From: Tor Didriksen
Date: May 18 2011 1:13pm
Subject: bzr push into mysql-trunk branch (tor.didriksen:3372 to 3373) Bug#12552221
List-Archive: http://lists.mysql.com/commits/137626
X-Bug: 12552221
Message-Id: <20110518131305.7430337B2@atum07.norway.sun.com>
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 3373 Tor Didriksen	2011-05-18
      Bug#12552221 - MEMORY LEAK IN UPDATE_REF_AND_KEYS
      
      Addendum: Use Mem_root_array<> rather than Array<> for sj_subselects.
      Remove (the now obsolete) Array<Elem> class.

    modified:
      sql/sql_array.h
      sql/sql_select.cc
      sql/sql_select.h
 3372 Tor Didriksen	2011-05-18 [merge]
      NULL merge trunk => opt-backporting

=== modified file 'sql/sql_array.h'
--- a/sql/sql_array.h	2010-11-05 22:14:29 +0000
+++ b/sql/sql_array.h	2011-05-18 13:12:02 +0000
@@ -79,75 +79,4 @@ public:
   }
 };
 
-
-/* 
-  Array of pointers to Elem that uses memory from MEM_ROOT
-
-  MEM_ROOT has no realloc() so this is supposed to be used for cases when
-  reallocations are rare.
-*/
-
-template <class Elem> class Array
-{
-  enum {alloc_increment = 16};
-  Elem **buffer;
-  uint n_elements, max_element;
-public:
-  Array(MEM_ROOT *mem_root, uint prealloc=16)
-  {
-    buffer= (Elem**)alloc_root(mem_root, prealloc * sizeof(Elem**));
-    max_element = buffer? prealloc : 0;
-    n_elements= 0;
-  }
-
-  Elem& at(int idx)
-  {
-    return *(((Elem*)buffer) + idx);
-  }
-
-  Elem **front()
-  {
-    return buffer;
-  }
-
-  Elem **back()
-  {
-    return buffer + n_elements;
-  }
-
-  bool append(MEM_ROOT *mem_root, Elem *el)
-  {
-    if (n_elements == max_element)
-    {
-      Elem **newbuf;
-      if (!(newbuf= (Elem**)alloc_root(mem_root, (n_elements + alloc_increment)*
-                                                  sizeof(Elem**))))
-      {
-        return FALSE;
-      }
-      memcpy(newbuf, buffer, n_elements*sizeof(Elem*));
-      buffer= newbuf;
-    }
-    buffer[n_elements++]= el;
-    return FALSE;
-  }
-
-  int elements()
-  {
-    return n_elements;
-  }
-
-  void clear()
-  {
-    n_elements= 0;
-  }
-
-  typedef int (*CMP_FUNC)(Elem * const *el1, Elem *const *el2);
-
-  void sort(CMP_FUNC cmp_func)
-  {
-    my_qsort(buffer, n_elements, sizeof(Elem*), (qsort_cmp)cmp_func);
-  }
-};
-
 #endif /* SQL_ARRAY_INCLUDED */

=== modified file 'sql/sql_select.cc'
--- a/sql/sql_select.cc	2011-05-18 11:44:39 +0000
+++ b/sql/sql_select.cc	2011-05-18 13:12:02 +0000
@@ -978,7 +978,7 @@ bool resolve_subquery(THD *thd, JOIN *jo
 
     /* Register the subquery for further processing in flatten_subqueries() */
     select_lex->outer_select()->join->
-      sj_subselects.append(thd->mem_root, in_exists_predicate);
+      sj_subselects.push_back(in_exists_predicate);
   }
   else
   {
@@ -4170,11 +4170,11 @@ bool JOIN::flatten_subqueries()
   Item_exists_subselect **subq_end;
   DBUG_ENTER("JOIN::flatten_subqueries");
 
-  if (sj_subselects.elements() == 0)
+  if (sj_subselects.empty())
     DBUG_RETURN(FALSE);
 
   /* First, convert child join's subqueries. We proceed bottom-up here */
-  for (subq= sj_subselects.front(), subq_end= sj_subselects.back(); 
+  for (subq= sj_subselects.begin(), subq_end= sj_subselects.end(); 
        subq != subq_end;
        subq++)
   {
@@ -4207,7 +4207,7 @@ bool JOIN::flatten_subqueries()
   {
     if (tbl->on_expr || tbl->in_outer_join_nest())
     {
-      subq= sj_subselects.front();
+      subq= sj_subselects.begin();
       arena= thd->activate_stmt_arena_if_needed(&backup);
       goto skip_conversion;
     }
@@ -4220,11 +4220,14 @@ bool JOIN::flatten_subqueries()
       - prefer correlated subqueries over uncorrelated;
       - prefer subqueries that have greater number of outer tables;
   */
-  sj_subselects.sort(subq_sj_candidate_cmp);
+  my_qsort(sj_subselects.begin(),
+           sj_subselects.size(), sj_subselects.element_size(),
+           reinterpret_cast<qsort_cmp>(subq_sj_candidate_cmp));
+
   // #tables-in-parent-query + #tables-in-subquery < MAX_TABLES
   /* Replace all subqueries to be flattened with Item_int(1) */
   arena= thd->activate_stmt_arena_if_needed(&backup);
-  for (subq= sj_subselects.front(); 
+  for (subq= sj_subselects.begin(); 
        subq != subq_end && 
        tables + (*subq)->unit->first_select()->join->tables < MAX_TABLES;
        subq++)
@@ -4235,7 +4238,7 @@ bool JOIN::flatten_subqueries()
       DBUG_RETURN(TRUE); /* purecov: inspected */
   }
  
-  for (subq= sj_subselects.front(); 
+  for (subq= sj_subselects.begin(); 
        subq != subq_end && 
        tables + (*subq)->unit->first_select()->join->tables < MAX_TABLES;
        subq++)

=== modified file 'sql/sql_select.h'
--- a/sql/sql_select.h	2011-05-18 11:44:39 +0000
+++ b/sql/sql_select.h	2011-05-18 13:12:02 +0000
@@ -1888,7 +1888,8 @@ public:
   bool union_part; ///< this subselect is part of union 
   bool optimized; ///< flag to avoid double optimization in EXPLAIN
   
-  Array<Item_exists_subselect> sj_subselects;
+  // true: No need to run DTORs on pointers.
+  Mem_root_array<Item_exists_subselect*, true> sj_subselects;
 
   /* Temporary tables used to weed-out semi-join duplicates */
   List<TABLE> sj_tmp_tables;
@@ -1913,7 +1914,7 @@ public:
        select_result *result_arg)
     : keyuse(thd_arg->mem_root),
       fields_list(fields_arg),
-      sj_subselects(thd_arg->mem_root, 4)
+      sj_subselects(thd_arg->mem_root)
   {
     init(thd_arg, fields_arg, select_options_arg, result_arg);
   }

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