow);
   free_sets(&sets);
-  my_free(found_set,MYF(0));
+  my_free(found_set);
   DBUG_PRINT("exit",("Replace table has %d states",sets.count));
   DBUG_RETURN(replace);
 }
@@ -9455,7 +9445,7 @@ 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(sets->set,MYF(0));
+    my_free(sets->set);
     return 1;
   }
   return 0;
@@ -9516,8 +9506,8 @@ void free_last_set(REP_SETS *sets)
 
 void free_sets(REP_SETS *sets)
 {
-  my_free(sets->set_buffer,MYF(0));
-  my_free(sets->bit_buffer,MYF(0));
+  my_free(sets->set_buffer);
+  my_free(sets->bit_buffer);
   return;
 }
 
@@ -9657,7 +9647,7 @@ 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((char*) pa->typelib.type_names,MYF(0));
+      my_free(pa->typelib.type_names);
       DBUG_RETURN (-1);
     }
     pa->max_count=(PC_MALLOC-MALLOC_OVERHEAD)/(sizeof(uchar*)+
@@ -9718,9 +9708,9 @@ void free_pointer_array(POINTER_ARRAY *pa)
   if (pa->typelib.count)
   {
     pa->typelib.count=0;
-    my_free((char*) pa->typelib.type_names,MYF(0));
+    my_free(pa->typelib.type_names);
     pa->typelib.type_names=0;
-    my_free(pa->str,MYF(0));
+    my_free(pa->str);
   }
 } /* free_pointer_array */