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MDEV-16708: fixed assert firing in the method THD::reset_for_the_next_command

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This commit is contained in:
Dmitry Shulga 2021-06-11 11:25:56 +07:00 committed by Sergei Golubchik
parent 994e3f40b5
commit fe78495053
2 changed files with 48 additions and 1 deletions
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22
sql/sql_binlog.cc
View File

@ -354,8 +354,28 @@ void mysql_client_binlog_statement(THD* thd)
(ev->flags & LOG_EVENT_SKIP_REPLICATION_F ?
OPTION_SKIP_REPLICATION : 0);
err= ev->apply_event(rgi);
{
/*
For conventional statements thd->lex points to thd->main_lex, that is
thd->lex == &thd->main_lex. On the other hand, for prepared statement
thd->lex points to the LEX object explicitly allocated for execution
of the prepared statement and in this case thd->lex != &thd->main_lex.
On handling the BINLOG statement, invocation of ev->apply_event(rgi)
initiates the following sequence of calls
Rows_log_event::do_apply_event -> THD::reset_for_next_command
Since the method THD::reset_for_next_command() contains assert
DBUG_ASSERT(lex == &main_lex)
this sequence of calls results in crash when a binlog event is
applied in PS mode. So, reset the current lex temporary to point to
thd->main_lex before running ev->apply_event() and restore its
original value on return.
*/
LEX *backup_lex;
thd->backup_and_reset_current_lex(&backup_lex);
err= ev->apply_event(rgi);
thd->restore_current_lex(backup_lex);
}
thd->variables.option_bits=
(thd->variables.option_bits & ~OPTION_SKIP_REPLICATION) |
save_skip_replication;

27
sql/sql_class.h
View File

@ -5453,6 +5453,33 @@ public:
return (variables.old_behavior & OLD_MODE_UTF8_IS_UTF8MB3 ?
MY_UTF8_IS_UTF8MB3 : 0);
}
/**
Save current lex to the output parameter and reset it to point to
main_lex. This method is called from mysql_client_binlog_statement()
to temporary
@param[out] backup_lex original value of current lex
*/
void backup_and_reset_current_lex(LEX **backup_lex)
{
*backup_lex= lex;
lex= &main_lex;
}
/**
Restore current lex to its original value it had before calling the method
backup_and_reset_current_lex().
@param backup_lex original value of current lex
*/
void restore_current_lex(LEX *backup_lex)
{
lex= backup_lex;
}
};