Make SQLString reallocation addaptive

Avoid doing reallocs
Prealloc some strings / provide extension allocation size to some strings
This gave a 25 % speedup in some mysql-test-run tests.



mysys/safemalloc.c:
  More DBUG_PRINT
sql/net_serv.cc:
  Make all mallocs() look the similar. (just-for-safety fix)
sql/protocol.cc:
  Ensure that communication packet buffer is allocated.
  (It's freed by stored precedures and some DLL statements)
sql/sp.cc:
  Fixed valgrind warning
sql/sql_select.cc:
  Set extent allocation for buffer that has a lot of append() calls.
sql/sql_show.cc:
  Fixed wrong usage of string buffer. Old code worked in test suite 'just-by-chance'
sql/sql_string.cc:
  Call realloc_with_extra_if_needed() in append() functions.
sql/sql_string.h:
  Added 'extra_alloc' member, to specify chunck size for realloc().
  extra_alloc is addaptive to catch cases where preallocation of buffers is not done properly.
  Simplified free() to allow compiler to optimize things better (and to keep things consistent).
  Fixed shrink() to take into account the extra memory added to the Alloced_length in realloc(). This saves us a realloc() per query.
sql/sql_test.cc:
  Set extent allocation for buffer that has a lot of append() calls.
sql/table.cc:
  Set extent allocation for buffer that has a lot of append() calls.

mysys/safemalloc.c

@@ -224,6 +224,8 @@ void *_myrealloc(register void *ptr, register size_t size,
   struct st_irem *irem;
   char *data;
   DBUG_ENTER("_myrealloc");
+  DBUG_PRINT("my",("ptr: 0x%lx  size: %lu  my_flags: %d", (long) ptr,
+                   (ulong) size, MyFlags));
 
   if (!ptr && (MyFlags & MY_ALLOW_ZERO_PTR))
     DBUG_RETURN(_mymalloc(size, filename, lineno, MyFlags));
@@ -245,6 +247,8 @@ void *_myrealloc(register void *ptr, register size_t size,
     (void) fflush(stderr);
     DBUG_RETURN((uchar*) NULL);
   }
+  DBUG_PRINT("my", ("old_size: %lu  -> new_size: %lu",
+                    (ulong) irem->datasize, (ulong) size));
 
   if ((data= _mymalloc(size,filename,lineno,MyFlags))) /* Allocate new area */
   {

sql/net_serv.cc

@@ -116,7 +116,7 @@ my_bool my_net_init(NET *net, Vio* vio)
   net->vio = vio;
   my_net_local_init(net);			/* Set some limits */
   if (!(net->buff=(uchar*) my_malloc((size_t) net->max_packet+
-				     NET_HEADER_SIZE + COMP_HEADER_SIZE,
+				     NET_HEADER_SIZE + COMP_HEADER_SIZE +1,
 				     MYF(MY_WME))))
     DBUG_RETURN(1);
   net->buff_end=net->buff+net->max_packet;
@@ -580,7 +580,7 @@ net_real_write(NET *net,const uchar *packet, size_t len)
     uchar *b;
     uint header_length=NET_HEADER_SIZE+COMP_HEADER_SIZE;
     if (!(b= (uchar*) my_malloc(len + NET_HEADER_SIZE +
-                                COMP_HEADER_SIZE, MYF(MY_WME))))
+                                COMP_HEADER_SIZE + 1, MYF(MY_WME))))
     {
       net->error= 2;
       net->last_errno= ER_OUT_OF_RESOURCES;

sql/protocol.cc

@@ -632,6 +632,9 @@ bool Protocol::send_fields(List<Item> *list, uint flags)
   uint count= 0;
 #endif
 
+  /* We have to reallocate it here as a stored procedure may have reset it */
+  (void) local_packet->alloc(thd->variables.net_buffer_length);
+
   while ((item=it++))
   {
     char *pos;

sql/sp.cc

@@ -785,7 +785,7 @@ db_load_routine(THD *thd, int type, sp_name *name, sp_head **sphp,
 
