[FR-devel] The Debugger Project and the Databus Inspector

[Curt Hibbs]

Laurent,

I just noticed that you signed up to lead the debugger project -- great! I
wish I had the bandwidth to have signed up for it as I've always found
debugging tools a lot of fun to create.

Anyway, I wanted to pass on an idea for something that we could use right
away, a Databus-Inspector. Since just about everything in FreeRIDE will flow
through the databus, understanding what's going on (when debugging) usually
means understanding the current and changing state of the databus.

I originally conceived of the databus concept when designing an Java
application framework for a past project. Once we implemented a databus
inspector, it was like we had been working in the dark and someone finally
turned on the lights! It decreased out debug time dramatically.

Below are some notes on this that I sent Rich a few days ago. Let me know
what you think.

I've attached a pdf file containing a short description of my Java version
of the databus inspector. (Contrary to what I said in my email to Rich, this
databus inspector actually maintained two past snapshots, and displayed
change slots as bright-red=recent; maroon=less-recent; black=unchanged.)

Curt


-----Original Message-----
From: Curt Hibbs [mailto:address@hidden
Sent: Monday, January 28, 2002 12:54 PM
To: Rich Kilmer
Cc: Curt Hibbs
Subject: Databus Inspector


Sometime real-soon-now we're going to need a visual databus inspector of
sorts. Its the kind of thing that can grow into a really useful debugging
aid, but it can start off pretty simple and still be useful.

The Java version that I had displayed a "snapshot" of the databus in a tree
widget. I used a snapshot instead of a real-time display to avoid the
problem  of the bus changing while you were trying look at it. The snapshot
could be refreshed manually or every "n" seconds (user specifiable).

Another advantage to using a snapshot, is that the inspector (we called it
the databus spy -- named after WinSpy) is that it knows what has changed
since the last snapshot (changed: current-slot != snapshot-slot). We
displayed changed slots in red and non-changed slots in black -- a very
useful feature.

Anyway, just wanted to capture this while I was thinking about it.

Curt

zspy.pdf
Description: Adobe PDF document