On Dec 9, 2008, at 4:58 AM, Thorbjørn Ravn Andersen wrote:
There was a request recently to make the argument replacement
mechanism more powerful in either slf4j or logback (cannot remember)
where Ceki mentioned that one of the major benefits of the {}-
approach was that it was measurably faster than the StringFormatter
in Java.
For this particular purpose I suggest that the fastest approach is
chosen as it will apply to all events actually processed. Would
lifting the slf4j code into log4j be an option - I believe that the
license allows it.
There are two formatters in the Java API, java.text.MessageFormat
(since JDK 1) and java.util.Formatter (since JDK 5). The SLF4J format
specifier resembles, but is incompatible with, the format specifier of
java.text.MessageFormat.
Actually the SLF4J formatting code (as far as I can tell) was
originally written as part of log4j 1.3 and already is used in LogSF
in the extras companion. LogMF provides the same services but uses
java.text.MessageFormat format specifiers. While these were in the
sandbox, there was a LogF which provided the same services using the
java.util.Formatter, however their wasn't sufficient demand to polish
that up for release. Still very doable.
LogMF and LogSF provided highly optimized message parameterization
compatible with log4j 1.2.8 and later. Keeping message formatting
distinct from the logger class allows supporting different formatters.
The supposed performance benefit of the SLF4J formatter over the
java.text.MessageFormat only occurs when you compare the performance
against naive use of java.text.MessageFormat. LogMF handles the
simplest pattern specifications (those just involving {0}, {1}, etc)
internally and only delegates to java.text.MessageFormat for more
complex pattern specifications, resulting in equivalent performance to
the SLF4J formatter on functionally equivalent format specifiers while
still supporting the full java.text.MessageFormat capabilities.
This very early thread on slf4j-dev (http://marc.info/?l=slf4j-dev&m=112327572703543&w=2
) discussed the potential use of java.text.MessageFormat pattern
specifiers long before SLF4J was frozen.
---------------------------------------------------------------------
To unsubscribe, e-mail: [EMAIL PROTECTED]
For additional commands, e-mail: [EMAIL PROTECTED]
