get # of response bytes sent for large/streaming content?

[Jeff Ambrosino]

I'm running a mod_perl cleanup handler from a reverse proxy ($r->pool->cleanup_register), and
I need to know the total # of bytes sent in a response so I can store this info in a database.
A real-world example would be the end user (browser) streaming a Quicktime movie, and I want
to know how long this took, measured in bytes.  Note the connection might be aborted at any
time, so the number may vary.  Apache already logs this info (transfer log), so
it must be available, but how do I get at this information programmatically? FYI I'm running
mod_perl 1.99_16 on Apache 2.0.54...

thanks
JB