src/test/perl/PostgreSQL/Test/Cluster.pm - master - githubmirror/postgres

src/test/perl/PostgreSQL/Test/Cluster.pm
4 085 строк101 KB
Fujii Masao
Allow PostgreSQL::Test::Cluster::start() to pass postmaster options
20 июл 2026, 15:40
20 июл 2026, 15:401009339

# Copyright (c) 2021-2026, PostgreSQL Global Development Group

=pod

=head1 NAME

PostgreSQL::Test::Cluster - class representing PostgreSQL server instance

=head1 SYNOPSIS

  use PostgreSQL::Test::Cluster;

  my $node = PostgreSQL::Test::Cluster->new('mynode');

  # Create a data directory with initdb
  $node->init();

  # Start the PostgreSQL server
  $node->start();

  # Add a setting and restart
  $node->append_conf('postgresql.conf', 'hot_standby = on');
  $node->restart();

  # Modify or delete an existing setting
  $node->adjust_conf('postgresql.conf', 'max_wal_senders', '10');

  # get pg_config settings
  # all the settings in one string
  $pgconfig = $node->config_data;
  # all the settings as a map
  %config_map = ($node->config_data);
  # specified settings
  ($incdir, $sharedir) = $node->config_data(qw(--includedir --sharedir));

  # run a query with psql, like:
  #   echo 'SELECT 1' | psql -qAXt postgres -v ON_ERROR_STOP=1
  $psql_stdout = $node->safe_psql('postgres', 'SELECT 1');

  # Run psql with a timeout, capturing stdout and stderr
  # as well as the psql exit code. Pass some extra psql
  # options. If there's an error from psql raise an exception.
  my ($stdout, $stderr, $timed_out);
  my $cmdret = $node->psql('postgres', 'SELECT pg_sleep(600)',
	  stdout => \$stdout, stderr => \$stderr,
	  timeout => $PostgreSQL::Test::Utils::timeout_default,
	  timed_out => \$timed_out,
	  extra_params => ['--single-transaction'],
	  on_error_die => 1)
  print "Sleep timed out" if $timed_out;

  # Similar thing, more convenient in common cases
  my ($cmdret, $stdout, $stderr) =
      $node->psql('postgres', 'SELECT 1');

  # run query every second until it returns 't'
  # or times out
  $node->poll_query_until('postgres', q|SELECT random() < 0.1;|')
    or croak "timed out";

  # Do an online pg_basebackup
  my $ret = $node->backup('testbackup1');

  # Take a backup of a stopped server
  $node->stop;
  my $ret = $node->backup_fs_cold('testbackup3')

  # Restore it to create a new independent node (not a replica)
  my $other_node = PostgreSQL::Test::Cluster->new('mycopy');
  $other_node->init_from_backup($node, 'testbackup');
  $other_node->start;

  # Stop the server
  $node->stop('fast');

  # Find a free, unprivileged TCP port to bind some other service to
  my $port = PostgreSQL::Test::Cluster::get_free_port();

=head1 DESCRIPTION

PostgreSQL::Test::Cluster contains a set of routines able to work on a PostgreSQL node,
allowing to start, stop, backup and initialize it with various options.
The set of nodes managed by a given test is also managed by this module.

In addition to node management, PostgreSQL::Test::Cluster instances have some wrappers
around Test::More functions to run commands with an environment set up to
point to the instance.

The IPC::Run module is required.

=cut

package PostgreSQL::Test::Cluster;

use strict;
use warnings FATAL => 'all';

use Carp;
use Config;
use Fcntl qw(:mode :flock :seek :DEFAULT);
use File::Basename;
use File::Path qw(rmtree mkpath);
use File::Spec;
use File::stat qw(stat);
use File::Temp ();
use IO::Socket::INET;
use IPC::Run;
use PostgreSQL::Version;
use PostgreSQL::Test::RecursiveCopy;
use Socket;
use Test::More;
use PostgreSQL::Test::Utils          ();
use PostgreSQL::Test::BackgroundPsql ();
use Text::ParseWords                 qw(shellwords);
use Time::HiRes                      qw(usleep);
use Scalar::Util                     qw(blessed);

our ($use_tcp, $test_localhost, $test_pghost, $last_host_assigned,
	$last_port_assigned, @all_nodes, $died, $portdir);

# the minimum version we believe to be compatible with this package without
# subclassing.
our $min_compat = 12;

# list of file reservations made by get_free_port
my @port_reservation_files;

# We want to choose a server port above the range that servers typically use
# on Unix systems and below the range those systems typically use for ephemeral
# client ports.
# That way we minimize the risk of getting a port collision. These two values
# are chosen to reflect that. We will always choose a port in this range.
my $port_lower_bound = 10200;
my $port_upper_bound = 32767;

INIT
{

	# Set PGHOST for backward compatibility.  This doesn't work for own_host
	# nodes, so prefer to not rely on this when writing new tests.
	$use_tcp = !$PostgreSQL::Test::Utils::use_unix_sockets;
	$test_localhost = "127.0.0.1";
	$last_host_assigned = 1;
	if ($use_tcp)
	{
		$test_pghost = $test_localhost;
	}
	else
	{
		# On windows, replace windows-style \ path separators with / when
		# putting socket directories either in postgresql.conf or libpq
		# connection strings, otherwise they are interpreted as escapes.
		$test_pghost = PostgreSQL::Test::Utils::tempdir_short;
		$test_pghost =~ s!\\!/!g if $PostgreSQL::Test::Utils::windows_os;
	}
	$ENV{PGHOST} = $test_pghost;
	$ENV{PGDATABASE} = 'postgres';

	# Tracking of last port value assigned to accelerate free port lookup.
	my $num_ports = $port_upper_bound - $port_lower_bound;
	$last_port_assigned = int(rand() * $num_ports) + $port_lower_bound;

	# Set the port lock directory

	# If we're told to use a directory (e.g. from a buildfarm client)
	# explicitly, use that
	$portdir = $ENV{PG_TEST_PORT_DIR};
	# Otherwise, try to use a directory at the top of the build tree
	# or as a last resort use the tmp_check directory
	my $build_dir = $ENV{top_builddir}
	  || $PostgreSQL::Test::Utils::tmp_check;
	$portdir ||= "$build_dir/portlock";
	$portdir =~ s!\\!/!g;
	# Make sure the directory exists
	mkpath($portdir) unless -d $portdir;

	#
	# Signal handlers
	#
	$SIG{TERM} = $SIG{INT} = sub { die "death by signal"; };
}

=pod

=head1 METHODS

=over

=item $node->port()

Get the port number assigned to the host. This won't necessarily be a TCP port
open on the local host since we prefer to use unix sockets if possible.

Use $node->connstr() if you want a connection string.

=cut

sub port
{
	my ($self) = @_;
	return $self->{_port};
}

=pod

=item $node->host()

Return the host (like PGHOST) for this instance. May be a UNIX socket path.

Use $node->connstr() if you want a connection string.

=cut

sub host
{
	my ($self) = @_;
	return $self->{_host};
}

=pod

=item $node->basedir()

The directory all the node's files will be within - datadir, archive directory,
backups, etc.

=cut

sub basedir
{
	my ($self) = @_;
	return $self->{_basedir};
}

=pod

=item $node->name()

The name assigned to the node at creation time.

=cut

sub name
{
	my ($self) = @_;
	return $self->{_name};
}

=pod

=item $node->logfile()

Path to the PostgreSQL log file for this instance.

=cut

sub logfile
{
	my ($self) = @_;
	return $self->{_logfile};
}

=pod

=item $node->connstr()

Get a libpq connection string that will establish a connection to
this node. Suitable for passing to psql, DBD::Pg, etc.

=cut

sub connstr
{
	my ($self, $dbname) = @_;
	my $pgport = $self->port;
	my $pghost = $self->host;
	if (!defined($dbname))
	{
		return "port=$pgport host=$pghost";
	}

	# Escape properly the database string before using it, only
	# single quotes and backslashes need to be treated this way.
	$dbname =~ s#\\#\\\\#g;
	$dbname =~ s#\'#\\\'#g;

	return "port=$pgport host=$pghost dbname='$dbname'";
}

=pod

=item $node->is_alive()

Check if the node is alive, using pg_isready.
Returns 1 if successful, 0 on failure.

=cut

sub is_alive
{
	my ($self) = @_;
	local %ENV = $self->_get_env();

	my $ret = PostgreSQL::Test::Utils::system_log(
		'pg_isready',
		'--timeout' => $PostgreSQL::Test::Utils::timeout_default,
		'--host' => $self->host,
		'--port' => $self->port);

	if ($ret != 0)
	{
		return 0;
	}
	return 1;
}

=pod

=item $node->raw_connect()

Open a raw TCP or Unix domain socket connection to the server. This is
used by low-level protocol and connection limit tests.

=cut

sub raw_connect
{
	my ($self) = @_;
	my $pgport = $self->port;
	my $pghost = $self->host;

	my $socket;
	if ($PostgreSQL::Test::Utils::use_unix_sockets)
	{
		require IO::Socket::UNIX;
		my $path = "$pghost/.s.PGSQL.$pgport";

		$socket = IO::Socket::UNIX->new(
			Type => SOCK_STREAM(),
			Peer => $path,
		) or croak "Cannot create socket - $IO::Socket::errstr\n";
	}
	else
	{
		$socket = IO::Socket::INET->new(
			PeerHost => $pghost,
			PeerPort => $pgport,
			Proto => 'tcp'
		) or croak "Cannot create socket - $IO::Socket::errstr\n";
	}
	return $socket;
}

=pod

=item $node->raw_connect_works()

Check if raw_connect() function works on this platform. This should
be called to SKIP any tests that require raw_connect().

This tries to connect to the server, to test whether it works or not,,
so the server is up and running. Otherwise this can return 0 even if
there's nothing wrong with raw_connect() itself.

Notably, raw_connect() does not work on Unix domain sockets on at least
Strawberry perl 5.26.3.1 on Windows. It dies with "not implemented on this
architecture".

=cut

sub raw_connect_works
{
	my ($self) = @_;

	# If we're using Unix domain sockets, we need a working
	# IO::Socket::UNIX implementation.
	if ($PostgreSQL::Test::Utils::use_unix_sockets)
	{
		eval {
			my $sock = $self->raw_connect();
			$sock->close();
		};
		if ($@ =~ /not implemented/)
		{
			diag "IO::Socket::UNIX does not work: $@";
			return 0;
		}
	}
	return 1;
}

=pod

=item $node->group_access()

Does the data dir allow group access?

=cut

sub group_access
{
	my ($self) = @_;

	my $dir_stat = stat($self->data_dir);

	defined($dir_stat)
	  or croak('unable to stat ' . $self->data_dir);

	return (S_IMODE($dir_stat->mode) == 0750);
}

=pod

=item $node->data_dir()

Returns the path to the data directory. postgresql.conf and pg_hba.conf are
always here.

=cut

sub data_dir
{
	my ($self) = @_;
	my $res = $self->basedir;
	return "$res/pgdata";
}

=pod

=item $node->archive_dir()

If archiving is enabled, WAL files go here.

=cut

sub archive_dir
{
	my ($self) = @_;
	my $basedir = $self->basedir;
	return "$basedir/archives";
}

=pod

=item $node->backup_dir()

The output path for backups taken with $node->backup()

=cut

sub backup_dir
{
	my ($self) = @_;
	my $basedir = $self->basedir;
	return "$basedir/backup";
}

=pod

=item $node->install_path()

The configured install path (if any) for the node.

=cut

sub install_path
{
	my ($self) = @_;
	return $self->{_install_path};
}

=pod

=item $node->pg_version()

The version number for the node, from PostgreSQL::Version.

=cut

sub pg_version
{
	my ($self) = @_;
	return $self->{_pg_version};
}

=pod

=item $node->config_data( option ...)

Return configuration data from pg_config, using options (if supplied).
The options will be things like '--sharedir'.

If no options are supplied, return a string in scalar context or a map in
array context.

If options are supplied, return the list of values.

=cut

sub config_data
{
	my ($self, @options) = @_;
	local %ENV = $self->_get_env();

	my ($stdout, $stderr);
	my $result =
	  IPC::Run::run [ $self->installed_command('pg_config'), @options ],
	  '>', \$stdout, '2>', \$stderr
	  or croak "could not execute pg_config";
	# standardize line endings
	$stdout =~ s/\r(?=\n)//g;
	# no options, scalar context: just hand back the output
	return $stdout unless (wantarray || @options);
	chomp($stdout);
	# exactly one option: hand back the output (minus LF)
	return $stdout if (@options == 1);
	my @lines = split(/\n/, $stdout);
	# more than one option: hand back the list of values;
	return @lines if (@options);
	# no options, array context: return a map
	my @map;
	foreach my $line (@lines)
	{
		my ($k, $v) = split(/ = /, $line, 2);
		push(@map, $k, $v);
	}
	return @map;
}

=pod

=item $node->info()

Return a string containing human-readable diagnostic information (paths, etc)
about this node.

=cut

sub info
{
	my ($self) = @_;
	my $_info = '';
	open my $fh, '>', \$_info or croak;
	print $fh "Name: " . $self->name . "\n";
	print $fh "Version: " . $self->{_pg_version} . "\n"
	  if $self->{_pg_version};
	print $fh "Data directory: " . $self->data_dir . "\n";
	print $fh "Backup directory: " . $self->backup_dir . "\n";
	print $fh "Archive directory: " . $self->archive_dir . "\n";
	print $fh "Connection string: " . $self->connstr . "\n";
	print $fh "Log file: " . $self->logfile . "\n";
	print $fh "Install Path: ", $self->{_install_path} . "\n"
	  if $self->{_install_path};
	close $fh or croak;
	return $_info;
}

=pod

=item $node->dump_info()

Print $node->info()

=cut

sub dump_info
{
	my ($self) = @_;
	print $self->info;
	return;
}


# Internal method to set up trusted pg_hba.conf for replication.  Not
# documented because you shouldn't use it, it's called automatically if needed.
sub set_replication_conf
{
	my ($self) = @_;
	my $pgdata = $self->data_dir;

	$self->host eq $test_pghost
	  or croak "set_replication_conf only works with the default host";

	open my $hba, '>>', "$pgdata/pg_hba.conf" or croak $!;
	print $hba
	  "\n# Allow replication (set up by PostgreSQL::Test::Cluster.pm)\n";
	if ($PostgreSQL::Test::Utils::windows_os
		&& !$PostgreSQL::Test::Utils::use_unix_sockets)
	{
		print $hba
		  "host replication all $test_localhost/32 sspi include_realm=1 map=regress\n";
	}
	close $hba;
	return;
}

=pod

=item $node->init(...)

