MDEV-10651, MDEV-14196 sys_vars.innodb_buffer_pool_* tests fail

- innodb_buffer_pool_dump_now_basic is modified to make sure it
  really performs a dump and waits till it completion, to avoid
  the apparent or hidden failure similar to MDEV-9713 / MDEV-10651
- innodb_buffer_pool_dump_pct_basic is modified to re-use the new
  code from innodb_buffer_pool_dump_now_basic and thus avoid
  the failure MDEV-10651
- innodb_buffer_pool_load_now_basic is re-written to simplify
  the logic by re-using the code innodb_buffer_pool_dump_now_basic
  and is given an opt file to avoid race conditions with
  buffer pool load performed upon server startup, which causes
  MDEV-14196 failure

mysql-test/suite/sys_vars/r/innodb_buffer_pool_dump_now_basic.result

-SET @orig = @@global.innodb_buffer_pool_dump_now;
-SELECT @orig;
-@orig
+SELECT @@global.innodb_buffer_pool_dump_now;
+@@global.innodb_buffer_pool_dump_now
 0
+SELECT variable_value INTO @old_dump_status FROM information_schema.global_status
+WHERE LOWER(variable_name) = 'innodb_buffer_pool_dump_status';
 SET GLOBAL innodb_buffer_pool_dump_now = ON;
 SELECT @@global.innodb_buffer_pool_dump_now;
 @@global.innodb_buffer_pool_dump_now

mysql-test/suite/sys_vars/r/innodb_buffer_pool_dump_pct_basic.result

@@ -2,7 +2,8 @@ SET @orig = @@global.innodb_buffer_pool_dump_pct;
 SELECT @orig;
 @orig
 100
-SET GLOBAL innodb_buffer_pool_dump_pct=3, GLOBAL innodb_buffer_pool_dump_now = ON;
+SET GLOBAL innodb_buffer_pool_dump_pct=3;
+# Do the dump
 SET GLOBAL innodb_buffer_pool_dump_pct=0;
 SELECT @@global.innodb_buffer_pool_dump_pct;
 @@global.innodb_buffer_pool_dump_pct

mysql-test/suite/sys_vars/r/innodb_buffer_pool_load_now_basic.result

-SET @orig = @@global.innodb_buffer_pool_load_now;
-SELECT @orig;
-@orig
+SELECT @@global.innodb_buffer_pool_load_now;
+@@global.innodb_buffer_pool_load_now
 0
-SET GLOBAL innodb_buffer_pool_dump_now = ON;
 SET GLOBAL innodb_buffer_pool_load_now = ON;
 SELECT variable_value
 FROM information_schema.global_status

mysql-test/suite/sys_vars/t/innodb_buffer_pool_dump_now_basic.test

@@ -5,8 +5,31 @@
 -- source include/have_innodb.inc
 
 # Check the default value
-SET @orig = @@global.innodb_buffer_pool_dump_now;
-SELECT @orig;
+SELECT @@global.innodb_buffer_pool_dump_now;
+
+-- let $file = `SELECT CONCAT(@@datadir, @@global.innodb_buffer_pool_filename)`
+-- error 0,1
+-- remove_file $file
+
+SELECT variable_value INTO @old_dump_status FROM information_schema.global_status
+    WHERE LOWER(variable_name) = 'innodb_buffer_pool_dump_status';
+
+# A previous test could have run buffer pool dump already;
+# in this case we want to make sure that the current time is different
+# from the timestamp in the status variable.
+# We should have had a smart wait condition here, like the commented one below,
+# let $wait_condition =
+#  SELECT TRIM(SUBSTR('$old_status', -8)) != DATE_FORMAT(CURTIME(), '%k:%i:%s');
+# -- source include/wait_condition.inc
+
+# ... but we can't because of MDEV-9867, so there will be just sleep instead.
+# And it might be not enough to sleep one second, so we'll have to sleep two.
+
+if (`SELECT variable_value LIKE '%completed at%' FROM information_schema.global_status
+     WHERE LOWER(variable_name) = 'innodb_buffer_pool_dump_status'`)
+{
+  -- sleep 2
+}
 
 # Do the dump
 SET GLOBAL innodb_buffer_pool_dump_now = ON;
@@ -15,11 +38,11 @@ SELECT @@global.innodb_buffer_pool_dump_now;
 
