BUG#23159: prepared_stmt_count should be status variable

Make Prepared_stmt_count a global status variable, accessible via
SHOW STATUS LIKE 'Prepared_stmt_count';.  Documentation should be
updated.

1 files changed, 25 insertions, 32 deletions

diff --git a/mysql-test/t/ps.test b/mysql-test/t/ps.test
index 5b488ae4393..fbeaaa494e0 100644
--- a/mysql-test/t/ps.test
+++ b/mysql-test/t/ps.test
@@ -811,6 +811,9 @@ drop table t1;
 # Bug#16365 Prepared Statements: DoS with too many open statements
 # Check that the limit @@max_prpeared_stmt_count works.
 #
+# This is also the test for bug#23159 prepared_stmt_count should be
+# status variable.
+#
 # Save the old value
 set @old_max_prepared_stmt_count= @@max_prepared_stmt_count;
 #
@@ -820,17 +823,17 @@ set @old_max_prepared_stmt_count= @@max_prepared_stmt_count;
 #
 --disable_ps_protocol
 #
-# A. Check that the new variables are present in SHOW VARIABLES list.
+# A. Check that the new variables are present in SHOW VARIABLES and
+# SHOW STATUS lists.
 #
 show variables like 'max_prepared_stmt_count';
-show variables like 'prepared_stmt_count';
+show status like 'prepared_stmt_count';
 #
-# B. Check that the new variables are selectable.
+# B. Check that the new system variable is selectable.
 #
-select @@max_prepared_stmt_count, @@prepared_stmt_count;
+select @@max_prepared_stmt_count;
 #
-# C. Check that max_prepared_stmt_count is settable (global only),
-#    whereas prepared_stmt_count is readonly.
+# C. Check that max_prepared_stmt_count is settable (global only).
 #
 set global max_prepared_stmt_count=-1;
 select @@max_prepared_stmt_count;
@@ -844,12 +847,6 @@ set @@max_prepared_stmt_count=1;
 set max_prepared_stmt_count=1;
 --error 1229 # ER_GLOBAL_VARIABLE
 set local max_prepared_stmt_count=1;
---error 1229 # ER_GLOBAL_VARIABLE
-set local prepared_stmt_count=0;
---error 1229 # ER_GLOBAL_VARIABLE
-set @@prepared_stmt_count=0;
---error 1232 # ER_WRONG_TYPE_FOR_VAR
-set global prepared_stmt_count=1;
 # set to a reasonable limit works
 set global max_prepared_stmt_count=1;
 select @@max_prepared_stmt_count;
@@ -857,47 +854,50 @@ select @@max_prepared_stmt_count;
 # D. Check that the variables actually work.
 #
 set global max_prepared_stmt_count=0;
-select @@max_prepared_stmt_count, @@prepared_stmt_count;
+select @@max_prepared_stmt_count;
+show status like 'prepared_stmt_count';
 --error 1105 # ER_UNKNOWN_ERROR
 prepare stmt from "select 1";
-select @@prepared_stmt_count;
+show status like 'prepared_stmt_count';
 set global max_prepared_stmt_count=1;
 prepare stmt from "select 1";
-select @@prepared_stmt_count;
+show status like 'prepared_stmt_count';
 --error 1105 # ER_UNKNOWN_ERROR
 prepare stmt1 from "select 1";
-select @@prepared_stmt_count;
+show status like 'prepared_stmt_count';
 deallocate prepare stmt;
-select @@prepared_stmt_count;
+show status like 'prepared_stmt_count';
 #
 # E. Check that we can prepare a statement with the same name 
 # successfully, without hitting the limit.
 #
 prepare stmt from "select 1";
-select @@prepared_stmt_count;
+show status like 'prepared_stmt_count';
 prepare stmt from "select 2";
-select @@prepared_stmt_count;
+show status like 'prepared_stmt_count';
 #
 # F. We can set the max below the current count. In this case no new 
 # statements should be allowed to prepare.
 #
-select @@prepared_stmt_count, @@max_prepared_stmt_count;
+show status like 'prepared_stmt_count';
+select @@max_prepared_stmt_count;
 set global max_prepared_stmt_count=0;
 --error 1105 # ER_UNKNOWN_ERROR
 prepare stmt from "select 1";
 # Result: the old statement is deallocated, the new is not created.
 --error 1243 # ER_UNKNOWN_STMT_HANDLER
 execute stmt;
-select @@prepared_stmt_count;
+show status like 'prepared_stmt_count';
 --error 1105 # ER_UNKNOWN_ERROR
 prepare stmt from "select 1";
-select @@prepared_stmt_count;
+show status like 'prepared_stmt_count';
 #
 # G. Show that the variables are up to date even after a connection with all
 # statements in it was terminated.
 #
 set global max_prepared_stmt_count=3;
-select @@max_prepared_stmt_count, @@prepared_stmt_count;
+select @@max_prepared_stmt_count;
+show status like 'prepared_stmt_count';
 prepare stmt from "select 1";
 connect (con1,localhost,root,,);
 connection con1;
@@ -908,18 +908,11 @@ prepare stmt2 from "select 4";
 connection default;
 --error 1105 # ER_UNKNOWN_ERROR 
 prepare stmt2 from "select 4";
-select @@max_prepared_stmt_count, @@prepared_stmt_count;
+select @@max_prepared_stmt_count;
+show status like 'prepared_stmt_count';
 disconnect con1;
 connection default;
-# Wait for the connection to die: deal with a possible race
 deallocate prepare stmt;
-let $count= `select @@prepared_stmt_count`;
-if ($count)
-{
---sleep 2
-  let $count= `select @@prepared_stmt_count`;
-}
-select @@max_prepared_stmt_count, @@prepared_stmt_count;
 #
 # Restore the old value.
 #