Initialize a new cluster for testing.

Authentication is set up so that only the current OS user can access the
cluster. On Unix, we use Unix domain socket connections, with the socket in
a directory that's only accessible to the current user to ensure that.
On Windows, we use SSPI authentication to ensure the same (by pg_regress
--config-auth).

WAL archiving can be enabled on this node by passing the keyword parameter
has_archiving => 1. This is disabled by default.

Data checksums can be forced off by passing no_data_checksums => 1.

postgresql.conf can be set up for replication by passing the keyword
parameter allows_streaming => 'logical' or 'physical' (passing 1 will also
suffice for physical replication) depending on type of replication that
should be enabled. This is disabled by default.

force_initdb => 1 will force the initialization of the cluster with a new
initdb rather than copying the data folder from a template.

The new node is set up in a fast but unsafe configuration where fsync is
disabled.

=cut

sub init
{
	my ($self, %params) = @_;
	my $port = $self->port;
	my $pgdata = $self->data_dir;
	my $host = $self->host;

	local %ENV = $self->_get_env();

	$params{allows_streaming} = 0 unless defined $params{allows_streaming};
	$params{force_initdb} = 0 unless defined $params{force_initdb};
	$params{has_archiving} = 0 unless defined $params{has_archiving};

	my $initdb_extra_opts_env = $ENV{PG_TEST_INITDB_EXTRA_OPTS};
	if (defined $initdb_extra_opts_env)
	{
		push @{ $params{extra} }, shellwords($initdb_extra_opts_env);
	}

	# This should override user-supplied initdb options.
	if ($params{no_data_checksums})
	{
		push @{ $params{extra} }, '--no-data-checksums';
	}

	mkdir $self->backup_dir;
	mkdir $self->archive_dir;

	# If available, if there aren't any parameters and if force_initdb is
	# disabled, use a previously initdb'd cluster as a template by copying it.
	# For a lot of tests, that's substantially cheaper. It does not seem
	# worth figuring out whether extra parameters affect compatibility, so
	# initdb is forced if any are defined.
	#
	# There's very similar code in pg_regress.c, but we can't easily
	# deduplicate it until we require perl at build time.
	if (   $params{force_initdb}
		or defined $params{extra}
		or !defined $ENV{INITDB_TEMPLATE})
	{
		note("initializing database system by running initdb");
		PostgreSQL::Test::Utils::system_or_bail(
			'initdb', '--no-sync',
			'--pgdata' => $pgdata,
			'--auth' => 'trust',
			@{ $params{extra} });
	}
	else
	{
		my @copycmd;
		my $expected_exitcode;

		note("initializing database system by copying initdb template");

		if ($PostgreSQL::Test::Utils::windows_os)
		{
			@copycmd = qw(robocopy /E /NJS /NJH /NFL /NDL /NP);
			$expected_exitcode = 1;    # 1 denotes files were copied
		}
		else
		{
			@copycmd = qw(cp -RPp);
			$expected_exitcode = 0;
		}

		@copycmd = (@copycmd, $ENV{INITDB_TEMPLATE}, $pgdata);

		my $ret = PostgreSQL::Test::Utils::system_log(@copycmd);

		# See http://perldoc.perl.org/perlvar.html#%24CHILD_ERROR
		if ($ret & 127 or $ret >> 8 != $expected_exitcode)
		{
			BAIL_OUT(
				sprintf("failed to execute command \"%s\": $ret",
					join(" ", @copycmd)));
		}
	}

	PostgreSQL::Test::Utils::system_or_bail($ENV{PG_REGRESS},
		'--config-auth', $pgdata, @{ $params{auth_extra} });

	open my $conf, '>>', "$pgdata/postgresql.conf" or croak $!;
	print $conf "\n# Added by PostgreSQL::Test::Cluster.pm\n";
	print $conf "fsync = off\n";
	print $conf "restart_after_crash = off\n";
	print $conf "log_line_prefix = '%m %b[%p] %q%a '\n";
	print $conf "log_statement = all\n";
	print $conf "log_replication_commands = on\n";
	print $conf "wal_retrieve_retry_interval = '500ms'\n";

	# If a setting tends to affect whether tests pass or fail, print it after
	# TEMP_CONFIG.  Otherwise, print it before TEMP_CONFIG, thereby permitting
	# overrides.  Settings that merely improve performance or ease debugging
	# belong before TEMP_CONFIG.
	print $conf PostgreSQL::Test::Utils::slurp_file($ENV{TEMP_CONFIG})
	  if defined $ENV{TEMP_CONFIG};

	if ($params{allows_streaming})
	{
		if ($params{allows_streaming} eq "logical")
		{
			print $conf "wal_level = logical\n";
		}
		else
		{
			print $conf "wal_level = replica\n";
		}
		print $conf "max_wal_senders = 10\n";
		print $conf "max_replication_slots = 10\n";
		print $conf "autovacuum_worker_slots = 3\n";
		print $conf "wal_log_hints = on\n";
		print $conf "hot_standby = on\n";
		# conservative settings to ensure we can run multiple postmasters:
		print $conf "shared_buffers = 1MB\n";
		print $conf "max_connections = 10\n";
		# limit disk space consumption, too:
		print $conf "max_wal_size = 128MB\n";
	}
	else
	{
		print $conf "wal_level = minimal\n";
		print $conf "max_wal_senders = 0\n";
	}

	print $conf "port = $port\n";
	if ($use_tcp)
	{
		print $conf "unix_socket_directories = ''\n";
		print $conf "listen_addresses = '$host'\n";
	}
	else
	{
		print $conf "unix_socket_directories = '$host'\n";
		print $conf "listen_addresses = ''\n";
	}
	close $conf;

	chmod($self->group_access ? 0640 : 0600, "$pgdata/postgresql.conf")
	  or croak("unable to set permissions for $pgdata/postgresql.conf");

	$self->set_replication_conf if $params{allows_streaming};
	$self->enable_archiving if $params{has_archiving};
	return;
}

=pod

=item $node->append_conf(filename, str)

A shortcut method to append to files like pg_hba.conf and postgresql.conf.

Does no validation or sanity checking. Does not reload the configuration
after writing.

A newline is automatically appended to the string.

=cut

sub append_conf
{
	my ($self, $filename, $str) = @_;

	my $conffile = $self->data_dir . '/' . $filename;

	PostgreSQL::Test::Utils::append_to_file($conffile, $str . "\n");

	chmod($self->group_access() ? 0640 : 0600, $conffile)
	  or croak("unable to set permissions for $conffile");

	return;
}

=pod

=item $node->adjust_conf(filename, setting, value, skip_equals)

Modify the named config file setting with the value. If the value is undefined,
instead delete the setting. If the setting is not present no action is taken.

This will write "$setting = $value\n" in place of the existing line,
unless skip_equals is true, in which case it will write
"$setting $value\n". If the value needs to be quoted it is the caller's
responsibility to do that.

=cut

sub adjust_conf
{
	my ($self, $filename, $setting, $value, $skip_equals) = @_;

	my $conffile = $self->data_dir . '/' . $filename;

	my $contents = PostgreSQL::Test::Utils::slurp_file($conffile);
	my @lines = split(/\n/, $contents);
	my @result;
	my $eq = $skip_equals ? '' : '= ';
	foreach my $line (@lines)
	{
		if ($line !~ /^$setting\W/)
		{
			push(@result, "$line\n");
		}
		elsif (defined $value)
		{
			push(@result, "$setting $eq$value\n");
		}
	}
	open my $fh, ">", $conffile
	  or croak "could not write \"$conffile\": $!";
	print $fh @result;
	close $fh;

	chmod($self->group_access() ? 0640 : 0600, $conffile)
	  or croak("unable to set permissions for $conffile");
}

=pod

=item $node->backup(backup_name)

Create a hot backup with B<pg_basebackup> in subdirectory B<backup_name> of
B<< $node->backup_dir >>, including the WAL.

By default, WAL files are fetched at the end of the backup, not streamed.
You can adjust that and other things by passing an array of additional
B<pg_basebackup> command line options in the keyword parameter backup_options.

You'll have to configure a suitable B<max_wal_senders> on the
target server since it isn't done by default.

=cut

sub backup
{
	my ($self, $backup_name, %params) = @_;
	my $backup_path = $self->backup_dir . '/' . $backup_name;
	my $name = $self->name;

	local %ENV = $self->_get_env();

	print "# Taking pg_basebackup $backup_name from node \"$name\"\n";
	PostgreSQL::Test::Utils::system_or_bail(
		'pg_basebackup', '--no-sync',
		'--pgdata' => $backup_path,
		'--host' => $self->host,
		'--port' => $self->port,
		'--checkpoint' => 'fast',
		@{ $params{backup_options} });
	print "# Backup finished\n";
	return;
}

=item $node->backup_fs_cold(backup_name)

Create a backup with a filesystem level copy in subdirectory B<backup_name> of
B<< $node->backup_dir >>, including WAL. The server must be
stopped as no attempt to handle concurrent writes is made.

Use B<backup> if you want to back up a running server.

=cut

sub backup_fs_cold
{
	my ($self, $backup_name) = @_;

	PostgreSQL::Test::RecursiveCopy::copypath(
		$self->data_dir,
		$self->backup_dir . '/' . $backup_name,
		filterfn => sub {
			my $src = shift;
			return ($src ne 'log' and $src ne 'postmaster.pid');
		});

	return;
}

=pod

=item $node->init_from_backup(root_node, backup_name, %params)

Initialize a node from a backup, which may come from this node or a different
node. root_node must be a PostgreSQL::Test::Cluster reference, backup_name the string name
of a backup previously created on that node with $node->backup.

Does not start the node after initializing it.

By default, the backup is assumed to be plain format.  To restore from
a tar-format backup, pass the name of the tar program to use in the
keyword parameter tar_program.

If there are tablespace present in the backup, include tablespace_map as
a keyword parameter whose values is a hash. When combine_with_prior is used,
the hash keys are the tablespace pathnames used in the backup; otherwise,
they are tablespace OIDs.  In either case, the values are the tablespace
pathnames that should be used for the target cluster.

To restore from an incremental backup, pass the parameter combine_with_prior
as a reference to an array of prior backup names with which this backup
is to be combined using pg_combinebackup.

Streaming replication can be enabled on this node by passing the keyword
parameter has_streaming => 1. This is disabled by default.

Restoring WAL segments from archives using restore_command can be enabled
by passing the keyword parameter has_restoring => 1. This is disabled by
default.

If has_restoring is used, standby mode is used by default.  To use
recovery mode instead, pass the keyword parameter standby => 0.

The backup is copied, leaving the original unmodified. pg_hba.conf is
unconditionally set to enable replication connections.

=cut

sub init_from_backup
{
	my ($self, $root_node, $backup_name, %params) = @_;
	my $backup_path = $root_node->backup_dir . '/' . $backup_name;
	my $host = $self->host;
	my $port = $self->port;
	my $node_name = $self->name;
	my $root_name = $root_node->name;

	$params{has_streaming} = 0 unless defined $params{has_streaming};
	$params{has_restoring} = 0 unless defined $params{has_restoring};
	$params{standby} = 1 unless defined $params{standby};

	print
	  "# Initializing node \"$node_name\" from backup \"$backup_name\" of node \"$root_name\"\n";
	croak "Backup \"$backup_name\" does not exist at $backup_path"
	  unless -d $backup_path;

	mkdir $self->backup_dir;
	mkdir $self->archive_dir;

	my $data_path = $self->data_dir;
	if (defined $params{combine_with_prior})
	{
		my @prior_backups = @{ $params{combine_with_prior} };
		my @prior_backup_path;

		for my $prior_backup_name (@prior_backups)
		{
			push @prior_backup_path,
			  $root_node->backup_dir . '/' . $prior_backup_name;
		}

		local %ENV = $self->_get_env();
		my @combineargs = ('pg_combinebackup', '--debug');
		if (exists $params{tablespace_map})
		{
			while (my ($olddir, $newdir) = each %{ $params{tablespace_map} })
			{
				push @combineargs, "-T$olddir=$newdir";
			}
		}
		# use the combine mode (clone/copy-file-range) if specified
		if (defined $params{combine_mode})
		{
			push @combineargs, $params{combine_mode};
		}
		push @combineargs, @prior_backup_path, $backup_path,
		  '--output' => $data_path;
		PostgreSQL::Test::Utils::system_or_bail(@combineargs);
	}
	elsif (defined $params{tar_program})
	{
		mkdir($data_path) || croak "mkdir $data_path: $!";
		PostgreSQL::Test::Utils::system_or_bail(
			$params{tar_program},
			'xf' => $backup_path . '/base.tar',
			'-C' => $data_path);
		PostgreSQL::Test::Utils::system_or_bail(
			$params{tar_program},
			'xf' => $backup_path . '/pg_wal.tar',
			'-C' => $data_path . '/pg_wal');

		# We need to generate a tablespace_map file.
		open(my $tsmap, ">", "$data_path/tablespace_map")
		  || croak "$data_path/tablespace_map: $!";

