Subject: [PATCH 2/2] Add fileval-bootval consistency check of GUC parameters

From: Kyotaro Horiguchi <[email-masked]>
Date: Mon, 30 May 2022 16:11:34 +0900

We should keep GUC variables consistent between the default values
written in postgresql.conf.sample and defined in guc.c. Add an
automated way to check for the consistency to the TAP test suite. Some
variables are still excluded since they cannot be checked simple way.
---
 src/backend/utils/misc/guc.c                  | 70 +++++++++++++++++++
 src/backend/utils/misc/postgresql.conf.sample |  6 +-
 src/include/catalog/pg_proc.dat               |  5 ++
 src/test/modules/test_misc/t/003_check_guc.pl | 57 +++++++++++++--
 4 files changed, 129 insertions(+), 9 deletions(-)

diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c
index dbbadc5a475..a700cbbf4bc 100644
--- a/src/backend/utils/misc/guc.c
+++ b/src/backend/utils/misc/guc.c
@@ -7526,6 +7526,76 @@ parse_and_validate_value(struct config_generic *record,
 	return true;
 }
 
+/*
+ * Helper function for pg_normalize_config_value().
+ * Makes a palloced copy of src then link val to it.
+ * DO NOT destroy val while dst is in use.
+ */
+static struct config_generic *
+copy_config_and_set_value(struct config_generic *src, union config_var_val *val)
+{
+	struct config_generic *dst;
+
+#define CREATE_CONFIG_COPY(dst, src, t)	\
+	dst = palloc(sizeof(struct t));				\
+	*(struct t *) dst = *(struct t *) src;		\
+	
+	switch (src->vartype)
+	{
+		case PGC_BOOL:
+			CREATE_CONFIG_COPY(dst, src, config_bool);
+			((struct config_bool *)dst)->variable = &val->boolval;
+			break;
+		case PGC_INT:
+			CREATE_CONFIG_COPY(dst, src, config_int);
+			((struct config_int *)dst)->variable = &val->intval;
+			break;
+		case PGC_REAL:
+			CREATE_CONFIG_COPY(dst, src, config_real);
+			((struct config_real *)dst)->variable = &val->realval;
+			break;
+		case PGC_STRING:
+			CREATE_CONFIG_COPY(dst, src, config_string);
+			((struct config_string *)dst)->variable = &val->stringval;
+			break;
+		case PGC_ENUM:
+			CREATE_CONFIG_COPY(dst, src, config_enum);
+			((struct config_enum *)dst)->variable = &val->enumval;
+			break;
+	}
+
+	return dst;
+}
+
+
+/*
+ * Normalize given value according to the specified GUC variable
+ */
+Datum
+pg_normalize_config_value(PG_FUNCTION_ARGS)
+{
+	char   *name = "";
+	char   *value = "";
+	struct config_generic *record;
+	char   *result;
+	void   *extra;
+	union config_var_val altval;
+
+	if (!PG_ARGISNULL(0))
+		name = text_to_cstring(PG_GETARG_TEXT_PP(0));
+	if (!PG_ARGISNULL(1))
+		value = text_to_cstring(PG_GETARG_TEXT_PP(1));
+
+	record = find_option(name, true, false, ERROR);
+
+	parse_and_validate_value(record, name, value, PGC_S_TEST, WARNING,
+							 &altval, &extra);
+	record = copy_config_and_set_value(record, &altval);
+
+	result = _ShowOption(record, true);
+
+	PG_RETURN_TEXT_P(cstring_to_text(result));
+}
 
 /*
  * Sets option `name' to given value.
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index b4bc06e5f5a..b6403a14496 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -476,7 +476,7 @@
 					# in all cases.
 
 # These are relevant when logging to syslog:
-#syslog_facility = 'LOCAL0'
+#syslog_facility = 'local0'
 #syslog_ident = 'postgres'
 #syslog_sequence_numbers = on
 #syslog_split_messages = on
@@ -709,7 +709,7 @@
 
 # - Locale and Formatting -
 
-#datestyle = 'iso, mdy'
+#datestyle = 'ISO, MDY'
 #intervalstyle = 'postgres'
 #timezone = 'GMT'
 #timezone_abbreviations = 'Default'     # Select the set of available time zone
@@ -721,7 +721,7 @@
 					# share/timezonesets/.
 #extra_float_digits = 1			# min -15, max 3; any value >0 actually
 					# selects precise output mode
-#client_encoding = sql_ascii		# actually, defaults to database
+#client_encoding = SQL_ASCII		# actually, defaults to database
 					# encoding
 
 # These settings are initialized by initdb, but they can be changed.
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 8873078c160..a92630d768b 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -6118,6 +6118,11 @@
   proname => 'pg_settings_get_flags', provolatile => 's', prorettype => '_text',
   proargtypes => 'text', prosrc => 'pg_settings_get_flags' },
 
