Re: [Log4cpp-devel] Modifying log4cpp to support realtime systems

[Konstantin L. <to....@gm...>]

S Roderick пишет:
> Actually, no. We derive from log4cpp::Category and extend it to use a  
> buffer of log4cpp::LoggingEvent entries. Attached to this buffer are  
> one or more Appender components, each of which contains an appender  
> internally. The category side is real-time, the appender side is not.  
> This is being integrated within a real-time robotics framework called  
> Orocos (http://orocos.org/). Our Category object contains a reference  
> to the real-time buffer, as well as overriding Category::callAppenders 
> () to push to the port instead of directly calling the appenders. This  
> provides the separation between the real-time and non-realtime parts  
> of the system. Orocos deals with creating the ports and associating  
> things correctly.
>
> So with the changes I'm proposing, the hiearachy maintainer needs to  
> create derived Category objects, and LoggingEvents must use a real- 
> time allocator (based on TLSF) to be useable within the real-time,  
> Category side of the system. Once everything is in the non-realtime  
> part of the system (ie within appenders and layouts), we no longer  
> care about real-time and can revert to std::string and the default  
> (very non-realtime) memory allocator.
>
> I hope this explains the situation better.
Yes. Thanx.
If I correctly understand all you wishes you need to collect and send 
all logging events into some sink in real-time manner. So base on this I 
propose next steps:
1. Create RT Category class.
2. Instruct somehow log4cpp to create RTCategory in HierarchyMaintainer .
3. Collect all events (not LogingEvents) in a rt buffer and send they 
into a sink - serialize and send to socket for example.
4. On other side of sink you may have some listener that receive, 
deserialize and invoke log4cpp with preconfigured nonrt 
categories/appenders to do real logging.

To do all this work you don't need to modify LoggingEvent, because you 
may use whatever logging event container you need in RTCategory - it is 
fully internal class in this context.

If my understanding and propositions is right we will move forward.