		# Extract tarfiles and add tablespace_map entries
		my @tstars = grep { /^\d+.tar/ }
		  PostgreSQL::Test::Utils::slurp_dir($backup_path);
		for my $tstar (@tstars)
		{
			my $tsoid = $tstar;
			$tsoid =~ s/\.tar$//;

			croak "no tablespace mapping for $tstar"
			  if !exists $params{tablespace_map}
			  || !exists $params{tablespace_map}{$tsoid};
			my $newdir = $params{tablespace_map}{$tsoid};

			mkdir($newdir) || croak "mkdir $newdir: $!";
			PostgreSQL::Test::Utils::system_or_bail(
				$params{tar_program},
				'xf' => $backup_path . '/' . $tstar,
				'-C' => $newdir);

			my $escaped_newdir = $newdir;
			$escaped_newdir =~ s/\\/\\\\/g;
			print $tsmap "$tsoid $escaped_newdir\n";
		}

		# Close tablespace_map.
		close($tsmap);
	}
	else
	{
		my @tsoids;
		rmdir($data_path);

		# Copy the main backup. If we see a tablespace directory for which we
		# have a tablespace mapping, skip it, but remember that we saw it.
		PostgreSQL::Test::RecursiveCopy::copypath(
			$backup_path,
			$data_path,
			filterfn => sub {
				my ($path) = @_;
				if ($path =~ /^pg_tblspc\/(\d+)$/
					&& exists $params{tablespace_map}{$1})
				{
					push @tsoids, $1;
					return 0;
				}
				return 1;
			});

		if (@tsoids > 0)
		{
			# We need to generate a tablespace_map file.
			open(my $tsmap, ">", "$data_path/tablespace_map")
			  || croak "$data_path/tablespace_map: $!";

			# Now use the list of tablespace links to copy each tablespace.
			for my $tsoid (@tsoids)
			{
				croak "no tablespace mapping for $tsoid"
				  if !exists $params{tablespace_map}
				  || !exists $params{tablespace_map}{$tsoid};

				my $olddir = $backup_path . '/pg_tblspc/' . $tsoid;
				my $newdir = $params{tablespace_map}{$tsoid};
				PostgreSQL::Test::RecursiveCopy::copypath($olddir, $newdir);

				my $escaped_newdir = $newdir;
				$escaped_newdir =~ s/\\/\\\\/g;
				print $tsmap "$tsoid $escaped_newdir\n";
			}

			# Close tablespace_map.
			close($tsmap);
		}
	}
	chmod(0700, $data_path) or croak $!;

	# Base configuration for this node
	$self->append_conf(
		'postgresql.conf',
		qq(
port = $port
));
	if ($use_tcp)
	{
		$self->append_conf('postgresql.conf', "listen_addresses = '$host'");
	}
	else
	{
		$self->append_conf('postgresql.conf',
			"unix_socket_directories = '$host'");
	}
	$self->enable_streaming($root_node) if $params{has_streaming};
	$self->enable_restoring($root_node, $params{standby})
	  if $params{has_restoring};
	return;
}

=pod

=item $node->rotate_logfile()

Switch to a new PostgreSQL log file.  This does not alter any running
PostgreSQL process.  Subsequent method calls, including pg_ctl invocations,
will use the new name.  Return the new name.

=cut

sub rotate_logfile
{
	my ($self) = @_;
	$self->{_logfile} = sprintf('%s_%d.log',
		$self->{_logfile_base},
		++$self->{_logfile_generation});
	return $self->{_logfile};
}

=pod

=item $node->start(%params) => success_or_failure

Wrapper for pg_ctl start

Start the node and wait until it is ready to accept connections.

=over

=item fail_ok => 1

By default, failure terminates the entire F<prove> invocation.  If given,
instead return a true or false value to indicate success or failure.

=item options => B<string>

Additional postmaster options passed as the value of pg_ctl's C<--options>
argument. This must be a single string, quoted as needed by the caller.
Do not specify C<cluster_name>; it is set from the node name.

=back

=cut

sub start
{
	my ($self, %params) = @_;
	my $port = $self->port;
	my $pgdata = $self->data_dir;
	my $name = $self->name;
	my $ret;
	my $options = "";

	$options .= "$params{options} "
	  if defined $params{options} && $params{options} ne "";

	$options .= "--cluster-name=$name";

	BAIL_OUT("node \"$name\" is already running") if defined $self->{_pid};

	print("### Starting node \"$name\"\n");

	# Temporarily unset PGAPPNAME so that the server doesn't
	# inherit it.  Otherwise this could affect libpqwalreceiver
	# connections in confusing ways.
	local %ENV = $self->_get_env(PGAPPNAME => undef);

	# Note: We set the cluster_name here, not in postgresql.conf (in
	# sub init) so that it does not get copied to standbys.
	# -w is now the default but having it here does no harm and helps
	# compatibility with older versions.
	$ret = PostgreSQL::Test::Utils::system_log(
		'pg_ctl', '--wait',
		'--pgdata' => $self->data_dir,
		'--log' => $self->logfile,
		'--options' => $options,
		'start');

	if ($ret != 0)
	{
		print "# pg_ctl start failed; see logfile for details: "
		  . $self->logfile . "\n";

		# pg_ctl could have timed out, so check to see if there's a pid file;
		# otherwise our END block will fail to shut down the new postmaster.
		$self->_update_pid(-1);

		BAIL_OUT("pg_ctl start failed") unless $params{fail_ok};
		return 0;
	}

	$self->_update_pid(1);
	return 1;
}

=pod

=item $node->kill9()

Send SIGKILL (signal 9) to the postmaster.

Note: if the node is already known stopped, this does nothing.
However, if we think it's running and it's not, it's important for
this to fail.  Otherwise, tests might fail to detect server crashes.

=cut

sub kill9
{
	my ($self) = @_;
	my $name = $self->name;
	return unless defined $self->{_pid};

	local %ENV = $self->_get_env();

	print "### Killing node \"$name\" using signal 9\n";
	kill(9, $self->{_pid});
	$self->{_pid} = undef;
	return;
}

=pod

=item $node->stop(mode)

Stop the node using pg_ctl -m $mode and wait for it to stop.

Note: if the node is already known stopped, this does nothing.
However, if we think it's running and it's not, it's important for
this to fail.  Otherwise, tests might fail to detect server crashes.

With optional extra param fail_ok => 1, returns 0 for failure
instead of bailing out.

The optional extra param timeout can be used to pass the pg_ctl
--timeout option.

=cut

sub stop
{
	my ($self, $mode, %params) = @_;
	my $pgdata = $self->data_dir;
	my $name = $self->name;
	my $ret;

	local %ENV = $self->_get_env();

	$mode = 'fast' unless defined $mode;
	return 1 unless defined $self->{_pid};

	print "### Stopping node \"$name\" using mode $mode\n";
	my @cmd = ('pg_ctl', '--pgdata' => $pgdata, '--mode' => $mode, 'stop');
	if ($params{timeout})
	{
		push(@cmd, ('--timeout' => $params{timeout}));
	}
	$ret = PostgreSQL::Test::Utils::system_log(@cmd);

	if ($ret != 0)
	{
		print "# pg_ctl stop failed: $ret\n";

		# Check to see if we still have a postmaster or not.
		$self->_update_pid(-1);

		BAIL_OUT("pg_ctl stop failed") unless $params{fail_ok};
		return 0;
	}

	$self->_update_pid(0);
	return 1;
}

=pod

=item $node->reload()

Reload configuration parameters on the node.

=cut

sub reload
{
	my ($self) = @_;
	my $port = $self->port;
	my $pgdata = $self->data_dir;
	my $name = $self->name;

	local %ENV = $self->_get_env();

	print "### Reloading node \"$name\"\n";
	PostgreSQL::Test::Utils::system_or_bail(
		'pg_ctl',
		'--pgdata' => $pgdata,
		'reload');
	return;
}

=pod

=item $node->restart()

Wrapper for pg_ctl restart.

With optional extra param fail_ok => 1, returns 0 for failure
instead of bailing out.

=over

=item fail_ok => 1

By default, failure terminates the entire F<prove> invocation.  If given,
instead return 0 for failure instead of bailing out.

=item log_unlike => B<pattern>

When defined, the logfile is inspected for the presence of the fragment by
matching the specified pattern. If the pattern matches against the logfile a
test failure will be logged.

=item log_like => B<pattern>

When defined, the logfile is inspected for the presence of the fragment by
matching the pattern. If the pattern doesn't match a test failure will be
logged.

=back

=cut

sub restart
{
	my ($self, %params) = @_;
	my $name = $self->name;
	my $ret;

	local %ENV = $self->_get_env(PGAPPNAME => undef);

	print "### Restarting node \"$name\"\n";

	my $log_location = -s $self->logfile;

	# -w is now the default but having it here does no harm and helps
	# compatibility with older versions.
	$ret = PostgreSQL::Test::Utils::system_log(
		'pg_ctl', '--wait',
		'--pgdata' => $self->data_dir,
		'--log' => $self->logfile,
		'restart');

	# Check for expected and/or unexpected log fragments if the caller
	# specified such checks in the params
	if (defined $params{log_unlike} || defined $params{log_like})
	{
		my $log =
		  PostgreSQL::Test::Utils::slurp_file($self->logfile, $log_location);
		unlike($log, $params{log_unlike}, "unexpected fragment found in log")
		  if defined $params{log_unlike};
		like($log, $params{log_like}, "expected fragment not found in log")
		  if defined $params{log_like};
	}

	if ($ret != 0)
	{
		print "# pg_ctl restart failed; see logfile for details: "
		  . $self->logfile . "\n";

		# pg_ctl could have timed out, so check to see if there's a pid file;
		# otherwise our END block will fail to shut down the new postmaster.
		$self->_update_pid(-1);

		BAIL_OUT("pg_ctl restart failed") unless $params{fail_ok};
		return 0;
	}

	$self->_update_pid(1);
	return 1;
}

=pod

=item $node->promote()

Wrapper for pg_ctl promote

=cut

sub promote
{
	my ($self) = @_;
	my $port = $self->port;
	my $pgdata = $self->data_dir;
	my $logfile = $self->logfile;
	my $name = $self->name;

	local %ENV = $self->_get_env();

	print "### Promoting node \"$name\"\n";
	PostgreSQL::Test::Utils::system_or_bail(
		'pg_ctl',
		'--pgdata' => $pgdata,
		'--log' => $logfile,
		'promote');
	return;
}

=pod

=item $node->logrotate()

Wrapper for pg_ctl logrotate

=cut

sub logrotate
{
	my ($self) = @_;
	my $port = $self->port;
	my $pgdata = $self->data_dir;
	my $logfile = $self->logfile;
	my $name = $self->name;

	local %ENV = $self->_get_env();

	print "### Rotating log in node \"$name\"\n";
	PostgreSQL::Test::Utils::system_or_bail(
		'pg_ctl',
		'--pgdata' => $pgdata,
		'--log' => $logfile,
		'logrotate');
	return;
}

# Internal routine to enable streaming replication on a standby node.
sub enable_streaming
{
	my ($self, $root_node) = @_;
	my $root_connstr = $root_node->connstr;
	my $name = $self->name;

	print "### Enabling streaming replication for node \"$name\"\n";
	$self->append_conf(
		$self->_recovery_file, qq(
primary_conninfo='$root_connstr'
));
	$self->set_standby_mode();
	return;
}

# Internal routine to enable archive recovery command on a standby node
sub enable_restoring
{
	my ($self, $root_node, $standby) = @_;
	my $path = $root_node->archive_dir;
	my $name = $self->name;

	print "### Enabling WAL restore for node \"$name\"\n";

	# On Windows, the path specified in the restore command needs to use
	# double back-slashes to work properly and to be able to detect properly
	# the file targeted by the copy command, so the directory value used
	# in this routine, using only one back-slash, need to be properly changed
	# first. Paths also need to be double-quoted to prevent failures where
	# the path contains spaces.
	$path =~ s{\\}{\\\\}g if ($PostgreSQL::Test::Utils::windows_os);
	my $copy_command =
	  $PostgreSQL::Test::Utils::windows_os
	  ? qq{copy "$path\\\\%f" "%p"}
	  : qq{cp "$path/%f" "%p"};

	$self->append_conf(
		$self->_recovery_file, qq(
restore_command = '$copy_command'
));
	if ($standby)
	{
		$self->set_standby_mode();
	}
	else
	{
		$self->set_recovery_mode();
	}
	return;
}

sub _recovery_file { return "postgresql.conf"; }

=pod

=item $node->set_recovery_mode()

Place recovery.signal file.

=cut

sub set_recovery_mode
{
	my ($self) = @_;

	$self->append_conf('recovery.signal', '');
	return;
}

=pod

=item $node->set_standby_mode()

Place standby.signal file.

