Commit 8995277a authored by unknown's avatar unknown

A fix and a test case for Bug#19399 "res 'Lost Connection' when

dropping/creating tables".

The bug could lead to a crash when multi-delete statements were
prepared and used with temporary tables.

The bug was caused by lack of clean-up of multi-delete tables before
re-execution of a prepared statement. In a statement like
DELETE t1 FROM t1, t2 WHERE ... the first table list (t1) is
moved to lex->auxilliary_table_list and excluded from lex->query_tables
or select_lex->tables. Thus it was unaccessible to reinit_stmt_before_use
and not cleaned up before re-execution of a prepared statement. 


mysql-test/r/ps.result:
  Updated test results (Bug#19399)
mysql-test/t/ps.test:
  A test case for Bug#19399 "Stored Procedures 'Lost Connection' when 
  dropping/creating tables": test that multi-delete
  tables are cleaned up properly before re-execution.
sql/sql_lex.cc:
  Always initialize auxilliary_table_list when we initialize the lex:
  this way we don't have to check that lex->sql_command equals to
  SQLCOM_DELETE_MULTI whenever we need to access auxilliary_table_list.
  In particular, in reinit_stmt_before_use we can simply check that
  auxilliary_table_list is not NULL and clean it up if the check returns
  a true value.
sql/sql_prepare.cc:
  Move the one table clean-up functionality to a method of st_table_list.
  Clean up auxiliary_table_list if it's not empty.
sql/table.cc:
  Implement st_table_list::reinit_before_use().
sql/table.h:
  Declare st_table_list::reinit_before_use().
parent d94521c3
......@@ -875,3 +875,17 @@ select @@max_prepared_stmt_count, @@prepared_stmt_count;
@@max_prepared_stmt_count @@prepared_stmt_count
3 0
set global max_prepared_stmt_count= @old_max_prepared_stmt_count;
drop table if exists t1;
create temporary table if not exists t1 (a1 int);
prepare stmt from "delete t1 from t1 where (cast(a1/3 as unsigned) * 3) = a1";
drop temporary table t1;
create temporary table if not exists t1 (a1 int);
execute stmt;
drop temporary table t1;
create temporary table if not exists t1 (a1 int);
execute stmt;
drop temporary table t1;
create temporary table if not exists t1 (a1 int);
execute stmt;
drop temporary table t1;
deallocate prepare stmt;
......@@ -926,4 +926,29 @@ select @@max_prepared_stmt_count, @@prepared_stmt_count;
set global max_prepared_stmt_count= @old_max_prepared_stmt_count;
--enable_ps_protocol
#
# Bug#19399 "Stored Procedures 'Lost Connection' when dropping/creating
# tables"
# Check that multi-delete tables are also cleaned up before re-execution.
#
--disable_warnings
drop table if exists t1;
create temporary table if not exists t1 (a1 int);
--enable_warnings
# exact delete syntax is essential
prepare stmt from "delete t1 from t1 where (cast(a1/3 as unsigned) * 3) = a1";
drop temporary table t1;
create temporary table if not exists t1 (a1 int);
# the server crashed on the next statement without the fix
execute stmt;
drop temporary table t1;
create temporary table if not exists t1 (a1 int);
# the problem was in memory corruption: repeat the test just in case
execute stmt;
drop temporary table t1;
create temporary table if not exists t1 (a1 int);
execute stmt;
drop temporary table t1;
deallocate prepare stmt;
# End of 4.1 tests
......@@ -125,6 +125,7 @@ void lex_start(THD *thd, uchar *buf,uint length)
lex->value_list.empty();
lex->update_list.empty();
lex->param_list.empty();
lex->auxilliary_table_list.empty();
lex->unit.next= lex->unit.master=
lex->unit.link_next= lex->unit.return_to= 0;
lex->unit.prev= lex->unit.link_prev= 0;
......
......@@ -1727,12 +1727,7 @@ static void reset_stmt_for_execute(Prepared_statement *stmt)
tables;
tables= tables->next)
{
/*
Reset old pointers to TABLEs: they are not valid since the tables
were closed in the end of previous prepare or execute call.
*/
tables->table= 0;
tables->table_list= 0;
tables->reinit_before_use(thd);
}
{
......@@ -1743,6 +1738,17 @@ static void reset_stmt_for_execute(Prepared_statement *stmt)
unit->reinit_exec_mechanism();
}
}
/*
Cleanup of the special case of DELETE t1, t2 FROM t1, t2, t3 ...
(multi-delete). We do a full clean up, although at the moment all we
need to clean in the tables of MULTI-DELETE list is 'table' member.
*/
for (TABLE_LIST *tables= (TABLE_LIST*) lex->auxilliary_table_list.first;
tables;
tables= tables->next)
{
tables->reinit_before_use(thd);
}
lex->current_select= &lex->select_lex;
if (lex->result)
lex->result->cleanup();
......
......@@ -1523,6 +1523,23 @@ db_type get_table_type(const char *name)
DBUG_RETURN(ha_checktype((enum db_type) (uint) *(head+3)));
}
/*
Cleanup this table for re-execution.
SYNOPSIS
st_table_list::reinit_before_use()
*/
void st_table_list::reinit_before_use(THD * /* thd */)
{
/*
Reset old pointers to TABLEs: they are not valid since the tables
were closed in the end of previous prepare or execute call.
*/
table= 0;
table_list= 0;
}
/*****************************************************************************
** Instansiate templates
......
......@@ -238,6 +238,11 @@ typedef struct st_table_list
bool cacheable_table; /* stop PS caching */
/* used in multi-upd privelege check */
bool table_in_update_from_clause;
/*
Cleanup for re-execution in a prepared statement or a stored
procedure.
*/
void reinit_before_use(THD *thd);
} TABLE_LIST;
typedef struct st_changed_table_list
......
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