Add isolation test for SERIALIZABLE READ ONLY DEFERRABLE.

This improves code coverage and lays a foundation for testing
similar issues in a distributed environment.

Author: Thomas Munro <[email protected]>
Reviewed-by: Michael Paquier <[email protected]>

8 files changed, 225 insertions, 0 deletions

diff --git a/src/test/isolation/expected/read-only-anomaly-2.out b/src/test/isolation/expected/read-only-anomaly-2.out
new file mode 100644
index 0000000000..f43aa6a299
--- /dev/null
+++ b/src/test/isolation/expected/read-only-anomaly-2.out
@@ -0,0 +1,44 @@
+Parsed test spec with 3 sessions
+
+starting permutation: s2rx s2ry s1ry s1wy s1c s2wx s2c s3c
+step s2rx: SELECT balance FROM bank_account WHERE id = 'X';
+balance        
+
+0              
+step s2ry: SELECT balance FROM bank_account WHERE id = 'Y';
+balance        
+
+0              
+step s1ry: SELECT balance FROM bank_account WHERE id = 'Y';
+balance        
+
+0              
+step s1wy: UPDATE bank_account SET balance = 20 WHERE id = 'Y';
+step s1c: COMMIT;
+step s2wx: UPDATE bank_account SET balance = -11 WHERE id = 'X';
+step s2c: COMMIT;
+step s3c: COMMIT;
+
+starting permutation: s2rx s2ry s1ry s1wy s1c s3r s3c s2wx
+step s2rx: SELECT balance FROM bank_account WHERE id = 'X';
+balance        
+
+0              
+step s2ry: SELECT balance FROM bank_account WHERE id = 'Y';
+balance        
+
+0              
+step s1ry: SELECT balance FROM bank_account WHERE id = 'Y';
+balance        
+
+0              
+step s1wy: UPDATE bank_account SET balance = 20 WHERE id = 'Y';
+step s1c: COMMIT;
+step s3r: SELECT id, balance FROM bank_account WHERE id IN ('X', 'Y') ORDER BY id;
+id             balance        
+
+X              0              
+Y              20             
+step s3c: COMMIT;
+step s2wx: UPDATE bank_account SET balance = -11 WHERE id = 'X';
+ERROR:  could not serialize access due to read/write dependencies among transactions
diff --git a/src/test/isolation/expected/read-only-anomaly-3.out b/src/test/isolation/expected/read-only-anomaly-3.out
new file mode 100644
index 0000000000..1c10ad7ebf
--- /dev/null
+++ b/src/test/isolation/expected/read-only-anomaly-3.out
@@ -0,0 +1,26 @@
+Parsed test spec with 3 sessions
+
+starting permutation: s2rx s2ry s1ry s1wy s1c s3r s2wx s2c s3c
+step s2rx: SELECT balance FROM bank_account WHERE id = 'X';
+balance        
+
+0              
+step s2ry: SELECT balance FROM bank_account WHERE id = 'Y';
+balance        
+
+0              
+step s1ry: SELECT balance FROM bank_account WHERE id = 'Y';
+balance        
+
+0              
+step s1wy: UPDATE bank_account SET balance = 20 WHERE id = 'Y';
+step s1c: COMMIT;
+step s3r: SELECT id, balance FROM bank_account WHERE id IN ('X', 'Y') ORDER BY id; <waiting ...>
+step s2wx: UPDATE bank_account SET balance = -11 WHERE id = 'X';
+step s2c: COMMIT;
+step s3r: <... completed>
+id             balance        
+
+X              -11            
+Y              20             
+step s3c: COMMIT;
diff --git a/src/test/isolation/expected/read-only-anomaly.out b/src/test/isolation/expected/read-only-anomaly.out
new file mode 100644
index 0000000000..d40425df28
--- /dev/null
+++ b/src/test/isolation/expected/read-only-anomaly.out
@@ -0,0 +1,25 @@
+Parsed test spec with 3 sessions
+
+starting permutation: s2rx s2ry s1ry s1wy s1c s3r s2wx s2c s3c
+step s2rx: SELECT balance FROM bank_account WHERE id = 'X';
+balance        
+
+0              
+step s2ry: SELECT balance FROM bank_account WHERE id = 'Y';
+balance        
+
+0              
+step s1ry: SELECT balance FROM bank_account WHERE id = 'Y';
+balance        
+
+0              
+step s1wy: UPDATE bank_account SET balance = 20 WHERE id = 'Y';
+step s1c: COMMIT;
+step s3r: SELECT id, balance FROM bank_account WHERE id IN ('X', 'Y') ORDER BY id;
+id             balance        
+
+X              0              
+Y              20             
+step s2wx: UPDATE bank_account SET balance = -11 WHERE id = 'X';
+step s2c: COMMIT;
+step s3c: COMMIT;
diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule
index 8e404b7a35..fc1918dedc 100644
--- a/src/test/isolation/isolation_schedule
+++ b/src/test/isolation/isolation_schedule
@@ -1,3 +1,6 @@
+test: read-only-anomaly
+test: read-only-anomaly-2
+test: read-only-anomaly-3
 test: read-write-unique
 test: read-write-unique-2
 test: read-write-unique-3
diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c
index f77f465751..4d18710bdf 100644
--- a/src/test/isolation/isolationtester.c
+++ b/src/test/isolation/isolationtester.c
@@ -231,6 +231,14 @@ main(int argc, char **argv)
 		appendPQExpBuffer(&wait_query, ",%s", backend_pids[i]);
 	appendPQExpBufferStr(&wait_query, "}'::integer[]");
 