=cut

sub set_standby_mode
{
	my ($self) = @_;

	$self->append_conf('standby.signal', '');
	return;
}

# Internal routine to enable archiving
sub enable_archiving
{
	my ($self) = @_;
	my $path = $self->archive_dir;
	my $name = $self->name;

	print "### Enabling WAL archiving for node \"$name\"\n";

	# On Windows, the path specified in the restore command needs to use
	# double back-slashes to work properly and to be able to detect properly
	# the file targeted by the copy command, so the directory value used
	# in this routine, using only one back-slash, need to be properly changed
	# first. Paths also need to be double-quoted to prevent failures where
	# the path contains spaces.
	$path =~ s{\\}{\\\\}g if ($PostgreSQL::Test::Utils::windows_os);
	my $copy_command =
	  $PostgreSQL::Test::Utils::windows_os
	  ? qq{copy "%p" "$path\\\\%f"}
	  : qq{cp "%p" "$path/%f"};

	# Enable archive_mode and archive_command on node
	$self->append_conf(
		'postgresql.conf', qq(
archive_mode = on
archive_command = '$copy_command'
));
	return;
}

# Internal method to update $self->{_pid}
# $is_running = 1: pid file should be there
# $is_running = 0: pid file should NOT be there
# $is_running = -1: we aren't sure
sub _update_pid
{
	my ($self, $is_running) = @_;
	my $name = $self->name;

	# If we can open the PID file, read its first line and that's the PID we
	# want.
	if (open my $pidfile, '<', $self->data_dir . "/postmaster.pid")
	{
		chomp($self->{_pid} = <$pidfile>);
		close $pidfile;

		# If we aren't sure what to expect, validate the PID using kill().
		# This protects against stale PID files left by crashed postmasters.
		if ($is_running == -1 && kill(0, $self->{_pid}) == 0)
		{
			print
			  "# Stale postmaster.pid file for node \"$name\": PID $self->{_pid} no longer exists\n";
			$self->{_pid} = undef;
			return;
		}

		print "# Postmaster PID for node \"$name\" is $self->{_pid}\n";

		# If we found a pidfile when there shouldn't be one, complain.
		BAIL_OUT("postmaster.pid unexpectedly present") if $is_running == 0;
		return;
	}

	$self->{_pid} = undef;
	print "# No postmaster PID for node \"$name\"\n";

	# Complain if we expected to find a pidfile.
	BAIL_OUT("postmaster.pid unexpectedly not present") if $is_running == 1;
	return;
}

=pod

=item PostgreSQL::Test::Cluster->new(node_name, %params)

Build a new object of class C<PostgreSQL::Test::Cluster> (or of a subclass, if you have
one), assigning a free port number.  Remembers the node, to prevent its port
number from being reused for another node, and to ensure that it gets
shut down when the test script exits.

=over

=item port => [1,65535]

By default, this function assigns a port number to each node.  Specify this to
force a particular port number.  The caller is responsible for evaluating
potential conflicts and privilege requirements.

=item own_host => 1

By default, all nodes use the same PGHOST value.  If specified, generate a
PGHOST specific to this node.  This allows multiple nodes to use the same
port.

=item install_path => '/path/to/postgres/installation'

Using this parameter is it possible to have nodes pointing to different
installations, for testing different versions together or the same version
with different build parameters. The provided path must be the parent of the
installation's 'bin' and 'lib' directories. In the common case where this is
not provided, Postgres binaries will be found in the caller's PATH.

=back

=cut

sub new
{
	my $class = shift;
	my ($name, %params) = @_;

	# Select a port.
	my $port;
	if (defined $params{port})
	{
		$port = $params{port};
	}
	else
	{
		# When selecting a port, we look for an unassigned TCP port number,
		# even if we intend to use only Unix-domain sockets.  This is clearly
		# necessary on $use_tcp (Windows) configurations, and it seems like a
		# good idea on Unixen as well.
		$port = get_free_port();
	}

	# Select a host.
	my $host = $test_pghost;
	if ($params{own_host})
	{
		if ($use_tcp)
		{
			$last_host_assigned++;
			$last_host_assigned > 254 and BAIL_OUT("too many own_host nodes");
			$host = '127.0.0.' . $last_host_assigned;
		}
		else
		{
			$host = "$test_pghost/$name"; # Assume $name =~ /^[-_a-zA-Z0-9]+$/
			mkdir $host;
		}
	}

	my $testname = basename($0);
	$testname =~ s/\.[^.]+$//;
	my $node = {
		_port => $port,
		_host => $host,
		_basedir =>
		  "$PostgreSQL::Test::Utils::tmp_check/t_${testname}_${name}_data",
		_name => $name,
		_logfile_generation => 0,
		_logfile_base =>
		  "$PostgreSQL::Test::Utils::log_path/${testname}_${name}",
		_logfile =>
		  "$PostgreSQL::Test::Utils::log_path/${testname}_${name}.log"
	};

	if ($params{install_path})
	{
		$node->{_install_path} = $params{install_path};
	}

	bless $node, $class;
	mkdir $node->{_basedir}
	  or
	  BAIL_OUT("could not create data directory \"$node->{_basedir}\": $!");

	$node->_set_pg_version;

	$node->dump_info;

	my $ver = $node->{_pg_version};

	# Use a subclass as defined below (or elsewhere) if this version
	# isn't fully compatible. Warn if the version is too old and thus we don't
	# have a subclass of this class.
	if (ref $ver && $ver < $min_compat)
	{
		my $maj = $ver->major(separator => '_');
		my $subclass = $class . "::V_$maj";
		if ($subclass->isa($class))
		{
			bless $node, $subclass;
		}
		else
		{
			carp
			  "PostgreSQL::Test::Cluster isn't fully compatible with version $ver";
		}
	}

	# Add node to list of nodes
	push(@all_nodes, $node);

	return $node;
}

# Private routine to run the pg_config binary found in our environment (or in
# our install_path, if we have one), and set the version from it
#
sub _set_pg_version
{
	my ($self) = @_;
	my $inst = $self->{_install_path};
	my $pg_config = "pg_config";

	if (defined $inst)
	{
		# If the _install_path is invalid, our PATH variables might find an
		# unrelated pg_config executable elsewhere.  Sanity check the
		# directory.
		BAIL_OUT("directory not found: $inst")
		  unless -d $inst;

		# If the directory exists but is not the root of a postgresql
		# installation, or if the user configured using
		# --bindir=$SOMEWHERE_ELSE, we're not going to find pg_config, so
		# complain about that, too.
		$pg_config = "$inst/bin/pg_config";
		BAIL_OUT("pg_config not found: $pg_config")
		  unless -e $pg_config
		  or ($PostgreSQL::Test::Utils::windows_os and -e "$pg_config.exe");
		BAIL_OUT("pg_config not executable: $pg_config")
		  unless $PostgreSQL::Test::Utils::windows_os or -x $pg_config;

		# Leave $pg_config install_path qualified, to be sure we get the right
		# version information, below, or die trying
	}

	local %ENV = $self->_get_env();

	# We only want the version field
	my $version_line = qx{$pg_config --version};
	BAIL_OUT("$pg_config failed: $!") if $?;

	$self->{_pg_version} = PostgreSQL::Version->new($version_line);

	BAIL_OUT("could not parse pg_config --version output: $version_line")
	  unless defined $self->{_pg_version};
}

# Private routine to return a copy of the environment with the PATH and
# (DY)LD_LIBRARY_PATH correctly set when there is an install path set for
# the node.
#
# Routines that call Postgres binaries need to call this routine like this:
#
#    local %ENV = $self->_get_env([%extra_settings]);
#
# A copy of the environment is taken and node's host and port settings are
# added as PGHOST and PGPORT, then the extra settings (if any) are applied.
# Any setting in %extra_settings with a value that is undefined is deleted;
# the remainder are set. Then the PATH and (DY)LD_LIBRARY_PATH are adjusted
# if the node's install path is set, and the copy environment is returned.
#
# The install path set in new() needs to be a directory containing
# bin and lib subdirectories as in a standard PostgreSQL installation, so this
# can't be used with installations where the bin and lib directories don't have
# a common parent directory.
sub _get_env
{
	my $self = shift;
	my %inst_env = (%ENV, PGHOST => $self->{_host}, PGPORT => $self->{_port});
	# the remaining arguments are modifications to make to the environment
	my %mods = (@_);
	while (my ($k, $v) = each %mods)
	{
		if (defined $v)
		{
			$inst_env{$k} = "$v";
		}
		else
		{
			delete $inst_env{$k};
		}
	}
	# now fix up the new environment for the install path
	my $inst = $self->{_install_path};
	if ($inst)
	{
		if ($PostgreSQL::Test::Utils::windows_os)
		{
			# Windows picks up DLLs from the PATH rather than *LD_LIBRARY_PATH
			# choose the right path separator
			if ($Config{osname} eq 'MSWin32')
			{
				$inst_env{PATH} = "$inst/bin;$inst/lib;$ENV{PATH}";
			}
			else
			{
				$inst_env{PATH} = "$inst/bin:$inst/lib:$ENV{PATH}";
			}
		}
		else
		{
			my $dylib_name =
			  $Config{osname} eq 'darwin'
			  ? "DYLD_LIBRARY_PATH"
			  : "LD_LIBRARY_PATH";
			$inst_env{PATH} = "$inst/bin:$ENV{PATH}";
			if (exists $ENV{$dylib_name})
			{
				$inst_env{$dylib_name} = "$inst/lib:$ENV{$dylib_name}";
			}
			else
			{
				$inst_env{$dylib_name} = "$inst/lib";
			}
		}
	}
	return (%inst_env);
}

=pod

=item $node->installed_command(cmd)

Get an installation path qualified command.

IPC::Run maintains a cache, %cmd_cache, mapping commands to paths.  Tests
which use nodes spanning more than one postgres installation path need to
avoid confusing which installation's binaries get run.  Setting $ENV{PATH} is
insufficient, as IPC::Run does not check to see if the path has changed since
caching a command.

=cut

sub installed_command
{
	my ($self, $cmd) = @_;

	# Nodes using alternate installation locations use their installation's
	# bin/ directory explicitly
	return join('/', $self->{_install_path}, 'bin', $cmd)
	  if defined $self->{_install_path};

	# Nodes implicitly using the default installation location rely on IPC::Run
	# to find the right binary, which should not cause %cmd_cache confusion,
	# because no nodes with other installation paths do it that way.
	return $cmd;
}

=pod

=item get_free_port()

Locate an unprivileged (high) TCP port that's not currently bound to
anything.  This is used by C<new()>, and also by some test cases that need to
start other, non-Postgres servers.

Ports assigned to existing PostgreSQL::Test::Cluster objects are automatically
excluded, even if those servers are not currently running.

The port number is reserved so that other concurrent test programs will not
try to use the same port.

Note: this is not an instance method. As it's not exported it should be
called from outside the module as C<PostgreSQL::Test::Cluster::get_free_port()>.

=cut

sub get_free_port
{
	my $found = 0;
	my $port = $last_port_assigned;

	while ($found == 0)
	{

		# advance $port, wrapping correctly around range end
		$port = $port_lower_bound if ++$port > $port_upper_bound;
		print "# Checking port $port\n";

		# Check first that candidate port number is not included in
		# the list of already-registered nodes.
		$found = 1;
		foreach my $node (@all_nodes)
		{
			$found = 0 if ($node->port == $port);
		}

		# Check to see if anything else is listening on this TCP port.
		# Seek a port available for all possible listen_addresses values,
		# so callers can harness this port for the widest range of purposes.
		# The 0.0.0.0 test achieves that for MSYS, which automatically sets
		# SO_EXCLUSIVEADDRUSE.  Testing 0.0.0.0 is insufficient for Windows
		# native Perl (https://stackoverflow.com/a/14388707), so we also
		# have to test individual addresses.  Doing that for 127.0.0/24
		# addresses other than 127.0.0.1 might fail with EADDRNOTAVAIL on
		# non-Linux, non-Windows kernels.
		#
		# Thus, 0.0.0.0 and individual 127.0.0/24 addresses are tested
		# only on Windows and only when TCP usage is requested.
		if ($found == 1)
		{
			foreach my $addr (qw(127.0.0.1),
				($use_tcp && $PostgreSQL::Test::Utils::windows_os)
				  ? qw(127.0.0.2 127.0.0.3 0.0.0.0)
				  : ())
			{
				if (!can_bind($addr, $port))
				{
					$found = 0;
					last;
				}
			}
			$found = _reserve_port($port) if $found;
		}
	}

	print "# Found port $port\n";

	# Update port for next time
	$last_port_assigned = $port;

	return $port;
}

# Internal routine to check whether a host:port is available to bind
sub can_bind
{
	my ($host, $port) = @_;
	my $iaddr = inet_aton($host);
	my $paddr = sockaddr_in($port, $iaddr);

	socket(SOCK, PF_INET, SOCK_STREAM, 0)
	  or croak "socket failed: $!";

	# As in postmaster, don't use SO_REUSEADDR on Windows
	setsockopt(SOCK, SOL_SOCKET, SO_REUSEADDR, pack("l", 1))
	  unless $PostgreSQL::Test::Utils::windows_os;
	my $ret = bind(SOCK, $paddr) && listen(SOCK, SOMAXCONN);
	close(SOCK);
	return $ret;
}

# Internal routine to reserve a port number
# Returns 1 if successful, 0 if port is already reserved.
sub _reserve_port
{
	my $port = shift;
	# open in rw mode so we don't have to reopen it and lose the lock
	my $filename = "$portdir/$port.rsv";
	sysopen(my $portfile, $filename, O_RDWR | O_CREAT)
	  || croak "opening port file $filename: $!";
	# take an exclusive lock to avoid concurrent access
	flock($portfile, LOCK_EX) || croak "locking port file $filename: $!";
	# see if someone else has or had a reservation of this port
	my $pid = <$portfile> || "0";
	chomp $pid;
	if ($pid + 0 > 0)
	{
		if (kill 0, $pid)
		{
			# process exists and is owned by us, so we can't reserve this port
			flock($portfile, LOCK_UN) || croak $!;
			close($portfile);
			return 0;
		}
	}
	# All good, go ahead and reserve the port
	seek($portfile, 0, SEEK_SET) || croak $!;
	# print the pid with a fixed width so we don't leave any trailing junk
	print $portfile sprintf("%10d\n", $$);
	flock($portfile, LOCK_UN) || croak $!;
	close($portfile);
	push(@port_reservation_files, $filename);
	return 1;
}

# Automatically shut down any still-running nodes (in the same order the nodes
# were created in) when the test script exits.
END
{

	# take care not to change the script's exit value
	my $exit_code = $?;

	foreach my $node (@all_nodes)
	{
		# During unclean termination (which could be a signal or some
		# other failure), we're not sure that the status of our nodes
		# has been correctly set up already, so try and update it to
		# improve our chances of shutting them down.
		$node->_update_pid(-1) if $exit_code != 0;

		# If that fails, don't let that foil other nodes' shutdown
		$node->teardown_node(fail_ok => 1);

		# skip clean if we are requested to retain the basedir
		next if defined $ENV{'PG_TEST_NOCLEAN'};

		# clean basedir on clean test invocation
		$node->clean_node
		  if $exit_code == 0 && PostgreSQL::Test::Utils::all_tests_passing();
	}

	unlink @port_reservation_files;

	$? = $exit_code;
}

=pod

=item $node->teardown_node()

Do an immediate stop of the node

Any optional extra parameter is passed to ->stop.

