[
Date Prev][
Date Next][
Thread Prev][
Thread Next][
Date Index][
Thread Index]
[
List Home]
|
Re: [aspectj-users] general tracing aspect
|
> > To stop the overhead of getLog() on every invocation, lazt init the Logs
> > into a Map held as an instance variable in the aspect and
> > keyed on the Class retrieved from sig.getDeclaringType().
One way to avoid the per-class Map lookup for the logger when you have an
instance of the class being logged is to cache a reference to the logger in each
instance. This trades space for time and works regardless of the per-class
logging implementation.
Wes
--------- MainLogging.java
package log;
import runtimeModel.Main; // use your own target here
/**
* Example of applying logging aspect
*/
public aspect MainLogging extends Logging {
declare parents: Main implements Loggable;
// alternatively...
declare parents: com.bigco.gui..* implements Loggable;
pointcut logPoints(Loggable me) : anyMethod(me);
}
--------- Logging.java
package log;
import java.util.Hashtable;
/**
* Logging aspect allows concrete implementation to select
* or define pointcuts, so long as it surfaces an instance.
*/
public abstract aspect Logging {
protected interface Loggable{}
private final Logger Loggable.logger
= Logger.getLogger(getClass());
abstract pointcut logPoints(Loggable me);
// alternate implementations
pointcut anyMethod(Loggable me) :
execution(* Loggable+.*(..)) && this(me);
pointcut anyPublicMethod(Loggable me) :
execution(public * Loggable+.*(..)) && this(me);
// more implementations...
before(Loggable me) : logPoints(me) {
me.logger.log("before " + thisJoinPoint);
}
after (Loggable me) returning: logPoints(me) {
me.logger.log(" after " + thisJoinPoint);
}
}
// Sample implementation, just to make this compile
class Logger {
static Hashtable loggers = new Hashtable();
public static Logger getLogger(Class c) {
Logger result = (Logger) loggers.get(c);
if (null == result) {
result = new Logger(c);
loggers.put(c, result);
}
return result;
}
final String className;
private Logger(Class c) {
className = c.getName();
}
public void log(String s) {
System.out.println(className + ": " + s);
}
}
Marc Tremblay wrote:
>
> FYI:
>
> >From looking at the source code for the Jakarta Commons logging project,
> it looks like the Logs are already cached in a Map by LogFactory, so in
> that case the only overhead is the actual call to getLog(...)
>
> Log4j on the other hand, appears to do considerably more work to
> retrieve a logger. Fortunately, the Jakarta Commons logging project can
> be used as a wrapper for Log4j and do this caching for us.
>
> So if your aspect will assume it's using the Jakarta Commons logging,
> there's maybe not much point to complicate it's code by adding another
> layer of caching.
>
> -- Marc
>
> On Wed, 2003-04-23 at 08:17, Jon Cundill wrote:
> > Hi,
> >
> > we use something like
> >
> > public static void traceEntry(Signature sig) {
> > Log log = LogFactory.getLog( sig.getDeclaringType() );
> > if( log.isDebugEnabled() )
> > {
> > log.debug( "ENTERED " + sig.getName());
> > }
> > }
> >
> > This is for jakarta commons logging, but I would think plain Log4j would
> > work similarly.
> > To stop the overhead of getLog() on every invocation, lazt init the Logs
> > into a Map held as an instance variable in the aspect and
> > keyed on the Class retrieved from sig.getDeclaringType().
> >
> > Jon
> >
> > -----Original Message-----
> > From: aspectj-users-admin@xxxxxxxxxxx
> > [mailto:aspectj-users-admin@xxxxxxxxxxx]On Behalf Of Nuno Oliveira
> > Sent: 23 April 2003 14:50
> > To: rhill@xxxxxxxxxx
> > Cc: aspectj-users@xxxxxxxxxxx
> > Subject: RE: [aspectj-users] general tracing aspect
> >
> >
> > Your reply was most welcome! thanks :)
> >
> > The solution you provided solves the problem of the class name to use in
> > advice but doesn't comply with my whish to have a single Logger instance per
> > class. This way every class will be logging to the same logger (the defined
> > one). What I would need would be a way to create a static logger instance
> > per-class using a type patern instead of a specific Type or a way to specify
> > that the logging is to take place in the logger variable that each class
> > already has.
