Wednesday, March 25, 2009

Logging & Tracing

Since I'm not at EclipseCon this week I trying to get some real work done here in Austin now that the crowds from SXSW have left town. I've been looking into the best way to build good diagnostic logging into the EDC debugger, mostly as a support tool. When people report problems that we can't reproduce we can ask them to create a log of debugger activity that can help us pinpoint the problem.

In Carbide we have a simple diagnostic log based on java.util.logging that works pretty well but then I noticed that Eclipse 3.5M6 includes a new Equinox tracing API. When your application normally keeps a log of activity it is probably best to use one of the various logging services to help manage it. But in this case I just want to be able to get more information to help debug problem situations. It looks like the new tracing API will be a nice way to do this: there is a simple way to trace function entry, exit, exceptions, and simple messages. Each trace call can be tied to a particular debug option so we should be able to turn on tracing for specific parts of the code without getting details about everything at once.

For example this traceEntry call includes the debug option for the EDC run control service and will log the properties passed in and on exit will log the new object created.

public ExecutionDMC contextAdded(Map properties) {
ThreadExecutionDMC newDMC = new ThreadExecutionDMC(this, properties);
getSession().dispatchEvent(new StartedEvent(newDMC), RunControl.this.getProperties());
EDCDebugger.getDefault().getTrace().traceExit(RUN_CONTROL_TRACE, newDMC);
return newDMC;

Eventually we'll need some UI to help people turn this on and off and maybe some tools to help them send the file or attach it to a bug.

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