fix recovery of 3pc state on reboot and add test for that

Author: kelvich

t/0000_precommit.pl

@@ -0,0 +1,73 @@
+use strict;
+use warnings;
+
+use PostgresNode;
+use TestLib;
+use Test::More tests => 2;
+
+my $psql_out = '';
+my $psql_rc  = '';
+
+my $node = get_new_node("london");
+$node->init(allows_streaming => 1);
+$node->append_conf(
+	'postgresql.conf', qq(
+	max_prepared_transactions = 10
+	log_checkpoints = true
+));
+$node->start;
+
+# Create table we'll use in the test transactions
+$node->psql('postgres', "CREATE TABLE t_precommit_tbl (id int, msg text)");
+
+###############################################################################
+# Check ordinary restart
+###############################################################################
+
+$node->psql(
+	'postgres', "
+	BEGIN;
+	INSERT INTO t_precommit_tbl VALUES (1, 'x');
+	PREPARE TRANSACTION 'xact_prepared';
+
+	BEGIN;
+	INSERT INTO t_precommit_tbl VALUES (2, 'x');
+	PREPARE TRANSACTION 'xact_precommited';
+
+	SELECT pg_precommit_prepared('xact_precommited', 'precommited');");
+$node->stop;
+$node->start;
+
+
+$node->psql(
+	'postgres',
+	"SELECT count(*) FROM pg_prepared_xacts WHERE state3pc = 'precommited'",
+	stdout => \$psql_out);
+is($psql_out, '1',
+	"Check that state3pc preserved during reboot");
+
+###############################################################################
+# Check crash/recover
+###############################################################################
+
+$node->psql(
+	'postgres', "
+	BEGIN;
+	INSERT INTO t_precommit_tbl VALUES (3, 'x');
+	PREPARE TRANSACTION 'xact_prepared_2';
+
+	BEGIN;
+	INSERT INTO t_precommit_tbl VALUES (4, 'x');
+	PREPARE TRANSACTION 'xact_precommited_2';
+
+	SELECT pg_precommit_prepared('xact_precommited_2', 'precommited');");
+$node->stop("immediate");
+$node->start;
+
+
+$node->psql(
+	'postgres',
+	"SELECT count(*) FROM pg_prepared_xacts WHERE state3pc = 'precommited'",
+	stdout => \$psql_out);
+is($psql_out, '2',
+	"Check that state3pc preserved during reboot");