Added read only system variable 'in_transaction' which tells if there's

an active transaction.

fixed a bug - not clearing "in transaction" status on set @@autocommit=1

mysql-test/r/status_user.result

@@ -186,4 +186,33 @@ bytes_sent <> 0, binlog_bytes_written <> 0
 from information_schema.client_statistics;
 connected_time <> 0	busy_time <> 0	bytes_received <> 0	bytes_sent <> 0	binlog_bytes_written <> 0
 1	1	1	1	1
+create table t1 (a int) engine=innodb;
+select @@in_transaction;
+@@in_transaction
+0
+begin;
+select @@in_transaction;
+@@in_transaction
+1
+insert into t1 values (1);
+select @@in_transaction;
+@@in_transaction
+1
+commit;
+select @@in_transaction;
+@@in_transaction
+0
+set @@autocommit=0;
+select @@in_transaction;
+@@in_transaction
+0
+insert into t1 values (2);
+select @@in_transaction;
+@@in_transaction
+1
+set @@autocommit=1;
+select @@in_transaction;
+@@in_transaction
+0
+drop table t1;
 set @@global.general_log=@save_general_log;

mysql-test/t/status_user.test

@@ -85,5 +85,25 @@ select connected_time <> 0, busy_time <> 0, bytes_received <> 0,
        bytes_sent <> 0, binlog_bytes_written <> 0
        from information_schema.client_statistics;
 
+#
+# Test of in transaction
+#
+
+create table t1 (a int) engine=innodb;
+select @@in_transaction;
+begin;
+select @@in_transaction;
+insert into t1 values (1);
+select @@in_transaction;
+commit;
+select @@in_transaction;
+set @@autocommit=0;
+select @@in_transaction;
+insert into t1 values (2);
+select @@in_transaction;
+set @@autocommit=1;
+select @@in_transaction;
+drop table t1;
+
 # Cleanup
 set @@global.general_log=@save_general_log;

sql/set_var.cc

@@ -156,6 +156,7 @@ static bool sys_update_slow_log_path(THD *thd, set_var * var);
 static void sys_default_slow_log_path(THD *thd, enum_var_type type);
 static void fix_sys_log_slow_filter(THD *thd, enum_var_type);
 static uchar *get_myisam_mmap_size(THD *thd);
+static uchar *in_transaction(THD *thd);
 static int check_max_allowed_packet(THD *thd,  set_var *var);
 static int check_net_buffer_length(THD *thd,  set_var *var);
 
@@ -997,6 +998,12 @@ static sys_var_enum_const     sys_plugin_maturity(&vars, "plugin_maturity",
                                                   &plugin_maturity,
                                                   &plugin_maturity_values);
 
+static sys_var_readonly       sys_in_transaction(&vars, "in_transaction",
+                                                 OPT_SESSION, SHOW_BOOL,
+                                                 in_transaction);
+
+
+
 bool sys_var::check(THD *thd, set_var *var)
 {
   var->save_result.ulonglong_value= var->value->val_int();
@@ -3269,35 +3276,26 @@ static bool set_option_log_bin_bit(THD *thd, set_var *var)
 
 static bool set_option_autocommit(THD *thd, set_var *var)
 {
-  /* The test is negative as the flag we use is NOT autocommit */
-
-  ulonglong org_options= thd->options;
+  ulonglong new_options= thd->options;
 
-  if (var->save_result.ulong_value != 0)
-    thd->options&= ~((sys_var_thd_bit*) var->var)->bit_flag;
+  /* The test is negative as the flag we use is NOT autocommit */
+  if (var->save_result.ulong_value)
+    new_options&= ~OPTION_NOT_AUTOCOMMIT;
   else
-    thd->options|= ((sys_var_thd_bit*) var->var)->bit_flag;
+    new_options|= OPTION_NOT_AUTOCOMMIT;
 
-  if ((org_options ^ thd->options) & OPTION_NOT_AUTOCOMMIT)
+  if ((new_options ^ thd->options) & OPTION_NOT_AUTOCOMMIT)
   {
-    if ((org_options & OPTION_NOT_AUTOCOMMIT))
+    if ((thd->options & OPTION_NOT_AUTOCOMMIT))
     {
-      /* We changed to auto_commit mode */
-      if (thd->transaction.xid_state.xa_state != XA_NOTR)
-      {
-        thd->options= org_options;
-        my_error(ER_XAER_RMFAIL, MYF(0),
-                 xa_state_names[thd->transaction.xid_state.xa_state]);
+      if (end_active_trans(thd))
         return 1;
-      }
-      thd->options&= ~(ulonglong) (OPTION_BEGIN | OPTION_KEEP_LOG);
-      thd->transaction.all.modified_non_trans_table= FALSE;
       thd->server_status|= SERVER_STATUS_AUTOCOMMIT;
-      if (ha_commit(thd))
-	return 1;
+      thd->options= new_options;
     }
     else
     {
+      thd->options= new_options;
       thd->transaction.all.modified_non_trans_table= FALSE;
       thd->server_status&= ~SERVER_STATUS_AUTOCOMMIT;
     }
@@ -3399,6 +3397,12 @@ static uchar *get_myisam_mmap_size(THD *thd)
   return (uchar *)&myisam_mmap_size;
 }
 
+static uchar *in_transaction(THD *thd)
+{
+  thd->sys_var_tmp.my_bool_value=
+    test(thd->server_status & SERVER_STATUS_IN_TRANS);
+  return (uchar*) &thd->sys_var_tmp.my_bool_value;
+}
 
 /****************************************************************************
   Main handling of variables: