Make two-phase tests of ECPG and main suite more concurrent-proof

The ECPG and main 2PC tests have been using rather-generic names for the
prepared transactions they generate.  This commit switches the 2PC
transactions to use more complex GIDs, reducing the risk of naming
conflicts.

The main 2PC tests also include scans of pg_prepared_xacts that do not
apply filters on the GID of the prepared transactions, making it
possible to fail the test when any 2PC transaction runs concurrently.
The CI has been able to see such failures with an installcheck
running the ECPG and the main regression test suites in parallel.  The
queries on pg_prepared_xacts gain quals to only look after the GIDs
generated locally.

The race is very hard to reproduce, so no backbatch is done for now.

Reported-by: Richard Guo
Discussion: https://postgr.es/m/CAMbWs4-mWCGbbE_bne5=AfqjYGDaUZmjCw2+soLjrdNA0xUDFw@mail.gmail.com

Author: michaelpq

src/interfaces/ecpg/test/expected/sql-twophase.c

@@ -79,15 +79,15 @@ if (sqlca.sqlcode < 0) sqlprint();}
 
 
 	strcpy(msg, "prepare transaction");
-	{ ECPGtrans(__LINE__, NULL, "prepare transaction 'gxid'");
+	{ ECPGtrans(__LINE__, NULL, "prepare transaction 'ecpg_twophase'");
 #line 32 "twophase.pgc"
 
 if (sqlca.sqlcode < 0) sqlprint();}
 #line 32 "twophase.pgc"
 
 
 	strcpy(msg, "commit prepared");
-	{ ECPGtrans(__LINE__, NULL, "commit prepared 'gxid'");
+	{ ECPGtrans(__LINE__, NULL, "commit prepared 'ecpg_twophase'");
 #line 35 "twophase.pgc"
 
 if (sqlca.sqlcode < 0) sqlprint();}

src/interfaces/ecpg/test/expected/sql-twophase.stderr

@@ -20,9 +20,9 @@
 [NO_PID]: sqlca: code: 0, state: 00000
 [NO_PID]: ecpg_process_output on line 29: OK: INSERT 0 1
 [NO_PID]: sqlca: code: 0, state: 00000
-[NO_PID]: ECPGtrans on line 32: action "prepare transaction 'gxid'"; connection "ecpg1_regression"
+[NO_PID]: ECPGtrans on line 32: action "prepare transaction 'ecpg_twophase'"; connection "ecpg1_regression"
 [NO_PID]: sqlca: code: 0, state: 00000
-[NO_PID]: ECPGtrans on line 35: action "commit prepared 'gxid'"; connection "ecpg1_regression"
+[NO_PID]: ECPGtrans on line 35: action "commit prepared 'ecpg_twophase'"; connection "ecpg1_regression"
 [NO_PID]: sqlca: code: 0, state: 00000
 [NO_PID]: ecpg_execute on line 38: query: drop table t1; with 0 parameter(s) on connection ecpg1_regression
 [NO_PID]: sqlca: code: 0, state: 00000

src/interfaces/ecpg/test/sql/twophase.pgc

@@ -29,10 +29,10 @@ int main(void)
 	exec sql insert into t1 values(1);
 
 	strcpy(msg, "prepare transaction");
-	exec sql prepare transaction 'gxid';
+	exec sql prepare transaction 'ecpg_twophase';
 
 	strcpy(msg, "commit prepared");
-	exec sql commit prepared 'gxid';
+	exec sql commit prepared 'ecpg_twophase';
 
 	strcpy(msg, "drop");
 	exec sql drop table t1;

src/test/regress/expected/prepared_xacts.out

@@ -17,29 +17,29 @@ SELECT * FROM pxtest1;
  bbb
 (1 row)
 
-PREPARE TRANSACTION 'foo1';
+PREPARE TRANSACTION 'regress_foo1';
 SELECT * FROM pxtest1;
  foobar 
 --------
  aaa
 (1 row)
 
