MDEV-20139 innodb.innodb_buffer_pool_dump_pct failed in buildbot with timeout

This test was using a sleep of 1 second in an attempt to ensure that the
timestamp that is part of an InnoDB status string would increase.
This not only prolongs the test execution time by 1+1 seconds, but it
also is inaccurate. It is possible that the actual sleep duration is
less than a second.

Let us wait for the creation of the file ib_buffer_pool and then wait
for the buffer pool dump completion. In that way, the test can complete
in a dozen or two milliseconds (1% of the previous duration) and work
more reliably.

mysql-test/suite/innodb/r/innodb_buffer_pool_dump_pct.result

@@ -3,17 +3,8 @@ col2 VARCHAR(25), col3 varchar(25)) ENGINE=InnoDB;
 CREATE INDEX idx1 ON tab5(col2(10));
 CREATE INDEX idx2 ON tab5(col3(10));
 SET GLOBAL innodb_buffer_pool_dump_pct=100;
-SELECT variable_value INTO @IBPDS
-FROM information_schema.global_status
-WHERE variable_name = 'INNODB_BUFFER_POOL_DUMP_STATUS';
 SET GLOBAL innodb_buffer_pool_dump_now=ON;
 SET GLOBAL innodb_buffer_pool_dump_pct=1;
-SELECT @@global.innodb_buffer_pool_dump_pct;
-@@global.innodb_buffer_pool_dump_pct
-1
-SELECT variable_value INTO @IBPDS
-FROM information_schema.global_status
-WHERE variable_name = 'INNODB_BUFFER_POOL_DUMP_STATUS';
 SET GLOBAL innodb_buffer_pool_dump_now=ON;
 SET GLOBAL innodb_buffer_pool_dump_pct=DEFAULT;
 DROP TABLE tab5;

mysql-test/suite/innodb/t/innodb_buffer_pool_dump_pct.test

@@ -35,49 +35,44 @@ SET GLOBAL innodb_buffer_pool_dump_pct=100;
 # - The granularity of the timestamp is one second.
 # - There could have been some dump caused by some previous test
 #   just a few milliseconds before.
-# In order to avoid conflict with previous tests, read the current value
-# of INNODB_BUFFER_POOL_DUMP_STATUS
-# and confirm that the timestamp is different after the dump
 #***********************************************************
 
-# Read the current value to compare with the new value.
-SELECT variable_value INTO @IBPDS
-FROM information_schema.global_status
-WHERE variable_name = 'INNODB_BUFFER_POOL_DUMP_STATUS';
-SET GLOBAL innodb_buffer_pool_dump_now=ON;
-
-# Sleep one second in order to ensure that the time stamp is
-# different at next dump
---sleep 1
+--error 0,1
+--remove_file $MYSQLD_DATADIR/ib_buffer_pool
 
+SET GLOBAL innodb_buffer_pool_dump_now=ON;
+perl;
+my $f="$ENV{MYSQLD_DATADIR}/ib_buffer_pool";
+my $count=300;
+until (-e $f)
+{
+  select(undef, undef, undef, .1);
+  die "File $f was not created\n" if (0 > --$count);
+}
+EOF
 let $wait_condition = SELECT count(*) = 1
 FROM information_schema.global_status
 WHERE variable_name = 'INNODB_BUFFER_POOL_DUMP_STATUS'
-AND variable_value != @IBPDS
 AND variable_value like 'Buffer pool(s) dump completed at%';
 --source include/wait_condition.inc
 
 --move_file $MYSQLD_DATADIR/ib_buffer_pool $MYSQLD_DATADIR/ib_buffer_pool100
 SET GLOBAL innodb_buffer_pool_dump_pct=1;
-SELECT @@global.innodb_buffer_pool_dump_pct;
-
-# Read the current value to compare with the new value.
---disable_warnings
-SELECT variable_value INTO @IBPDS
-FROM information_schema.global_status
-WHERE variable_name = 'INNODB_BUFFER_POOL_DUMP_STATUS';
---enable_warnings
-
 SET GLOBAL innodb_buffer_pool_dump_now=ON;
 
-# Sleep one second in order to ensure that the time stamp is
-# different at next dump
---sleep 1
+perl;
+my $f="$ENV{MYSQLD_DATADIR}/ib_buffer_pool";
+my $count=300;
+until (-e $f)
+{
+  select(undef, undef, undef, .1);
+  die "File $f was not created\n" if (0 > --$count);
+}
+EOF
 
 let $wait_condition = SELECT count(*) = 1
 FROM information_schema.global_status
 WHERE variable_name = 'INNODB_BUFFER_POOL_DUMP_STATUS'
-AND variable_value != @IBPDS
 AND variable_value like 'Buffer pool(s) dump completed at%';
 --source include/wait_condition.inc