=cut

sub teardown_node
{
	my ($self, %params) = @_;

	$self->stop('immediate', %params);
	return;
}

=pod

=item $node->clean_node()

Remove the base directory of the node if the node has been stopped.

=cut

sub clean_node
{
	my $self = shift;

	rmtree $self->{_basedir} unless defined $self->{_pid};
	return;
}

=pod

=item $node->safe_psql($dbname, $sql) => stdout

Invoke B<psql> to run B<sql> on B<dbname> and return its stdout on success.
Die if the SQL produces an error. Runs with B<ON_ERROR_STOP> set.

Takes optional extra params like timeout and timed_out parameters with the same
options as psql.

=cut

sub safe_psql
{
	my ($self, $dbname, $sql, %params) = @_;

	local %ENV = $self->_get_env();

	my ($stdout, $stderr);

	my $ret = $self->psql(
		$dbname, $sql,
		%params,
		stdout => \$stdout,
		stderr => \$stderr,
		on_error_die => 1,
		on_error_stop => 1);

	# psql can emit stderr from NOTICEs etc
	if ($stderr ne "")
	{
		print "#### Begin standard error\n";
		print $stderr;
		print "\n#### End standard error\n";
	}

	return $stdout;
}

=pod

=item $node->psql($dbname, $sql, %params) => psql_retval

Invoke B<psql> to execute B<$sql> on B<$dbname> and return the return value
from B<psql>, which is run with on_error_stop by default so that it will
stop running sql and return 3 if the passed SQL results in an error.

As a convenience, if B<psql> is called in array context it returns an
array containing ($retval, $stdout, $stderr).

psql is invoked in tuples-only unaligned mode with reading of B<.psqlrc>
disabled.  That may be overridden by passing extra psql parameters.

stdout and stderr are transformed to UNIX line endings if on Windows. Any
trailing newline is removed.

Dies on failure to invoke psql but not if psql exits with a nonzero
return code (unless on_error_die specified).

If psql exits because of a signal, an exception is raised.

=over

=item stdout => \$stdout

B<stdout>, if given, must be a scalar reference to which standard output is
written.  If not given, standard output is not redirected and will be printed
unless B<psql> is called in array context, in which case it's captured and
returned.

=item stderr => \$stderr

Same as B<stdout> but gets standard error. If the same scalar is passed for
both B<stdout> and B<stderr> the results may be interleaved unpredictably.

=item on_error_stop => 1

By default, the B<psql> method invokes the B<psql> program with ON_ERROR_STOP=1
set, so SQL execution is stopped at the first error and exit code 3 is
returned.  Set B<on_error_stop> to 0 to ignore errors instead.

=item on_error_die => 0

By default, this method returns psql's result code. Pass on_error_die to
instead die with an informative message.

=item timeout => 'interval'

Set a timeout for the psql call as an interval accepted by B<IPC::Run::timer>
(integer seconds is fine).  This method raises an exception on timeout, unless
the B<timed_out> parameter is also given.

=item timed_out => \$timed_out

If B<timeout> is set and this parameter is given, the scalar it references
is set to true if the psql call times out.

=item connstr => B<value>

If set, use this as the connection string for the connection to the
backend.

=item replication => B<value>

If set, add B<replication=value> to the conninfo string.
Passing the literal value C<database> results in a logical replication
connection.

=item extra_params => ['--single-transaction']

If given, it must be an array reference containing additional parameters to B<psql>.

=back

e.g.

	my ($stdout, $stderr, $timed_out);
	my $cmdret = $node->psql('postgres', 'SELECT pg_sleep(600)',
		stdout => \$stdout, stderr => \$stderr,
		timeout => $PostgreSQL::Test::Utils::timeout_default,
		timed_out => \$timed_out,
		extra_params => ['--single-transaction'])

will set $cmdret to undef and $timed_out to a true value.

	$node->psql('postgres', $sql, on_error_die => 1);

dies with an informative message if $sql fails.

=cut

sub psql
{
	my ($self, $dbname, $sql, %params) = @_;

	local %ENV = $self->_get_env();

	my $stdout = $params{stdout};
	my $stderr = $params{stderr};
	my $replication = $params{replication};
	my $timeout = undef;
	my $timeout_exception = 'psql timed out';

	# Build the connection string.
	my $psql_connstr;
	if (defined $params{connstr})
	{
		$psql_connstr = $params{connstr};
	}
	else
	{
		$psql_connstr = $self->connstr($dbname);
	}
	$psql_connstr .= defined $replication ? " replication=$replication" : "";

	my @psql_params = (
		$self->installed_command('psql'),
		'--no-psqlrc', '--no-align', '--tuples-only', '--quiet',
		'--dbname' => $psql_connstr,
		'--file' => '-');

	# If the caller wants an array and hasn't passed stdout/stderr
	# references, allocate temporary ones to capture them so we
	# can return them. Otherwise we won't redirect them at all.
	if (wantarray)
	{
		if (!defined($stdout))
		{
			my $temp_stdout = "";
			$stdout = \$temp_stdout;
		}
		if (!defined($stderr))
		{
			my $temp_stderr = "";
			$stderr = \$temp_stderr;
		}
	}

	$params{on_error_stop} = 1 unless defined $params{on_error_stop};
	$params{on_error_die} = 0 unless defined $params{on_error_die};

	push @psql_params, '--variable' => 'ON_ERROR_STOP=1'
	  if $params{on_error_stop};
	push @psql_params, @{ $params{extra_params} }
	  if defined $params{extra_params};

	$timeout =
	  IPC::Run::timeout($params{timeout}, exception => $timeout_exception)
	  if (defined($params{timeout}));

	${ $params{timed_out} } = 0 if defined $params{timed_out};

	# IPC::Run would otherwise append to existing contents:
	$$stdout = "" if ref($stdout);
	$$stderr = "" if ref($stderr);

	my $ret;

	# Run psql and capture any possible exceptions.  If the exception is
	# because of a timeout and the caller requested to handle that, just return
	# and set the flag.  Otherwise, and for any other exception, rethrow.
	#
	# For background, see
	# https://metacpan.org/release/ETHER/Try-Tiny-0.24/view/lib/Try/Tiny.pm
	do
	{
		local $@;
		eval {
			my @ipcrun_opts = (\@psql_params, '<' => \$sql);
			push @ipcrun_opts, '>' => $stdout if defined $stdout;
			push @ipcrun_opts, '2>' => $stderr if defined $stderr;
			push @ipcrun_opts, $timeout if defined $timeout;

			IPC::Run::run @ipcrun_opts;
			$ret = $?;
		};
		my $exc_save = $@;

		# we need a dummy $stderr from hereon, if we didn't collect it
		if (!defined $stderr)
		{
			my $errtxt = "<not collected>";
			$stderr = \$errtxt;
		}

		if ($exc_save)
		{

			# IPC::Run::run threw an exception. re-throw unless it's a
			# timeout, which we'll handle by testing is_expired
			croak $exc_save
			  if (blessed($exc_save)
				|| $exc_save !~ /^\Q$timeout_exception\E/);

			$ret = undef;

			croak "Got timeout exception '$exc_save' but timer not expired?!"
			  unless $timeout->is_expired;

			if (defined($params{timed_out}))
			{
				${ $params{timed_out} } = 1;
			}
			else
			{
				croak "psql timed out: stderr: '$$stderr'\n"
				  . "while running '@psql_params'";
			}
		}
	};

	if (defined $$stdout)
	{
		chomp $$stdout;
	}

	if (defined $$stderr)
	{
		chomp $$stderr;
	}

	# See http://perldoc.perl.org/perlvar.html#%24CHILD_ERROR
	# We don't use IPC::Run::Simple to limit dependencies.
	#
	# We always die on signal.
	if (defined $ret)
	{
		my $core = $ret & 128 ? " (core dumped)" : "";
		croak "psql exited with signal "
		  . ($ret & 127)
		  . "$core: '$$stderr' while running '@psql_params'"
		  if $ret & 127;
		$ret = $ret >> 8;
	}

	if ($ret && $params{on_error_die})
	{
		croak "psql error: stderr: '$$stderr'\nwhile running '@psql_params'"
		  if $ret == 1;
		croak "connection error: '$$stderr'\nwhile running '@psql_params'"
		  if $ret == 2;
		croak
		  "error running SQL: '$$stderr'\nwhile running '@psql_params' with sql '$sql'"
		  if $ret == 3;
		croak "psql returns $ret: '$$stderr'\nwhile running '@psql_params'";
	}

	if (wantarray)
	{
		return ($ret, $$stdout, $$stderr);
	}
	else
	{
		return $ret;
	}
}

=pod

=item $node->background_psql($dbname, %params) => PostgreSQL::Test::BackgroundPsql instance

Invoke B<psql> on B<$dbname> and return a BackgroundPsql object.

psql is invoked in tuples-only unaligned mode with reading of B<.psqlrc>
disabled.  That may be overridden by passing extra psql parameters.

Dies on failure to invoke psql, or if psql fails to connect.  Errors occurring
later are the caller's problem.  psql runs with on_error_stop by default so
that it will stop running sql and return 3 if passed SQL results in an error.

Be sure to "quit" the returned object when done with it.

=over

=item on_error_stop => 1

By default, the B<psql> method invokes the B<psql> program with ON_ERROR_STOP=1
set, so SQL execution is stopped at the first error and exit code 3 is
returned.  Set B<on_error_stop> to 0 to ignore errors instead.

=item timeout => 'interval'

Set a timeout for a background psql session. By default, timeout of
$PostgreSQL::Test::Utils::timeout_default is set up.

=item connstr => B<value>

If set, use this as the connection string for the connection to the
backend.

=item replication => B<value>

If set, add B<replication=value> to the conninfo string.
Passing the literal value C<database> results in a logical replication
connection.

=item extra_params => ['--single-transaction']

If given, it must be an array reference containing additional parameters to B<psql>.

=item wait => 1

By default, this method will not return until connection has completed (or
failed). Set B<wait> to 0 to return immediately instead. (Clients can call the
session's C<wait_connect> method manually when needed.)

=back

=cut

sub background_psql
{
	my ($self, $dbname, %params) = @_;

	local %ENV = $self->_get_env();

	my $replication = $params{replication};
	my $timeout = undef;

	# Build the connection string.
	my $psql_connstr;
	if (defined $params{connstr})
	{
		$psql_connstr = $params{connstr};
	}
	else
	{
		$psql_connstr = $self->connstr($dbname);
	}
	$psql_connstr .= defined $replication ? " replication=$replication" : "";

	my @psql_params = (
		$self->installed_command('psql'),
		'--no-psqlrc', '--no-align',
		'--tuples-only', '--quiet',
		'--dbname' => $psql_connstr,
		'--file' => '-');

	$params{on_error_stop} = 1 unless defined $params{on_error_stop};
	$params{wait} = 1 unless defined $params{wait};
	$timeout = $params{timeout} if defined $params{timeout};

	push @psql_params, '--set' => 'ON_ERROR_STOP=1' if $params{on_error_stop};
	push @psql_params, @{ $params{extra_params} }
	  if defined $params{extra_params};

	return PostgreSQL::Test::BackgroundPsql->new(0, \@psql_params, $timeout,
		$params{wait});
}

=pod

=item $node->interactive_psql($dbname, %params) => BackgroundPsql instance

Invoke B<psql> on B<$dbname> and return a BackgroundPsql object, which the
caller may use to send interactive input to B<psql>.

A timeout of $PostgreSQL::Test::Utils::timeout_default is set up.

psql is invoked in tuples-only unaligned mode with reading of B<.psqlrc>
disabled.  That may be overridden by passing extra psql parameters.

Dies on failure to invoke psql, or if psql fails to connect.
Errors occurring later are the caller's problem.

Be sure to "quit" the returned object when done with it.

=over

=item extra_params => ['--single-transaction']

If given, it must be an array reference containing additional parameters to B<psql>.

=item history_file => B<path>

Cause the interactive B<psql> session to write its command history to B<path>.
If not given, the history is sent to B</dev/null>.

=back

This requires IO::Pty in addition to IPC::Run.

=cut

sub interactive_psql
{
	my ($self, $dbname, %params) = @_;

	local %ENV = $self->_get_env();

	# Since the invoked psql will believe it's interactive, it will use
	# readline/libedit if available.  We need to adjust some environment
	# settings to prevent unwanted side-effects.

	# Developers would not appreciate tests adding a bunch of junk to
	# their ~/.psql_history, so redirect readline history somewhere else.
	# If the calling script doesn't specify anything, just bit-bucket it.
	$ENV{PSQL_HISTORY} = $params{history_file} || '/dev/null';

	# Another pitfall for developers is that they might have a ~/.inputrc
	# file that changes readline's behavior enough to affect the test.
	# So ignore any such file.
	$ENV{INPUTRC} = '/dev/null';

	# Unset TERM so that readline/libedit won't use any terminal-dependent
	# escape sequences; that leads to way too many cross-version variations
	# in the output.
	delete $ENV{TERM};
	# Some versions of readline inspect LS_COLORS, so for luck unset that too.
	delete $ENV{LS_COLORS};

	my @psql_params = (
		$self->installed_command('psql'),
		'--no-psqlrc', '--no-align', '--tuples-only',
		'--dbname' => $self->connstr($dbname));

	push @psql_params, @{ $params{extra_params} }
	  if defined $params{extra_params};

	return PostgreSQL::Test::BackgroundPsql->new(1, \@psql_params);
}

# Common sub of pgbench-invoking interfaces.  Makes any requested script files
# and returns pgbench command-line options causing use of those files.
sub _pgbench_make_files
{
	my ($self, $files) = @_;
	my @file_opts;

	if (defined $files)
	{

		# note: files are ordered for determinism
		for my $fn (sort keys %$files)
		{
			my $filename = $self->basedir . '/' . $fn;
			push @file_opts, '--file' => $filename;

			# cleanup file weight
			$filename =~ s/\@\d+$//;

			# filenames are expected to be unique on a test
			if (-e $filename)
			{
				ok(0, "$filename must not already exist");
				unlink $filename or croak "cannot unlink $filename: $!";
			}
			PostgreSQL::Test::Utils::append_to_file($filename, $$files{$fn});
		}
	}

	return @file_opts;
}

=pod

=item $node->pgbench($opts, $stat, $out, $err, $name, $files, @args)

Invoke B<pgbench>, with parameters and files.