+{ oid => '9956', descr => 'normalize value to the unit of specified GUC',
+  proname => 'pg_normalize_config_value', proisstrict => 'f',
+  provolatile => 's', prorettype => 'text', proargtypes => 'text text',
+  proargnames => '{varname,value}', prosrc => 'pg_normalize_config_value' },
+
 { oid => '3329', descr => 'show config file settings',
   proname => 'pg_show_all_file_settings', prorows => '1000', proretset => 't',
   provolatile => 'v', prorettype => 'record', proargtypes => '',
diff --git a/src/test/modules/test_misc/t/003_check_guc.pl b/src/test/modules/test_misc/t/003_check_guc.pl
index 60459ef759e..dfb2d203247 100644
--- a/src/test/modules/test_misc/t/003_check_guc.pl
+++ b/src/test/modules/test_misc/t/003_check_guc.pl
@@ -11,18 +11,40 @@ my $node = PostgreSQL::Test::Cluster->new('main');
 $node->init;
 $node->start;
 
+# parameter names that cannot get consistency check performed
+my @ignored_parameters = (
+	'data_directory',
+	'hba_file',
+	'ident_file',
+	'krb_server_keyfile',
+	'max_stack_depth',
+	'bgwriter_flush_after',
+	'wal_sync_method',
+	'checkpoint_flush_after',
+	'timezone_abbreviations',
+	'lc_messages'
+  );
+
 # Grab the names of all the parameters that can be listed in the
 # configuration sample file.  config_file is an exception, it is not
 # in postgresql.conf.sample but is part of the lists from guc.c.
 my $all_params = $node->safe_psql(
 	'postgres',
-	"SELECT name
+	"SELECT lower(name), vartype, unit, boot_val, '!'
      FROM pg_settings
    WHERE NOT 'NOT_IN_SAMPLE' = ANY (pg_settings_get_flags(name)) AND
        name <> 'config_file'
      ORDER BY 1");
 # Note the lower-case conversion, for consistency.
-my @all_params_array = split("\n", lc($all_params));
+my %all_params_hash;
+foreach my $line (split("\n", $all_params))
+{
+	my @f = split('\|', $line);
+	fail("query returned wrong number of columns: $#f : $line") if ($#f != 4);
+	$all_params_hash{$f[0]}->{type} = $f[1];
+	$all_params_hash{$f[0]}->{unit} = $f[2];
+	$all_params_hash{$f[0]}->{bootval} = $f[3];
+}
 
 # Grab the names of all parameters marked as NOT_IN_SAMPLE.
 my $not_in_sample = $node->safe_psql(
@@ -43,7 +65,7 @@ my @gucs_in_file;
 
 # Read the sample file line-by-line, checking its contents to build a list
 # of everything known as a GUC.
-my $num_tests = 0;
+my @check_elems = ();
 open(my $contents, '<', $sample_file)
   || die "Could not open $sample_file: $!";
 while (my $line = <$contents>)
@@ -53,11 +75,16 @@ while (my $line = <$contents>)
 	# file.
 	# - Valid configuration options are followed immediately by " = ",
 	# with one space before and after the equal sign.
-	if ($line =~ m/^#?([_[:alpha:]]+) = .*/)
+	if ($line =~ m/^#?([_[:alpha:]]+) = (.*)$/)
 	{
 		# Lower-case conversion matters for some of the GUCs.
 		my $param_name = lc($1);
 
+		# extract value
+		my $file_value = $2;
+		$file_value =~ s/\s*#.*$//;		# strip trailing comment
+		$file_value =~ s/^'(.*)'$/$1/;	# strip quotes
+
 		# Ignore some exceptions.
 		next if $param_name eq "include";
 		next if $param_name eq "include_dir";
@@ -66,19 +93,37 @@ while (my $line = <$contents>)
 		# Update the list of GUCs found in the sample file, for the
 		# follow-up tests.
 		push @gucs_in_file, $param_name;
+
+		# Check for consistency between bootval and file value.
+		if (!grep { $_ eq $param_name } @ignored_parameters)
+		{
+			push (@check_elems, "('$param_name','$file_value')");
+		}
 	}
 }
 
 close $contents;
 
+# run consistency check between config-file's default value and boot values.
+my $check_query =
+  'SELECT f.n, f.v, s.boot_val FROM (VALUES '.
+  join(',', @check_elems).
+  ') f(n,v) JOIN pg_settings s ON s.name = f.n '.
+  'JOIN pg_settings_get_flags(s.name) flags ON true '.
+  "WHERE 'DYNAMIC_DEFAULT' <> ALL(flags) AND " .
+  'pg_normalize_config_value(f.n, f.v) <> '.
+  'pg_normalize_config_value(f.n, s.boot_val)';
+
+is ($node->safe_psql('postgres', $check_query), '',
+	'check if fileval-bootval consistency is fine');
+
 # Cross-check that all the GUCs found in the sample file match the ones
 # fetched above.  This maps the arrays to a hash, making the creation of
 # each exclude and intersection list easier.
 my %gucs_in_file_hash  = map { $_ => 1 } @gucs_in_file;
-my %all_params_hash    = map { $_ => 1 } @all_params_array;
 my %not_in_sample_hash = map { $_ => 1 } @not_in_sample_array;
 
-my @missing_from_file = grep(!$gucs_in_file_hash{$_}, @all_params_array);
+my @missing_from_file = grep(!$gucs_in_file_hash{$_}, keys %all_params_hash);
 is(scalar(@missing_from_file),
 	0, "no parameters missing from postgresql.conf.sample");
 
-- 
2.17.1

--xaMk4Io5JJdpkLEb--