Make new replication slot test code less racy

The new test code added in ead9e51e8236 is racy -- it hinges on
shared-memory state, which changes before the WARNING message is logged.
Put it the other way around.

Backpatch to 13.

Author: Álvaro Herrera <alvherre@alvh.no-ip.org>
Discussion: https://postgr.es/m/202107161809.zclasccpfcg3@alvherre.pgsql

diff --git a/src/test/recovery/t/019_replslot_limit.pl b/src/test/recovery/t/019_replslot_limit.pl
index 319a41b27ba3a3fbcf299754a37ad0f148029610..921a3c4a427b34c52017c25273d21f4852c93245 100644 (file)
--- a/src/test/recovery/t/019_replslot_limit.pl
+++ b/src/test/recovery/t/019_replslot_limit.pl
@@ -174,18 +174,21 @@ ok( !find_in_log(
 my $logstart = get_log_size($node_master);
 advance_wal($node_master, 7);
 
-# This slot should be broken, wait for that to happen
-$node_master->poll_query_until(
-   'postgres',
-   qq[SELECT wal_status = 'lost' FROM pg_replication_slots
-   WHERE slot_name = 'rep1']);
-
-# WARNING should be issued
-ok( find_in_log(
-       $node_master,
-       "invalidating slot \"rep1\" because its restart_lsn [0-9A-F/]+ exceeds max_slot_wal_keep_size",
-       $logstart),
-   'check that the warning is logged');
+# wait until the WARNING is issued
+my $invalidated = 0;
+for (my $i = 0; $i < 10000; $i++)
+{
+   if (find_in_log(
+           $node_master,
+           "invalidating slot \"rep1\" because its restart_lsn [0-9A-F/]+ exceeds max_slot_wal_keep_size",
+           $logstart))
+   {
+       $invalidated = 1;
+       last;
+   }
+   usleep(100_000);
+}
+ok($invalidated, 'check that slot invalidation has been logged');
 
 $result = $node_master->safe_psql(
    'postgres',