Hate to follow up on myself, but the System.setErr method reassigns the System.err
variable. This can be deduced without experimentation because the user calls the
System.err variable directly to print to the console, whatever it might be. Thus, the
reference itself must change to allow the System.err variable to point to the new
target stream.
The funny part is that the err variable is declared 'public final' in the JDK source
code. The setErr method makes a call to setErr0 which is declared as being 'native'.
It looks like the native part is circumventing the JDK restrictions. I find this quite
entertaining. Ceki
At 00:58 13.03.2001 +0100, Ceki Gülcü wrote:
>Running the risk of disappointing you here, although not full of bugs, log4j is not
>bug-free as bugs creep out regularly. They just get corrected quickly before many
>people are affected by them.
>
>The PrintStream se = System.err; LogLog.setPrintStream(see); combination is simple
>and rather bright. I initially overlooked the PrintStream se = System.err; part,
>making me think that a lot of code needed to be modified to cater for the redirected
>console case. The remedy looked worse than the illness. My fears are largely
>unfounded and the solution should work quite well if one is careful.
>
>Regards, Ceki
>
>ps: I wonder if System.err always refers to the real STDERR or if really gets
>reassigned with the setErr call. It's easy to find out...
>
>At 23:20 12.03.2001 +0000, Joseph Panico wrote:
>>Of course log4j is completely bug free, but that doesn't preclude user error. For
>instance, I neglected to add appenders in my config file (actually I intentionally
>left them out, thinking that would simply turn off logging) and then log4j went into
>an infinite loop. The setPrintStream makes sense to me.
>>
>>joe
>>
>>
>>>From: Jim Moore <[EMAIL PROTECTED]>
>>>Reply-To: "LOG4J Users Mailing List" <[EMAIL PROTECTED]>
>>>To: 'LOG4J Users Mailing List' <[EMAIL PROTECTED]>
>>>Subject: RE: diverting System.stderr/stdout into log4j
>>>Date: Mon, 12 Mar 2001 18:10:37 -0500
>>>
>>>It doesn't. I haven't worried about it, since log4j doesn't contain any
>>>bugs and therefore it would never happen... :)
>>>
>>>Probably the best way to handle it is to add a
>>>LogLog.setPrintStream(PrintStream) method, so you can do something like:
>>>
>>>// remember STDERR
>>>PrintStream se = System.err;
>>>
>>>// make sure everything sent to System.err is logged
>>>System.setErr(new PrintStream(new LoggingOutputStream(Category.getRoot(),
>>> Priority.WARN), true));
>>>
>>>// make sure everything sent to System.out is also logged
>>>System.setOut(new PrintStream(new LoggingOutputStream(Category.getRoot(),
>>> Priority.INFO), true));
>>>
>>>// prevent infinate recursion in LogLog
>>>LogLog.setPrintStream(se);
>>>
>>>
>>>I can't think of any other way to do it in the current version besides
>>>getting extremely kludgey by checking the stack to see if it's being called
>>>from LogLog and logging out the the "real" STDERR then in the
>>>LoggingOutputStream. It can be done on the theory that LogLog wouldn't be
>>>called very often, but still...
>>>
>>>-Jim Moore
>>>
>>>
>>>-----Original Message-----
>>>From: Ceki Gülcü [mailto:[EMAIL PROTECTED]]
>>>Sent: Monday, March 12, 2001 5:15 PM
>>>To: LOG4J Users Mailing List
>>>Subject: RE: diverting System.stderr/stdout into log4j
>>>
>>>
>>>Jim, Joseph,
>>>
>>>Here is a link containing Jim's code:
>>>
>>>http://marc.theaimsgroup.com/?l=log4j-user&m=98097669218571&w=2
>>>
>>>How does this code handle the infinite recursion problem mentioned by
>>>Joseph? Ceki
>>>
>>>At 17:03 12.03.2001 -0500, Jim Moore wrote:
>>>>Go to the mailing list archives (theAimsGroup.com is the best) and search
>>>>for the thread with the subject of "Capturing System.err"
>>>>
>>>>-Jim Moore
>>>>"I think so, Brain; but if we gave peas a chance, won't the lima beans get
>>>>jealous?" - Pinky
>>>>
>>>>
>>>>-----Original Message-----
>>>>From: Joseph Panico [mailto:[EMAIL PROTECTED]]
>>>>Sent: Monday, March 12, 2001 4:43 PM
>>>>To: [EMAIL PROTECTED]
>>>>Subject: diverting System.stderr/stdout into log4j
>>>>
>>>>
>>>>Folks,
>>>>
>>>>We use a number of third-party packages that do stderr.print... at various
>>>>random places in their code. I'm finding it quite useful to divert these
>>>>messages into our log4j heirarchy. I do this by replacing stderr/stdout
>>>with
>>>>
>>>>my own PrintStreams that log the lines to a special log4j Category-- as
>>>>suggested on this list a while back. The only fly-in-the-ointment with this
>>>
>>>>scheme is LogLog. If there is a problem with log4j such that it cannot log
>>>>for some reason, then log4j internals use LogLog to attempt to print an
>>>>error message. This obviously leads to an infinite recursion. Has anyone
>>>>else been bothered by this? Would it make sense to add interface to LogLog
>>>>which would set the PrintStream it uses to log its error messages to?
>>>>
>>>>thanks for any ideas
>>>>
>>>>joe
>>>
>>>I hope to see you at my ApacheCon 2001 presentation
>>>entitled "Log4j, A Logging Package for Java".
>>>
>>>See http://ApacheCon.Com/2001/US/ for more details.
>>>
>>>----
>>>Ceki Gülcü Web: http://qos.ch
>>>av. de Rumine 5 email: [EMAIL PROTECTED] (preferred)
>>>CH-1005 Lausanne [EMAIL PROTECTED]
>>>Switzerland Tel: ++41 21 351 23 15
>>>
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>>>To unsubscribe, e-mail: [EMAIL PROTECTED]
>>>For additional commands, e-mail: [EMAIL PROTECTED]
>>
>>_________________________________________________________________
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>
>
>I hope to see you at my ApacheCon 2001 presentation
>entitled "Log4j, A Logging Package for Java".
>
>See http://ApacheCon.Com/2001/US/ for more details.
>
>----
>Ceki Gülcü Web: http://qos.ch
>av. de Rumine 5 email: [EMAIL PROTECTED] (preferred)
>CH-1005 Lausanne [EMAIL PROTECTED]
>Switzerland Tel: ++41 21 351 23 15
>
>
>---------------------------------------------------------------------
>To unsubscribe, e-mail: [EMAIL PROTECTED]
>For additional commands, e-mail: [EMAIL PROTECTED]
I hope to see you at my ApacheCon 2001 presentation
entitled "Log4j, A Logging Package for Java".
See http://ApacheCon.Com/2001/US/ for more details.
----
Ceki Gülcü Web: http://qos.ch
av. de Rumine 5 email: [EMAIL PROTECTED] (preferred)
CH-1005 Lausanne [EMAIL PROTECTED]
Switzerland Tel: ++41 21 351 23 15
---------------------------------------------------------------------
To unsubscribe, e-mail: [EMAIL PROTECTED]
For additional commands, e-mail: [EMAIL PROTECTED]
