diff options
Diffstat (limited to 'sql/sql_lex.h')
| -rw-r--r-- | sql/sql_lex.h | 16 |
1 files changed, 16 insertions, 0 deletions
diff --git a/sql/sql_lex.h b/sql/sql_lex.h index d91e3907fb3..5c0367632e1 100644 --- a/sql/sql_lex.h +++ b/sql/sql_lex.h @@ -1184,6 +1184,22 @@ typedef struct st_lex : public Query_tables_list bool escape_used; + /* + Special case for SELECT .. FOR UPDATE and LOCK TABLES .. WRITE. + + Protect from a impending GRL as otherwise the thread might deadlock + if it starts waiting for the GRL in mysql_lock_tables. + + The protection is needed because there is a race between setting + the global read lock and waiting for all open tables to be closed. + The problem is a circular wait where a thread holding "old" open + tables will wait for the global read lock to be released while the + thread holding the global read lock will wait for all "old" open + tables to be closed -- the flush part of flush tables with read + lock. + */ + bool protect_against_global_read_lock; + st_lex(); virtual ~st_lex() |