   {
     Parser_state parser_state;
-    if (parser_state.init(thd, defstr.c_ptr(), defstr.length()))
+    if (parser_state.init(thd, defstr.c_ptr_safe(), defstr.length()))
     {
       ret= SP_INTERNAL_ERROR;
       goto end;

sql/sql_select.cc

@@ -15997,6 +15997,7 @@ change_to_use_tmp_fields(THD *thd, Item **ref_pointer_array,
 	  char buff[256];
 	  String str(buff,sizeof(buff),&my_charset_bin);
 	  str.length(0);
+          str.extra_allocation(1024);
 	  item->print(&str, QT_ORDINARY);
 	  item_field->name= sql_strmake(str.ptr(),str.length());
 	}

sql/sql_show.cc

@@ -4329,7 +4329,7 @@ static int get_schema_column_record(THD *thd, TABLE_LIST *tables,
       base_type [(dimension)] [unsigned] [zerofill].
       For DATA_TYPE column we extract only base type.
     */
-    tmp_buff= strchr(type.ptr(), '(');
+    tmp_buff= strchr(type.c_ptr_safe(), '(');
     if (!tmp_buff)
       /*
         if there is no dimention part then check the presence of

sql/sql_string.cc

@@ -411,7 +411,7 @@ bool String::append(const String &s)
 {
   if (s.length())
   {
-    if (realloc(str_length+s.length()))
+    if (realloc_with_extra_if_needed(str_length+s.length()))
       return TRUE;
     memcpy(Ptr+str_length,s.ptr(),s.length());
     str_length+=s.length();
@@ -436,7 +436,7 @@ bool String::append(const char *s,uint32 arg_length)
   {
     uint32 add_length=arg_length * str_charset->mbmaxlen;
     uint dummy_errors;
-    if (realloc(str_length+ add_length))
+    if (realloc_with_extra_if_needed(str_length+ add_length))
       return TRUE;
     str_length+= copy_and_convert(Ptr+str_length, add_length, str_charset,
 				  s, arg_length, &my_charset_latin1,
@@ -447,7 +447,7 @@ bool String::append(const char *s,uint32 arg_length)
   /*
     For an ASCII compatinble string we can just append.
   */
-  if (realloc(str_length+arg_length))
+  if (realloc_with_extra_if_needed(str_length+arg_length))
     return TRUE;
   memcpy(Ptr+str_length,s,arg_length);
   str_length+=arg_length;
@@ -478,14 +478,14 @@ bool String::append(const char *s,uint32 arg_length, CHARSET_INFO *cs)
   {
     uint32 add_length= arg_length / cs->mbminlen * str_charset->mbmaxlen;
     uint dummy_errors;
-    if (realloc(str_length + add_length)) 
+    if (realloc_with_extra_if_needed(str_length + add_length)) 
       return TRUE;
     str_length+= copy_and_convert(Ptr+str_length, add_length, str_charset,
 				  s, arg_length, cs, &dummy_errors);
   }
   else
   {
-    if (realloc(str_length + arg_length)) 
+    if (realloc_with_extra_if_needed(str_length + arg_length)) 
       return TRUE;
     memcpy(Ptr + str_length, s, arg_length);
     str_length+= arg_length;
@@ -497,7 +497,7 @@ bool String::append(const char *s,uint32 arg_length, CHARSET_INFO *cs)
 #ifdef TO_BE_REMOVED
 bool String::append(FILE* file, uint32 arg_length, myf my_flags)
 {
-  if (realloc(str_length+arg_length))
+  if (realloc_with_extra_if_needed(str_length+arg_length))
     return TRUE;
   if (my_fread(file, (uchar*) Ptr + str_length, arg_length, my_flags))
   {
@@ -511,7 +511,7 @@ bool String::append(FILE* file, uint32 arg_length, myf my_flags)
 
 bool String::append(IO_CACHE* file, uint32 arg_length)
 {
-  if (realloc(str_length+arg_length))
+  if (realloc_with_extra_if_needed(str_length+arg_length))
     return TRUE;
   if (my_b_read(file, (uchar*) Ptr + str_length, arg_length))
   {
@@ -527,7 +527,7 @@ bool String::append_with_prefill(const char *s,uint32 arg_length,
 {
   int t_length= arg_length > full_length ? arg_length : full_length;
 
