MDEV-33348 ALTER TABLE lock waiting stages are indistinguishable

Several points of synchronization during ALTER TABLE COPY looked identical
in the progress report query. Besides, if its the late lock upgrade stage,
the data would be:
STAGE   0
MAX_STAGE       0
PROGRESS        0.000

which looks irrelevant.

This patch moves thd_progress_deinit call after the last lock upgrade.

Also, for online alter, if there is nothing to replicate, the
progress and max_progress values would be 0, which discard the result data
on the side of sql_show, see processlist_callback in sql_show.cc.
So now the minimal max_progress will be 1. To avoid 0% progress in the
report, minimax progress value is also set to 1, so we will see 100% if
there's nothing to replicate.

mysql-test/main/alter_table_online.result

@@ -238,3 +238,33 @@ ERROR 0A000: LOCK=NONE is not supported. Reason: Function or expression 'NEXTVAL
 drop table t2;
 drop table t1;
 drop sequence s;
+#
+# MDEV-33348 ALTER TABLE lock waiting stages are indistinguishable
+#
+connect  con2, localhost, root,,;
+create or replace table t1 (a int);
+show create table t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `a` int(11) DEFAULT NULL
+) ENGINE=MyISAM DEFAULT CHARSET=latin1 COLLATE=latin1_swedish_ci
+insert t1 values (5);
+connection con2;
+begin;
+select * from t1;
+a
+5
+connection default;
+alter table t1 add b int NULL, algorithm= copy, lock= none;
+connection con2;
+select stage, state, info from information_schema.processlist where id = @con;
+stage	4
+state	Waiting for table metadata lock
+info	alter table t1 add b int NULL, algorithm= copy, lock= none
+rollback;
+connection default;
+drop table t1;
+disconnect con2;
+#
+# End of 11.2 tests
+#

mysql-test/main/alter_table_online.test

@@ -246,3 +246,45 @@ alter table t2 modify b int not null default (nextval(s)), lock=none;
 drop table t2;
 drop table t1;
 drop sequence s;
+
+--echo #
+--echo # MDEV-33348 ALTER TABLE lock waiting stages are indistinguishable
+--echo #
+--connect (con2, localhost, root,,)
+
+create or replace table t1 (a int);
+show create table t1;
+insert t1 values (5);
+
+--connection con2
+begin;
+select * from t1;
+--connection default
+--let $con= `select connection_id()`
+send alter table t1 add b int NULL, algorithm= copy, lock= none;
+
+
+--connection con2
+disable_query_log;
+eval set @con= $con;
+enable_query_log;
+
+
+let $wait_condition= select stage = 4 and progress = 100
+                              and state= "Waiting for table metadata lock"
+                       from information_schema.processlist where id = @con;
+--source include/wait_condition.inc
+
+query_vertical select stage, state, info from information_schema.processlist where id = @con;
+
+rollback;
+
+--connection default
+reap;
+
+drop table t1;
+--disconnect con2
+
+--echo #
+--echo # End of 11.2 tests
+--echo #

sql/sql_table.cc

@@ -11364,6 +11364,15 @@ do_continue:;
       new_table->mark_columns_needed_for_insert();
       mysql_bin_log.write_table_map(thd, new_table, 1);
     }
+
+    /*
+      if ORDER BY: sorting
+      always: copying, building indexes.
+      if online: reading up the binlog (second binlog is being written)
+                 reading up the second binlog under exclusive lock
+    */
+    thd_progress_init(thd, MY_TEST(order) + 2 + 2 * MY_TEST(online));
+    
     if (copy_data_between_tables(thd, table, new_table,
                                  ignore,
                                  order_num, order, &copied, &deleted,
@@ -11532,6 +11541,8 @@ do_continue:;
                             NULL);
   table_list->table= table= NULL;                  /* Safety */
 
+  thd_progress_end(thd);
+
   DBUG_PRINT("info", ("is_table_renamed: %d  engine_changed: %d",
                       alter_ctx.is_table_renamed(), engine_changed));
 
@@ -11761,6 +11772,8 @@ err_new_table_cleanup:
   DBUG_PRINT("error", ("err_new_table_cleanup"));
   thd->variables.option_bits&= ~OPTION_BIN_COMMIT_OFF;
 
+  thd_progress_end(thd);
+
   /*
     No default value was provided for a DATE/DATETIME field, the
     current sql_mode doesn't allow the '0000-00-00' value and
@@ -11890,7 +11903,7 @@ static int online_alter_read_from_binlog(THD *thd, rpl_group_info *rgi,
 
   IO_CACHE *log_file= log->flip();
 
-  thd_progress_report(thd, 0, my_b_write_tell(log_file));
+  thd_progress_report(thd, 1, MY_MAX(1, my_b_write_tell(log_file)));
 
   Has_default_error_handler hdeh;
   thd->push_internal_handler(&hdeh);
@@ -11957,14 +11970,6 @@ copy_data_between_tables(THD *thd, TABLE *from, TABLE *to,
   MYSQL_TIME query_start;
   DBUG_ENTER("copy_data_between_tables");
 
-  /*
-    if ORDER BY: sorting
-    always: copying, building indexes.
-    if online: reading up the binlog (second binlog is being written)
-               reading up the second binlog under exclusive lock
-  */
-  thd_progress_init(thd, MY_TEST(order) + 2 + 2 * MY_TEST(online));
-
   if (!(copy= new (thd->mem_root) Copy_field[to->s->fields]))
     DBUG_RETURN(-1);
 
@@ -12431,7 +12436,6 @@ copy_data_between_tables(THD *thd, TABLE *from, TABLE *to,
   if (error < 0 && !from->s->tmp_table &&
       to->file->extra(HA_EXTRA_PREPARE_FOR_RENAME))
     error= 1;
-  thd_progress_end(thd);
   DBUG_RETURN(error > 0 ? -1 : 0);
 }