Unable to reuse a PostgreSQL connection in a transaction when specifying a default transaction isolation level

[capgen628]

Describe the bug When using a default transaction isolation level on AtomikosDataSource with an underlying PGXADataSource, it is not possible to take a connection from the data source twice in a transaction.

To Reproduce The following test case demonstrates the issue

  private AtomikosDataSourceBean atomikosDataSource;
  private UserTransaction atomikosTransactionManager;

  @Before
  public void setUp() throws Exception {
    XADataSource dataSource = (XADataSource)Class.forName("org.postgresql.xa.PGXADataSource").newInstance();
    dataSource.getClass().getMethod("setURL", String.class).invoke(dataSource, "jdbc:postgresql://localhost:5432/postgres");
    dataSource.getClass().getMethod("setUser", String.class).invoke(dataSource, "postgres");
    dataSource.getClass().getMethod("setPassword", String.class).invoke(dataSource, "manager");

    final UserTransactionManager atomikosTransactionManager = new UserTransactionManager();
    atomikosTransactionManager.init();
    this.atomikosTransactionManager = atomikosTransactionManager;

    atomikosDataSource = new AtomikosDataSourceBean();
    atomikosDataSource.setMaxIdleTime(10*60);
    atomikosDataSource.setMinPoolSize(0);
    atomikosDataSource.setMaxPoolSize(5);
    atomikosDataSource.setUniqueResourceName("Test Data Source");
    atomikosDataSource.setXaDataSource(dataSource);
    atomikosDataSource.setDefaultIsolationLevel(Connection.TRANSACTION_READ_COMMITTED);
  }

  @After
  public void tearDown() {
    atomikosDataSource.close();
  }

  @Test
  public void testConnectionReuse() throws Exception {
    atomikosTransactionManager.begin();
    try {
      try (Connection connection = atomikosDataSource.getConnection()) {
        try (PreparedStatement statement = connection.prepareStatement("SELECT 1")) {
          statement.executeQuery();
        }
      }

      try (Connection connection = atomikosDataSource.getConnection()) {
        try (PreparedStatement statement = connection.prepareStatement("SELECT 1")) {
          statement.executeQuery();
        }
      }
    } finally {
      atomikosTransactionManager.rollback();
    }
  }

This results in the following warning and the then exception that fails the test

13:15:09,416 WARN  [com.atomikos.jdbc.internal.JdbcConnectionProxyHelper] (main) cannot set isolation level to 2
org.postgresql.util.PSQLException: Cannot change transaction isolation level in the middle of a transaction.
    at org.postgresql.jdbc.PgConnection.setTransactionIsolation(PgConnection.java:928)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.postgresql.ds.PGPooledConnection$ConnectionHandler.invoke(PGPooledConnection.java:337)
    at com.sun.proxy.$Proxy8.setTransactionIsolation(Unknown Source)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.postgresql.xa.PGXAConnection$ConnectionHandler.invoke(PGXAConnection.java:148)
    at com.sun.proxy.$Proxy8.setTransactionIsolation(Unknown Source)
    at com.atomikos.jdbc.internal.JdbcConnectionProxyHelper.setIsolationLevel(JdbcConnectionProxyHelper.java:31)
    at com.atomikos.jdbc.internal.AtomikosXAPooledConnection.doCreateConnectionProxy(AtomikosXAPooledConnection.java:92)
    at com.atomikos.jdbc.internal.AtomikosXAPooledConnection.doCreateConnectionProxy(AtomikosXAPooledConnection.java:30)
    at com.atomikos.datasource.pool.AbstractXPooledConnection.createConnectionProxy(AbstractXPooledConnection.java:74)
    at com.atomikos.datasource.pool.ConnectionPoolWithConcurrentValidation.concurrentlyTryToRecycle(ConnectionPoolWithConcurrentValidation.java:50)
    at com.atomikos.datasource.pool.ConnectionPoolWithConcurrentValidation.recycleConnectionIfPossible(ConnectionPoolWithConcurrentValidation.java:31)
    at com.atomikos.datasource.pool.ConnectionPool.findExistingOpenConnectionForCallingThread(ConnectionPool.java:144)
    at com.atomikos.datasource.pool.ConnectionPool.borrowConnection(ConnectionPool.java:111)
    at com.atomikos.jdbc.internal.AbstractDataSourceBean.getConnection(AbstractDataSourceBean.java:349)
    at TestPostgresql.testConnectionReuse(TestPostgresql.java:60)

com.atomikos.datasource.ResourceException: XA resource 'Test Data Source': resume for XID 'XID: 31302E34342E32302E3134342E746D313634383231343130383934363030303031:31302E34342E32302E3134342E746D31' raised -3: the XA resource detected an internal error
    at com.atomikos.datasource.xa.XAResourceTransaction.resume(XAResourceTransaction.java:225)
    at com.atomikos.datasource.xa.session.BranchEnlistedStateHandler.<init>(BranchEnlistedStateHandler.java:40)
    at com.atomikos.datasource.xa.session.NotInBranchStateHandler.checkEnlistBeforeUse(NotInBranchStateHandler.java:46)
    at com.atomikos.datasource.xa.session.TransactionContext.checkEnlistBeforeUse(TransactionContext.java:58)
    at com.atomikos.datasource.xa.session.SessionHandleState.notifyBeforeUse(SessionHandleState.java:163)
    at com.atomikos.jdbc.internal.AtomikosJdbcConnectionProxy.enlist(AtomikosJdbcConnectionProxy.java:88)
    at com.atomikos.jdbc.internal.AtomikosJdbcConnectionProxy.updateTransactionContext(AtomikosJdbcConnectionProxy.java:61)
    at com.atomikos.jdbc.internal.AbstractJdbcConnectionProxy.prepareStatement(AbstractJdbcConnectionProxy.java:64)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at com.atomikos.util.DynamicProxySupport.callProxiedMethod(DynamicProxySupport.java:159)
    at com.atomikos.util.DynamicProxySupport.invoke(DynamicProxySupport.java:116)
    at com.sun.proxy.$Proxy10.prepareStatement(Unknown Source)
    at TestPostgresql.testConnectionReuse(TestPostgresql.java:61)
        ...
Caused by: org.postgresql.xa.PGXAException: Invalid protocol state requested. Attempted transaction interleaving is not supported. xid=XID: 31302E34342E32302E3134342E746D313634383231343130383934363030303031:31302E34342E32302E3134342E746D31, currentXid=null, state=IDLE, flags=2,097,152
    at org.postgresql.xa.PGXAConnection.start(PGXAConnection.java:210)
    at com.atomikos.datasource.xa.XAResourceTransaction.resume(XAResourceTransaction.java:219)
    ... 47 more

Additional context

This can be avoided with a simple check in JdbcConnectionProxyHelper to avoid setting the isolation level if it is already correct.