Hi,
as with R7 the LogService is deprecated and instead the LoggerFactory should be
used, I wanted to start integrating the LoggerFactory in the Eclipse Platform.
But there is not much information about how the usage should be.
>From what I understand so far, the idea is similar to SLF4J that a Logger
>instance is created via LoggerFactory. The Logger provides API for logging
>similar to SLF4J, even with placeholder parameters and exception logging (I
>like that pretty much).
But there is one thing I am not sure if I understand everything correctly. With
SLF4J the LoggerFactory is static and the best practice is to create one Logger
instance per class by using the LoggerFactory on a static field. This is done
to reduce the needed amount of memory for cases where a lot of instances are
created of a type. With OSGi R7 the LoggerFactory is a service and not a static
helper class. So for DS I need to specify a reference. But actually I don't
want the LoggerFactory, I want a Logger. And I don't want to create a Logger
instance per log statement. I therefore thought of the following pattern for
getting an OSGi Logger in my component:
@Component
public class StringInverterImpl implements StringInverter {
private Logger logger;
@Override
public String invert(String input) {
logger.info("received {} to invert", input);
return new StringBuilder(input).reverse().toString();
}
@Reference
void setLoggerFactory(LoggerFactory factory) {
this.logger = factory.getLogger(getClass());
}
}
So I have a mandatory reference to LoggerFactory, and once the reference is
set, I use it to get the Logger instance. Since the reference is static and
mandatory I don't need to take care if the LoggerFactory comes and goes at
runtime. And as the service instance typically only exists once, there is also
no memory overhead with this. For multi-instance components created by a
factory, this could even have the advantage to create a Logger with a name that
corresponds to the instance. Which would in turn make the log outputs more
speaking in terms of knowing which component instance created the log output.
Would this be the recommended way of using logging in R7? Are my observations
correct or do I misunderstand something?
I would be happy to even write a small blog post about that topic if nobody
else is currently writing something with regards to logging in R7.
Mit freundlichen Grüßen / Best regards
Dirk Fauth
Automotive Service Solutions, ESI application (AA-AS/EIS2-EU)
Robert Bosch GmbH | Postfach 11 29 | 73201 Plochingen | GERMANY |
www.bosch.com<http://www.bosch.com>
Tel. +49 7153 666-1155 | [email protected]<mailto:[email protected]>
Sitz: Stuttgart, Registergericht: Amtsgericht Stuttgart, HRB 14000;
Aufsichtsratsvorsitzender: Franz Fehrenbach; Geschäftsführung: Dr. Volkmar
Denner,
Prof. Dr. Stefan Asenkerschbaumer, Dr. Rolf Bulander, Dr. Stefan Hartung, Dr.
Markus Heyn, Dr. Dirk Hoheisel,
Christoph Kübel, Uwe Raschke, Peter Tyroller
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