-  if (realloc(str_length + t_length))
+  if (realloc_with_extra_if_needed(str_length + t_length))
     return TRUE;
   t_length= full_length - arg_length;
   if (t_length > 0)
@@ -636,7 +636,7 @@ bool String::replace(uint32 offset,uint32 arg_length,
     {
       if (diff)
       {
-	if (realloc(str_length+(uint32) diff))
+	if (realloc_with_extra_if_needed(str_length+(uint32) diff))
 	  return TRUE;
 	bmove_upp((uchar*) Ptr+str_length+diff, (uchar*) Ptr+str_length,
 		  str_length-offset-arg_length);

sql/sql_string.h

@@ -53,23 +53,24 @@ uint convert_to_printable(char *to, size_t to_len,
 class String
 {
   char *Ptr;
-  uint32 str_length,Alloced_length;
+  uint32 str_length,Alloced_length, extra_alloc;
   bool alloced;
   CHARSET_INFO *str_charset;
 public:
   String()
   { 
-    Ptr=0; str_length=Alloced_length=0; alloced=0; 
+    Ptr=0; str_length=Alloced_length=extra_alloc=0; alloced=0; 
     str_charset= &my_charset_bin; 
   }
   String(uint32 length_arg)
   { 
-    alloced=0; Alloced_length=0; (void) real_alloc(length_arg); 
+    alloced=0; Alloced_length= extra_alloc= 0; (void) real_alloc(length_arg); 
     str_charset= &my_charset_bin;
   }
   String(const char *str, CHARSET_INFO *cs)
   { 
-    Ptr=(char*) str; str_length=(uint) strlen(str); Alloced_length=0; alloced=0;
+    Ptr=(char*) str; str_length= (uint32) strlen(str);
+    Alloced_length= extra_alloc= 0; alloced=0;
     str_charset=cs;
   }
   /*
@@ -79,18 +80,18 @@ class String
   */
   String(const char *str,uint32 len, CHARSET_INFO *cs)
   { 
-    Ptr=(char*) str; str_length=len; Alloced_length=0; alloced=0;
+    Ptr=(char*) str; str_length=len; Alloced_length= extra_alloc=0; alloced=0;
     str_charset=cs;
   }
   String(char *str,uint32 len, CHARSET_INFO *cs)
   { 
-    Ptr=(char*) str; Alloced_length=str_length=len; alloced=0;
+    Ptr=(char*) str; Alloced_length=str_length=len; extra_alloc= 0; alloced=0;
     str_charset=cs;
   }
   String(const String &str)
   { 
     Ptr=str.Ptr ; str_length=str.str_length ;
-    Alloced_length=str.Alloced_length; alloced=0; 
+    Alloced_length=str.Alloced_length; extra_alloc= 0; alloced=0; 
     str_charset=str.str_charset;
   }
   static void *operator new(size_t size, MEM_ROOT *mem_root) throw ()
@@ -106,8 +107,10 @@ class String
   inline CHARSET_INFO *charset() const { return str_charset; }
   inline uint32 length() const { return str_length;}
   inline uint32 alloced_length() const { return Alloced_length;}
+  inline uint32 extra_allocation() const { return extra_alloc;}
   inline char& operator [] (uint32 i) const { return Ptr[i]; }
   inline void length(uint32 len) { str_length=len ; }
+  inline void extra_allocation(uint32 len) { extra_alloc= len; }
   inline bool is_empty() const { return (str_length == 0); }
   inline void mark_as_const() { Alloced_length= 0;}
   inline const char *ptr() const { return Ptr; }
@@ -136,23 +139,21 @@ class String
   {
     DBUG_ASSERT(&str != this);
     free();
-    Ptr=(char*) str.ptr()+offset; str_length=arg_length; alloced=0;
+    Ptr=(char*) str.ptr()+offset; str_length=arg_length;
