# name       : innodb_deadlock_count.patch
# introduced : 11 or before
# maintainer : Yasufumi
#
#!!! notice !!!
# Any small change to this file in the main branch
# should be done or reviewed by the maintainer!
--- a/storage/innobase/handler/ha_innodb.cc
+++ b/storage/innobase/handler/ha_innodb.cc
@@ -691,6 +691,8 @@
   (char*) &export_vars.innodb_dblwr_pages_written,	  SHOW_LONG},
   {"dblwr_writes",
   (char*) &export_vars.innodb_dblwr_writes,		  SHOW_LONG},
+  {"deadlocks",
+  (char*) &export_vars.innodb_deadlocks,		  SHOW_LONG},
   {"dict_tables",
   (char*) &export_vars.innodb_dict_tables,		  SHOW_LONG},
   {"have_atomic_builtins",
--- a/storage/innobase/include/lock0lock.h
+++ b/storage/innobase/include/lock0lock.h
@@ -43,6 +43,7 @@
 #endif /* UNIV_DEBUG */
 /* Buffer for storing information about the most recent deadlock error */
 extern FILE*	lock_latest_err_file;
+extern ulint	srv_n_lock_deadlock_count;
 
 /*********************************************************************//**
 Gets the size of a lock struct.
--- a/storage/innobase/include/srv0srv.h
+++ b/storage/innobase/include/srv0srv.h
@@ -770,6 +770,7 @@
 	ulint innodb_buffer_pool_read_ahead_evicted;/*!< srv_read_ahead evicted*/
 	ulint innodb_dblwr_pages_written;	/*!< srv_dblwr_pages_written */
 	ulint innodb_dblwr_writes;		/*!< srv_dblwr_writes */
+	ulint innodb_deadlocks;
 	ibool innodb_have_atomic_builtins;	/*!< HAVE_ATOMIC_BUILTINS */
 	ulint innodb_log_waits;			/*!< srv_log_waits */
 	ulint innodb_log_write_requests;	/*!< srv_log_write_requests */
--- a/storage/innobase/lock/lock0lock.c
+++ b/storage/innobase/lock/lock0lock.c
@@ -3330,6 +3330,7 @@
 		break;
 
 	case LOCK_VICTIM_IS_START:
+		srv_n_lock_deadlock_count++;
 		fputs("*** WE ROLL BACK TRANSACTION (2)\n",
 		      lock_latest_err_file);
 		break;
--- a/storage/innobase/srv/srv0srv.c
+++ b/storage/innobase/srv/srv0srv.c
@@ -477,6 +477,7 @@
 static ulint	srv_n_rows_deleted_old		= 0;
 static ulint	srv_n_rows_read_old		= 0;
 
+UNIV_INTERN ulint		srv_n_lock_deadlock_count	= 0;
 UNIV_INTERN ulint		srv_n_lock_wait_count		= 0;
 UNIV_INTERN ulint		srv_n_lock_wait_current_count	= 0;
 UNIV_INTERN ib_int64_t	srv_n_lock_wait_time		= 0;
@@ -2293,6 +2294,7 @@
 	export_vars.innodb_buffer_pool_pages_data = LRU_len;
 	export_vars.innodb_buffer_pool_pages_dirty = flush_list_len;
 	export_vars.innodb_buffer_pool_pages_free = free_len;
+	export_vars.innodb_deadlocks = srv_n_lock_deadlock_count;
 #ifdef UNIV_DEBUG
 	export_vars.innodb_buffer_pool_pages_latched
 		= buf_get_latched_pages_number();
--- /dev/null
+++ b/mysql-test/r/percona_innodb_deadlock_count.result
@@ -0,0 +1,28 @@
+# Establish connection con1 (user=root)
+# Establish connection con2 (user=root)
+# Establish connection con3 (user=root)
+# Drop test table
+drop table if exists t;
+# Create test table
+create table t(a INT PRIMARY KEY, b INT) engine=InnoDB;
+# Insert two rows to test table
+insert into t values(2,1);
+insert into t values(1,2);
+# Switch to connection con1
+BEGIN;
+SELECT b FROM t WHERE a=1 FOR UPDATE;
+# Switch to connection con2
+BEGIN;
+SELECT b FROM t WHERE a=2 FOR UPDATE;
+# Switch to connection con1
+SELECT b FROM t WHERE a=2 FOR UPDATE;
+# Switch to connection con2
+SELECT b FROM t WHERE a=1 FOR UPDATE;
+# Switch to connection con1
+ROLLBACK;
+# Switch to connection con2
+ROLLBACK;
+# Switch to connection con3
+Deadlocks: 1
+# Drop test table
+drop table t;
--- /dev/null
+++ b/mysql-test/t/percona_innodb_deadlock_count.test
@@ -0,0 +1,61 @@
+--source include/have_innodb.inc
+--echo # Establish connection con1 (user=root)
+connect (con1,localhost,root,,);
+--echo # Establish connection con2 (user=root)
+connect (con2,localhost,root,,);
+--echo # Establish connection con3 (user=root)
+connect (con3,localhost,root,,);
+--echo # Drop test table
+--disable_warnings
+drop table if exists t;
+--enable_warnings
+
+--echo # Create test table
+create table t(a INT PRIMARY KEY, b INT) engine=InnoDB;
+--echo # Insert two rows to test table
+insert into t values(2,1);
+insert into t values(1,2);
+
+#--echo # Save current deadlock count
+let $current = `SELECT VARIABLE_VALUE FROM INFORMATION_SCHEMA.GLOBAL_STATUS WHERE VARIABLE_NAME = 'Innodb_deadlocks'`;
+
+--disable_result_log
+
+--echo # Switch to connection con1
+connection con1;
+BEGIN; SELECT b FROM t WHERE a=1 FOR UPDATE;
+
+--echo # Switch to connection con2
+connection con2;
+BEGIN; SELECT b FROM t WHERE a=2 FOR UPDATE;
+
+--echo # Switch to connection con1
+connection con1;
+SEND SELECT b FROM t WHERE a=2 FOR UPDATE;
+
+--echo # Switch to connection con2
+connection con2;
+SEND SELECT b FROM t WHERE a=1 FOR UPDATE;
+
+--echo # Switch to connection con1
+connection con1;
+--error 0, ER_LOCK_DEADLOCK
+reap;
+ROLLBACK;
+
+--echo # Switch to connection con2
+connection con2;
+--error 0, ER_LOCK_DEADLOCK
+reap;
+ROLLBACK;
+
+--echo # Switch to connection con3
+connection con3;
+let $result = `SELECT VARIABLE_VALUE FROM INFORMATION_SCHEMA.GLOBAL_STATUS WHERE VARIABLE_NAME = 'Innodb_deadlocks'`;
+
+--enable_result_log
+
+let $diff = `SELECT $result - $current`;
+echo Deadlocks: $diff;
+--echo # Drop test table
+drop table t;