People are in general confused about the Log Service ... The Log Service does not store any logs, it just acts as a dispatcher. I understand the confusion since the Log Service is mandated to have a small buffer for the initial start up and provides an API to get the buffer.
For what you want, you should add a Log Listener with the Log Reader services. What you want is quite easy with Declarative Services. This is a component that implements your requirements :
@Component(provide = {}, immediate = true) public class Logger extends Thread
implements LogListener {
final BlockingQueue<LogEntry> queue = new ArrayBlockingQueue<LogEntry>(1000);
File root;
@Reference void setLR(LogReaderService lr) {
lr.addLogListener(this);
}
@Activate void activate(BundleContext context, Map<String,Object> props) {
if ( props.containsKey("root"))
root = new File((String) props.get("root"));
else
root = context.getDataFile("logs");
root.mkdirs();
start();
}
@Deactivate void deactivate() {
interrupt();
}
@Override public void logged(LogEntry entry) {
queue.offer(entry); // ignore full silently
}
public void run() {
while (true)
try {
LogEntry entry = queue.take();
File file = getPath(entry);
if (file.isFile()) {
long days = TimeUnit.MILLISECONDS.toDays(System.currentTimeMillis()
- file.lastModified());
if (days > 2) file.delete();
}
try (OutputStream raf = new FileOutputStream(file, true)) {
String s = String.format("%tT [%03d] %s%n", entry.getTime(), entry
.getBundle().getBundleId(), entry.getMessage());
raf.write(s.getBytes("UTF-8"));
}
} catch (InterruptedException ie) {
return;
} catch (Exception e) {
throw new RuntimeException(e);
}
}
private File getPath(LogEntry entry) {
long rollover = TimeUnit.MILLISECONDS.toDays(System.currentTimeMillis()) % 7;
String eba = "eba"; // fill in eba from entry.getBundle()?
return new File(root, "log-" + eba + "-" + rollover + ".msg");
}
}
This could of course be done a bit more efficient, but that is left as an exercise.