[slf4j-user] Configuration properties within logger context

[ceki]

Hi Daniel,

You can obtain the LoggerContext via SLF4J's logger factory. Here is the 
code.

  LoggerContext lc = (LoggerContext) LoggerFactory.getILoggerFactory();

Once you have the LoggerContext you can retrieve its properties. If this 
is not an option, as of logback 1.0.0, properties are scoped. Properties 
can be in local scope, context scope and in system scope.
See [1].

In a logback.xml config file, you can define a property in system scope 
as follows:

<configuration>
  <property scope="system" name="worker.interval" value="101" />
  ...
</configuration>

The system property can be retrieved in the usual way:

   String workerIntervalAsStr = System.getProperty("worker.interval");


HTH,

-- 
Ceki
http://twitter.com/#!/ceki

[1] http://logback.qos.ch/manual/configuration.html#variableSubstitution


On 10.02.2012 16:49, Daniel Ferber wrote:
> Hi Ceki,
>
> Sorry I was not able to explain my intention. Here is an example.
>
> A worker class iterates over data until a result is found. The worker
> allows to register a callback that executes nextIteration() on each
> iteration. The callback logs some properties that describe the progress
> of the worker. But writes log only on every “interval” calls, to prevent
> cluttering the log, since the worker will execute a million of iterations.
>
>
> Worker w = new Worker().
> w.addCallback(new ContinuousCallback()) {
>
> int counter= 0;
>
> void nextIteration() {
>
> int interval = Integer.parseInt(logger.getProperty(“worker.interval”));
>
> if (logger.isInforEnabled() && counter++ % interval == 0) {
>
> // collect attributesArray
>
> logger.info <http://logger.info>(“i={}, convergence={}, ... ",
> attributesArray) ;
>
> }
>
> }
> }
>
> I would like to get the “interval” from the log configuration (eg, for
> logback):
>
> <configuration>
>
> <property name=“worker.interval” value=“100” />
>
> <logger name="callback" level="INFO" />
>
> </configuration>
>
> I think that “interval” is a property that controls how data is logged
> and I think it would be more elegant being able to set the property
> together with the logger configuration.
>
> There seems that I can get properties from a LoggerContext withing
> logback, but I understand that slf4j does not exposes this context.
>
> Best regards,
>
> Daniel Felix Ferber
>
>
> 2012/2/9 ceki <ceki at qos.ch <mailto:ceki at qos.ch>>
>
>
>     Hi Daniel,
>
>     I don't follow you. Could you provide an *example* of what you have
>     in mind (assume you have complete liberty with the SLF4J API) ?
>
>     --
>     Ceki
>     http://twitter.com/#!/ceki <http://twitter.com/#%21/ceki>
>
>
>     On 09.02.2012 14:45, Daniel Felix Ferber wrote:
>
>         Hi all,
>
>         I was wondering about slf4j being able to get properties defined
>         within the
>         configuration file form the logger framework (eg logback or
>         log4j). Would that
>         be a reasonable use for slf4j?
>
>         1) I would configure the granularity (amount of content) of a
>         log message that
>         reports the result of a long-running execution.
>
>         2) Also, I would configure the number of step between two log
>         messages on a
>         long-running task.
>
>         For the first case, I could define several loggers (a simple
>         one, a detailed
>         one). I don't think I should use two levels, since the report
>         cannot be
>         considered 'info', not 'debug' or 'trace'.
>
>         For the second case, I am not sure how to handle it. Currently
>         the application
>         has a configuration property that defines how log will behave
>         (number of steps,
>         amount of details). But taking it rigorously, these are not
>         application
>         configuration, but logger configuration.
>
>         Best regards,
>         Daniel Felix Ferber
>