=over

=item $opts

Options as a string to be split on spaces.

=item $stat

Expected exit status.

=item $out

Reference to a regexp list that must match stdout.

=item $err

Reference to a regexp list that must match stderr.

=item $name

Name of test for error messages.

=item $files

Reference to filename/contents dictionary.

=item @args

Further raw options or arguments.

=back

=cut

sub pgbench
{
	local $Test::Builder::Level = $Test::Builder::Level + 1;

	my ($self, $opts, $stat, $out, $err, $name, $files, @args) = @_;
	my @cmd = (
		'pgbench',
		split(/\s+/, $opts),
		$self->_pgbench_make_files($files), @args);

	$self->command_checks_all(\@cmd, $stat, $out, $err, $name);
}

=pod

=item $node->connect_ok($connstr, $test_name, %params)

Attempt a connection with a custom connection string.  This is expected
to succeed.

=over

=item sql => B<value>

If this parameter is set, this query is used for the connection attempt
instead of the default.

=item expected_stdout => B<value>

If this regular expression is set, matches it with the output generated.

=item expected_stderr => B<value>

If this regular expression is set, matches it against the standard error
stream; otherwise stderr must be empty.

=item log_like => [ qr/required message/ ]

=item log_unlike => [ qr/prohibited message/ ]

See C<log_check(...)>.

=back

=cut

sub connect_ok
{
	local $Test::Builder::Level = $Test::Builder::Level + 1;
	my ($self, $connstr, $test_name, %params) = @_;

	my $sql;
	if (defined($params{sql}))
	{
		$sql = $params{sql};
	}
	else
	{
		$sql = "SELECT \$\$connected with $connstr\$\$";
	}

	my $log_location = -s $self->logfile;

	# Never prompt for a password, any callers of this routine should
	# have set up things properly, and this should not block.
	my ($ret, $stdout, $stderr) = $self->psql(
		'postgres',
		$sql,
		extra_params => ['-w'],
		connstr => "$connstr",
		on_error_stop => 0);

	is($ret, 0, $test_name);

	if (defined($params{expected_stdout}))
	{
		like($stdout, $params{expected_stdout}, "$test_name: stdout matches");
	}

	if (defined($params{expected_stderr}))
	{
		if (like(
				$stderr, $params{expected_stderr},
				"$test_name: stderr matches")
			&& ($ret != 0))
		{
			# In this case (failing test but matching stderr) we'll have
			# swallowed the output needed to debug. Put it back into the logs.
			diag("$test_name: full stderr:\n" . $stderr);
		}
	}
	else
	{
		is($stderr, "", "$test_name: no stderr");
	}

	$self->log_check($test_name, $log_location, %params);
}

=pod

=item $node->connect_fails($connstr, $test_name, %params)

Attempt a connection with a custom connection string.  This is expected
to fail.

=over

=item expected_stderr => B<value>

If this regular expression is set, matches it to the output generated
by B<psql>.

=item log_like => [ qr/required message/ ]

=item log_unlike => [ qr/prohibited message/ ]

See C<log_check(...)>.  CAUTION: use of either option requires that
the server's log_min_messages be at least DEBUG2, and that no other
client backend is launched concurrently.  These requirements allow
C<connect_fails> to wait to see the postmaster-log report of backend
exit, without which there is a race condition as to whether we will
see the expected backend log output.

=back

=cut

sub connect_fails
{
	local $Test::Builder::Level = $Test::Builder::Level + 1;
	my ($self, $connstr, $test_name, %params) = @_;

	my $log_location = -s $self->logfile;

	# Never prompt for a password, any callers of this routine should
	# have set up things properly, and this should not block.
	my ($ret, $stdout, $stderr) = $self->psql(
		'postgres',
		undef,
		extra_params => ['-w'],
		connstr => "$connstr");

	isnt($ret, 0, $test_name);

	if (defined($params{expected_stderr}))
	{
		like($stderr, $params{expected_stderr}, "$test_name: matches");
	}

	if (defined($params{log_like}) or defined($params{log_unlike}))
	{
		$self->wait_for_log(
			qr/DEBUG:  (?:00000: )?forked new client backend, pid=(\d+) socket.*DEBUG:  (?:00000: )?client backend \(PID \1\) exited with exit code \d/s,
			$log_location);

		$self->log_check($test_name, $log_location, %params);
	}
}

=pod

=item $node->poll_query_until($dbname, $query [, $expected ])

Run B<$query> repeatedly, until it returns the B<$expected> result
('t', or SQL boolean true, by default).
Continues polling if B<psql> returns an error result.
Times out after $PostgreSQL::Test::Utils::timeout_default seconds.
Returns 1 if successful, 0 if timed out.

=cut

sub poll_query_until
{
	my ($self, $dbname, $query, $expected) = @_;

	local %ENV = $self->_get_env();

	$expected = 't' unless defined($expected);    # default value

	my $cmd = [
		$self->installed_command('psql'), '--no-psqlrc',
		'--no-align', '--tuples-only',
		'--dbname' => $self->connstr($dbname)
	];
	my ($stdout, $stderr);
	my $max_attempts = 10 * $PostgreSQL::Test::Utils::timeout_default;
	my $attempts = 0;

	while ($attempts < $max_attempts)
	{
		my $result = IPC::Run::run $cmd,
		  '<' => \$query,
		  '>' => \$stdout,
		  '2>' => \$stderr;

		chomp($stdout);
		chomp($stderr);

		if ($stdout eq $expected && $stderr eq '')
		{
			return 1;
		}

		# Wait 0.1 second before retrying.
		usleep(100_000);

		$attempts++;
	}

	# Give up. Print the output from the last attempt, hopefully that's useful
	# for debugging.
	diag qq(poll_query_until timed out executing this query:
$query
expecting this output:
$expected
last actual query output:
$stdout
with stderr:
$stderr);
	return 0;
}

=pod

=item $node->command_ok(...)

Runs a shell command like PostgreSQL::Test::Utils::command_ok, but with PGHOST and PGPORT set
so that the command will default to connecting to this PostgreSQL::Test::Cluster.

=cut

sub command_ok
{
	local $Test::Builder::Level = $Test::Builder::Level + 1;

	my $self = shift;

	local %ENV = $self->_get_env();

	PostgreSQL::Test::Utils::command_ok(@_);
	return;
}

=pod

=item $node->command_fails(...)

PostgreSQL::Test::Utils::command_fails with our connection parameters. See command_ok(...)

=cut

sub command_fails
{
	local $Test::Builder::Level = $Test::Builder::Level + 1;

	my $self = shift;

	local %ENV = $self->_get_env();

	PostgreSQL::Test::Utils::command_fails(@_);
	return;
}

=pod

=item $node->command_like(...)

PostgreSQL::Test::Utils::command_like with our connection parameters. See command_ok(...)

=cut

sub command_like
{
	local $Test::Builder::Level = $Test::Builder::Level + 1;

	my $self = shift;

	local %ENV = $self->_get_env();

	PostgreSQL::Test::Utils::command_like(@_);
	return;
}

=pod

=item $node->command_fails_like(...)

PostgreSQL::Test::Utils::command_fails_like with our connection parameters. See command_ok(...)

=cut

sub command_fails_like
{
	local $Test::Builder::Level = $Test::Builder::Level + 1;

	my $self = shift;

	local %ENV = $self->_get_env();

	PostgreSQL::Test::Utils::command_fails_like(@_);
	return;
}

=pod

=item $node->command_ok_or_fails_like(...)

PostgreSQL::Test::Utils::command_ok_or_fails_like with our connection parameters. See command_ok(...)

=cut

sub command_ok_or_fails_like
{
	local $Test::Builder::Level = $Test::Builder::Level + 1;

	my $self = shift;

	local %ENV = $self->_get_env();

	return PostgreSQL::Test::Utils::command_ok_or_fails_like(@_);
}

=pod

=item $node->command_checks_all(...)

PostgreSQL::Test::Utils::command_checks_all with our connection parameters. See
command_ok(...)

=cut

sub command_checks_all
{
	local $Test::Builder::Level = $Test::Builder::Level + 1;

	my $self = shift;

	local %ENV = $self->_get_env();

	PostgreSQL::Test::Utils::command_checks_all(@_);
	return;
}

=pod

=item $node->issues_sql_like(cmd, expected_sql, test_name)

Run a command on the node, then verify that $expected_sql appears in the
server log file.

=cut

sub issues_sql_like
{
	local $Test::Builder::Level = $Test::Builder::Level + 1;

	my ($self, $cmd, $expected_sql, $test_name) = @_;

	local %ENV = $self->_get_env();

	my $log_location = -s $self->logfile;

	my $result = PostgreSQL::Test::Utils::run_log($cmd);
	ok($result, "@$cmd exit code 0");
	my $log =
	  PostgreSQL::Test::Utils::slurp_file($self->logfile, $log_location);
	like($log, $expected_sql, "$test_name: SQL found in server log");
	return;
}

=pod

=item $node->issues_sql_unlike(cmd, unexpected_sql, test_name)

Run a command on the node, then verify that $unexpected_sql does not appear in
the server log file.

=cut

sub issues_sql_unlike
{
	local $Test::Builder::Level = $Test::Builder::Level + 1;

	my ($self, $cmd, $unexpected_sql, $test_name) = @_;

	local %ENV = $self->_get_env();

	my $log_location = -s $self->logfile;

	my $result = PostgreSQL::Test::Utils::run_log($cmd);
	ok($result, "@$cmd exit code 0");
	my $log =
	  PostgreSQL::Test::Utils::slurp_file($self->logfile, $log_location);
	unlike($log, $unexpected_sql, "$test_name: SQL not found in server log");
	return;
}

=pod

=item $node->log_content()

Returns the contents of log of the node

=cut

sub log_content
{
	my ($self) = @_;
	return PostgreSQL::Test::Utils::slurp_file($self->logfile);
}

=pod

=item $node->log_check($test_name, $offset, %params)

Check contents of server logs.

=over

=item $test_name

Name of test for error messages.

=item $offset

Offset of the log file.

=item log_like => [ qr/required message/ ]

If given, it must be an array reference containing a list of regular
expressions that must match against the server log, using
C<Test::More::like()>.

=item log_unlike => [ qr/prohibited message/ ]

If given, it must be an array reference containing a list of regular
expressions that must NOT match against the server log.  They will be
passed to C<Test::More::unlike()>.

=back

=cut

sub log_check
{
	my ($self, $test_name, $offset, %params) = @_;

	my (@log_like, @log_unlike);
	if (defined($params{log_like}))
	{
		@log_like = @{ $params{log_like} };
	}
	if (defined($params{log_unlike}))
	{
		@log_unlike = @{ $params{log_unlike} };
	}

	if (@log_like or @log_unlike)
	{
		my $log_contents =
		  PostgreSQL::Test::Utils::slurp_file($self->logfile, $offset);

		while (my $regex = shift @log_like)
		{
			like($log_contents, $regex, "$test_name: log matches");
		}
		while (my $regex = shift @log_unlike)
		{
			unlike($log_contents, $regex, "$test_name: log does not match");
		}
	}
}

=pod

=item log_contains(pattern, offset)

Find pattern in logfile of node after offset byte.

=cut

sub log_contains
{
	my ($self, $pattern, $offset) = @_;

	return PostgreSQL::Test::Utils::slurp_file($self->logfile, $offset) =~
	  m/$pattern/;
}

=pod

=item $node->run_log(...)

Runs a shell command like PostgreSQL::Test::Utils::run_log, but with connection parameters set
so that the command will default to connecting to this PostgreSQL::Test::Cluster.

=cut

sub run_log
{
	my $self = shift;

	local %ENV = $self->_get_env();

	return PostgreSQL::Test::Utils::run_log(@_);
}

=pod

=item $node->lsn(mode)

Look up WAL locations on the server:

 * insert location (primary only, error on replica)
 * write location (primary only, error on replica)
 * flush location (primary only, error on replica)
 * receive location (always undef on primary)
 * replay location (always undef on primary)

mode must be specified.

=cut

sub lsn
{
	my ($self, $mode) = @_;
	my %modes = (
		'insert' => 'pg_current_wal_insert_lsn()',
		'flush' => 'pg_current_wal_flush_lsn()',
		'write' => 'pg_current_wal_lsn()',
		'receive' => 'pg_last_wal_receive_lsn()',
		'replay' => 'pg_last_wal_replay_lsn()');

	$mode = '<undef>' if !defined($mode);
	croak "unknown mode for 'lsn': '$mode', valid modes are "
	  . join(', ', keys %modes)
	  if !defined($modes{$mode});

	my $result = $self->safe_psql('postgres', "SELECT $modes{$mode}");
	chomp($result);
	if ($result eq '')
	{
		return;
	}
	else
	{
		return $result;
	}
}

=pod

=item $node->write_wal($tli, $lsn, $segment_size, $data)

Write some arbitrary data in WAL for the given segment at $lsn (in bytes).
This should be called while the cluster is not running.

Returns the path of the WAL segment written to.

=cut

sub write_wal
{
	my ($self, $tli, $lsn, $segment_size, $data) = @_;

	# Calculate segment number and offset position in segment based on the
	# input LSN.
	my $segment = $lsn / $segment_size;
	my $offset = $lsn % $segment_size;
	my $path =
	  sprintf("%s/pg_wal/%08X%08X%08X", $self->data_dir, $tli, 0, $segment);

	open my $fh, "+<:raw", $path or croak "could not open WAL segment $path";
	seek($fh, $offset, SEEK_SET) or croak "could not seek WAL segment $path";
	print $fh $data;
	close $fh;

	return $path;
}

=pod

=item $node->emit_wal($size)

Emit a WAL record of arbitrary size, using pg_logical_emit_message().

Returns the end LSN of the record inserted, in bytes.

=cut

sub emit_wal
{
	my ($self, $size) = @_;

	return int(
		$self->safe_psql(
			'postgres',
			"SELECT pg_logical_emit_message(true, '', repeat('a', $size)) - '0/0'"
		));
}


# Private routine returning the current insert LSN of a node, in bytes.
# Used by the routines below in charge of advancing WAL to arbitrary
# positions.  The insert LSN is returned in bytes.
sub _get_insert_lsn
{
	my ($self) = @_;
	return int(
		$self->safe_psql(
			'postgres', "SELECT pg_current_wal_insert_lsn() - '0/0'"));
}

=pod

=item $node->advance_wal_out_of_record_splitting_zone($wal_block_size)

Advance WAL at the end of a page, making sure that we are far away enough
from the end of a page that we could insert a couple of small records.

This inserts a few records of a fixed size, until the threshold gets close
enough to the end of the WAL page inserting records to.

Returns the end LSN up to which WAL has advanced, in bytes.

=cut

sub advance_wal_out_of_record_splitting_zone
{
	my ($self, $wal_block_size) = @_;

	my $page_threshold = $wal_block_size / 4;
	my $end_lsn = $self->_get_insert_lsn();
	my $page_offset = $end_lsn % $wal_block_size;
	while ($page_offset >= $wal_block_size - $page_threshold)
	{
		$self->emit_wal($page_threshold);
		$end_lsn = $self->_get_insert_lsn();
		$page_offset = $end_lsn % $wal_block_size;
	}
	return $end_lsn;
}

=pod

=item $node->advance_wal_to_record_splitting_zone($wal_block_size)

Advance WAL so close to the end of a page that an XLogRecordHeader would not
fit on it.

Returns the end LSN up to which WAL has advanced, in bytes.

=cut

sub advance_wal_to_record_splitting_zone
{
	my ($self, $wal_block_size) = @_;

	# Size of record header.
	my $RECORD_HEADER_SIZE = 24;

	my $end_lsn = $self->_get_insert_lsn();
	my $page_offset = $end_lsn % $wal_block_size;

	# Get fairly close to the end of a page in big steps
	while ($page_offset <= $wal_block_size - 512)
	{
		$self->emit_wal($wal_block_size - $page_offset - 256);
		$end_lsn = $self->_get_insert_lsn();
		$page_offset = $end_lsn % $wal_block_size;
	}

	# Calibrate our message size so that we can get closer 8 bytes at
	# a time.
	my $message_size = $wal_block_size - 80;
	while ($page_offset <= $wal_block_size - $RECORD_HEADER_SIZE)
	{
		$self->emit_wal($message_size);
		$end_lsn = $self->_get_insert_lsn();

		my $old_offset = $page_offset;
		$page_offset = $end_lsn % $wal_block_size;

		# Adjust the message size until it causes 8 bytes changes in
		# offset, enough to be able to split a record header.
		my $delta = $page_offset - $old_offset;
		if ($delta > 8)
		{
			$message_size -= 8;
		}
		elsif ($delta <= 0)
		{
			$message_size += 8;
		}
	}
	return $end_lsn;
}

=pod

=item $node->check_extension(extension_name)

Scan pg_available_extensions to check that an extension is available in an
installation.

Returns 1 if the extension is available, 0 otherwise.

=cut

sub check_extension
{
	my ($self, $extension_name) = @_;

	my $result = $self->safe_psql('postgres',
		"SELECT count(*) > 0 FROM pg_available_extensions WHERE name = '$extension_name';"
	);

	return $result eq 't' ? 1 : 0;
}

=pod

=item $node->wait_for_event(backend_type, wait_event_name)

Poll pg_stat_activity until backend_type reaches wait_event_name.

=cut

sub wait_for_event
{
	my ($self, $backend_type, $wait_event_name) = @_;

	$self->poll_query_until(
		'postgres', qq[
		SELECT count(*) > 0 FROM pg_stat_activity
		WHERE backend_type = '$backend_type' AND wait_event = '$wait_event_name'
	])
	  or croak
	  qq(timed out when waiting for $backend_type to reach wait event '$wait_event_name');

	return;
}

=pod

=item $node->wait_for_catchup(standby_name, mode, target_lsn)

Wait until the standby identified by standby_name has reached the specified
or default target_lsn for the given 'mode'.  By default the replay_lsn
is waited for, but 'mode' may be specified to wait for any of
sent|write|flush|replay.

When doing physical replication, the standby is usually identified by
passing its PostgreSQL::Test::Cluster instance.  When doing logical
replication, standby_name identifies a subscription.

When not in recovery, the default value of target_lsn is $node->lsn('write'),
which ensures that the standby has caught up to what has been committed on
the primary.

When in recovery, the default value of target_lsn is $node->lsn('replay')
instead which ensures that the cascaded standby has caught up to what has been
replayed on the standby.

If you pass an explicit value of target_lsn, it should almost always be
the primary's write LSN; so this parameter is seldom needed except when
querying some intermediate replication node rather than the primary.

When the standby is passed as a PostgreSQL::Test::Cluster instance and the
mode is replay, write, or flush, the function uses WAIT FOR LSN on the
standby for latch-based wakeup instead of polling.  If the standby has been
promoted, if the session is interrupted by a recovery conflict, or if the
standby is unreachable, it falls back to polling.

For 'sent' mode, when the standby is passed as a string (e.g., a
subscription name), when the sparc64+ext4 bug is detected, or as a fallback
from the above, the function polls pg_stat_replication on the upstream.
The replication connection must be in a streaming state for this path.

Requires that the 'postgres' db exists and is accessible.

This is not a test. It croak()s on failure.

=cut

sub wait_for_catchup
{
	my ($self, $standby_name, $mode, $target_lsn) = @_;
	$mode = defined($mode) ? $mode : 'replay';
	my %valid_modes =
	  ('sent' => 1, 'write' => 1, 'flush' => 1, 'replay' => 1);
	croak "unknown mode $mode for 'wait_for_catchup', valid modes are "
	  . join(', ', keys(%valid_modes))
	  unless exists($valid_modes{$mode});

	# Keep a reference to the standby node if passed as an object, so we can
	# use WAIT FOR LSN on it later.
	my $standby_node;
	if (blessed($standby_name)
		&& $standby_name->isa("PostgreSQL::Test::Cluster"))
	{
		$standby_node = $standby_name;
		$standby_name = $standby_name->name;
	}
	if (!defined($target_lsn))
	{
		my $isrecovery =
		  $self->safe_psql('postgres', "SELECT pg_is_in_recovery()");
		chomp($isrecovery);
		if ($isrecovery eq 't')
		{
			$target_lsn = $self->lsn('replay');
		}
		else
		{
			$target_lsn = $self->lsn('write');
		}
	}
	print "Waiting for replication conn "
	  . $standby_name . "'s "
	  . $mode
	  . "_lsn to pass "
	  . $target_lsn . " on "
	  . $self->name . "\n";
	# Before release 12 walreceiver just set the application name to
	# "walreceiver"

	# Use WAIT FOR LSN on the standby when:
	# - The standby was passed as a Cluster object (so we can connect to it)
	# - The mode is replay, write, or flush (not 'sent')
	# - There is no sparc64+ext4 bug
	# This is more efficient than polling pg_stat_replication on the upstream,
	# as WAIT FOR LSN uses a latch-based wakeup mechanism.
	#
	# We skip the pg_is_in_recovery() pre-check and just attempt WAIT FOR
	# LSN directly.  If the standby was promoted, it returns 'not_in_recovery'
	# and we fall back to polling.
	if (   defined($standby_node)
		&& ($mode ne 'sent')
		&& (!PostgreSQL::Test::Utils::has_wal_read_bug))
	{
		# Map mode names to WAIT FOR LSN mode names
		my %mode_map = (
			'replay' => 'standby_replay',
			'write' => 'standby_write',
			'flush' => 'standby_flush',);
		my $wait_mode = $mode_map{$mode};
		my $timeout = $PostgreSQL::Test::Utils::timeout_default;
		my $wait_query =
		  qq[WAIT FOR LSN '${target_lsn}' WITH (MODE '${wait_mode}', timeout '${timeout}s', no_throw);];

		# Try WAIT FOR LSN. If it succeeds, we're done. If it returns
		# 'not_in_recovery' (standby was promoted), fall back to polling.
		# If the session is interrupted (e.g., killed by recovery conflict),
		# fall back to polling on the upstream which is immune to standby-
		# side conflicts.
		my $output;
		local $@;
		my $wait_succeeded = eval {
			$output = $standby_node->safe_psql('postgres', $wait_query);
			chomp($output);
			1;
		};

		if ($wait_succeeded && $output eq 'success')
		{
			print "done\n";
			return;
		}

		# 'not in recovery' means the standby was promoted.
		if ($wait_succeeded && $output eq 'not in recovery')
		{
			diag
			  "WAIT FOR LSN returned 'not in recovery', falling back to polling";
		}
		# 'timeout' is a hard failure - no point falling back to polling.
		elsif ($wait_succeeded)
		{
			my $details = $self->safe_psql('postgres',
				"SELECT * FROM pg_catalog.pg_stat_replication");
			diag qq(WAIT FOR LSN returned '$output'
pg_stat_replication on upstream:
${details});
			croak
			  "WAIT FOR LSN '$wait_mode' to '$target_lsn' returned '$output'";
		}
		# WAIT FOR LSN was interrupted.  Fall back to polling if this
		# looks like a recovery conflict.  We match the English error
		# message "conflict with recovery" which is reliable because the
		# test suite runs with LC_MESSAGES=C.  Other errors should fail
		# immediately rather than being masked by a silent fallback.
		elsif ($@ =~ /conflict with recovery/i)
		{
			diag qq(WAIT FOR LSN interrupted, falling back to polling:
$@);
		}
		else
		{
			croak "WAIT FOR LSN failed: $@";
		}
	}

	# Fall back to polling pg_stat_replication on the upstream for:
	# - 'sent' mode (no corresponding WAIT FOR LSN mode)
	# - When standby_name is a string (e.g., subscription name)
	# - When the standby is no longer in recovery (was promoted)
	# - When WAIT FOR LSN was interrupted (e.g., killed by a recovery conflict)
	my $query = qq[SELECT '$target_lsn' <= ${mode}_lsn AND state = 'streaming'
         FROM pg_catalog.pg_stat_replication
         WHERE application_name IN ('$standby_name', 'walreceiver')];
	if (!$self->poll_query_until('postgres', $query))
	{
		if (PostgreSQL::Test::Utils::has_wal_read_bug)
		{
			# Mimic having skipped the test file.  If >0 tests have run, the
			# harness won't accept a skip; otherwise, it won't accept
			# done_testing().  Force a nonzero count by running one test.
			ok(1, 'dummy test before skip for filesystem bug');
			carp "skip rest: timed out waiting for catchup & filesystem bug";
			done_testing();
			exit 0;
		}
		else
		{
			# Fetch additional detail for debugging purposes
			$query = qq[SELECT * FROM pg_catalog.pg_stat_replication];
			my $details = $self->safe_psql('postgres', $query);
			diag qq(Last pg_stat_replication contents:
${details});
			croak "timed out waiting for catchup";
		}
	}
	print "done\n";
	return;
}

=pod

=item $node->wait_for_replay_catchup($standby_name [, $base_node ])

Wait for the replication connection with application_name I<$standby_name>
until its B<replay> replication column in pg_stat_replication in I<$node>
equals or passes the I<$base_node>'s B<replay_lsn>. If I<$base_node> is
omitted, the LSN to wait for is obtained from I<$node>.

The replication connection must be in a streaming state.

Requires that the 'postgres' db exists and is accessible.

This is not a test. It croak()s on failure.

=cut

sub wait_for_replay_catchup
{
	my ($self, $standby_name, $node) = @_;
	$node = defined($node) ? $node : $self;

	$self->wait_for_catchup($standby_name, 'replay', $node->lsn('flush'));
}

=item $node->wait_for_slot_catchup(slot_name, mode, target_lsn)

Wait for the named replication slot to equal or pass the supplied target_lsn.
The location used is the restart_lsn unless mode is given, in which case it may
be 'restart' or 'confirmed_flush'.

Requires that the 'postgres' db exists and is accessible.

This is not a test. It croak()s on failure.

If the slot is not active, will time out after poll_query_until's timeout.

target_lsn may be any arbitrary lsn, but is typically $primary_node->lsn('insert').

Note that for logical slots, restart_lsn is held down by the oldest in-progress tx.

