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List:       log4j-dev
Subject:    RE: For Ceki: Problem working with SMTPAppender
From:       Ceki Gulcu <ceki_gulcu () yahoo ! com>
Date:       2001-12-05 8:32:00
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Max,

Thank you for bug report and related discussion. The
SMTPAppender.append method is called by
AppenderSkeleton.doAppend method which has the
if(closed) check. Your additional check is not
necesserary.

Regarding appender=null. I don't see the point of
setting a method parameter to null. Unless I am
missing an important point in which case I apologize,
your logic is flawed.  Please supply a small program
to illustrate the bug you have identified as I don't
see a bug. Regards, Ceki

--- Max Stolyarov <MStolyarov@Novarra.com> wrote:
> Ceki,
> 
>    Thanks for responding to my e-mail. I did some
> more checking and I think
> that AppenderAttachableImpl class and SMPTAppender
> class both share the
> blame for what was happening. Below is the code that
> I modified for the
> SMPTAppender class's append() method and
> checkEntryConditions() method:
> 
>   /**
>      Perform SMTPAppender specific appending
> actions, mainly adding
>      the event to a cyclic buffer and checking if
> the event triggers
>      an e-mail to be sent. */
>   public
>   void append(LoggingEvent event) {
> 
>     // MAX: Modified checkEntryCondition() method to
> return false if this
>     // appender is closed
>     if(!checkEntryConditions()) {
>       return;
>     }
> 
>     event.getThreadName();
>     event.getNDC();
>     if(locationInfo) {
>       event.setLocationInformation();
>     }
>     cb.add(event);
>     if(evaluator.isTriggeringEvent(event)) {
>       sendBuffer();
>     }
>   }
> 
>  /**
>      This method determines if there is a sense in
> attempting to append.
> 
>      <p>It checks whether there is a set output
> target and also if
>      there is a set layout. If these checks fail,
> then the boolean
>      value <code>false</code> is returned. */
>   protected
>   boolean checkEntryConditions() {
> 
>     // MAX: Added to prevent events from being send
> if this appender was
>     // closed
>     if(this.closed)
>         return false;
> 
>     if(this.msg == null) {
>       errorHandler.error("Message object not
> configured.");
>       return false;
>     }
> 
>     if(this.evaluator == null) {
>       errorHandler.error("No
> TriggeringEventEvaluator is set for appender
> ["+
> 			 name+"].");
>       return false;
>     }
> 
> The original code for checkEntryConditions() did not
> check whether or not
> the appender in question was closed or not and
> therefore did not return
> false in the case when the appender was closed; I
> added this check. Also,
> the append() method never properly acted to the
> condition when
> checkEntryConditions() returned false. The original
> code simple displayed
> the message, but never terminated the call to this
> method by returning from
> it; I also added this condition.
> 
> Finally, appending message to any appender that was
> closed and removed from
> the Appender Vector should also fail because the
> appender should no longer
> exist. But what I found was that in the code of 
> 
>  <AppenderAttachableImpl.java>
> 
>   public
>   void removeAppender(Appender appender) {
>     if(appender == null || appenderList == null) 
>       return;
>     appenderList.removeElement(appender);
> 
>     // MAX: When appender is removed from the
> appenderList, it is just
> removed
>     // from the Vector, but is not dereferenced. We
> will dereference it by
>     // setting it to null
>     appender=null;
>   }
> 
> appender that was removed from appenderList was
> never dereferences, it was
> never set to NULL. Therefore, if application already
> had a reference to this
> appender, it did not matter if it was removed from
> the list when it came to
> sending and processing events; messages were still
> send when appender was
> closed and removed from the appender list. So, what
> I did I set appender
> that was just removed to NULL (this also can be done
> inside the
> removeElement(appender) method called just above my
> statement). When I did
> that I was no longer able to send events using
> appender that was removed by
> closing.  
> 
> 
> On the other hand, Ceki, can you please tell me if
> my logic was correct or
> if I should have done anything different to resolve
> the problem. If you feel
> that I did things properly, can you please tell me
> what do I need to do to
> submit this as a bug so it can be modified for
> others in future releases of
> log4j. Thanks
> 
> Max
> 
> -----Original Message-----
> From: Ceki Gulcu [mailto:ceki@qos.ch]
> Sent: Saturday, December 01, 2001 4:30 AM
> To: Log4J Developers List
> Subject: Re: For Ceki: Problem working with
> SMTPAppender
> 
> 
> 
> Max,
> 
> Any appender extending AppenderSkeleton will refuse
> to log after its close
> method is called. SMTPAppender falls into this case.
> In any case, you should
> remove the appender that was closed. Are you
> absolutely sure that the close
> method of SMTPAppender was called? I suggest you
> insert a System.out.println
> in SMTPAppender.close to make sure it is called on
> the right appender.
> 
> By the way, what were the modifications that solved
> the problem? 
> 
> With regards to the new version of log4j, I don't
> think upgrading to log4j
> 1.2 will not solve the SMTPAppender issue. On the
> other hand, unless you
> extended the Category class, you can consider
> version 1.2 as a drop in
> replacement for 1.1.3. Just try it... 
> 
> Regards, Ceki
> 
> 
> 
> At 17:27 30.11.2001 -0600, you wrote:
> >Hi Ceki,
> >
> >  After reading number of messages on this
> developer forum, I can see that
> >you are the person who may be able to help me. In
> my application I am using
> >SMTPAppender to send log events to my e-mail
> address when something
> happens.
> >I use management interface to create and remove
> SMTPAppenders, based on
> >their name and other parameters, such as filter
> specifications. What I
> >resently noticed was that if I remove SMTPAppender
> try to generate dummy
> >alerts, I am still receiving e-mail messages. It
> seems like SMTPAppender is
> >still active after I explicetly closed it. Also, if
> I would create another
> >appender with the same name and try to generate
> more log events, I now
> >receive two e-mails for each log event generate. 
> >
> >In trying to resolve this problem I went and
> modified SMTPAppender class
> 
=== message truncated ===


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