import java.sql.SQLException;
import java.sql.CallableStatement;
import java.sql.Connection;
import java.sql.DriverManager;

public class JdbcCancelTest {
    
    Connection c;
    CallableStatement st;
    
    static final String PG_ERR_QUERY_CANCELLED = "57014";
            
    class Waiter extends Thread {
        @Override
        public void run() {
            try {
                st = c.prepareCall("SELECT pg_advisory_lock(1);");
                System.out.println("[Waiter] Sending query...");
                st.execute();
                System.out.println("[Waiter] Query finished OK");
            } catch (SQLException ex) {
                if (ex.getSQLState().equals(PG_ERR_QUERY_CANCELLED)) {
                    System.out.println("[Waiter] Query cancelled successfully");
                } else {  
                    System.out.println("[Waiter] DB error string: " + ex.getMessage() + " (SQLState: " + ex.getSQLState() + ")");
                }
            }
        }
    }
    
    class Killer extends Thread {
        @Override
        public void run() {
            try {
                System.out.println("[Killer] Cancelling query...");
                st.cancel();
                System.out.println("[Killer] Query cancel sent");
            } catch (SQLException ex) {
                System.out.println("[Killer] Unexpected exception: " + ex);
            }
        }
    }
    
    void runtest() throws InterruptedException {
        try {
            c = DriverManager.getConnection("jdbc:postgresql://localhost:5432/DBNAME?user=USERNAME&password=PASSWORD");
            Waiter w = new Waiter();
            Killer k = new Killer();
            w.start();
            Thread.sleep(10000);
            k.start();
        } catch ( SQLException ex ) {
            System.out.println(ex);
        }
    }
    
    public static void main(String[] args) throws ClassNotFoundException, InterruptedException {
        Class.forName("org.postgresql.Driver");
        JdbcCancelTest t = new JdbcCancelTest();
        t.runtest();
    }
}