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https://issues.apache.org/jira/browse/LOG4J2-555?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13917300#comment-13917300
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Ralph Goers edited comment on LOG4J2-555 at 3/2/14 6:39 AM:
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AbstractLogger is correct. Applications that invoke its methods will work
correctly. The problem here is that all the calls from a custom logger should
use the log(final Marker marker, final String fqcn, final Level level, final
Message data, final Throwable t) method of AbstractLoggerWrapper and provide
the fqcn.
I should add that at one point AbstractLogger had code similar to what you are
suggesting. It generally did not work because in most cases the application is
not calling a method in the subclass but is directly calling a method in
AbstractLogger, thus the FQCN needs to be for AbstractLogger, not the subclass.
I should also add that when AbstractLogger was first written it only had a
single abstract log method. Last year all the other log methods were added to
allow callers more flexibility to log at a specific level. We should document
that those methods are for users and should never be used by a Logger
implementation.
was (Author: ralph.go...@dslextreme.com):
AbstractLogger is correct. Applications that invoke its methods will work
correctly. The problem here is that all the calls from a custom logger should
use the log(final Marker marker, final String fqcn, final Level level, final
Message data, final Throwable t) method of AbstractLoggerWrapper and provide
the fqcn.
I should add that at one point AbstractLogger had code similar to what you are
suggesting. It generally did not work because in most cases the application is
not calling a method in the subclass but is directly calling a method in
AbstractLogger, thus the FQCN needs to be for AbstractLogger, not the subclass.
> Location-based functionality broken in AbstractLoggerWrapper subclasses
> -----------------------------------------------------------------------
>
> Key: LOG4J2-555
> URL: https://issues.apache.org/jira/browse/LOG4J2-555
> Project: Log4j 2
> Issue Type: Bug
> Components: API, Core
> Affects Versions: 2.0-rc1
> Reporter: Remko Popma
> Assignee: Remko Popma
> Fix For: 2.0-rc2
>
>
> *How to reproduce*
> * Create a custom logger that extends {{AbstractLoggerWrapper}} (or generate
> one with the tool attached to LOG4J2-519)
> * In the custom logger provide a public method that invokes the {{log(Level,
> String)}} method
> * Configure a pattern layout that uses location, like %C for the logger FQCN
> * From a sample app, call the public method on your custom logger.
> * The output will show the class name of the custom logger instead of the
> class name of the calling class in the sample application.
> *Cause*
> {{AbstractLogger}}'s FQCN field is {{static final}} and initialized to
> {{AbstractLogger.class.getName()}}. Then, in
> {{Log4jLogEvent#calcLocation()}}, when walking over the stack trace elements,
> the element _following_ the FQCN is returned. So only loggers that directly
> subclass from {{AbstractLogger}} will work correctly. Loggers that inherit
> from {{AbstractLoggerWrapper}} are two levels removed from {{AbstractLogger}}
> and the {{calcLocation()}} method will not work correctly.
> *Solution*
> I think {{AbstractLogger}}'s FQCN field should be made non-static, and
> initialized to {{getClass().getName()}} in the constructor of
> {{AbstractLogger}}. {{Log4jLogEvent#calcLocation()}} can then be modified to
> return the {{StackElement}} whose class name matches the FQCN, instead of the
> next element. Location-based functionality should then work for arbitrarily
> deep subclass hierarchies of AbstractLogger.
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