WL#3602 (SET GLOBAL READONLY)

Bug#11733 (COMMITs should not happen if read-only is set)
Bug#22009 (Can write to a read-only server under some circumstances)

See the work log for details

The change consist of
a) acquiring the global read lock in SET GLOBAL READONLY
b) honoring opt_readonly in ha_commit_trans(),
c) honoring opt_readonly in mysql_lock_tables().

a) takes care of the server stability,
b) makes the transactional tables safe (Bug 11733)
c) makes the non transactional tables safe (Bug 22009)


mysql-test/r/read_only.result:
  WL#3602 (SET GLOBAL READONLY)
mysql-test/t/read_only.test:
  WL#3602 (SET GLOBAL READONLY)
sql/handler.cc:
  WL#3602 (SET GLOBAL READONLY)
sql/lock.cc:
  WL#3602 (SET GLOBAL READONLY)
sql/set_var.cc:
  WL#3602 (SET GLOBAL READONLY)
sql/set_var.h:
  WL#3602 (SET GLOBAL READONLY)
mysql-test/r/read_only_innodb.result:
  WL#3602 (SET GLOBAL READONLY)
mysql-test/t/read_only_innodb.test:
  WL#3602 (SET GLOBAL READONLY)

1 files changed, 14 insertions, 0 deletions

diff --git a/sql/set_var.h b/sql/set_var.h
index 01669b378e1..14792f4a7c8 100644
--- a/sql/set_var.h
+++ b/sql/set_var.h
@@ -905,6 +905,20 @@ public:
 };
 
 
+/**
+  Handler for setting the system variable --read-only.
+*/
+
+class sys_var_opt_readonly :public sys_var_bool_ptr
+{
+public:
+  sys_var_opt_readonly(const char *name_arg, my_bool *value_arg) :
+    sys_var_bool_ptr(name_arg, value_arg) {};
+  ~sys_var_opt_readonly() {};
+  bool update(THD *thd, set_var *var);
+};
+
+
 class sys_var_thd_lc_time_names :public sys_var_thd
 {
 public: