Use "template" data directory in tests

When running all (or just many) of our tests, a significant portion of both
CPU time and IO is spent running initdb. Most of those initdb runs don't
specify any options influencing properties of the created data directory.

Avoid most of that overhead by creating a "template" data directory, alongside
the temporary installation. Instead of running initdb, pg_regress and tap
tests can copy that data directory. When a tap test specifies options to
initdb, the template data directory is not used. That could be relaxed for
some options, but it's not clear it's worth the effort.

There unfortunately is some duplication between pg_regress.c and Cluster.pm,
but there are no easy ways of sharing that code without introducing additional
complexity.

Reviewed-by: Daniel Gustafsson <daniel@yesql.se>
Discussion: https://postgr.es/m/20220120021859.3zpsfqn4z7ob7afz@alap3.anarazel.de

1 files changed, 44 insertions, 2 deletions

diff --git a/src/test/perl/PostgreSQL/Test/Cluster.pm b/src/test/perl/PostgreSQL/Test/Cluster.pm
index 41409ba1bed..426f94ff09c 100644
--- a/src/test/perl/PostgreSQL/Test/Cluster.pm
+++ b/src/test/perl/PostgreSQL/Test/Cluster.pm
@@ -522,8 +522,50 @@ sub init
 	mkdir $self->backup_dir;
 	mkdir $self->archive_dir;
 
-	PostgreSQL::Test::Utils::system_or_bail('initdb', '-D', $pgdata, '-A',
-		'trust', '-N', @{ $params{extra} });
+	# If available and if there aren't any parameters, use a previously
+	# initdb'd cluster as a template by copying it. For a lot of tests, that's
+	# substantially cheaper. Do so only if there aren't parameters, it doesn't
+	# seem worth figuring out whether they affect compatibility.
+	#
+	# There's very similar code in pg_regress.c, but we can't easily
+	# deduplicate it until we require perl at build time.
+	if (defined $params{extra} or !defined $ENV{INITDB_TEMPLATE})
+	{
+		note("initializing database system by running initdb");
+		PostgreSQL::Test::Utils::system_or_bail('initdb', '-D', $pgdata, '-A',
+			'trust', '-N', @{ $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 -a);
+			$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} });