=cut

sub wait_for_slot_catchup
{
	my ($self, $slot_name, $mode, $target_lsn) = @_;
	$mode = defined($mode) ? $mode : 'restart';
	if (!($mode eq 'restart' || $mode eq 'confirmed_flush'))
	{
		croak "valid modes are restart, confirmed_flush";
	}
	croak 'target lsn must be specified' unless defined($target_lsn);
	print "Waiting for replication slot "
	  . $slot_name . "'s "
	  . $mode
	  . "_lsn to pass "
	  . $target_lsn . " on "
	  . $self->name . "\n";
	my $query =
	  qq[SELECT '$target_lsn' <= ${mode}_lsn FROM pg_catalog.pg_replication_slots WHERE slot_name = '$slot_name';];
	if (!$self->poll_query_until('postgres', $query))
	{
		# Fetch additional detail for debugging purposes
		$query = qq[SELECT * FROM pg_catalog.pg_replication_slots];
		my $details = $self->safe_psql('postgres', $query);
		diag qq(Last pg_replication_slots contents:
${details});
		croak "timed out waiting for catchup";
	}
	print "done\n";
	return;
}

=pod

=item $node->wait_for_subscription_sync(publisher, subname, dbname)

Wait for all tables in pg_subscription_rel to complete the initial
synchronization (i.e to be either in 'syncdone' or 'ready' state).

If the publisher node is given, additionally, check if the subscriber has
caught up to what has been committed on the primary. This is useful to
ensure that the initial data synchronization has been completed after
creating a new subscription.

If there is no active replication connection from this peer, wait until
poll_query_until timeout.

This is not a test. It croak()s on failure.

=cut

sub wait_for_subscription_sync
{
	my ($self, $publisher, $subname, $dbname) = @_;
	my $name = $self->name;

	$dbname = defined($dbname) ? $dbname : 'postgres';

	# Wait for all tables to finish initial sync.
	print "Waiting for all subscriptions in \"$name\" to synchronize data\n";
	my $query =
	  qq[SELECT count(1) = 0 FROM pg_subscription_rel WHERE srsubstate NOT IN ('r', 's');];
	if (!$self->poll_query_until($dbname, $query))
	{
		# Fetch additional detail for debugging purposes
		$query = qq[SELECT * FROM pg_subscription_rel];
		my $details = $self->safe_psql($dbname, $query);
		diag qq(Last pg_subscription_rel contents:
${details});
		croak "timed out waiting for subscriber to synchronize data";
	}

	# Then, wait for the replication to catchup if required.
	if (defined($publisher))
	{
		croak 'subscription name must be specified' unless defined($subname);
		$publisher->wait_for_catchup($subname);
	}

	print "done\n";
	return;
}

=pod

=item $node->wait_for_log(regexp, offset)

Waits for the contents of the server log file, starting at the given offset, to
match the supplied regular expression.  Checks the entire log if no offset is
given.  Times out after $PostgreSQL::Test::Utils::timeout_default seconds.

If successful, returns the length of the entire log file, in bytes.

=cut

sub wait_for_log
{
	my ($self, $regexp, $offset) = @_;

	return PostgreSQL::Test::Utils::wait_for_file($self->logfile, $regexp,
		$offset);
}

=pod

=item $node->query_hash($dbname, $query, @columns)

Execute $query on $dbname, replacing any appearance of the string __COLUMNS__
within the query with a comma-separated list of @columns.

If __COLUMNS__ does not appear in the query, its result columns must EXACTLY
match the order and number (but not necessarily alias) of supplied @columns.

The query must return zero or one rows.

Return a hash-ref representation of the results of the query, with any empty
or null results as defined keys with an empty-string value. There is no way
to differentiate between null and empty-string result fields.

If the query returns zero rows, return a hash with all columns empty. There
is no way to differentiate between zero rows returned and a row with only
null columns.

=cut

sub query_hash
{
	my ($self, $dbname, $query, @columns) = @_;
	croak 'calls in array context for multi-row results not supported yet'
	  if (wantarray);

	# Replace __COLUMNS__ if found
	substr($query, index($query, '__COLUMNS__'), length('__COLUMNS__')) =
	  join(', ', @columns)
	  if index($query, '__COLUMNS__') >= 0;
	my $result = $self->safe_psql($dbname, $query);

	# hash slice, see http://stackoverflow.com/a/16755894/398670 .
	#
	# Fills the hash with empty strings produced by x-operator element
	# duplication if result is an empty row
	#
	my %val;
	@val{@columns} =
	  $result ne '' ? split(qr/\|/, $result, -1) : ('',) x scalar(@columns);
	return \%val;
}

=pod

=item $node->slot(slot_name)

Return hash-ref of replication slot data for the named slot, or a hash-ref with
all values '' if not found. Does not differentiate between null and empty string
for fields, no field is ever undef.

The restart_lsn and confirmed_flush_lsn fields are returned verbatim, and also
as a 2-list of [highword, lowword] integer. Since we rely on Perl 5.14 we can't
"use bigint", it's from 5.20, and we can't assume we have Math::Bigint from CPAN
either.

=cut

sub slot
{
	my ($self, $slot_name) = @_;
	my @columns = (
		'plugin', 'slot_type', 'datoid', 'database',
		'active', 'active_pid', 'xmin', 'catalog_xmin',
		'restart_lsn');
	return $self->query_hash(
		'postgres',
		"SELECT __COLUMNS__ FROM pg_catalog.pg_replication_slots WHERE slot_name = '$slot_name'",
		@columns);
}

=pod

=item $node->pg_recvlogical_upto(self, dbname, slot_name, endpos, timeout_secs, ...)

Invoke pg_recvlogical to read from slot_name on dbname until LSN endpos, which
corresponds to pg_recvlogical --endpos.  Gives up after timeout (if nonzero).

Disallows pg_recvlogical from internally retrying on error by passing --no-loop.

Plugin options are passed as additional keyword arguments.

If called in scalar context, returns stdout, and croak()s on timeout or nonzero return.

If called in array context, returns a tuple of (retval, stdout, stderr, timeout).
timeout is the IPC::Run::Timeout object whose is_expired method can be tested
to check for timeout. retval is undef on timeout.

=cut

sub pg_recvlogical_upto
{
	my ($self, $dbname, $slot_name, $endpos, $timeout_secs, %plugin_options)
	  = @_;

	local %ENV = $self->_get_env();

	my ($stdout, $stderr);

	my $timeout_exception = 'pg_recvlogical timed out';

	croak 'slot name must be specified' unless defined($slot_name);
	croak 'endpos must be specified' unless defined($endpos);

	my @cmd = (
		$self->installed_command('pg_recvlogical'),
		'--slot' => $slot_name,
		'--dbname' => $self->connstr($dbname),
		'--endpos' => $endpos,
		'--file' => '-',
		'--no-loop', '--start');

	while (my ($k, $v) = each %plugin_options)
	{
		croak "= is not permitted to appear in replication option name"
		  if ($k =~ qr/=/);
		push @cmd, "--option" => "$k=$v";
	}

	my $timeout;
	$timeout =
	  IPC::Run::timeout($timeout_secs, exception => $timeout_exception)
	  if $timeout_secs;
	my $ret = 0;

	do
	{
		local $@;
		eval {
			IPC::Run::run(\@cmd, '>' => \$stdout, '2>' => \$stderr, $timeout);
			$ret = $?;
		};
		my $exc_save = $@;
		if ($exc_save)
		{

			# IPC::Run::run threw an exception. re-throw unless it's a
			# timeout, which we'll handle by testing is_expired
			croak $exc_save
			  if (blessed($exc_save) || $exc_save !~ qr/$timeout_exception/);

			$ret = undef;

			croak "Got timeout exception '$exc_save' but timer not expired?!"
			  unless $timeout->is_expired;

			croak
			  "$exc_save waiting for endpos $endpos with stdout '$stdout', stderr '$stderr'"
			  unless wantarray;
		}
	};

	if (wantarray)
	{
		return ($ret, $stdout, $stderr, $timeout);
	}
	else
	{
		croak
		  "pg_recvlogical exited with code '$ret', stdout '$stdout' and stderr '$stderr'"
		  if $ret;
		return $stdout;
	}
}

=pod

=item $node->corrupt_page_checksum(self, file, page_offset)

Intentionally corrupt the checksum field of one page in a file.
The server must be stopped for this to work reliably.

The file name should be specified relative to the cluster datadir.
page_offset had better be a multiple of the cluster's block size.

=cut

sub corrupt_page_checksum
{
	my ($self, $file, $page_offset) = @_;
	my $pgdata = $self->data_dir;
	my $pageheader;

	open my $fh, '+<', "$pgdata/$file" or croak "open($file) failed: $!";
	binmode $fh;
	sysseek($fh, $page_offset, 0) or croak "sysseek failed: $!";
	sysread($fh, $pageheader, 24) or croak "sysread failed: $!";
	# This inverts the pd_checksum field (only); see struct PageHeaderData
	$pageheader ^= "\0\0\0\0\0\0\0\0\xff\xff";
	sysseek($fh, $page_offset, 0) or croak "sysseek failed: $!";
	syswrite($fh, $pageheader) or croak "syswrite failed: $!";
	close $fh;

	return;
}

=pod

=item $node->log_standby_snapshot(self, standby, slot_name)

Log a standby snapshot on primary once the slot restart_lsn is determined on
the standby.

=cut

sub log_standby_snapshot
{
	my ($self, $standby, $slot_name) = @_;

	# Once the slot's restart_lsn is determined, the standby looks for
	# xl_running_xacts WAL record from the restart_lsn onwards. First wait
	# until the slot restart_lsn is determined.

	$standby->poll_query_until(
		'postgres', qq[
		SELECT restart_lsn IS NOT NULL
		FROM pg_catalog.pg_replication_slots WHERE slot_name = '$slot_name'
	])
	  or croak
	  "timed out waiting for logical slot to calculate its restart_lsn";

	# Then arrange for the xl_running_xacts record for which the standby is
	# waiting.
	$self->safe_psql('postgres', 'SELECT pg_log_standby_snapshot()');
}

=pod

=item $node->create_logical_slot_on_standby(self, primary, slot_name, dbname)

Create logical replication slot on given standby

=cut

sub create_logical_slot_on_standby
{
	my ($self, $primary, $slot_name, $dbname) = @_;
	my ($stdout, $stderr);

	my $handle;

	$handle = IPC::Run::start(
		[
			'pg_recvlogical',
			'--dbname' => $self->connstr($dbname),
			'--plugin' => 'test_decoding',
			'--slot' => $slot_name,
			'--create-slot'
		],
		'>' => \$stdout,
		'2>' => \$stderr);

	# Arrange for the xl_running_xacts record for which pg_recvlogical is
	# waiting.
	$primary->log_standby_snapshot($self, $slot_name);

	$handle->finish();

	is($self->slot($slot_name)->{'slot_type'},
		'logical', $slot_name . ' on standby created')
	  or croak "could not create slot" . $slot_name;
}

=pod

=item $node->validate_slot_inactive_since(self, slot_name, reference_time)

Validate inactive_since value of a given replication slot against the reference
time and return it.

=cut

sub validate_slot_inactive_since
{
	my ($self, $slot_name, $reference_time) = @_;
	my $name = $self->name;

	my $inactive_since = $self->safe_psql(
		'postgres',
		qq(SELECT inactive_since FROM pg_replication_slots
			WHERE slot_name = '$slot_name' AND inactive_since IS NOT NULL;)
	);

	# Check that the inactive_since is sane
	is( $self->safe_psql(
			'postgres',
			qq[SELECT '$inactive_since'::timestamptz > to_timestamp(0) AND
				'$inactive_since'::timestamptz > '$reference_time'::timestamptz;]
		),
		't',
		"last inactive time for slot $slot_name is valid on node $name")
	  or croak
	  "could not validate captured inactive_since for slot $slot_name";

	return $inactive_since;
}

=pod

=item $node->advance_wal(num)

Advance WAL of node by given number of segments.

=cut

sub advance_wal
{
	my ($self, $num) = @_;

	# Advance by $n segments (= (wal_segment_size * $num) bytes).
	# pg_switch_wal() forces a WAL flush, making pg_logical_emit_message()
	# safe to use in non-transactional mode.
	for (my $i = 0; $i < $num; $i++)
	{
		$self->safe_psql(
			'postgres', qq{
			SELECT pg_logical_emit_message(false, '', 'foo');
			SELECT pg_switch_wal();
			});
	}
}

=item $node->checksum_enable_offline()

Enable data page checksums in an offline cluster with B<pg_checksums>. The
caller is responsible for ensuring that the cluster is in the right state for
this operation.

=cut

sub checksum_enable_offline
{
	my ($self) = @_;

	print "# Enabling checksums in \"$self->data_dir\"\n";
	PostgreSQL::Test::Utils::system_or_bail('pg_checksums', '-D',
		$self->data_dir, '-e');
	return;
}

=item $node->checksum_disable_offline()

Disable data page checksums in an offline cluster with B<pg_checksums>. The
caller is responsible for ensuring that the cluster is in the right state for
this operation.

=cut

sub checksum_disable_offline
{
	my ($self) = @_;

	print "# Disabling checksums in \"$self->data_dir\"\n";
	PostgreSQL::Test::Utils::system_or_bail('pg_checksums', '-D',
		$self->data_dir, '-d');
	return;
}

=pod

=back

=cut

##########################################################################

package PostgreSQL::Test::Cluster::V_11
  ;    ## no critic (ProhibitMultiplePackages)

use parent -norequire, qw(PostgreSQL::Test::Cluster);

# https://www.postgresql.org/docs/11/release-11.html

# max_wal_senders + superuser_reserved_connections must be < max_connections
# uses recovery.conf

sub _recovery_file { return "recovery.conf"; }

sub set_standby_mode
{
	my $self = shift;
	$self->append_conf("recovery.conf", "standby_mode = on\n");
}

sub init
{
	my ($self, %params) = @_;
	$self->SUPER::init(%params);
	$self->adjust_conf('postgresql.conf', 'max_wal_senders',
		$params{allows_streaming} ? 5 : 0);
}

##########################################################################

package PostgreSQL::Test::Cluster::V_10
  ;    ## no critic (ProhibitMultiplePackages)

use parent -norequire, qw(PostgreSQL::Test::Cluster::V_11);

# https://www.postgresql.org/docs/10/release-10.html

########################################################################

1;