From 6b6cb174452c553437ba7949aa25f305f599d6b7 Mon Sep 17 00:00:00 2001
From: Alvaro Herrera <alvherre@alvh.no-ip.org>
Date: Fri, 11 Jun 2021 12:21:45 -0400
Subject: [PATCH v3] Add test case for invalidating an active replication slot
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The code to signal a running walsender was completely uncovered before.

This test involves sending SIGSTOP to a walreceiver and running a
checkpoint while advancing WAL.  I'm not very certain that this test is
stable, so it's in master only, and separate from the code-fix commit so
that it can be reverted easily if need be.

Author: �lvaro Herrera <alvherre@alvh.no-ip.org>
Discussion: https://postgr.es/m/202106102202.mjw4huiix7lo@alvherre.pgsql
---
 src/test/recovery/t/019_replslot_limit.pl | 79 ++++++++++++++++++++++-
 1 file changed, 76 insertions(+), 3 deletions(-)

diff --git a/src/test/recovery/t/019_replslot_limit.pl b/src/test/recovery/t/019_replslot_limit.pl
index 7094aa0704..dcadfe1252 100644
--- a/src/test/recovery/t/019_replslot_limit.pl
+++ b/src/test/recovery/t/019_replslot_limit.pl
@@ -11,7 +11,7 @@ use TestLib;
 use PostgresNode;
 
 use File::Path qw(rmtree);
-use Test::More tests => 14;
+use Test::More tests => $TestLib::windows_os ? 14 : 17;
 use Time::HiRes qw(usleep);
 
 $ENV{PGDATABASE} = 'postgres';
@@ -211,8 +211,8 @@ for (my $i = 0; $i < 10000; $i++)
 }
 ok($failed, 'check that replication has been broken');
 
-$node_primary->stop('immediate');
-$node_standby->stop('immediate');
+$node_primary->stop;
+$node_standby->stop;
 
 my $node_primary2 = get_new_node('primary2');
 $node_primary2->init(allows_streaming => 1);
@@ -253,6 +253,79 @@ my @result =
 		timeout => '60'));
 is($result[1], 'finished', 'check if checkpoint command is not blocked');
 
+$node_primary2->stop;
+$node_standby->stop;
+
+# The next test depends on Perl's `kill`, which apparently is not
+# portable to Windows.  (It would be nice to use Test::More's `subtest`,
+# but that's not in the ancient version we require.)
+if ($TestLib::windows_os)
+{
+	done_testing();
+	exit;
+}
+
+# Get a slot terminated while the walsender is active
+# We do this by sending SIGSTOP to the walreceiver.  Skip this on Windows.
+my $node_primary3 = get_new_node('primary3');
+$node_primary3->init(allows_streaming => 1, extra => ['--wal-segsize=1']);
+$node_primary3->append_conf(
+	'postgresql.conf', qq(
+	min_wal_size = 2MB
+	max_wal_size = 2MB
+	log_checkpoints = yes
+	max_slot_wal_keep_size = 1MB
+	));
+$node_primary3->start;
+$node_primary3->safe_psql('postgres',
+	"SELECT pg_create_physical_replication_slot('rep3')");
+# Take backup
+$backup_name = 'my_backup';
+$node_primary3->backup($backup_name);
+# Create standby
+my $node_standby3 = get_new_node('standby_3');
+$node_standby3->init_from_backup($node_primary3, $backup_name,
+	has_streaming => 1);
+$node_standby3->append_conf('postgresql.conf', "primary_slot_name = 'rep3'");
+$node_standby3->start;
+$node_primary3->wait_for_catchup($node_standby3->name, 'replay');
+my $pid = $node_standby3->safe_psql('postgres',
+	"SELECT pid FROM pg_stat_activity WHERE backend_type = 'walreceiver'");
+like($pid, qr/^[0-9]+$/, "have walreceiver pid $pid");
+
+# freeze walreceiver. Slot will still be active, but it won't advance
+kill 'STOP', $pid;
+$logstart = get_log_size($node_primary3);
+advance_wal($node_primary3, 2);
+
+my ($in, $out, $timer, $h);
+$timer = IPC::Run::timeout(180);
+$h = $node_primary3->background_psql('postgres', \$in, \$out, $timer);
+$in .= qq{
+checkpoint;
+};
+$h->pump_nb;
+ok(find_in_log($node_primary3, "to release replication slot"),
+	"walreceiver termination logged");
+
+advance_wal($node_primary3, 2);
+
+# Now let it continue to its demise
+kill 'CONT', $pid;
+
+$node_primary3->poll_query_until('postgres',
+	"SELECT wal_status FROM pg_replication_slots WHERE slot_name = 'rep3'",
+	"lost")
+  or die "timed out waiting for slot to be lost";
+
+ok( find_in_log(
+		$node_primary3, 'invalidating slot "rep3" because its restart_lsn'),
+	"slot invalidation logged");
+
+
+$node_primary3->stop;
+$node_standby3->stop;
+
 #####################################
 # Advance WAL of $node by $n segments
 sub advance_wal
-- 
2.20.1