Transactions should be committed before restoring the transaction isolation level in `restoreOriginalAtributes`

[YHaoNan]

Quartz Version: 2.3.2
Database Version: KingbaseES V009R001C001B0030 on x86_64-pc-linux-gnu, compiled by gcc (GCC) 4.8.5 20150623 (Red Hat 4.8.5-28), 64-bit (Based PGSql)

java.sql.Connection.setTransactionIsolation documentation says:

Note: If this method is called during a transaction, the result is implementation-defined.

In AttributeRestoringConnectionInvocationHandler, you call setTransactionIsolation before you commit / rollback the transaction. So the result is non-determined.

/**
 * Attempts to restore the auto commit and transaction isolation connection
 * attributes of the wrapped connection to their original values (if they
 * were overwritten).
 */
public void restoreOriginalAtributes() {
    try {
        if (overwroteOriginalAutoCommitValue) {
            conn.setAutoCommit(originalAutoCommitValue);
        }
    } catch (Throwable t) {
        getLog().warn("Failed restore connection's original auto commit setting.", t);
    }
    
    try {    
        if (overwroteOriginalTxIsolationValue) {
            conn.setTransactionIsolation(originalTxIsolationValue);
        }
    } catch (Throwable t) {
        getLog().warn("Failed restore connection's original transaction isolation setting.", t);
    }
}

In Kingbase, following exception will raised:

com.kingbase8.util.KSQLException: Cannot change transaction isolation lev in the middle of a transaction.

RISK:

1. Polluting connections in the shared connection pool(because failed of restore).

   But i think one (who share the same connection pool with you) can not assume anything about the connections in pool.

2. I don't know if can cause starvation of other lock competitors(because not commit the transaction)