     if (str.Alloced_length)
       Alloced_length=str.Alloced_length-offset;
-    else
-      Alloced_length=0;
     str_charset=str.str_charset;
   }
   inline void set(char *str,uint32 arg_length, CHARSET_INFO *cs)
   {
     free();
-    Ptr=(char*) str; str_length=Alloced_length=arg_length ; alloced=0;
+    Ptr=(char*) str; str_length=Alloced_length=arg_length;
     str_charset=cs;
   }
   inline void set(const char *str,uint32 arg_length, CHARSET_INFO *cs)
   {
     free();
-    Ptr=(char*) str; str_length=arg_length; Alloced_length=0 ; alloced=0;
+    Ptr=(char*) str; str_length=arg_length;
     str_charset=cs;
   }
   bool set_ascii(const char *str, uint32 arg_length);
@@ -203,11 +204,11 @@ class String
     if (alloced)
     {
       alloced=0;
-      Alloced_length=0;
       my_free(Ptr,MYF(0));
-      Ptr=0;
-      str_length=0;				/* Safety */
     }
+    Alloced_length= extra_alloc= 0;
+    Ptr=0;
+    str_length=0;				/* Safety */
   }
   inline bool alloc(uint32 arg_length)
   {
@@ -217,9 +218,21 @@ class String
   }
   bool real_alloc(uint32 arg_length);			// Empties old string
   bool realloc(uint32 arg_length);
-  inline void shrink(uint32 arg_length)		// Shrink buffer
+  bool realloc_with_extra(uint32 arg_length)
+  {
+    if (extra_alloc < 4096)
+      extra_alloc= extra_alloc*2+128;
+    return realloc(arg_length + extra_alloc);
+  }
+  bool realloc_with_extra_if_needed(uint32 arg_length)
   {
     if (arg_length < Alloced_length)
+      return 0;
+    return realloc_with_extra(arg_length);
+  }
+  inline void shrink(uint32 arg_length)		// Shrink buffer
+  {
+    if (ALIGN_SIZE(arg_length+1) < Alloced_length)
     {
       char *new_ptr;
       if (!(new_ptr=(char*) my_realloc(Ptr,arg_length,MYF(0))))
@@ -246,7 +259,6 @@ class String
       DBUG_ASSERT(!s.uses_buffer_owned_by(this));
       free();
       Ptr=s.Ptr ; str_length=s.str_length ; Alloced_length=s.Alloced_length;
-      alloced=0;
     }
     return *this;
   }
@@ -281,7 +293,7 @@ class String
     }
     else
     {
-      if (realloc(str_length+1))
+      if (realloc_with_extra(str_length + 1))
 	return 1;
       Ptr[str_length++]=chr;
     }

sql/sql_test.cc

@@ -57,9 +57,10 @@ print_where(COND *cond,const char *info, enum_query_type query_type)
 {
   if (cond)
   {
-    char buff[256];
+    char buff[1024];
     String str(buff,(uint32) sizeof(buff), system_charset_info);
     str.length(0);
+    str.extra_allocation(1024);
     cond->print(&str, query_type);
     str.append('\0');
     DBUG_LOCK_FILE;

sql/table.cc

@@ -3328,11 +3328,13 @@ Table_check_intact::check(TABLE *table, const TABLE_FIELD_DEF *table_def)
       is backward compatible.
     */
   }
-  char buffer[STRING_BUFFER_USUAL_SIZE];
+  char buffer[1024];
   for (i=0 ; i < table_def->count; i++, field_def++)
   {
     String sql_type(buffer, sizeof(buffer), system_charset_info);
     sql_type.length(0);
+    /* Allocate min 256 characters at once */
+    sql_type.extra_allocation(256);
     if (i < table->s->fields)
     {
       Field *field= table->field[i];