Bug#19904003 INNODB_LIMIT_OPTIMISTIC_INSERT_DEBUG=1 CAUSES INFINITE PAGE SPLIT

The debug configuration parameter innodb_optimistic_insert_debug
which was introduced for testing corner cases in B-tree handling
had a bug in it. The value 1 would trigger an infinite sequence
of page splits.

Fix: When the value 1 is specified, disable this debug feature.
Approved by Yasufumi Kinoshita

mysql-test/suite/innodb/r/insert_debug.result

+#
+# Bug#19904003 INNODB_LIMIT_OPTIMISTIC_INSERT_DEBUG=1
+# CAUSES INFINITE PAGE SPLIT
+#
+SET GLOBAL innodb_change_buffering_debug=1;
+SET GLOBAL innodb_limit_optimistic_insert_debug=1;
+CREATE TABLE t1(c1 INT PRIMARY KEY) ENGINE=InnoDB
+PARTITION BY HASH (c1) PARTITIONS 15;
+DROP TABLE t1;
+SET GLOBAL innodb_change_buffering_debug=0;
+SET GLOBAL innodb_limit_optimistic_insert_debug=0;

mysql-test/suite/innodb/t/insert_debug.test

+--source include/have_innodb.inc
+--source include/have_debug.inc
+
+--echo #
+--echo # Bug#19904003 INNODB_LIMIT_OPTIMISTIC_INSERT_DEBUG=1
+--echo # CAUSES INFINITE PAGE SPLIT
+--echo #
+
+SET GLOBAL innodb_change_buffering_debug=1;
+SET GLOBAL innodb_limit_optimistic_insert_debug=1;
+CREATE TABLE t1(c1 INT PRIMARY KEY) ENGINE=InnoDB
+PARTITION BY HASH (c1) PARTITIONS 15;
+DROP TABLE t1;
+
+SET GLOBAL innodb_change_buffering_debug=0;
+SET GLOBAL innodb_limit_optimistic_insert_debug=0;

storage/innobase/include/btr0cur.ic

 /*****************************************************************************
 
-Copyright (c) 1994, 2012, Oracle and/or its affiliates. All Rights Reserved.
+Copyright (c) 1994, 2014, Oracle and/or its affiliates. All Rights Reserved.
 
 This program is free software; you can redistribute it and/or modify it under
 the terms of the GNU General Public License as published by the Free Software
@@ -28,7 +28,7 @@ Created 10/16/1994 Heikki Tuuri
 
 #ifdef UNIV_DEBUG
 # define LIMIT_OPTIMISTIC_INSERT_DEBUG(NREC, CODE)\
-if (btr_cur_limit_optimistic_insert_debug\
+if (btr_cur_limit_optimistic_insert_debug > 1\
     && (NREC) >= (ulint)btr_cur_limit_optimistic_insert_debug) {\
         CODE;\
 }