LP #1466414: Deadlocks missed by INFORMATION_SCHEMA.INNODB_METRICS lock_deadlocks counter

**Reported in Launchpad by Laurynas Biveinis last update 26-05-2016 14:20:36

Copy of http://bugs.mysql.com/bug.php?id=77399 (the testcase is based on percona_innodb_deadlock_count with I_S.I_M support added)

[18 Jun 8:22] Laurynas Biveinis
Description:
Some deadlocks do not bump the INFORMATION_SCHEMA.INNODB_METRICS lock_deadlocks counter. The MTR below will result in

SELECT NAME, COUNT, COMMENT FROM INFORMATION_SCHEMA.INNODB_METRICS WHERE NAME="lock_deadlocks";
NAME COUNT COMMENT
lock_deadlocks 0 Number of deadlocks

But if you check ie. engine status, you will see

------------------------
LATEST DETECTED DEADLOCK
------------------------
2015-06-18 11:20:16 10d7a0000

• • • (1) TRANSACTION:
      TRANSACTION 1292, ACTIVE 0 sec starting index read
      ... info ...

How to repeat:
--source include/have_innodb.inc

connect (con1,localhost,root,,);
connect (con2,localhost,root,,);

create table t(a INT PRIMARY KEY, b INT) engine=InnoDB;
insert into t values(2,1);
insert into t values(1,2);

SET GLOBAL innodb_monitor_reset=lock_deadlocks;

connection con1;
BEGIN; SELECT b FROM t WHERE a=1 FOR UPDATE;

connection con2;
BEGIN; SELECT b FROM t WHERE a=2 FOR UPDATE;

connection con1;
SEND SELECT b FROM t WHERE a=2 FOR UPDATE;

connection con2;
SEND SELECT b FROM t WHERE a=1 FOR UPDATE;

connection con1;
--error 0,ER_LOCK_DEADLOCK
reap;
ROLLBACK;

connection con2;
--error 0,ER_LOCK_DEADLOCK
reap;
ROLLBACK;

connection default;

SELECT NAME, COUNT, COMMENT FROM INFORMATION_SCHEMA.INNODB_METRICS WHERE NAME="lock_deadlocks";