> >
> > Thanks again.
> > Nuno
> >
> > -----Original Message-----
> > From: Gilles DODINET [mailto:rhill@xxxxxxxxxx]
> > Sent: Wednesday, April 23, 2003 1:20 PM
> > To: Nuno Oliveira
> > Subject: Re: [aspectj-users] general tracing aspect
> >
> >
> > what about something like
> >
> > interface Loggable {}
> > declare parent : my.package.* implements Loggable;
> >
> > //init logger as soon as possible (<init> ? <clinit> ?)
> > private Logger Loggable.anotherLogger;
> >
> > pointcut method(Loggable o) :
> > within(Loggable+)
> > && execution(* *(..))
> > && this(o);
> >
> > before(Loggable o): method(o)
> > {
> > o.anotherLogger.enter(
> >
> > thisJoinPointStaticPart.getSignature().getName() ,
> > thisJoinPoint.getArgs());
> > }
> >
> > i have not tested it, tho i think that it should work, with quite little
> > modifications. please provide me with some feedbacks :)
> >
> > -- gd
> >
> >
> > > Message du 23/04/03 12:40
> > > De : Nuno Oliveira <noliveira@xxxxxx>
> > > A : aspectj-users@xxxxxxxxxxx
> > > Copie à :
> > > Objet : [aspectj-users] general tracing aspect
> > > Hello all,
> > >
> > > I have a bunch of classes each with its own static instance of a log4j
> > > logger. This instances all have the same name 'logger'. I want to add
> > > enter-leave tracing to each of the methods of all classes but would be
> > > interested in making this with a single aspect. However I'm having trouble
> > > with the sintax to refer to the logger in my advice, without using the
> > class
> > > name -which would defeat the purpose. I cannot use type patterns in
> > advice,
> > > rigth ? Can anyone provide any hints ? Using aspectJ, a sintatically wrong
> > > expression of my needs would be:
> > >
> > > package my.package;
> > >
> > > privileged aspect TraceEnterLeave
> > > {
> > > pointcut method(): within(my.package..*) && execution(* *(..));
> > >
> > > before(): method()
> > > {
> > >
> > >
> > (my.package..*).logger.enter(thisJoinPointStaticPart.getSignature().getName(
> > > ) ,
> > > thisJoinPoint.getArgs());
> > > }
> > >
> > > after() returning(Object o): method()
> > > {
> > >
> > >
> > (my.package..*).logger.leave(thisJoinPointStaticPart.getSignature().getName(
> > > ), o);
> > > }
> > > }
> > >
> > > A related question would be how to migrate the static logger declaration
> > in
> > > each class to that tracing aspect ? Could I use a type pattern to get the
> > > class name to instatiate each logger ?
> > >
> > > Thanks in advance.
> > >
> > > Nuno
> > >
> > > _______________________________________________
> > > aspectj-users mailing list
> > > aspectj-users@xxxxxxxxxxx
> > > http://dev.eclipse.org/mailman/listinfo/aspectj-users
> > >
> > _______________________________________________
> > aspectj-users mailing list
> > aspectj-users@xxxxxxxxxxx
> > http://dev.eclipse.org/mailman/listinfo/aspectj-users
> >
> > _______________________________________________
> > aspectj-users mailing list
> > aspectj-users@xxxxxxxxxxx
> > http://dev.eclipse.org/mailman/listinfo/aspectj-users
> _______________________________________________
> aspectj-users mailing list
> aspectj-users@xxxxxxxxxxx
> http://dev.eclipse.org/mailman/listinfo/aspectj-users
