DO NOT REPLY [Bug 7145] New: - sql lib: empty query result cause exception and leave db connection open

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http://nagoya.apache.org/bugzilla/show_bug.cgi?id=7145

sql lib: empty query result cause exception and leave db connection open

           Summary: sql lib: empty query result cause exception and leave db
                    connection open
           Product: XalanJ2
           Version: CurrentCVS
          Platform: Other
        OS/Version: Other
            Status: NEW
          Severity: Normal
          Priority: Other
         Component: org.apache.xalan.lib.sql
        AssignedTo: xalan-dev@xml.apache.org
        ReportedBy: klemens.hemm@empolis.com


1. sql queries that produce zero output rows causes a null pointer exception if
streaming mode is active.
2. a subsequent error: the database connection isn't closed if the bug above
occurs, resulting in many open hanging database connections. It's a problem of
its own, since other bugs also can cause hanging connections.

bug 1:
around line 683 in SQLDocument.java the member variable m_LastRowIdx = -1 and
the setElementAt throws a null pointer exception if the query has produced no
result rows

       if (m_StreamingMode)
       {
         // We are at the end, so let's untie the mark
         m_nextsib.setElementAt(DTM.NULL, m_LastRowIdx);
       }

I tried the following fix and it worked, but I`m not quite sure whether this is
the correct fix
       if (m_StreamingMode && (m_LastRowIdx!=-1))

bug 2:
in the method 'query' in XConnection.java (around line 700) the following code
fragment doesn't close the connection for the null pointer exception above

   catch (Exception e)
   {
     if ((doc != null) && (mgrDefault != null))
     {
       doc.closeOnError();
       mgrDefault.release(doc, true);
     }

     if (DEBUG) System.out.println("exception in query()");
     buildErrorDocument(exprContext, e);
     return null;
   }

I added an additional
       try  {
         if (null != con) m_ConnectionPool.releaseConnectionOnError(con);
       } catch(Exception e1) { }
that solved the problem of open hanging connections.

Even if bug 1 does not occur, maybe other errors cause bug 2 to occur, resulting
in hanging connections

Klemens