entrusc / slf4j-osgi Goto Github PK

It's possible if a LogService bundle is swapped that in the typical usage of a slf4j logger, the logging for the class may stop working until the bundle is restarted. Below would be the example

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class MyClass {
  private Logger logger = LoggerFactory.getLogger(MyClass.class);

  public void doSomething() {
    logger.trace("MyClass.doSomething");
  }
}

As you can see, there's a single call to the LoggerFactory which will return the instance available at that point. Assuming there is a LogService available, the value will be initialized to the current OSGiLogger. If the LogService goes away an EmptyLogger will be set as the current Logger in the LogFactory, but that won't update the references to the OSGiLogger that all the classes which asked the LogFactory have. The original implementation that this one is based on always returned the same log factory and within that log factory handled the change.

To update this version, a similar mechanism should be used (ie, an OSGiLogger which is updated with the current service reference whenever it changes, and can handle having a null service reference. Alternatively some form of a proxy object could be returned and the object that proxy wraps could be updated as needed.