 -- Test pg_prepared_xacts system view
-SELECT gid FROM pg_prepared_xacts;
- gid  
-------
- foo1
+SELECT gid FROM pg_prepared_xacts WHERE gid ~ '^regress_' ORDER BY gid;
+     gid      
+--------------
+ regress_foo1
 (1 row)
 
 -- Test ROLLBACK PREPARED
-ROLLBACK PREPARED 'foo1';
+ROLLBACK PREPARED 'regress_foo1';
 SELECT * FROM pxtest1;
  foobar 
 --------
  aaa
 (1 row)
 
-SELECT gid FROM pg_prepared_xacts;
+SELECT gid FROM pg_prepared_xacts WHERE gid ~ '^regress_' ORDER BY gid;
  gid 
 -----
 (0 rows)
@@ -54,14 +54,14 @@ SELECT * FROM pxtest1;
  ddd
 (2 rows)
 
-PREPARE TRANSACTION 'foo2';
+PREPARE TRANSACTION 'regress_foo2';
 SELECT * FROM pxtest1;
  foobar 
 --------
  aaa
 (1 row)
 
-COMMIT PREPARED 'foo2';
+COMMIT PREPARED 'regress_foo2';
 SELECT * FROM pxtest1;
  foobar 
 --------
@@ -79,26 +79,26 @@ SELECT * FROM pxtest1;
  eee
 (2 rows)
 
-PREPARE TRANSACTION 'foo3';
-SELECT gid FROM pg_prepared_xacts;
- gid  
-------
- foo3
+PREPARE TRANSACTION 'regress_foo3';
+SELECT gid FROM pg_prepared_xacts WHERE gid ~ '^regress_' ORDER BY gid;
+     gid      
+--------------
+ regress_foo3
 (1 row)
 
 BEGIN TRANSACTION ISOLATION LEVEL SERIALIZABLE;
 INSERT INTO pxtest1 VALUES ('fff');
 -- This should fail, because the gid foo3 is already in use
-PREPARE TRANSACTION 'foo3';
-ERROR:  transaction identifier "foo3" is already in use
+PREPARE TRANSACTION 'regress_foo3';
+ERROR:  transaction identifier "regress_foo3" is already in use
 SELECT * FROM pxtest1;
  foobar 
 --------
  aaa
  ddd
 (2 rows)
 
-ROLLBACK PREPARED 'foo3';
+ROLLBACK PREPARED 'regress_foo3';
 SELECT * FROM pxtest1;
  foobar 
 --------
@@ -116,11 +116,11 @@ SELECT * FROM pxtest1;
  eee
 (2 rows)
 
-PREPARE TRANSACTION 'foo4';
-SELECT gid FROM pg_prepared_xacts;
- gid  
-------
- foo4
+PREPARE TRANSACTION 'regress_foo4';
+SELECT gid FROM pg_prepared_xacts WHERE gid ~ '^regress_' ORDER BY gid;
+     gid      
+--------------
+ regress_foo4
 (1 row)
 
 BEGIN TRANSACTION ISOLATION LEVEL SERIALIZABLE;
@@ -136,15 +136,15 @@ INSERT INTO pxtest1 VALUES ('fff');
 ERROR:  could not serialize access due to read/write dependencies among transactions
 DETAIL:  Reason code: Canceled on identification as a pivot, during write.
 HINT:  The transaction might succeed if retried.
-PREPARE TRANSACTION 'foo5';
-SELECT gid FROM pg_prepared_xacts;
- gid  
-------
- foo4
+PREPARE TRANSACTION 'regress_foo5';
+SELECT gid FROM pg_prepared_xacts WHERE gid ~ '^regress_' ORDER BY gid;
+     gid      
+--------------
+ regress_foo4
 (1 row)
 
