BUG#21414: SP: Procedure undroppable, to some extent

The problem was that if after FLUSH TABLES WITH READ LOCK the user
issued DROP/ALTER PROCEDURE/FUNCTION the operation would fail (as
expected), but after UNLOCK TABLE any attempt to execute the same
operation would lead to the error 1305 "PROCEDURE/FUNCTION does not
exist", and an attempt to execute any stored function will also fail.

This happened because under FLUSH TABLES WITH READ LOCK we couldn't open
and lock mysql.proc table for update, and this fact was erroneously
remembered by setting mysql_proc_table_exists to false, so subsequent
statements believed that mysql.proc doesn't exist, and thus that there
are no functions and procedures in the database.

As a solution, we remove mysql_proc_table_exists flag completely.  The
reason is that this optimization didn't work most of the time anyway.
Even if open of mysql.proc failed for some reason when we were trying to
call a function or a procedure, we were setting mysql_proc_table_exists
back to true to force table reopen for the sake of producing the same
error message (the open can fail for number of reasons).  The solution
could have been to remember the reason why open failed, but that's a lot
of code for optimization of a rare case.  Hence we simply remove this
optimization.


mysql-test/r/sp.result:
  Add result for bug#21414: SP: Procedure undroppable, to some extent.
mysql-test/t/sp.test:
  Remove no longer relevant comment.
  Add test case for bug#21414: SP: Procedure undroppable, to some extent.
sql/mysql_priv.h:
  Remove declaration of mysql_proc_table_exists.
sql/sp.cc:
  Remove references to mysql_proc_table_exists.
sql/sql_acl.cc:
  Remove reference to mysql_proc_table_exists.

1 files changed, 8 insertions, 0 deletions

diff --git a/mysql-test/r/sp.result b/mysql-test/r/sp.result
index 854935b071b..b08ce0528a3 100644
--- a/mysql-test/r/sp.result
+++ b/mysql-test/r/sp.result
@@ -5394,4 +5394,12 @@ Procedure	sql_mode	Create Procedure
 bug21416		CREATE DEFINER=`root`@`localhost` PROCEDURE `bug21416`()
 show create procedure bug21416
 drop procedure bug21416|
+DROP PROCEDURE IF EXISTS bug21414|
+CREATE PROCEDURE bug21414() SELECT 1|
+FLUSH TABLES WITH READ LOCK|
+DROP PROCEDURE bug21414|
+ERROR HY000: Can't execute the query because you have a conflicting read lock
+UNLOCK TABLES|
+The following should succeed.
+DROP PROCEDURE bug21414|
 drop table t1,t2;