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MDEV-28881 Fix memory leak caused by STL usage

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Dep_analysis_context::create_unique_pseudo_key_if_needed() was using
std::set which allocated memory outside MEM_ROOT and so required
explicit deallocation. This has been solved by replacing std::set with
MY_BITMAP which is allocated on MEM_ROOT
This commit is contained in:
Oleg Smirnov 2022-07-07 19:57:38 +04:00
parent c03d50fccf
commit afadd58ee5
1 changed files with 29 additions and 17 deletions
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46
sql/opt_table_elimination.cc
View file

@ -33,7 +33,6 @@
#include "sql_select.h" #include "sql_select.h"
#include "opt_trace.h" #include "opt_trace.h"
#include "my_json_writer.h" #include "my_json_writer.h"
#include <set>
/* /*
OVERVIEW OVERVIEW
@ -473,10 +472,11 @@ class Dep_module_pseudo_key : public Dep_module
{ {
public: public:
Dep_module_pseudo_key(Dep_value_table *table_arg, Dep_module_pseudo_key(Dep_value_table *table_arg,
std::set<field_index_t>&& field_indexes) MY_BITMAP *exposed_fields,
: table(table_arg), derived_table_field_indexes(field_indexes) uint exposed_fields_num)
: table(table_arg), exposed_fields_map(exposed_fields)
{ {
unbound_args= static_cast<uint>(field_indexes.size()); unbound_args= exposed_fields_num;
} }
Dep_value_table *table; Dep_value_table *table;
@ -492,15 +492,15 @@ public:
private: private:
/* /*
Set of field numbers (indexes) in the derived table's SELECT list Bitmap of field numbers in the derived table's SELECT list
which are included in the GROUP BY expression. which are included in the GROUP BY expression.
For example, unique pseudo-key for SQL For example, unique pseudo-key for SQL
"SELECT count(*), b, a FROM t1 GROUP BY a, b" "SELECT count(*), b, a FROM t1 GROUP BY a, b"
will include two elements: {2} and {1}, since "a" and "b" are on the will include two elements: {2} and {1}, since "a" and "b" are on the
GROUP BY list and also are present on the SELECT list with indexes 2 and 1 GROUP BY list and also are present on the SELECT list with numbers 2 and 1
(numeration starts from 0). (numeration starts from 0).
*/ */
std::set<field_index_t> derived_table_field_indexes; MY_BITMAP *exposed_fields_map;
class Value_iter class Value_iter
{ {
@ -577,7 +577,7 @@ public:
to see if expression equality_mods[expr_no] depends on the given field. to see if expression equality_mods[expr_no] depends on the given field.
*/ */
MY_BITMAP expr_deps; MY_BITMAP expr_deps;
Dep_value_table *create_table_value(TABLE_LIST *table_list); Dep_value_table *create_table_value(TABLE_LIST *table_list);
Dep_value_field *get_field_value(Field *field); Dep_value_field *get_field_value(Field *field);
@ -1729,8 +1729,19 @@ void Dep_analysis_context::create_unique_pseudo_key_if_needed(
if (first_select && first_select->join && if (first_select && first_select->join &&
first_select->group_list.elements > 0) first_select->group_list.elements > 0)
{ {
auto max_possible_elements= first_select->join->fields_list.elements;
void *buf;
MY_BITMAP *exposed_fields= (MY_BITMAP*)
current_thd->alloc(sizeof(MY_BITMAP));
if (!(buf= current_thd->alloc(bitmap_buffer_size(max_possible_elements))) ||
my_bitmap_init(exposed_fields, (my_bitmap_map*)buf,
max_possible_elements))
// Memory allocation failed
return;
bitmap_clear_all(exposed_fields);
uint exposed_fields_count= 0;
bool valid= true; bool valid= true;
std::set<field_index_t> exposed_fields_indexes;
for (auto cur_group= first_select->group_list.first; for (auto cur_group= first_select->group_list.first;
cur_group; cur_group;
cur_group= cur_group->next) cur_group= cur_group->next)
@ -1745,8 +1756,8 @@ void Dep_analysis_context::create_unique_pseudo_key_if_needed(
valid= false; valid= false;
break; break;
} }
auto field_idx= find_field_in_list(first_select->join->fields_list, elem); auto field_no= find_field_in_list(first_select->join->fields_list, elem);
if (field_idx == -1) if (field_no == -1)
{ {
/* /*
This GROUP BY element is not present in the select list. This is a This GROUP BY element is not present in the select list. This is a
@ -1759,13 +1770,14 @@ void Dep_analysis_context::create_unique_pseudo_key_if_needed(
valid= false; valid= false;
break; break;
} }
exposed_fields_indexes.insert(field_idx); bitmap_set_bit(exposed_fields, field_no);
exposed_fields_count++;
} }
if (valid) if (valid)
{ {
Dep_module_pseudo_key *pseudo_key; Dep_module_pseudo_key *pseudo_key;
pseudo_key= new Dep_module_pseudo_key(tbl_dep, pseudo_key= new Dep_module_pseudo_key(tbl_dep, exposed_fields,
std::move(exposed_fields_indexes)); exposed_fields_count);
tbl_dep->pseudo_key= pseudo_key; tbl_dep->pseudo_key= pseudo_key;
} }
} }
@ -1950,12 +1962,12 @@ Dep_module_pseudo_key::get_next_unbound_value(Dep_analysis_context *dac,
/* /*
Check if column number field_index is covered by the pseudo-key. Check if column number field_no is covered by the pseudo-key.
*/ */
bool Dep_module_pseudo_key::covers_field(int field_index) bool Dep_module_pseudo_key::covers_field(int field_no)
{ {
return derived_table_field_indexes.count(field_index) > 0; return bitmap_is_set(exposed_fields_map, field_no) > 0;
} }