Extend the abilities of libpq's target_session_attrs parameter.

In addition to the existing options of "any" and "read-write", we
now support "read-only", "primary", "standby", and "prefer-standby".
"read-write" retains its previous meaning of "transactions are
read-write by default", and "read-only" inverts that.  The other
three modes test specifically for hot-standby status, which is not
quite the same thing.  (Setting default_transaction_read_only on
a primary server renders it read-only to this logic, but not a
standby.)

Furthermore, if talking to a v14 or later server, no extra network
round trip is needed to detect the session's status; the GUC_REPORT
variables delivered by the server are enough.  When talking to an
older server, a SHOW or SELECT query is issued to detect session
read-only-ness or server hot-standby state, as needed.

Haribabu Kommi, Greg Nancarrow, Vignesh C, Tom Lane; reviewed at
various times by Laurenz Albe, Takayuki Tsunakawa, Peter Smith.

Discussion: https://postgr.es/m/CAF3+xM+8-ztOkaV9gHiJ3wfgENTq97QcjXQt+rbFQ6F7oNzt9A@mail.gmail.com

1 files changed, 74 insertions, 8 deletions

diff --git a/src/test/recovery/t/001_stream_rep.pl b/src/test/recovery/t/001_stream_rep.pl
index 9e31a53de7..07a9912ce2 100644
--- a/src/test/recovery/t/001_stream_rep.pl
+++ b/src/test/recovery/t/001_stream_rep.pl
@@ -3,7 +3,7 @@ use strict;
 use warnings;
 use PostgresNode;
 use TestLib;
-use Test::More tests => 36;
+use Test::More tests => 49;
 
 # Initialize primary node
 my $node_primary = get_new_node('primary');
@@ -85,7 +85,7 @@ sub test_target_session_attrs
 	my $node2_port = $node2->port;
 	my $node2_name = $node2->name;
 
-	my $target_name = $target_node->name;
+	my $target_name = $target_node->name if (defined $target_node);
 
 	# Build connection string for connection attempt.
 	my $connstr = "host=$node1_host,$node2_host ";
@@ -97,10 +97,25 @@ sub test_target_session_attrs
 	my ($ret, $stdout, $stderr) =
 	  $node1->psql('postgres', 'SHOW port;',
 		extra_params => [ '-d', $connstr ]);
-	is( $status == $ret && $stdout eq $target_node->port,
-		1,
-		"connect to node $target_name if mode \"$mode\" and $node1_name,$node2_name listed"
-	);
+	if ($status == 0)
+	{
+		is( $status == $ret && $stdout eq $target_node->port,
+			1,
+			"connect to node $target_name if mode \"$mode\" and $node1_name,$node2_name listed"
+		);
+	}
+	else
+	{
+		print "status = $status\n";
+		print "ret = $ret\n";
+		print "stdout = $stdout\n";
+		print "stderr = $stderr\n";
+
+		is( $status == $ret,
+			1,
+			"fail to connect to any nodes if mode \"$mode\" and $node1_name,$node2_name listed"
+		);
+	}
 
 	return;
 }
@@ -114,13 +129,64 @@ test_target_session_attrs($node_standby_1, $node_primary, $node_primary,
 	"read-write", 0);
 
 # Connect to primary in "any" mode with primary,standby1 list.
-test_target_session_attrs($node_primary, $node_standby_1, $node_primary, "any",
-	0);
+test_target_session_attrs($node_primary, $node_standby_1, $node_primary,
+	"any", 0);
 
 # Connect to standby1 in "any" mode with standby1,primary list.
 test_target_session_attrs($node_standby_1, $node_primary, $node_standby_1,
 	"any", 0);
 
+# Connect to primary in "primary" mode with primary,standby1 list.
+test_target_session_attrs($node_primary, $node_standby_1, $node_primary,
+	"primary", 0);
+
+# Connect to primary in "primary" mode with standby1,primary list.
+test_target_session_attrs($node_standby_1, $node_primary, $node_primary,
+	"primary", 0);
+
+# Connect to standby1 in "read-only" mode with primary,standby1 list.
+test_target_session_attrs($node_primary, $node_standby_1, $node_standby_1,
+	"read-only", 0);
+
+# Connect to standby1 in "read-only" mode with standby1,primary list.
+test_target_session_attrs($node_standby_1, $node_primary, $node_standby_1,
+	"read-only", 0);
+
+# Connect to primary in "prefer-standby" mode with primary,primary list.
+test_target_session_attrs($node_primary, $node_primary, $node_primary,
+	"prefer-standby", 0);
+
+# Connect to standby1 in "prefer-standby" mode with primary,standby1 list.
+test_target_session_attrs($node_primary, $node_standby_1, $node_standby_1,
+	"prefer-standby", 0);
+
+# Connect to standby1 in "prefer-standby" mode with standby1,primary list.
+test_target_session_attrs($node_standby_1, $node_primary, $node_standby_1,
+	"prefer-standby", 0);
+
+# Connect to standby1 in "standby" mode with primary,standby1 list.
+test_target_session_attrs($node_primary, $node_standby_1, $node_standby_1,
+	"standby", 0);
+
+# Connect to standby1 in "standby" mode with standby1,primary list.
+test_target_session_attrs($node_standby_1, $node_primary, $node_standby_1,
+	"standby", 0);
+
+# Fail to connect in "read-write" mode with standby1,standby2 list.
+test_target_session_attrs($node_standby_1, $node_standby_2, undef,
+	"read-write", 2);
+
+# Fail to connect in "primary" mode with standby1,standby2 list.
+test_target_session_attrs($node_standby_1, $node_standby_2, undef,
+	"primary", 2);
+
+# Fail to connect in "read-only" mode with primary,primary list.
+test_target_session_attrs($node_primary, $node_primary, undef,
+	"read-only", 2);
+
+# Fail to connect in "standby" mode with primary,primary list.
+test_target_session_attrs($node_primary, $node_primary, undef, "standby", 2);
+
 # Test for SHOW commands using a WAL sender connection with a replication
 # role.
 note "testing SHOW commands for replication connection";