[ODE] Framework for reproducing bugs

[nlin@nlin.net]

Hi,

I noticed a question earlier about a random LCP solver error which caused
things to blow up intermittently. In my engine I have a reproducible
framework built in so that I can replay any sequence of events for
debugging.

Would it be a good idea to build something like this into ODE? I.e.
if you seem to have a problematic configuration which blows up, then
you turn on some logging facility in ODE before calling any other ODE
functions. Then, every call to any ODE function is recorded (only needs
to monitor the public calls, since that is the only interface external
users have).  Add to this a "playback" facility for reading back the
stream of calls, and you have a way of reproducing any bug. (Only within
a particular ODE version, of course, since behavior may change with
releases.) Then users could say "with snapshot ode-011008 I am getting a
blowup after function call number 273 in the attached stream", and
anybody could reproduce and debug it.

-Norman