+	/* Also detect certain wait events. */
+	appendPQExpBufferStr(&wait_query,
+						 " OR EXISTS ("
+						 "  SELECT * "
+						 "  FROM pg_catalog.pg_stat_activity "
+						 "  WHERE pid = $1 "
+						 "  AND wait_event IN ('SafeSnapshot'))");
+
 	res = PQprepare(conns[0], PREP_WAITING, wait_query.data, 0, NULL);
 	if (PQresultStatus(res) != PGRES_COMMAND_OK)
 	{
diff --git a/src/test/isolation/specs/read-only-anomaly-2.spec b/src/test/isolation/specs/read-only-anomaly-2.spec
new file mode 100644
index 0000000000..9812f49ee4
--- /dev/null
+++ b/src/test/isolation/specs/read-only-anomaly-2.spec
@@ -0,0 +1,42 @@
+# The example from the paper "A read-only transaction anomaly under snapshot
+# isolation"[1].
+#
+# Here we test that serializable snapshot isolation (SERIALIZABLE) doesn't
+# suffer from the anomaly, because s2 is aborted upon detection of a cycle.
+#
+# [1] http://www.cs.umb.edu/~poneil/ROAnom.pdf
+
+setup
+{
+	CREATE TABLE bank_account (id TEXT PRIMARY KEY, balance DECIMAL NOT NULL);
+	INSERT INTO bank_account (id, balance) VALUES ('X', 0), ('Y', 0);
+}
+
+teardown
+{
+	DROP TABLE bank_account;
+}
+
+session "s1"
+setup 		{ BEGIN TRANSACTION ISOLATION LEVEL SERIALIZABLE; }
+step "s1ry"	{ SELECT balance FROM bank_account WHERE id = 'Y'; }
+step "s1wy"	{ UPDATE bank_account SET balance = 20 WHERE id = 'Y'; }
+step "s1c" 	{ COMMIT; }
+
+session "s2"
+setup		{ BEGIN TRANSACTION ISOLATION LEVEL SERIALIZABLE; }
+step "s2rx"	{ SELECT balance FROM bank_account WHERE id = 'X'; }
+step "s2ry"	{ SELECT balance FROM bank_account WHERE id = 'Y'; }
+step "s2wx"	{ UPDATE bank_account SET balance = -11 WHERE id = 'X'; }
+step "s2c"	{ COMMIT; }
+
+session "s3"
+setup		{ BEGIN TRANSACTION ISOLATION LEVEL SERIALIZABLE; }
+step "s3r"	{ SELECT id, balance FROM bank_account WHERE id IN ('X', 'Y') ORDER BY id; }
+step "s3c"	{ COMMIT; }
+
+# without s3, s1 and s2 commit
+permutation "s2rx" "s2ry" "s1ry" "s1wy" "s1c" "s2wx" "s2c" "s3c"
+
+# once s3 observes the data committed by s1, a cycle is created and s2 aborts
+permutation "s2rx" "s2ry" "s1ry" "s1wy" "s1c" "s3r" "s3c" "s2wx"
diff --git a/src/test/isolation/specs/read-only-anomaly-3.spec b/src/test/isolation/specs/read-only-anomaly-3.spec
new file mode 100644
index 0000000000..58a159a949
--- /dev/null
+++ b/src/test/isolation/specs/read-only-anomaly-3.spec
@@ -0,0 +1,39 @@
+# The example from the paper "A read-only transaction anomaly under snapshot
+# isolation"[1].
+#
+# Here we test that serializable snapshot isolation can avoid the anomaly
+# without aborting any tranasctions, by instead causing s3 to be deferred
+# until a safe snapshot can be taken.