-ROLLBACK PREPARED 'foo4';
-SELECT gid FROM pg_prepared_xacts;
+ROLLBACK PREPARED 'regress_foo4';
+SELECT gid FROM pg_prepared_xacts WHERE gid ~ '^regress_' ORDER BY gid;
  gid 
 -----
 (0 rows)
@@ -165,7 +165,7 @@ SELECT pg_advisory_xact_lock_shared(1);
 
 (1 row)
 
-PREPARE TRANSACTION 'foo6';  -- fails
+PREPARE TRANSACTION 'regress_foo6';  -- fails
 ERROR:  cannot PREPARE while holding both session-level and transaction-level locks on the same object
 -- Test subtransactions
 BEGIN TRANSACTION ISOLATION LEVEL SERIALIZABLE;
@@ -176,7 +176,7 @@ BEGIN TRANSACTION ISOLATION LEVEL SERIALIZABLE;
   ROLLBACK TO a;
   SAVEPOINT b;
   INSERT INTO pxtest2 VALUES (3);
-PREPARE TRANSACTION 'regress-one';
+PREPARE TRANSACTION 'regress_sub1';
 CREATE TABLE pxtest3(fff int);
 -- Test shared invalidation
 BEGIN TRANSACTION ISOLATION LEVEL SERIALIZABLE;
@@ -192,7 +192,7 @@ BEGIN TRANSACTION ISOLATION LEVEL SERIALIZABLE;
  1
 (1 row)
 
-PREPARE TRANSACTION 'regress-two';
+PREPARE TRANSACTION 'regress_sub2';
 -- No such cursor
 FETCH 1 FROM foo;
 ERROR:  cursor "foo" does not exist
@@ -202,11 +202,11 @@ ERROR:  relation "pxtest2" does not exist
 LINE 1: SELECT * FROM pxtest2;
                       ^
 -- There should be two prepared transactions
-SELECT gid FROM pg_prepared_xacts;
-     gid     
--------------
- regress-one
- regress-two
+SELECT gid FROM pg_prepared_xacts WHERE gid ~ '^regress_' ORDER BY gid;
+     gid      
+--------------
+ regress_sub1
+ regress_sub2
 (2 rows)
 
 -- pxtest3 should be locked because of the pending DROP
@@ -217,11 +217,11 @@ rollback;
 -- Disconnect, we will continue testing in a different backend
 \c -
 -- There should still be two prepared transactions
-SELECT gid FROM pg_prepared_xacts;
-     gid     
--------------
- regress-one
- regress-two
+SELECT gid FROM pg_prepared_xacts WHERE gid ~ '^regress_' ORDER BY gid;
+     gid      
+--------------
+ regress_sub1
+ regress_sub2
 (2 rows)
 
 -- pxtest3 should still be locked because of the pending DROP
@@ -230,7 +230,7 @@ lock table pxtest3 in access share mode nowait;
 ERROR:  could not obtain lock on relation "pxtest3"
 rollback;
 -- Commit table creation
-COMMIT PREPARED 'regress-one';
+COMMIT PREPARED 'regress_sub1';
 \d pxtest2
               Table "public.pxtest2"
  Column |  Type   | Collation | Nullable | Default 
@@ -245,20 +245,20 @@ SELECT * FROM pxtest2;
 (2 rows)
 
 -- There should be one prepared transaction
-SELECT gid FROM pg_prepared_xacts;
-     gid     
--------------
- regress-two
+SELECT gid FROM pg_prepared_xacts WHERE gid ~ '^regress_' ORDER BY gid;
+     gid      
+--------------
+ regress_sub2
 (1 row)
 
 -- Commit table drop
-COMMIT PREPARED 'regress-two';
+COMMIT PREPARED 'regress_sub2';
 SELECT * FROM pxtest3;
 ERROR:  relation "pxtest3" does not exist
 LINE 1: SELECT * FROM pxtest3;
                       ^
 -- There should be no prepared transactions
-SELECT gid FROM pg_prepared_xacts;
+SELECT gid FROM pg_prepared_xacts WHERE gid ~ '^regress_' ORDER BY gid;
  gid 
 -----
 (0 rows)