 # Wait for the dump to complete
 let $wait_condition =
-  SELECT SUBSTR(variable_value, 1, 33) = 'Buffer pool(s) dump completed at '
+  SELECT variable_value != @old_dump_status
+     AND SUBSTR(variable_value, 1, 33) = 'Buffer pool(s) dump completed at '
   FROM information_schema.global_status
   WHERE LOWER(variable_name) = 'innodb_buffer_pool_dump_status';
 -- source include/wait_condition.inc
 
 # Confirm that the dump file has been created
--- let $file = `SELECT CONCAT(@@datadir, @@global.innodb_buffer_pool_filename)`
 -- file_exists $file

mysql-test/suite/sys_vars/t/innodb_buffer_pool_dump_pct_basic.test

@@ -8,19 +8,15 @@
 SET @orig = @@global.innodb_buffer_pool_dump_pct;
 SELECT @orig;
 
-# Do the dump
-SET GLOBAL innodb_buffer_pool_dump_pct=3, GLOBAL innodb_buffer_pool_dump_now = ON;
+SET GLOBAL innodb_buffer_pool_dump_pct=3;
 
-# Wait for the dump to complete
-let $wait_condition =
-  SELECT SUBSTR(variable_value, 1, 33) = 'Buffer pool(s) dump completed at '
-  FROM information_schema.global_status
-  WHERE LOWER(variable_name) = 'innodb_buffer_pool_dump_status';
--- source include/wait_condition.inc
+--echo # Do the dump
 
-# Confirm that the dump file has been created
--- let $file = `SELECT CONCAT(@@datadir, @@global.innodb_buffer_pool_filename)`
--- file_exists $file
+--disable_query_log
+--disable_result_log
+--source innodb_buffer_pool_dump_now_basic.test
+--enable_result_log
+--enable_query_log
 
 --disable_warnings
 SET GLOBAL innodb_buffer_pool_dump_pct=0;

mysql-test/suite/sys_vars/t/innodb_buffer_pool_load_now_basic.opt

+--innodb-buffer-pool-load-at-startup=off

mysql-test/suite/sys_vars/t/innodb_buffer_pool_load_now_basic.test

@@ -5,42 +5,22 @@
 -- source include/have_innodb.inc
 
 # Check the default value
-SET @orig = @@global.innodb_buffer_pool_load_now;
-SELECT @orig;
+SELECT @@global.innodb_buffer_pool_load_now;
 
-let $old_status= `SELECT variable_value FROM information_schema.global_status
-    WHERE LOWER(variable_name) = 'innodb_buffer_pool_dump_status'`;
+# Make sure there is a dump file to load
 
-# A previous test could have run buffer pool dump already; 
-# in this case we want to make sure that the current time is different 
-# from the timestamp in the status variable.
-# We should have had a smart wait condition here, like the commented one below,
-# but we can't because of MDEV-9867, so there will be just sleep instead.
-# And it might be not enough to sleep one second, so we'll have to sleep two. 
-# let $wait_condition =
-#  SELECT TRIM(SUBSTR('$old_status', -8)) != DATE_FORMAT(CURTIME(), '%k:%i:%s');
-# -- source include/wait_condition.inc
-
-if (`SELECT variable_value LIKE '%dump completed at%' FROM information_schema.global_status
-     WHERE LOWER(variable_name) = 'innodb_buffer_pool_dump_status'`)
-{
-  -- sleep 2
-}
-
-# Do the dump
-SET GLOBAL innodb_buffer_pool_dump_now = ON;
-
-# Wait for the dump to complete
-let $wait_condition =
-  SELECT variable_value != '$old_status'
-     AND SUBSTR(variable_value, 1, 33) = 'Buffer pool(s) dump completed at '
-  FROM information_schema.global_status
-  WHERE LOWER(variable_name) = 'innodb_buffer_pool_dump_status';
--- source include/wait_condition.inc
-
-# Confirm the file is really created
 -- let $file = `SELECT CONCAT(@@datadir, @@global.innodb_buffer_pool_filename)`
+-- error 0,1
 -- file_exists $file
+if ($errno)
+{
+  # Dump file does not exist, get it created
+  --disable_query_log
+  --disable_result_log
+  --source innodb_buffer_pool_dump_now_basic.test
+  --enable_result_log
+  --enable_query_log
+}
 
 # Load the dump
 SET GLOBAL innodb_buffer_pool_load_now = ON;