+#
+# [1] http://www.cs.umb.edu/~poneil/ROAnom.pdf
+
+setup
+{
+	CREATE TABLE bank_account (id TEXT PRIMARY KEY, balance DECIMAL NOT NULL);
+	INSERT INTO bank_account (id, balance) VALUES ('X', 0), ('Y', 0);
+}
+
+teardown
+{
+	DROP TABLE bank_account;
+}
+
+session "s1"
+setup 		{ BEGIN TRANSACTION ISOLATION LEVEL SERIALIZABLE; }
+step "s1ry"	{ SELECT balance FROM bank_account WHERE id = 'Y'; }
+step "s1wy"	{ UPDATE bank_account SET balance = 20 WHERE id = 'Y'; }
+step "s1c" 	{ COMMIT; }
+
+session "s2"
+setup		{ BEGIN TRANSACTION ISOLATION LEVEL SERIALIZABLE; }
+step "s2rx"	{ SELECT balance FROM bank_account WHERE id = 'X'; }
+step "s2ry"	{ SELECT balance FROM bank_account WHERE id = 'Y'; }
+step "s2wx"	{ UPDATE bank_account SET balance = -11 WHERE id = 'X'; }
+step "s2c"	{ COMMIT; }
+
+session "s3"
+setup		{ BEGIN TRANSACTION ISOLATION LEVEL SERIALIZABLE READ ONLY DEFERRABLE; }
+step "s3r"	{ SELECT id, balance FROM bank_account WHERE id IN ('X', 'Y') ORDER BY id; }
+step "s3c"	{ COMMIT; }
+
+permutation "s2rx" "s2ry" "s1ry" "s1wy" "s1c" "s3r" "s2wx" "s2c" "s3c"
diff --git a/src/test/isolation/specs/read-only-anomaly.spec b/src/test/isolation/specs/read-only-anomaly.spec
new file mode 100644
index 0000000000..d331e4200a
--- /dev/null
+++ b/src/test/isolation/specs/read-only-anomaly.spec
@@ -0,0 +1,38 @@
+# The example from the paper "A read-only transaction anomaly under snapshot
+# isolation"[1].
+#
+# Here we use snapshot isolation (REPEATABLE READ), so that s3 sees a state of
+# afairs that is not consistent with any serial ordering of s1 and s2.
+#
+# [1] http://www.cs.umb.edu/~poneil/ROAnom.pdf
+
+setup
+{
+	CREATE TABLE bank_account (id TEXT PRIMARY KEY, balance DECIMAL NOT NULL);
+	INSERT INTO bank_account (id, balance) VALUES ('X', 0), ('Y', 0);
+}
+
+teardown
+{
+	DROP TABLE bank_account;
+}
+
+session "s1"
+setup 		{ BEGIN TRANSACTION ISOLATION LEVEL REPEATABLE READ; }
+step "s1ry"	{ SELECT balance FROM bank_account WHERE id = 'Y'; }
+step "s1wy"	{ UPDATE bank_account SET balance = 20 WHERE id = 'Y'; }
+step "s1c" 	{ COMMIT; }
+
+session "s2"
+setup		{ BEGIN TRANSACTION ISOLATION LEVEL REPEATABLE READ; }
+step "s2rx"	{ SELECT balance FROM bank_account WHERE id = 'X'; }
+step "s2ry"	{ SELECT balance FROM bank_account WHERE id = 'Y'; }
+step "s2wx"	{ UPDATE bank_account SET balance = -11 WHERE id = 'X'; }
+step "s2c"	{ COMMIT; }
+
+session "s3"
+setup		{ BEGIN TRANSACTION ISOLATION LEVEL REPEATABLE READ; }
+step "s3r"	{ SELECT id, balance FROM bank_account WHERE id IN ('X', 'Y') ORDER BY id; }
+step "s3c"	{ COMMIT; }
+
+permutation "s2rx" "s2ry" "s1ry" "s1wy" "s1c" "s3r" "s2wx" "s2c" "s3c"