On 9/6/13 5:35 AM, Bergquist, Brett wrote:
I finally broke down and wrote RollingFileStream which provides (and borrows) most of the
functionality of java.logger.FileHandler to provide a rolling file stream. Having derby.log grow
forever on long running systems is just not acceptable anymore ;) Realistically, I would like to
provide this back to the derby community somehow as I found many requests for such a feature while
searching and many references to using "derby.stream.error.method" or
"derby.stream.error.field", but no good implementation of such.
I built a DerbyUtil.jar which the class along with a configurator class which can read a
"derbylog.properties" file for configuration information. I would like to locate this file at the
same place as "derby.properties" so the configurator needs to find out what
"derby.system.home" is set to. Because of the default security policy installed by the network
server and because my DerbyUtil.jar is separate, it cannot access the property. Create and installing my
own security policy is also a bit of a pain as the network server is started by Glassfish and there really is
not much opportunity to pass startup parameters.
So is there someway to locate the location that "derby.ssystem.home" is pointing to in
my class that is being invoke by "derby.stream.error.field"?
How about a proposal that "derby.stream.error.field" can point to a static method that
can take 0 or 1 parameters and if one parameter, it is passed the value of
"derby.system.home" as a String. This seems to be a simple change and could easily be
accommodated by first using reflection to find the method that takes 0 parameters and if not found,
retry with finding the method that takes one string parameter?
Brett
Hi Brett,
You could use
org.apache.derby.iapi.services.property.PropertyUtil.getSystemProperty()
to get the value of derby.system.home. That method will wrap the call to
System.getProperty() in a privileged block which runs with the
privileges granted to the Derby engine jar. PropertyUtil isn't part of
the Derby public api so this isn't technically a supported approach and
we reserve the right to change the behavior of that class. However, that
class doesn't change much so you can probably get away with this. At
the end of this message there's an example dummy error logger which uses
PropertyUtil to lookup the value of derby.system.home. To test this out,
boot the network server with this setting:
-Dderby.stream.error.field=DummyErrorLogger.DEL
Hope this helps,
-Rick
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.Writer;
import org.apache.derby.iapi.services.property.PropertyUtil;
public class DummyErrorLogger extends OutputStreamWriter
{
public static final Writer DEL = makeErrorLogger();
public DummyErrorLogger( OutputStream os )
{
super( os );
}
private static DummyErrorLogger makeErrorLogger()
{
System.out.println( "Making the error logger..." );
String derbySystemHome = PropertyUtil.getSystemProperty(
"derby.system.home" );
System.out.println( "derbySystemHome = " + derbySystemHome );
return new DummyErrorLogger( System.out );
}
}
